Lefun: Add command serializers

app/src/main/java/nodomain/freeyourgadget/gadgetbridge/devices/lefun/LefunConstants.java

@@ -23,9 +23,52 @@ import java.util.UUID;
 import static nodomain.freeyourgadget.gadgetbridge.service.btle.AbstractBTLEDeviceSupport.BASE_UUID;
 
 public class LefunConstants {
+    // BLE UUIDs
     public static final UUID UUID_SERVICE_LEFUN = UUID.fromString(String.format(BASE_UUID, "18D0"));
 
+    // Coordinator constants
     public static final String ADVERTISEMENT_NAME = "Lefun";
     public static final String MANUFACTURER_NAME = "Teng Jin Da";
     public static int NUM_ALARM_SLOTS = 5;
+
+    // Commands
+    public static final byte CMD_REQUEST_ID = (byte)0xab;
+    public static final byte CMD_RESPONSE_ID = 0x55;
+
+    public static final int CMD_MAX_LENGTH = 20;
+    // 3 header bytes plus checksum
+    public static final int CMD_HEADER_LENGTH = 4;
+
+    public static final byte CMD_FIRMWARE_INFO = 0x00;
+    public static final byte CMD_BONDING_REQUEST = 0x01;
+    public static final byte CMD_SETTINGS = 0x02;
+    public static final byte CMD_BATTERY_LEVEL = 0x03;
+    public static final byte CMD_TIME = 0x04;
+    public static final byte CMD_ALARM = 0x05;
+    public static final byte CMD_PROFILE = 0x06;
+    public static final byte CMD_UI_PAGES = 0x07;
+    public static final byte CMD_FEATURES = 0x08;
+    public static final byte CMD_FIND_DEVICE = 0x09;
+    public static final byte CMD_FIND_PHONE = 0x0a;
+    public static final byte CMD_SEDENTARY_REMINDER_INTERVAL = 0x0b;
+    public static final byte CMD_HYDRATION_REMINDER_INTERVAL = 0x0c;
+    public static final byte CMD_REMOTE_CAMERA = 0x0d;
+    public static final byte CMD_REMOTE_CAMERA_TRIGGERED = 0x0e;
+    public static final byte CMD_PPG_START = 0x0f;
+    public static final byte CMD_PPG_RESULT = 0x10;
+    public static final byte CMD_PPG_DATA = 0x11;
+    public static final byte CMD_STEPS_DATA = 0x12;
+    public static final byte CMD_ACTIVITY_DATA = 0x13;
+    public static final byte CMD_SLEEP_TIME_DATA = 0x14;
+    public static final byte CMD_SLEEP_DATA = 0x15;
+    public static final byte CMD_NOTIFICATION = 0x17;
+    public static final byte CMD_LANGUAGE = 0x21;
+    public static final byte CMD_UNKNOWN_22 = 0x22;
+    public static final byte CMD_UNKNOWN_25 = 0x25;
+    public static final byte CMD_UNKNOWN_80 = (byte)0x80;
+
+    public static final int PPG_TYPE_INVALID = -1;
+    public static final int PPG_TYPE_HEART_RATE = 0;
+    public static final int PPG_TYPE_BLOOD_PRESSURE = 1;
+    public static final int PPG_TYPE_BLOOD_OXYGEN = 2;
 }

app/src/main/java/nodomain/freeyourgadget/gadgetbridge/devices/lefun/LefunFeatureSupport.java

@@ -0,0 +1,41 @@
+/*  Copyright (C) 2016-2020 Andreas Shimokawa, Carsten Pfeiffer, Daniele
+    Gobbetti
+    Copyright (C) 2020 Yukai Li
+
+    This file is part of Gadgetbridge.
+
+    Gadgetbridge is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Affero General Public License as published
+    by the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    Gadgetbridge is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Affero General Public License for more details.
+
+    You should have received a copy of the GNU Affero General Public License
+    along with this program.  If not, see <http://www.gnu.org/licenses/>. */
+package nodomain.freeyourgadget.gadgetbridge.devices.lefun;
+
+public class LefunFeatureSupport {
+    public static final int SUPPORT_HEART_RATE = 1 << 2;
+    public static final int SUPPORT_BLOOD_PRESSURE = 1 << 3;
+    public static final int SUPPORT_FAKE_ECG = 1 << 10;
+    public static final int SUPPORT_ECG = 1 << 11;
+    public static final int SUPPORT_WALLPAPER_UPLOAD = 1 << 12;
+
+    public static final int RESERVE_BLOOD_OXYGEN = 1 << 0;
+    public static final int RESERVE_CLOCK_FACE_UPLOAD = 1 << 3;
+    public static final int RESERVE_CONTACTS = 1 << 5;
+    public static final int RESERVE_WALLPAPER = 1 << 6;
+    public static final int RESERVE_REMOTE_CAMERA = 1 << 7;
+
+    public static boolean checkSupported(short deviceSupport, int featureSupport) {
+        return (deviceSupport & featureSupport) == featureSupport;
+    }
+
+    public static boolean checkNotReserved(short deviceReserve, int featureReserve) {
+        return !((deviceReserve & featureReserve) == featureReserve);
+    }
+}

app/src/main/java/nodomain/freeyourgadget/gadgetbridge/devices/lefun/commands/AlarmCommand.java

@@ -0,0 +1,174 @@
+/*  Copyright (C) 2016-2020 Andreas Shimokawa, Carsten Pfeiffer, Daniele
+    Gobbetti
+    Copyright (C) 2020 Yukai Li
+
+    This file is part of Gadgetbridge.
+
+    Gadgetbridge is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Affero General Public License as published
+    by the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    Gadgetbridge is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Affero General Public License for more details.
+
+    You should have received a copy of the GNU Affero General Public License
+    along with this program.  If not, see <http://www.gnu.org/licenses/>. */
+package nodomain.freeyourgadget.gadgetbridge.devices.lefun.commands;
+
+import java.nio.ByteBuffer;
+
+import nodomain.freeyourgadget.gadgetbridge.devices.lefun.LefunConstants;
+
+public class AlarmCommand extends BaseCommand {
+    public static final int DOW_SUNDAY = 0;
+    public static final int DOW_MONDAY = 1;
+    public static final int DOW_TUESDAY = 2;
+    public static final int DOW_WEDNESDAY = 3;
+    public static final int DOW_THURSDAY = 4;
+    public static final int DOW_FRIDAY = 5;
+    public static final int DOW_SATURDAY = 6;
+
+    private byte op;
+    private byte index;
+    private boolean enabled;
+    // Snooze is not implemented how you think it would be
+    // Number of snoozes is decremented every time the alarm triggers, and the alarm time
+    // is moved forward by number of minutes in snooze time. It never gets reset to the
+    // original time.
+    private byte numOfSnoozes;
+    private byte snoozeTime;
+    private byte dayOfWeek;
+    private byte hour;
+    private byte minute;
+
+    private boolean setSuccess;
+
+    public byte getOp() {
+        return op;
+    }
+
+    public void setOp(byte op) {
+        if (op != OP_GET && op != OP_SET)
+            throw new IllegalArgumentException("Operation must be get or set");
+        this.op = op;
+    }
+
+    public byte getIndex() {
+        return index;
+    }
+
+    public void setIndex(byte index) {
+        if (index < 0 || index >= LefunConstants.NUM_ALARM_SLOTS)
+            throw new IllegalArgumentException("Index must be between 0 and "
+                    + (LefunConstants.NUM_ALARM_SLOTS - 1) + " inclusive");
+        this.index = index;
+    }
+
+    public boolean isEnabled() {
+        return enabled;
+    }
+
+    public void setEnabled(boolean enabled) {
+        this.enabled = enabled;
+    }
+
+    public byte getNumOfSnoozes() {
+        return numOfSnoozes;
+    }
+
+    public void setNumOfSnoozes(byte numOfSnoozes) {
+        this.numOfSnoozes = numOfSnoozes;
+    }
+
+    public byte getSnoozeTime() {
+        return snoozeTime;
+    }
+
+    public void setSnoozeTime(byte snoozeTime) {
+        this.snoozeTime = snoozeTime;
+    }
+
+    public boolean getDayOfWeek(int day) {
+        if (day < 0 || day > 6)
+            throw new IllegalArgumentException("Invalid day of week");
+        return getBit(dayOfWeek, 1 << day);
+    }
+
+    public void setDayOfWeek(int day, boolean enabled) {
+        if (day < 0 || day > 6)
+            throw new IllegalArgumentException("Invalid day of week");
+        dayOfWeek = setBit(dayOfWeek, 1 << day, enabled);
+    }
+
+    public byte getHour() {
+        return hour;
+    }
+
+    public void setHour(byte hour) {
+        if (hour < 0 || hour > 23)
+            throw new IllegalArgumentException("Hour must be between 0 and 23 inclusive");
+        this.hour = hour;
+    }
+
+    public byte getMinute() {
+        return minute;
+    }
+
+    public void setMinute(byte minute) {
+        if (minute < 0 || minute > 59)
+            throw new IllegalArgumentException("Minute must be between 0 and 59 inclusive");
+        this.minute = minute;
+    }
+
+    public boolean isSetSuccess() {
+        return setSuccess;
+    }
+
+    @Override
+    protected void deserializeParams(byte id, ByteBuffer params) {
+        validateId(id, LefunConstants.CMD_ALARM);
+
+        if (params.limit() < 2)
+            throwUnexpectedLength();
+
+        op = params.get();
+        index = params.get();
+        if (op == OP_GET) {
+            if (params.limit() != 8)
+                throwUnexpectedLength();
+
+            enabled = params.get() == 1;
+            numOfSnoozes = params.get();
+            snoozeTime = params.get();
+            dayOfWeek = params.get();
+            hour = params.get();
+            minute = params.get();
+        } else if (op == OP_SET) {
+            if (params.limit() != 3)
+                throwUnexpectedLength();
+
+            setSuccess = params.get() == 1;
+        } else {
+            throw new IllegalArgumentException("Invalid operation type received");
+        }
+    }
+
+    @Override
+    protected byte serializeParams(ByteBuffer params) {
+        params.put(op);
+        // No alarm ID for get; all of them are returned
+        if (op == OP_SET) {
+            params.put(index);
+            params.put((byte)(enabled ? 1: 0));
+            params.put(numOfSnoozes);
+            params.put(snoozeTime);
+            params.put(dayOfWeek);
+            params.put(hour);
+            params.put(minute);
+        }
+        return LefunConstants.CMD_ALARM;
+    }
+}

app/src/main/java/nodomain/freeyourgadget/gadgetbridge/devices/lefun/commands/BaseCommand.java

@@ -0,0 +1,148 @@
+/*  Copyright (C) 2016-2020 Andreas Shimokawa, Carsten Pfeiffer, Daniele
+    Gobbetti
+    Copyright (C) 2020 Yukai Li
+
+    This file is part of Gadgetbridge.
+
+    Gadgetbridge is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Affero General Public License as published
+    by the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    Gadgetbridge is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Affero General Public License for more details.
+
+    You should have received a copy of the GNU Affero General Public License
+    along with this program.  If not, see <http://www.gnu.org/licenses/>. */
+package nodomain.freeyourgadget.gadgetbridge.devices.lefun.commands;
+
+import java.nio.ByteBuffer;
+import java.nio.ByteOrder;
+
+import nodomain.freeyourgadget.gadgetbridge.devices.lefun.LefunConstants;
+
+public abstract class BaseCommand {
+    // Common constants
+    public static final byte OP_GET = 0;
+    public static final byte OP_SET = 1;
+
+    abstract protected void deserializeParams(byte id, ByteBuffer params);
+    abstract protected byte serializeParams(ByteBuffer params);
+
+    public void deserialize(byte[] response) {
+        if (response.length < LefunConstants.CMD_HEADER_LENGTH)
+            throw new IllegalArgumentException("Response is too short");
+        if (calculateChecksum(response, 0, response.length - 1) != response[response.length - 1])
+            throw new IllegalArgumentException("Incorrect message checksum");
+        ByteBuffer buffer = ByteBuffer.wrap(response, LefunConstants.CMD_HEADER_LENGTH - 1,
+                response.length - LefunConstants.CMD_HEADER_LENGTH);
+        buffer.order(ByteOrder.BIG_ENDIAN);
+        deserializeParams(response[2], buffer);
+    }
+
+    public byte[] serialize() {
+        ByteBuffer buffer = ByteBuffer.allocate(LefunConstants.CMD_MAX_LENGTH - LefunConstants.CMD_HEADER_LENGTH);
+        buffer.order(ByteOrder.BIG_ENDIAN);
+        byte id = serializeParams(buffer);
+        return makeCommand(id, buffer);
+    }
+
+    static protected byte calculateChecksum(byte[] data, int offset, int length) {
+        byte checksum = 0;
+        for (int i = offset; i < offset + length; ++i) {
+            byte b = data[i];
+            for (int j = 0; j < 8; ++j) {
+                if (((b ^ checksum) & 1) == 0) {
+                    checksum >>= 1;
+                } else {
+                    checksum = (byte) ((checksum ^ 0x18) >> 1 | 0x80);
+                }
+                b >>= 1;
+            }
+        }
+        return checksum;
+    }
+
+    /**
+     * Builds a command given ID and parameters buffer.
+     *
+     * @param id     the command ID
+     * @param params the parameters buffer
+     * @return the assembled command buffer
+     */
+    protected byte[] makeCommand(byte id, ByteBuffer params) {
+        if (params.position() > LefunConstants.CMD_MAX_LENGTH - LefunConstants.CMD_HEADER_LENGTH)
+            throw new IllegalArgumentException("params is too long to fit");
+
+        int paramsLength = params.position();
+        byte[] request = new byte[paramsLength + LefunConstants.CMD_HEADER_LENGTH];
+        request[0] = LefunConstants.CMD_REQUEST_ID;
+        request[1] = (byte) request.length;
+        request[2] = id;
+        params.flip();
+        params.get(request, LefunConstants.CMD_HEADER_LENGTH - 1, paramsLength);
+        request[request.length - 1] = calculateChecksum(request, 0, request.length - 1);
+        return request;
+    }
+
+    protected void throwUnexpectedLength() {
+        throw new IllegalArgumentException("Unexpected parameters length");
+    }
+
+    protected void validateId(byte id, byte expectedId) {
+        if (id != expectedId)
+            throw new IllegalArgumentException("Wrong command ID");
+    }
+
+    protected void validateIdAndLength(byte id, ByteBuffer params, byte expectedId, int expectedLength) {
+        validateId(id, expectedId);
+        if (params.limit() != expectedLength)
+            throwUnexpectedLength();
+    }
+
+    protected boolean getBit(int value, int mask) {
+        return (value & mask) != 0;
+    }
+
+    protected int setBit(int value, int mask, boolean set) {
+        if (set) {
+            return value | mask;
+        } else {
+            return value & ~mask;
+        }
+    }
+
+    protected short setBit(short value, int mask, boolean set) {
+        if (set) {
+            return (short)(value | mask);
+        } else {
+            return (short)(value & ~mask);
+        }
+    }
+
+    protected byte setBit(byte value, int mask, boolean set) {
+        if (set) {
+            return (byte)(value | mask);
+        } else {
+            return (byte)(value & ~mask);
+        }
+    }
+
+    /**
+     * Find index of first bit that is set
+     * @param value
+     * @return
+     */
+    protected int getLowestSetBitIndex(int value) {
+        if (value == 0) return -1;
+
+        int i = 0;
+        while ((value & 1) == 0) {
+            ++i;
+            value >>= 1;
+        }
+        return i;
+    }
+}

app/src/main/java/nodomain/freeyourgadget/gadgetbridge/devices/lefun/commands/Cmd22Command.java

@@ -0,0 +1,84 @@
+/*  Copyright (C) 2016-2020 Andreas Shimokawa, Carsten Pfeiffer, Daniele
+    Gobbetti
+    Copyright (C) 2020 Yukai Li
+
+    This file is part of Gadgetbridge.
+
+    Gadgetbridge is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Affero General Public License as published
+    by the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    Gadgetbridge is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Affero General Public License for more details.
+
+    You should have received a copy of the GNU Affero General Public License
+    along with this program.  If not, see <http://www.gnu.org/licenses/>. */
+package nodomain.freeyourgadget.gadgetbridge.devices.lefun.commands;
+
+import java.nio.ByteBuffer;
+
+import nodomain.freeyourgadget.gadgetbridge.devices.lefun.LefunConstants;
+
+public class Cmd22Command extends BaseCommand {
+    private byte op;
+    private short unknown;
+
+    private boolean setSuccess;
+
+    public byte getOp() {
+        return op;
+    }
+
+    public void setOp(byte op) {
+        if (op != OP_GET && op != OP_SET)
+            throw new IllegalArgumentException("Operation must be get or set");
+        this.op = op;
+    }
+
+    public short getUnknown() {
+        return unknown;
+    }
+
+    public void setUnknown(short unknown) {
+        this.unknown = unknown;
+    }
+
+    public boolean isSetSuccess() {
+        return setSuccess;
+    }
+
+    @Override
+    protected void deserializeParams(byte id, ByteBuffer params) {
+        validateId(id, LefunConstants.CMD_UNKNOWN_22);
+
+        if (params.limit() < 1)
+            throwUnexpectedLength();
+
+        op = params.get();
+        if (op == OP_GET) {
+            if (params.limit() != 3)
+                throwUnexpectedLength();
+
+            unknown = params.getShort();
+        } else if (op == OP_SET) {
+            if (params.limit() != 2)
+                throwUnexpectedLength();
+
+            setSuccess = params.get() == 1;
+        } else {
+            throw new IllegalArgumentException("Invalid operation type received");
+        }
+    }
+
+    @Override
+    protected byte serializeParams(ByteBuffer params) {
+        params.put(op);
+        if (op == OP_SET) {
+            params.putShort(unknown);
+        }
+        return LefunConstants.CMD_UNKNOWN_22;
+    }
+}

app/src/main/java/nodomain/freeyourgadget/gadgetbridge/devices/lefun/commands/Cmd25Command.java

@@ -0,0 +1,86 @@
+/*  Copyright (C) 2016-2020 Andreas Shimokawa, Carsten Pfeiffer, Daniele
+    Gobbetti
+    Copyright (C) 2020 Yukai Li
+
+    This file is part of Gadgetbridge.
+
+    Gadgetbridge is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Affero General Public License as published
+    by the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    Gadgetbridge is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Affero General Public License for more details.
+
+    You should have received a copy of the GNU Affero General Public License
+    along with this program.  If not, see <http://www.gnu.org/licenses/>. */
+package nodomain.freeyourgadget.gadgetbridge.devices.lefun.commands;
+
+import java.nio.ByteBuffer;
+
+import nodomain.freeyourgadget.gadgetbridge.devices.lefun.LefunConstants;
+
+public class Cmd25Command extends BaseCommand {
+    private byte op;
+    private int unknown;
+
+    private boolean setSuccess;
+
+    public byte getOp() {
+        return op;
+    }
+
+    public void setOp(byte op) {
+        if (op != OP_GET && op != OP_SET)
+            throw new IllegalArgumentException("Operation must be get or set");
+        this.op = op;
+    }
+
+    public int getUnknown() {
+        return unknown;
+    }
+
+    public void setUnknown(int unknown) {
+        if (unknown < 0 || unknown > 65000)
+            throw new IllegalArgumentException("Value must be between 0 and 65000 inclusive");
+        this.unknown = unknown;
+    }
+
+    public boolean isSetSuccess() {
+        return setSuccess;
+    }
+
+    @Override
+    protected void deserializeParams(byte id, ByteBuffer params) {
+        validateId(id, LefunConstants.CMD_UNKNOWN_25);
+
+        if (params.limit() < 1)
+            throwUnexpectedLength();
+
+        op = params.get();
+        if (op == OP_GET) {
+            if (params.limit() != 5)
+                throwUnexpectedLength();
+
+            unknown = params.getInt();
+        } else if (op == OP_SET) {
+            if (params.limit() != 2)
+                throwUnexpectedLength();
+
+            setSuccess = params.get() == 1;
+        } else {
+            throw new IllegalArgumentException("Invalid operation type received");
+        }
+    }
+
+    @Override
+    protected byte serializeParams(ByteBuffer params) {
+        params.put(op);
+        if (op == OP_SET) {
+            params.putInt(unknown);
+        }
+        return LefunConstants.CMD_UNKNOWN_25;
+    }
+}

app/src/main/java/nodomain/freeyourgadget/gadgetbridge/devices/lefun/commands/FeaturesCommand.java

@@ -0,0 +1,95 @@
+/*  Copyright (C) 2016-2020 Andreas Shimokawa, Carsten Pfeiffer, Daniele
+    Gobbetti
+    Copyright (C) 2020 Yukai Li
+
+    This file is part of Gadgetbridge.
+
+    Gadgetbridge is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Affero General Public License as published
+    by the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    Gadgetbridge is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Affero General Public License for more details.
+
+    You should have received a copy of the GNU Affero General Public License
+    along with this program.  If not, see <http://www.gnu.org/licenses/>. */
+package nodomain.freeyourgadget.gadgetbridge.devices.lefun.commands;
+
+import java.nio.ByteBuffer;
+
+import nodomain.freeyourgadget.gadgetbridge.devices.lefun.LefunConstants;
+
+public class FeaturesCommand extends BaseCommand {
+    public static final int FEATURE_RAISE_TO_WAKE = 0;
+    public static final int FEATURE_SEDENTARY_REMINDER = 1;
+    public static final int FEATURE_HYDRATION_REMINDER = 2;
+    public static final int FEATURE_REMOTE_CAMERA = 3;
+    public static final int FEATURE_UNKNOWN_4 = 4;
+    public static final int FEATURE_ANTI_LOST = 5;
+
+    private byte op;
+    private short features;
+
+    private boolean setSuccess;
+
+    public byte getOp() {
+        return op;
+    }
+
+    public void setOp(byte op) {
+        if (op != OP_GET && op != OP_SET)
+            throw new IllegalArgumentException("Operation must be get or set");
+        this.op = op;
+    }
+
+    public boolean getFeature(int index) {
+        if (index < 0 || index > 5)
+            throw new IllegalArgumentException("Index must be between 0 and 5 inclusive");
+        return getBit(features, 1 << index);
+    }
+
+    public void setFeature(int index, boolean enabled) {
+        if (index < 0 || index > 5)
+            throw new IllegalArgumentException("Index must be between 0 and 5 inclusive");
+        features = setBit(features, 1 << index, enabled);
+    }
+
+    public boolean isSetSuccess() {
+        return setSuccess;
+    }
+
+    @Override
+    protected void deserializeParams(byte id, ByteBuffer params) {
+        validateId(id, LefunConstants.CMD_FEATURES);
+
+        if (params.limit() < 1)
+            throwUnexpectedLength();
+
+        op = params.get();
+        if (op == OP_GET) {
+            if (params.limit() != 3)
+                throwUnexpectedLength();
+
+            features = params.getShort();
+        } else if (op == OP_SET) {
+            if (params.limit() != 2)
+                throwUnexpectedLength();
+
+            setSuccess = params.get() == 1;
+        } else {
+            throw new IllegalArgumentException("Invalid operation type received");
+        }
+    }
+
+    @Override
+    protected byte serializeParams(ByteBuffer params) {
+        params.put(op);
+        if (op == OP_SET) {
+            params.putShort(features);
+        }
+        return LefunConstants.CMD_FEATURES;
+    }
+}

app/src/main/java/nodomain/freeyourgadget/gadgetbridge/devices/lefun/commands/FindDeviceCommand.java

@@ -0,0 +1,43 @@
+package nodomain.freeyourgadget.gadgetbridge.devices.lefun.commands;
+
+import java.nio.ByteBuffer;
+
+/*  Copyright (C) 2016-2020 Andreas Shimokawa, Carsten Pfeiffer, Daniele
+    Gobbetti
+    Copyright (C) 2020 Yukai Li
+
+    This file is part of Gadgetbridge.
+
+    Gadgetbridge is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Affero General Public License as published
+    by the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    Gadgetbridge is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Affero General Public License for more details.
+
+    You should have received a copy of the GNU Affero General Public License
+    along with this program.  If not, see <http://www.gnu.org/licenses/>. */
+import nodomain.freeyourgadget.gadgetbridge.devices.lefun.LefunConstants;
+
+public class FindDeviceCommand extends BaseCommand {
+    private boolean success;
+
+    public boolean isSuccess() {
+        return success;
+    }
+
+    @Override
+    protected void deserializeParams(byte id, ByteBuffer params) {
+        validateIdAndLength(id, params, LefunConstants.CMD_FIND_DEVICE, 1);
+
+        success = params.get() == 1;
+    }
+
+    @Override
+    protected byte serializeParams(ByteBuffer params) {
+        return LefunConstants.CMD_FIND_DEVICE;
+    }
+}

app/src/main/java/nodomain/freeyourgadget/gadgetbridge/devices/lefun/commands/FindPhoneCommand.java

@@ -0,0 +1,35 @@
+/*  Copyright (C) 2016-2020 Andreas Shimokawa, Carsten Pfeiffer, Daniele
+    Gobbetti
+    Copyright (C) 2020 Yukai Li
+
+    This file is part of Gadgetbridge.
+
+    Gadgetbridge is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Affero General Public License as published
+    by the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    Gadgetbridge is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Affero General Public License for more details.
+
+    You should have received a copy of the GNU Affero General Public License
+    along with this program.  If not, see <http://www.gnu.org/licenses/>. */
+package nodomain.freeyourgadget.gadgetbridge.devices.lefun.commands;
+
+import java.nio.ByteBuffer;
+
+import nodomain.freeyourgadget.gadgetbridge.devices.lefun.LefunConstants;
+
+public class FindPhoneCommand extends BaseCommand {
+    @Override
+    protected void deserializeParams(byte id, ByteBuffer params) {
+        validateIdAndLength(id, params, LefunConstants.CMD_FIND_PHONE, 0);
+    }
+
+    @Override
+    protected byte serializeParams(ByteBuffer params) {
+        return LefunConstants.CMD_FIND_PHONE;
+    }
+}

app/src/main/java/nodomain/freeyourgadget/gadgetbridge/devices/lefun/commands/GetActivityDataCommand.java

@@ -0,0 +1,110 @@
+/*  Copyright (C) 2016-2020 Andreas Shimokawa, Carsten Pfeiffer, Daniele
+    Gobbetti
+    Copyright (C) 2020 Yukai Li
+
+    This file is part of Gadgetbridge.
+
+    Gadgetbridge is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Affero General Public License as published
+    by the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    Gadgetbridge is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Affero General Public License for more details.
+
+    You should have received a copy of the GNU Affero General Public License
+    along with this program.  If not, see <http://www.gnu.org/licenses/>. */
+package nodomain.freeyourgadget.gadgetbridge.devices.lefun.commands;
+
+import java.nio.ByteBuffer;
+
+import nodomain.freeyourgadget.gadgetbridge.devices.lefun.LefunConstants;
+
+public class GetActivityDataCommand extends BaseCommand {
+    private byte daysAgo;
+    private byte totalRecords;
+    private byte currentRecord;
+    private byte year;
+    private byte month;
+    private byte day;
+    private byte hour;
+    private byte minute;
+    private short steps;
+    private short distance; // m
+    private short calories; // calories
+
+    public byte getDaysAgo() {
+        return daysAgo;
+    }
+
+    public void setDaysAgo(byte daysAgo) {
+        if (daysAgo < 0 || daysAgo > 6)
+            throw new IllegalArgumentException("Days ago must be between 0 and 6 inclusive");
+        this.daysAgo = daysAgo;
+    }
+
+    public byte getTotalRecords() {
+        return totalRecords;
+    }
+
+    public byte getCurrentRecord() {
+        return currentRecord;
+    }
+
+    public byte getYear() {
+        return year;
+    }
+
+    public byte getMonth() {
+        return month;
+    }
+
+    public byte getDay() {
+        return day;
+    }
+
+    public byte getHour() {
+        return hour;
+    }
+
+    public byte getMinute() {
+        return minute;
+    }
+
+    public short getSteps() {
+        return steps;
+    }
+
+    public short getDistance() {
+        return distance;
+    }
+
+    public short getCalories() {
+        return calories;
+    }
+
+    @Override
+    protected void deserializeParams(byte id, ByteBuffer params) {
+        validateIdAndLength(id, params, LefunConstants.CMD_ACTIVITY_DATA, 14);
+
+        daysAgo = params.get();
+        totalRecords = params.get();
+        currentRecord = params.get();
+        year = params.get();
+        month = params.get();
+        day = params.get();
+        hour = params.get();
+        minute = params.get();
+        steps = params.getShort();
+        distance = params.getShort();
+        calories = params.getShort();
+    }
+
+    @Override
+    protected byte serializeParams(ByteBuffer params) {
+        params.put(daysAgo);
+        return LefunConstants.CMD_ACTIVITY_DATA;
+    }
+}

app/src/main/java/nodomain/freeyourgadget/gadgetbridge/devices/lefun/commands/GetBatteryLevelCommand.java

@@ -0,0 +1,43 @@
+/*  Copyright (C) 2016-2020 Andreas Shimokawa, Carsten Pfeiffer, Daniele
+    Gobbetti
+    Copyright (C) 2020 Yukai Li
+
+    This file is part of Gadgetbridge.
+
+    Gadgetbridge is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Affero General Public License as published
+    by the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    Gadgetbridge is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Affero General Public License for more details.
+
+    You should have received a copy of the GNU Affero General Public License
+    along with this program.  If not, see <http://www.gnu.org/licenses/>. */
+package nodomain.freeyourgadget.gadgetbridge.devices.lefun.commands;
+
+import java.nio.ByteBuffer;
+
+import nodomain.freeyourgadget.gadgetbridge.devices.lefun.LefunConstants;
+
+public class GetBatteryLevelCommand extends BaseCommand {
+    private byte batteryLevel;
+
+    public byte getBatteryLevel() {
+        return batteryLevel;
+    }
+
+    @Override
+    protected void deserializeParams(byte id, ByteBuffer params) {
+        validateIdAndLength(id, params, LefunConstants.CMD_BATTERY_LEVEL, 1);
+
+        batteryLevel = params.get();
+    }
+
+    @Override
+    protected byte serializeParams(ByteBuffer params) {
+        return LefunConstants.CMD_BATTERY_LEVEL;
+    }
+}

app/src/main/java/nodomain/freeyourgadget/gadgetbridge/devices/lefun/commands/GetFirmwareInfoCommand.java

@@ -0,0 +1,78 @@
+package nodomain.freeyourgadget.gadgetbridge.devices.lefun.commands;
+
+import java.nio.ByteBuffer;
+/*  Copyright (C) 2016-2020 Andreas Shimokawa, Carsten Pfeiffer, Daniele
+    Gobbetti
+    Copyright (C) 2020 Yukai Li
+
+    This file is part of Gadgetbridge.
+
+    Gadgetbridge is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Affero General Public License as published
+    by the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    Gadgetbridge is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Affero General Public License for more details.
+
+    You should have received a copy of the GNU Affero General Public License
+    along with this program.  If not, see <http://www.gnu.org/licenses/>. */
+import java.nio.charset.StandardCharsets;
+
+import nodomain.freeyourgadget.gadgetbridge.devices.lefun.LefunConstants;
+
+public class GetFirmwareInfoCommand extends BaseCommand {
+    private short supportCode;
+    private short devTypeReserveCode;
+    private String typeCode;
+    private short hardwareVersion;
+    private short softwareVersion;
+    private String vendorCode;
+
+    public short getSupportCode() {
+        return supportCode;
+    }
+
+    public short getDevTypeReserveCode() {
+        return devTypeReserveCode;
+    }
+
+    public String getTypeCode() {
+        return typeCode;
+    }
+
+    public short getHardwareVersion() {
+        return hardwareVersion;
+    }
+
+    public short getSoftwareVersion() {
+        return softwareVersion;
+    }
+
+    public String getVendorCode() {
+        return vendorCode;
+    }
+
+    @Override
+    protected void deserializeParams(byte id, ByteBuffer params) {
+        validateIdAndLength(id, params, LefunConstants.CMD_FIRMWARE_INFO, 16);
+
+        supportCode = (short)(params.get() | (params.get() << 8));
+        devTypeReserveCode = params.getShort();
+        byte[] typeCodeBytes = new byte[4];
+        params.get(typeCodeBytes);
+        typeCode = new String(typeCodeBytes, StandardCharsets.US_ASCII);
+        hardwareVersion = params.getShort();
+        softwareVersion = params.getShort();
+        byte[] vendorCodeBytes = new byte[4];
+        params.get(vendorCodeBytes);
+        vendorCode = new String(vendorCodeBytes, StandardCharsets.US_ASCII);
+    }
+
+    @Override
+    protected byte serializeParams(ByteBuffer params) {
+        return LefunConstants.CMD_FIRMWARE_INFO;
+    }
+}

app/src/main/java/nodomain/freeyourgadget/gadgetbridge/devices/lefun/commands/GetPpgDataCommand.java

@@ -0,0 +1,118 @@
+package nodomain.freeyourgadget.gadgetbridge.devices.lefun.commands;
+
+import java.nio.ByteBuffer;
+
+import nodomain.freeyourgadget.gadgetbridge.devices.lefun.LefunConstants;
+
+public class GetPpgDataCommand extends BaseCommand {
+    private byte ppgType;
+    private short totalRecords;
+    private short currentRecord;
+    private byte year;
+    private byte month;
+    private byte day;
+    private byte hour;
+    private byte minute;
+    private byte second;
+    private byte[] ppgData;
+
+    public int getPpgType() {
+        return getLowestSetBitIndex(ppgType);
+    }
+
+    public void setPpgType(int type) {
+        if (type < 0 || type > 2)
+            throw new IllegalArgumentException("Invalid PPG type");
+        this.ppgType = (byte)(1 << type);
+    }
+
+    public short getTotalRecords() {
+        return totalRecords;
+    }
+
+    public short getCurrentRecord() {
+        return currentRecord;
+    }
+
+    public byte getYear() {
+        return year;
+    }
+
+    public byte getMonth() {
+        return month;
+    }
+
+    public byte getDay() {
+        return day;
+    }
+
+    public byte getHour() {
+        return hour;
+    }
+
+    public byte getMinute() {
+        return minute;
+    }
+
+    public byte getSecond() {
+        return second;
+    }
+
+    public byte[] getPpgData() {
+        return ppgData;
+    }
+
+    @Override
+    protected void deserializeParams(byte id, ByteBuffer params) {
+        validateId(id, LefunConstants.CMD_PPG_DATA);
+
+        if (params.limit() < 9)
+            throwUnexpectedLength();
+
+        ppgType = params.get();
+        totalRecords = params.get();
+        currentRecord = params.get();
+        year = params.get();
+        month = params.get();
+        day = params.get();
+        hour = params.get();
+        minute = params.get();
+        second = params.get();
+
+        int typeIndex = getPpgType();
+        int dataLength;
+        switch (typeIndex) {
+            case LefunConstants.PPG_TYPE_HEART_RATE:
+            case LefunConstants.PPG_TYPE_BLOOD_OXYGEN:
+                dataLength = 1;
+                break;
+            case LefunConstants.PPG_TYPE_BLOOD_PRESSURE:
+                dataLength = 2;
+                break;
+            default:
+                throw new IllegalArgumentException("Unknown PPG type");
+        }
+
+        if (params.limit() < dataLength + 9)
+            throwUnexpectedLength();
+
+        ppgData = new byte[dataLength];
+        params.get(ppgData);
+
+        // Extended count/index
+        if (params.limit() == dataLength + 11)
+        {
+            totalRecords |= params.get() << 8;
+            currentRecord |= params.get() << 8;
+        }
+        else if (params.limit() > dataLength + 11) {
+            throwUnexpectedLength();
+        }
+    }
+
+    @Override
+    protected byte serializeParams(ByteBuffer params) {
+        params.put(ppgType);
+        return LefunConstants.CMD_PPG_DATA;
+    }
+}

app/src/main/java/nodomain/freeyourgadget/gadgetbridge/devices/lefun/commands/GetSleepDataCommand.java

@@ -0,0 +1,102 @@
+package nodomain.freeyourgadget.gadgetbridge.devices.lefun.commands;
+
+/*  Copyright (C) 2016-2020 Andreas Shimokawa, Carsten Pfeiffer, Daniele
+    Gobbetti
+    Copyright (C) 2020 Yukai Li
+
+    This file is part of Gadgetbridge.
+
+    Gadgetbridge is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Affero General Public License as published
+    by the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    Gadgetbridge is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Affero General Public License for more details.
+
+    You should have received a copy of the GNU Affero General Public License
+    along with this program.  If not, see <http://www.gnu.org/licenses/>. */
+import java.nio.ByteBuffer;
+
+import nodomain.freeyourgadget.gadgetbridge.devices.lefun.LefunConstants;
+
+public class GetSleepDataCommand extends BaseCommand {
+    public static final int SLEEP_TYPE_AWAKE = 1;
+    public static final int SLEEP_TYPE_LIGHT_SLEEP = 2;
+    public static final int SLEEP_TYPE_DEEP_SLEEP = 3;
+
+    private byte daysAgo;
+    private short totalRecords;
+    private short currentRecord;
+    private byte year;
+    private byte month;
+    private byte day;
+    private byte hour;
+    private byte minute;
+    private byte sleepType;
+
+    public byte getDaysAgo() {
+        return daysAgo;
+    }
+
+    public void setDaysAgo(byte daysAgo) {
+        if (daysAgo < 0 || daysAgo > 6)
+            throw new IllegalArgumentException("Days ago must be between 0 and 6 inclusive");
+        this.daysAgo = daysAgo;
+    }
+
+    public short getTotalRecords() {
+        return totalRecords;
+    }
+
+    public short getCurrentRecord() {
+        return currentRecord;
+    }
+
+    public byte getYear() {
+        return year;
+    }
+
+    public byte getMonth() {
+        return month;
+    }
+
+    public byte getDay() {
+        return day;
+    }
+
+    public byte getHour() {
+        return hour;
+    }
+
+    public byte getMinute() {
+        return minute;
+    }
+
+    public byte getSleepType() {
+        return sleepType;
+    }
+
+    @Override
+    protected void deserializeParams(byte id, ByteBuffer params) {
+        validateIdAndLength(id, params, LefunConstants.CMD_SLEEP_DATA, 11);
+
+        daysAgo = params.get();
+        totalRecords = params.getShort();
+        currentRecord = params.getShort();
+        year = params.get();
+        month = params.get();
+        day = params.get();
+        hour = params.get();
+        minute = params.get();
+        sleepType = params.get();
+    }
+
+    @Override
+    protected byte serializeParams(ByteBuffer params) {
+        params.put(daysAgo);
+        return LefunConstants.CMD_SLEEP_DATA;
+    }
+}

app/src/main/java/nodomain/freeyourgadget/gadgetbridge/devices/lefun/commands/GetSleepTimeCommand.java

@@ -0,0 +1,75 @@
+/*  Copyright (C) 2016-2020 Andreas Shimokawa, Carsten Pfeiffer, Daniele
+    Gobbetti
+    Copyright (C) 2020 Yukai Li
+
+    This file is part of Gadgetbridge.
+
+    Gadgetbridge is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Affero General Public License as published
+    by the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    Gadgetbridge is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Affero General Public License for more details.
+
+    You should have received a copy of the GNU Affero General Public License
+    along with this program.  If not, see <http://www.gnu.org/licenses/>. */
+package nodomain.freeyourgadget.gadgetbridge.devices.lefun.commands;
+
+import java.nio.ByteBuffer;
+
+import nodomain.freeyourgadget.gadgetbridge.devices.lefun.LefunConstants;
+
+public class GetSleepTimeCommand extends BaseCommand {
+    private byte daysAgo;
+    private byte year;
+    private byte month;
+    private byte day;
+    private short minutes;
+
+    public byte getDaysAgo() {
+        return daysAgo;
+    }
+
+    public void setDaysAgo(byte daysAgo) {
+        if (daysAgo < 0 || daysAgo > 6)
+            throw new IllegalArgumentException("Days ago must be between 0 and 6 inclusive");
+        this.daysAgo = daysAgo;
+    }
+
+    public byte getYear() {
+        return year;
+    }
+
+    public byte getMonth() {
+        return month;
+    }
+
+    public byte getDay() {
+        return day;
+    }
+
+    public short getMinutes() {
+        return minutes;
+    }
+
+
+    @Override
+    protected void deserializeParams(byte id, ByteBuffer params) {
+        validateIdAndLength(id, params, LefunConstants.CMD_SLEEP_TIME_DATA, 6);
+
+        daysAgo = params.get();
+        year = params.get();
+        month = params.get();
+        day = params.get();
+        minutes = params.getShort();
+    }
+
+    @Override
+    protected byte serializeParams(ByteBuffer params) {
+        params.put(daysAgo);
+        return LefunConstants.CMD_SLEEP_TIME_DATA;
+    }
+}

app/src/main/java/nodomain/freeyourgadget/gadgetbridge/devices/lefun/commands/GetStepsDataCommand.java

@@ -0,0 +1,86 @@
+/*  Copyright (C) 2016-2020 Andreas Shimokawa, Carsten Pfeiffer, Daniele
+    Gobbetti
+    Copyright (C) 2020 Yukai Li
+
+    This file is part of Gadgetbridge.
+
+    Gadgetbridge is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Affero General Public License as published
+    by the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    Gadgetbridge is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Affero General Public License for more details.
+
+    You should have received a copy of the GNU Affero General Public License
+    along with this program.  If not, see <http://www.gnu.org/licenses/>. */
+package nodomain.freeyourgadget.gadgetbridge.devices.lefun.commands;
+
+import java.nio.ByteBuffer;
+
+import nodomain.freeyourgadget.gadgetbridge.devices.lefun.LefunConstants;
+
+public class GetStepsDataCommand extends BaseCommand {
+    private byte daysAgo;
+    private byte year;
+    private byte month;
+    private byte day;
+    private int steps;
+    private int distance; // m
+    private int calories; // calories
+
+    public byte getDaysAgo() {
+        return daysAgo;
+    }
+
+    public void setDaysAgo(byte daysAgo) {
+        if (daysAgo < 0 || daysAgo > 6)
+            throw new IllegalArgumentException("Days ago must be between 0 and 6 inclusive");
+        this.daysAgo = daysAgo;
+    }
+
+    public byte getYear() {
+        return year;
+    }
+
+    public byte getMonth() {
+        return month;
+    }
+
+    public byte getDay() {
+        return day;
+    }
+
+    public int getSteps() {
+        return steps;
+    }
+
+    public int getDistance() {
+        return distance;
+    }
+
+    public int getCalories() {
+        return calories;
+    }
+
+    @Override
+    protected void deserializeParams(byte id, ByteBuffer params) {
+        validateIdAndLength(id, params, LefunConstants.CMD_STEPS_DATA, 16);
+
+        daysAgo = params.get();
+        year = params.get();
+        month = params.get();
+        day = params.get();
+        steps = params.getInt();
+        distance = params.getInt();
+        calories = params.getInt();
+    }
+
+    @Override
+    protected byte serializeParams(ByteBuffer params) {
+        params.put(daysAgo);
+        return LefunConstants.CMD_STEPS_DATA;
+    }
+}

app/src/main/java/nodomain/freeyourgadget/gadgetbridge/devices/lefun/commands/HydrationReminderIntervalCommand.java

@@ -0,0 +1,86 @@
+/*  Copyright (C) 2016-2020 Andreas Shimokawa, Carsten Pfeiffer, Daniele
+    Gobbetti
+    Copyright (C) 2020 Yukai Li
+
+    This file is part of Gadgetbridge.
+
+    Gadgetbridge is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Affero General Public License as published
+    by the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    Gadgetbridge is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Affero General Public License for more details.
+
+    You should have received a copy of the GNU Affero General Public License
+    along with this program.  If not, see <http://www.gnu.org/licenses/>. */
+package nodomain.freeyourgadget.gadgetbridge.devices.lefun.commands;
+
+import java.nio.ByteBuffer;
+
+import nodomain.freeyourgadget.gadgetbridge.devices.lefun.LefunConstants;
+
+public class HydrationReminderIntervalCommand extends BaseCommand {
+    private byte op;
+    private byte hydrationReminderInterval;
+
+    private boolean setSuccess;
+
+    public byte getOp() {
+        return op;
+    }
+
+    public void setOp(byte op) {
+        if (op != OP_GET && op != OP_SET)
+            throw new IllegalArgumentException("Operation must be get or set");
+        this.op = op;
+    }
+
+    public byte getHydrationReminderInterval() {
+        return hydrationReminderInterval;
+    }
+
+    public void setHydrationReminderInterval(byte hydrationReminderInterval) {
+        if (hydrationReminderInterval == 0)
+            throw new IllegalArgumentException("Interval must be non-zero");
+        this.hydrationReminderInterval = hydrationReminderInterval;
+    }
+
+    public boolean isSetSuccess() {
+        return setSuccess;
+    }
+
+    @Override
+    protected void deserializeParams(byte id, ByteBuffer params) {
+        validateId(id, LefunConstants.CMD_HYDRATION_REMINDER_INTERVAL);
+
+        if (params.limit() < 1)
+            throwUnexpectedLength();
+
+        op = params.get();
+        if (op == OP_GET) {
+            if (params.limit() != 2)
+                throwUnexpectedLength();
+
+            hydrationReminderInterval = params.get();
+        } else if (op == OP_SET) {
+            if (params.limit() != 2)
+                throwUnexpectedLength();
+
+            setSuccess = params.get() == 1;
+        } else {
+            throw new IllegalArgumentException("Invalid operation type received");
+        }
+    }
+
+    @Override
+    protected byte serializeParams(ByteBuffer params) {
+        params.put(op);
+        if (op == OP_SET) {
+            params.put(hydrationReminderInterval);
+        }
+        return LefunConstants.CMD_HYDRATION_REMINDER_INTERVAL;
+    }
+}

app/src/main/java/nodomain/freeyourgadget/gadgetbridge/devices/lefun/commands/NotificationCommand.java

@@ -0,0 +1,121 @@
+/*  Copyright (C) 2016-2020 Andreas Shimokawa, Carsten Pfeiffer, Daniele
+    Gobbetti
+    Copyright (C) 2020 Yukai Li
+
+    This file is part of Gadgetbridge.
+
+    Gadgetbridge is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Affero General Public License as published
+    by the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    Gadgetbridge is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Affero General Public License for more details.
+
+    You should have received a copy of the GNU Affero General Public License
+    along with this program.  If not, see <http://www.gnu.org/licenses/>. */
+package nodomain.freeyourgadget.gadgetbridge.devices.lefun.commands;
+
+import java.nio.ByteBuffer;
+
+import nodomain.freeyourgadget.gadgetbridge.devices.lefun.LefunConstants;
+
+public class NotificationCommand extends BaseCommand {
+    public static final byte SERVICE_TYPE_CALL = 0;
+    public static final byte SERVICE_TYPE_TEXT = 1;
+    public static final byte SERVICE_TYPE_QQ = 2;
+    public static final byte SERVICE_TYPE_WECHAT = 3;
+    public static final byte SERVICE_TYPE_EXTENDED = 4;
+
+    public static final byte EXTENDED_SERVICE_TYPE_FACEBOOK = 1;
+    public static final byte EXTENDED_SERVICE_TYPE_TWITTER = 2;
+    public static final byte EXTENDED_SERVICE_TYPE_LINKEDIN = 3;
+    public static final byte EXTENDED_SERVICE_TYPE_WHATSAPP = 4;
+    public static final byte EXTENDED_SERVICE_TYPE_LINE = 5;
+    public static final byte EXTENDED_SERVICE_TYPE_KAKAOTALK = 6;
+
+    private byte serviceType;
+    private byte totalPieces;
+    private byte currentPiece;
+    private byte extendedServiceType;
+    private byte[] payload;
+
+    public int getServiceType() {
+        return getLowestSetBitIndex(serviceType);
+    }
+
+    public void setServiceType(int type) {
+        if (type < 0 || type > 4)
+            throw new IllegalArgumentException("Invalid service type");
+        this.serviceType = (byte)(1 << type);
+    }
+
+    public byte getTotalPieces() {
+        return totalPieces;
+    }
+
+    public void setTotalPieces(byte totalPieces) {
+        // This check isn't on device, but should probably be added
+        if (totalPieces == 0)
+            throw new IllegalArgumentException("Total pieces must not be 0");
+        this.totalPieces = totalPieces;
+    }
+
+    public byte getCurrentPiece() {
+        return currentPiece;
+    }
+
+    public void setCurrentPiece(byte currentPiece) {
+        // This check isn't on device, but should probably be added
+        if (currentPiece == 0)
+            throw new IllegalArgumentException("Current piece must not be 0");
+        this.currentPiece = currentPiece;
+    }
+
+    public byte getExtendedServiceType() {
+        return extendedServiceType;
+    }
+
+    public void setExtendedServiceType(byte extendedServiceType) {
+        this.extendedServiceType = extendedServiceType;
+    }
+
+    public byte[] getPayload() {
+        return payload;
+    }
+
+    public void setPayload(byte[] payload) {
+        if (payload == null)
+            throw new IllegalArgumentException("Payload must not be null");
+        if (payload.length > 13)
+            throw new IllegalArgumentException("Payload is too long");
+        this.payload = payload;
+    }
+
+    @Override
+    protected void deserializeParams(byte id, ByteBuffer params) {
+        // We should not receive a response for this
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    protected byte serializeParams(ByteBuffer params) {
+        boolean hasExtendedServiceType = (serviceType & (1 << SERVICE_TYPE_EXTENDED)) != 0
+                && (extendedServiceType & 0x0f) != 0 ;
+        int maxPayloadLength = hasExtendedServiceType ? 12 : 13;
+
+        if (payload.length > maxPayloadLength)
+            throw new IllegalStateException("Payload is too long");
+
+        params.put(serviceType);
+        params.put(totalPieces);
+        params.put(currentPiece);
+        if (hasExtendedServiceType)
+            params.put(extendedServiceType);
+        params.put(payload);
+
+        return LefunConstants.CMD_NOTIFICATION;
+    }
+}

app/src/main/java/nodomain/freeyourgadget/gadgetbridge/devices/lefun/commands/PpgResultCommand.java

@@ -0,0 +1,72 @@
+/*  Copyright (C) 2016-2020 Andreas Shimokawa, Carsten Pfeiffer, Daniele
+    Gobbetti
+    Copyright (C) 2020 Yukai Li
+
+    This file is part of Gadgetbridge.
+
+    Gadgetbridge is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Affero General Public License as published
+    by the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    Gadgetbridge is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Affero General Public License for more details.
+
+    You should have received a copy of the GNU Affero General Public License
+    along with this program.  If not, see <http://www.gnu.org/licenses/>. */
+package nodomain.freeyourgadget.gadgetbridge.devices.lefun.commands;
+
+import java.nio.ByteBuffer;
+
+import nodomain.freeyourgadget.gadgetbridge.devices.lefun.LefunConstants;
+
+public class PpgResultCommand extends BaseCommand {
+    private byte ppgType;
+    private byte[] ppgData;
+
+    public int getPpgType() {
+        return getLowestSetBitIndex(ppgType);
+    }
+
+    public byte[] getPpgData() {
+        return ppgData;
+    }
+
+    @Override
+    protected void deserializeParams(byte id, ByteBuffer params) {
+        validateId(id, LefunConstants.CMD_PPG_RESULT);
+
+        if (params.limit() < 1)
+            throwUnexpectedLength();
+
+        ppgType = params.get();
+
+        int typeIndex = getPpgType();
+        int dataLength;
+        switch (typeIndex) {
+            case LefunConstants.PPG_TYPE_HEART_RATE:
+            case LefunConstants.PPG_TYPE_BLOOD_OXYGEN:
+                dataLength = 1;
+                break;
+            case LefunConstants.PPG_TYPE_BLOOD_PRESSURE:
+                dataLength = 2;
+                break;
+            default:
+                throw new IllegalArgumentException("Unknown PPG type");
+        }
+
+        if (params.limit() != dataLength + 1)
+            throwUnexpectedLength();
+
+        ppgData = new byte[dataLength];
+        params.get(ppgData);
+    }
+
+    @Override
+    protected byte serializeParams(ByteBuffer params) {
+        // No handler on device side
+        throw new UnsupportedOperationException();
+    }
+}

app/src/main/java/nodomain/freeyourgadget/gadgetbridge/devices/lefun/commands/ProfileCommand.java

@@ -0,0 +1,130 @@
+/*  Copyright (C) 2016-2020 Andreas Shimokawa, Carsten Pfeiffer, Daniele
+    Gobbetti
+    Copyright (C) 2020 Yukai Li
+
+    This file is part of Gadgetbridge.
+
+    Gadgetbridge is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Affero General Public License as published
+    by the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    Gadgetbridge is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Affero General Public License for more details.
+
+    You should have received a copy of the GNU Affero General Public License
+    along with this program.  If not, see <http://www.gnu.org/licenses/>. */
+package nodomain.freeyourgadget.gadgetbridge.devices.lefun.commands;
+
+import java.nio.ByteBuffer;
+
+import nodomain.freeyourgadget.gadgetbridge.devices.lefun.LefunConstants;
+
+public class ProfileCommand extends BaseCommand {
+    public static final byte GENDER_FEMALE = 0;
+    public static final byte GENDER_MALE = 1;
+
+    private byte op;
+    private byte gender;
+    private byte height; // cm
+    private byte weight; // kg
+    private byte age; // years
+
+    private boolean setSuccess;
+
+    public byte getOp() {
+        return op;
+    }
+
+    public void setOp(byte op) {
+        if (op != OP_GET && op != OP_SET)
+            throw new IllegalArgumentException("Operation must be get or set");
+        this.op = op;
+    }
+
+    public byte getGender() {
+        return gender;
+    }
+
+    public void setGender(byte gender) {
+        if (gender != GENDER_FEMALE && gender != GENDER_MALE)
+            throw new IllegalArgumentException("Invalid gender");
+        this.gender = gender;
+    }
+
+    public byte getHeight() {
+        return height;
+    }
+
+    public void setHeight(byte height) {
+        int intHeight = (int)height & 0xff;
+        if (intHeight < 40 || intHeight > 210)
+            throw new IllegalArgumentException("Height must be between 40 and 210 cm inclusive");
+        this.height = height;
+    }
+
+    public byte getWeight() {
+        return weight;
+    }
+
+    public void setWeight(byte weight) {
+        int intWeight = (int)weight & 0xff;
+        if (intWeight < 5 || intWeight > 200)
+            throw new IllegalArgumentException("Weight must be between 5 and 200 kg inclusive");
+        this.weight = weight;
+    }
+
+    public byte getAge() {
+        return age;
+    }
+
+    public void setAge(byte age) {
+        if (age < 0 || age > 110)
+            throw new IllegalArgumentException("Age must be between 0 and 110 years inclusive");
+        this.age = age;
+    }
+
+    public boolean isSetSuccess() {
+        return setSuccess;
+    }
+
+    @Override
+    protected void deserializeParams(byte id, ByteBuffer params) {
+        validateId(id, LefunConstants.CMD_PROFILE);
+
+        if (params.limit() < 1)
+            throwUnexpectedLength();
+
+        op = params.get();
+        if (op == OP_GET) {
+            if (params.limit() != 5)
+                throwUnexpectedLength();
+
+            gender = params.get();
+            height = params.get();
+            weight = params.get();
+            age = params.get();
+        } else if (op == OP_SET) {
+            if (params.limit() != 2)
+                throwUnexpectedLength();
+
+            setSuccess = params.get() == 1;
+        } else {
+            throw new IllegalArgumentException("Invalid operation type received");
+        }
+    }
+
+    @Override
+    protected byte serializeParams(ByteBuffer params) {
+        params.put(op);
+        if (op == OP_SET) {
+            params.put(gender);
+            params.put(height);
+            params.put(weight);
+            params.put(age);
+        }
+        return LefunConstants.CMD_PROFILE;
+    }
+}

app/src/main/java/nodomain/freeyourgadget/gadgetbridge/devices/lefun/commands/RemoteCameraTriggeredCommand.java

@@ -0,0 +1,36 @@
+/*  Copyright (C) 2016-2020 Andreas Shimokawa, Carsten Pfeiffer, Daniele
+    Gobbetti
+    Copyright (C) 2020 Yukai Li
+
+    This file is part of Gadgetbridge.
+
+    Gadgetbridge is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Affero General Public License as published
+    by the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    Gadgetbridge is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Affero General Public License for more details.
+
+    You should have received a copy of the GNU Affero General Public License
+    along with this program.  If not, see <http://www.gnu.org/licenses/>. */
+package nodomain.freeyourgadget.gadgetbridge.devices.lefun.commands;
+
+import java.nio.ByteBuffer;
+
+import nodomain.freeyourgadget.gadgetbridge.devices.lefun.LefunConstants;
+
+public class RemoteCameraTriggeredCommand extends BaseCommand {
+    @Override
+    protected void deserializeParams(byte id, ByteBuffer params) {
+        validateIdAndLength(id, params, LefunConstants.CMD_REMOTE_CAMERA_TRIGGERED, 0);
+    }
+
+    @Override
+    protected byte serializeParams(ByteBuffer params) {
+        // No handler on device side
+        throw new UnsupportedOperationException();
+    }
+}

app/src/main/java/nodomain/freeyourgadget/gadgetbridge/devices/lefun/commands/RequestBondingCommand.java

@@ -0,0 +1,46 @@
+/*  Copyright (C) 2016-2020 Andreas Shimokawa, Carsten Pfeiffer, Daniele
+    Gobbetti
+    Copyright (C) 2020 Yukai Li
+
+    This file is part of Gadgetbridge.
+
+    Gadgetbridge is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Affero General Public License as published
+    by the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    Gadgetbridge is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Affero General Public License for more details.
+
+    You should have received a copy of the GNU Affero General Public License
+    along with this program.  If not, see <http://www.gnu.org/licenses/>. */
+package nodomain.freeyourgadget.gadgetbridge.devices.lefun.commands;
+
+import java.nio.ByteBuffer;
+
+import nodomain.freeyourgadget.gadgetbridge.devices.lefun.LefunConstants;
+
+public class RequestBondingCommand extends BaseCommand {
+    public static final byte STATUS_ALREADY_BONDED = 0;
+    public static final byte STATUS_BONDING_SUCCESSFUL = 1;
+
+    private byte status;
+
+    public byte getStatus() {
+        return status;
+    }
+
+    @Override
+    protected void deserializeParams(byte id, ByteBuffer params) {
+        validateIdAndLength(id, params, LefunConstants.CMD_BONDING_REQUEST, 1);
+
+        status = params.get();
+    }
+
+    @Override
+    protected byte serializeParams(ByteBuffer params) {
+        return LefunConstants.CMD_BONDING_REQUEST;
+    }
+}

app/src/main/java/nodomain/freeyourgadget/gadgetbridge/devices/lefun/commands/SedentaryReminderIntervalCommand.java

@@ -0,0 +1,86 @@
+/*  Copyright (C) 2016-2020 Andreas Shimokawa, Carsten Pfeiffer, Daniele
+    Gobbetti
+    Copyright (C) 2020 Yukai Li
+
+    This file is part of Gadgetbridge.
+
+    Gadgetbridge is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Affero General Public License as published
+    by the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    Gadgetbridge is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Affero General Public License for more details.
+
+    You should have received a copy of the GNU Affero General Public License
+    along with this program.  If not, see <http://www.gnu.org/licenses/>. */
+package nodomain.freeyourgadget.gadgetbridge.devices.lefun.commands;
+
+import java.nio.ByteBuffer;
+
+import nodomain.freeyourgadget.gadgetbridge.devices.lefun.LefunConstants;
+
+public class SedentaryReminderIntervalCommand extends BaseCommand {
+    private byte op;
+    private byte sedentaryReminderInterval;
+
+    private boolean setSuccess;
+
+    public byte getOp() {
+        return op;
+    }
+
+    public void setOp(byte op) {
+        if (op != OP_GET && op != OP_SET)
+            throw new IllegalArgumentException("Operation must be get or set");
+        this.op = op;
+    }
+
+    public byte getSedentaryReminderInterval() {
+        return sedentaryReminderInterval;
+    }
+
+    public void setSedentaryReminderInterval(byte sedentaryReminderInterval) {
+        if (sedentaryReminderInterval == 0)
+            throw new IllegalArgumentException("Interval must be non-zero");
+        this.sedentaryReminderInterval = sedentaryReminderInterval;
+    }
+
+    public boolean isSetSuccess() {
+        return setSuccess;
+    }
+
+    @Override
+    protected void deserializeParams(byte id, ByteBuffer params) {
+        validateId(id, LefunConstants.CMD_SEDENTARY_REMINDER_INTERVAL);
+
+        if (params.limit() < 1)
+            throwUnexpectedLength();
+
+        op = params.get();
+        if (op == OP_GET) {
+            if (params.limit() != 2)
+                throwUnexpectedLength();
+
+            sedentaryReminderInterval = params.get();
+        } else if (op == OP_SET) {
+            if (params.limit() != 2)
+                throwUnexpectedLength();
+
+            setSuccess = params.get() == 1;
+        } else {
+            throw new IllegalArgumentException("Invalid operation type received");
+        }
+    }
+
+    @Override
+    protected byte serializeParams(ByteBuffer params) {
+        params.put(op);
+        if (op == OP_SET) {
+            params.put(sedentaryReminderInterval);
+        }
+        return LefunConstants.CMD_SEDENTARY_REMINDER_INTERVAL;
+    }
+}

app/src/main/java/nodomain/freeyourgadget/gadgetbridge/devices/lefun/commands/SetLanguageCommand.java

@@ -0,0 +1,54 @@
+package nodomain.freeyourgadget.gadgetbridge.devices.lefun.commands;
+
+import java.nio.ByteBuffer;
+
+import nodomain.freeyourgadget.gadgetbridge.devices.lefun.LefunConstants;
+
+/*  Copyright (C) 2016-2020 Andreas Shimokawa, Carsten Pfeiffer, Daniele
+    Gobbetti
+    Copyright (C) 2020 Yukai Li
+
+    This file is part of Gadgetbridge.
+
+    Gadgetbridge is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Affero General Public License as published
+    by the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    Gadgetbridge is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Affero General Public License for more details.
+
+    You should have received a copy of the GNU Affero General Public License
+    along with this program.  If not, see <http://www.gnu.org/licenses/>. */
+public class SetLanguageCommand extends BaseCommand {
+    private byte language;
+
+    private boolean setSuccess;
+
+    public byte getLanguage() {
+        return language;
+    }
+
+    public void setLanguage(byte language) {
+        this.language = language;
+    }
+
+    public boolean isSetSuccess() {
+        return setSuccess;
+    }
+
+    @Override
+    protected void deserializeParams(byte id, ByteBuffer params) {
+        validateIdAndLength(id, params, LefunConstants.CMD_LANGUAGE, 1);
+
+        setSuccess = params.get() == 1;
+    }
+
+    @Override
+    protected byte serializeParams(ByteBuffer params) {
+        params.put(language);
+        return LefunConstants.CMD_LANGUAGE;
+    }
+}

app/src/main/java/nodomain/freeyourgadget/gadgetbridge/devices/lefun/commands/SetRemoteCameraCommand.java

@@ -0,0 +1,54 @@
+/*  Copyright (C) 2016-2020 Andreas Shimokawa, Carsten Pfeiffer, Daniele
+    Gobbetti
+    Copyright (C) 2020 Yukai Li
+
+    This file is part of Gadgetbridge.
+
+    Gadgetbridge is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Affero General Public License as published
+    by the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    Gadgetbridge is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Affero General Public License for more details.
+
+    You should have received a copy of the GNU Affero General Public License
+    along with this program.  If not, see <http://www.gnu.org/licenses/>. */
+package nodomain.freeyourgadget.gadgetbridge.devices.lefun.commands;
+
+import java.nio.ByteBuffer;
+
+import nodomain.freeyourgadget.gadgetbridge.devices.lefun.LefunConstants;
+
+public class SetRemoteCameraCommand extends BaseCommand {
+    private boolean remoteCameraEnabled;
+
+    private boolean setSuccess;
+
+    public boolean getRemoteCameraEnabled() {
+        return remoteCameraEnabled;
+    }
+
+    public void setRemoteCameraEnabled(boolean remoteCameraEnabled) {
+        this.remoteCameraEnabled = remoteCameraEnabled;
+    }
+
+    public boolean isSetSuccess() {
+        return setSuccess;
+    }
+
+    @Override
+    protected void deserializeParams(byte id, ByteBuffer params) {
+        validateIdAndLength(id, params, LefunConstants.CMD_REMOTE_CAMERA, 1);
+
+        setSuccess = params.get() == 1;
+    }
+
+    @Override
+    protected byte serializeParams(ByteBuffer params) {
+        params.put((byte)(remoteCameraEnabled ? 1 : 0));
+        return LefunConstants.CMD_REMOTE_CAMERA;
+    }
+}

app/src/main/java/nodomain/freeyourgadget/gadgetbridge/devices/lefun/commands/SettingsCommand.java

@@ -0,0 +1,117 @@
+/*  Copyright (C) 2016-2020 Andreas Shimokawa, Carsten Pfeiffer, Daniele
+    Gobbetti
+    Copyright (C) 2020 Yukai Li
+
+    This file is part of Gadgetbridge.
+
+    Gadgetbridge is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Affero General Public License as published
+    by the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    Gadgetbridge is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Affero General Public License for more details.
+
+    You should have received a copy of the GNU Affero General Public License
+    along with this program.  If not, see <http://www.gnu.org/licenses/>. */
+package nodomain.freeyourgadget.gadgetbridge.devices.lefun.commands;
+
+import java.nio.ByteBuffer;
+
+import nodomain.freeyourgadget.gadgetbridge.devices.lefun.LefunConstants;
+
+public class SettingsCommand extends BaseCommand {
+    public static final byte AM_PM_24_HOUR = 0;
+    public static final byte AM_PM_12_HOUR = 1;
+    public static final byte MEASUREMENT_UNIT_METRIC = 0;
+    public static final byte MEASUREMENT_UNIT_IMPERIAL = 1;
+
+    private byte op;
+    private byte option1;
+    private byte amPmIndicator;
+    private byte measurementUnit;
+
+    private boolean setSuccess;
+
+    public byte getOp() {
+        return op;
+    }
+
+    public void setOp(byte op) {
+        if (op != OP_GET && op != OP_SET)
+            throw new IllegalArgumentException("Operation must be get or set");
+        this.op = op;
+    }
+
+    public byte getOption1() {
+        return option1;
+    }
+
+    public void setOption1(byte option1) {
+        if (option1 < 0 || option1 > 24)
+            throw new IllegalArgumentException("option1 must be between 0 and 24 inclusive");
+        this.option1 = option1;
+    }
+
+    public byte getAmPmIndicator() {
+        return amPmIndicator;
+    }
+
+    public void setAmPmIndicator(byte amPmIndicator) {
+        if (amPmIndicator != AM_PM_12_HOUR && amPmIndicator != AM_PM_24_HOUR)
+            throw new IllegalArgumentException("Indicator must be 12 or 24 hours");
+        this.amPmIndicator = amPmIndicator;
+    }
+
+    public byte getMeasurementUnit() {
+        return measurementUnit;
+    }
+
+    public void setMeasurementUnit(byte measurementUnit) {
+        if (measurementUnit != MEASUREMENT_UNIT_METRIC && measurementUnit != MEASUREMENT_UNIT_IMPERIAL)
+            throw new IllegalArgumentException(("Unit must be metric or imperial"));
+        this.measurementUnit = measurementUnit;
+    }
+
+    public boolean isSetSuccess() {
+        return setSuccess;
+    }
+
+    @Override
+    protected void deserializeParams(byte id, ByteBuffer params) {
+        validateId(id, LefunConstants.CMD_SETTINGS);
+
+        if (params.limit() < 1)
+            throwUnexpectedLength();
+
+        op = params.get();
+        if (op == OP_GET) {
+            if (params.limit() != 4)
+                throwUnexpectedLength();
+
+            option1 = params.get();
+            amPmIndicator = params.get();
+            measurementUnit = params.get();
+        } else if (op == OP_SET) {
+            if (params.limit() != 2)
+                throwUnexpectedLength();
+
+            setSuccess = params.get() == 1;
+        } else {
+            throw new IllegalArgumentException("Invalid operation type received");
+        }
+    }
+
+    @Override
+    protected byte serializeParams(ByteBuffer params) {
+        params.put(op);
+        if (op == OP_SET) {
+            params.put(option1);
+            params.put(amPmIndicator);
+            params.put(measurementUnit);
+        }
+        return LefunConstants.CMD_SETTINGS;
+    }
+}

app/src/main/java/nodomain/freeyourgadget/gadgetbridge/devices/lefun/commands/StartPpgSensingCommand.java

@@ -0,0 +1,57 @@
+/*  Copyright (C) 2016-2020 Andreas Shimokawa, Carsten Pfeiffer, Daniele
+    Gobbetti
+    Copyright (C) 2020 Yukai Li
+
+    This file is part of Gadgetbridge.
+
+    Gadgetbridge is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Affero General Public License as published
+    by the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    Gadgetbridge is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Affero General Public License for more details.
+
+    You should have received a copy of the GNU Affero General Public License
+    along with this program.  If not, see <http://www.gnu.org/licenses/>. */
+package nodomain.freeyourgadget.gadgetbridge.devices.lefun.commands;
+
+import java.nio.ByteBuffer;
+
+import nodomain.freeyourgadget.gadgetbridge.devices.lefun.LefunConstants;
+
+public class StartPpgSensingCommand extends BaseCommand {
+    private byte ppgType;
+
+    private boolean setSuccess;
+
+    public int getPpgType() {
+        return getLowestSetBitIndex(ppgType);
+    }
+
+    public void setPpgType(int type) {
+        if (type < 0 || type > 2)
+            throw new IllegalArgumentException("Invalid PPG type");
+        this.ppgType = (byte)(1 << type);
+    }
+
+    public boolean isSetSuccess() {
+        return setSuccess;
+    }
+
+    @Override
+    protected void deserializeParams(byte id, ByteBuffer params) {
+        validateIdAndLength(id, params, LefunConstants.CMD_PPG_START, 2);
+
+        ppgType = params.get();
+        setSuccess = params.get() == 1;
+    }
+
+    @Override
+    protected byte serializeParams(ByteBuffer params) {
+        params.put(ppgType);
+        return LefunConstants.CMD_PPG_START;
+    }
+}

app/src/main/java/nodomain/freeyourgadget/gadgetbridge/devices/lefun/commands/TimeCommand.java

@@ -0,0 +1,149 @@
+/*  Copyright (C) 2016-2020 Andreas Shimokawa, Carsten Pfeiffer, Daniele
+    Gobbetti
+    Copyright (C) 2020 Yukai Li
+
+    This file is part of Gadgetbridge.
+
+    Gadgetbridge is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Affero General Public License as published
+    by the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    Gadgetbridge is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Affero General Public License for more details.
+
+    You should have received a copy of the GNU Affero General Public License
+    along with this program.  If not, see <http://www.gnu.org/licenses/>. */
+package nodomain.freeyourgadget.gadgetbridge.devices.lefun.commands;
+
+import java.nio.ByteBuffer;
+
+import nodomain.freeyourgadget.gadgetbridge.devices.lefun.LefunConstants;
+
+public class TimeCommand extends BaseCommand {
+    private byte op;
+    private byte year;
+    private byte month;
+    private byte day;
+    private byte hour;
+    private byte minute;
+    private byte second;
+
+    private boolean setSuccess;
+
+    public byte getOp() {
+        if (op != OP_GET && op != OP_SET)
+            throw new IllegalArgumentException("Operation must be get or set");
+        return op;
+    }
+
+    public void setOp(byte op) {
+        this.op = op;
+    }
+
+    public byte getYear() {
+        return year;
+    }
+
+    public void setYear(byte year) {
+        this.year = year;
+    }
+
+    public byte getMonth() {
+        return month;
+    }
+
+    public void setMonth(byte month) {
+        if (month < 1 || month > 12)
+            throw new IllegalArgumentException("Month must be between 1 and 12 inclusive");
+        this.month = month;
+    }
+
+    public byte getDay() {
+        return day;
+    }
+
+    public void setDay(byte day) {
+        if (day < 1 || day > 31)
+            throw new IllegalArgumentException("Day must be between 1 and 31 inclusive");
+        this.day = day;
+    }
+
+    public byte getHour() {
+        return hour;
+    }
+
+    public void setHour(byte hour) {
+        if (hour < 0 || hour > 23)
+            throw new IllegalArgumentException("Hour must be between 0 and 23 inclusive");
+        this.hour = hour;
+    }
+
+    public byte getMinute() {
+        return minute;
+    }
+
+    public void setMinute(byte minute) {
+        if (minute < 0 || minute > 59)
+            throw new IllegalArgumentException("Minute must be between 0 and 59 inclusive");
+        this.minute = minute;
+    }
+
+    public byte getSecond() {
+        return second;
+    }
+
+    public void setSecond(byte second) {
+        if (second < 0 || second > 59)
+            throw new IllegalArgumentException("Second must be between 0 and 59 inclusive");
+        this.second = second;
+    }
+
+    public boolean isSetSuccess() {
+        return setSuccess;
+    }
+
+    @Override
+    protected void deserializeParams(byte id, ByteBuffer params) {
+        validateId(id, LefunConstants.CMD_TIME);
+
+        if (params.limit() < 1)
+            throwUnexpectedLength();
+
+        op = params.get();
+        if (op == OP_GET) {
+            if (params.limit() != 7)
+                throwUnexpectedLength();
+
+            year = params.get();
+            month = params.get();
+            day = params.get();
+            hour = params.get();
+            minute = params.get();
+            second = params.get();
+        } else if (op == OP_SET) {
+            if (params.limit() != 2)
+                throwUnexpectedLength();
+
+            setSuccess = params.get() == 1;
+        } else {
+            throw new IllegalArgumentException("Invalid operation type received");
+        }
+    }
+
+    @Override
+    protected byte serializeParams(ByteBuffer params) {
+        params.put(op);
+        if (op == OP_SET) {
+            params.put(year);
+            params.put(month);
+            params.put(day);
+            params.put(hour);
+            params.put(minute);
+            params.put(second);
+        }
+        return LefunConstants.CMD_TIME;
+    }
+}

app/src/main/java/nodomain/freeyourgadget/gadgetbridge/devices/lefun/commands/UiPagesCommand.java

@@ -0,0 +1,91 @@
+/*  Copyright (C) 2016-2020 Andreas Shimokawa, Carsten Pfeiffer, Daniele
+    Gobbetti
+    Copyright (C) 2020 Yukai Li
+
+    This file is part of Gadgetbridge.
+
+    Gadgetbridge is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Affero General Public License as published
+    by the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    Gadgetbridge is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Affero General Public License for more details.
+
+    You should have received a copy of the GNU Affero General Public License
+    along with this program.  If not, see <http://www.gnu.org/licenses/>. */
+package nodomain.freeyourgadget.gadgetbridge.devices.lefun.commands;
+
+import java.nio.ByteBuffer;
+
+import nodomain.freeyourgadget.gadgetbridge.devices.lefun.LefunConstants;
+
+public class UiPagesCommand extends BaseCommand {
+    // I don't know which pages since they're not implemented in my watch, so no
+    // constants here for now
+
+    private byte op;
+    private short pages;
+
+    private boolean setSuccess;
+
+    public byte getOp() {
+        return op;
+    }
+
+    public void setOp(byte op) {
+        if (op != OP_GET && op != OP_SET)
+            throw new IllegalArgumentException("Operation must be get or set");
+        this.op = op;
+    }
+
+    public boolean getPage(int index) {
+        if (index < 0 || index >= 16)
+            throw new IllegalArgumentException("Index must be between 0 and 15 inclusive");
+        return getBit(pages, 1 << index);
+    }
+
+    public void setPage(int index, boolean enabled) {
+        if (index < 0 || index >= 16)
+            throw new IllegalArgumentException("Index must be between 0 and 15 inclusive");
+        pages = setBit(pages, 1 << index, enabled);
+    }
+
+    public boolean isSetSuccess() {
+        return setSuccess;
+    }
+
+    @Override
+    protected void deserializeParams(byte id, ByteBuffer params) {
+        validateId(id, LefunConstants.CMD_UI_PAGES);
+
+        if (params.limit() < 1)
+            throwUnexpectedLength();
+
+        op = params.get();
+        if (op == OP_GET) {
+            if (params.limit() != 3)
+                throwUnexpectedLength();
+
+            pages = params.getShort();
+        } else if (op == OP_SET) {
+            if (params.limit() != 2)
+                throwUnexpectedLength();
+
+            setSuccess = params.get() == 1;
+        } else {
+            throw new IllegalArgumentException("Invalid operation type received");
+        }
+    }
+
+    @Override
+    protected byte serializeParams(ByteBuffer params) {
+        params.put(op);
+        if (op == OP_SET) {
+            params.putShort(pages);
+        }
+        return LefunConstants.CMD_UI_PAGES;
+    }
+}