package com.topjohnwu.magisk;

import android.content.ContentProvider;
import android.content.ContentValues;
import android.content.Context;
import android.content.pm.ProviderInfo;
import android.database.Cursor;
import android.database.MatrixCursor;
import android.net.Uri;
import android.os.Environment;
import android.os.ParcelFileDescriptor;
import android.provider.OpenableColumns;
import android.text.TextUtils;
import android.webkit.MimeTypeMap;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.util.HashMap;
import java.util.Map;

/**
 * Modified from androidx.core.content.FileProvider
 */
public class FileProvider extends ContentProvider {
    private static final String[] COLUMNS = {OpenableColumns.DISPLAY_NAME, OpenableColumns.SIZE};

    private static final File DEVICE_ROOT = new File("/");

    private static final HashMap<String, PathStrategy> sCache = new HashMap<>();

    private PathStrategy mStrategy;

    @Override
    public boolean onCreate() {
        return true;
    }

    @Override
    public void attachInfo(Context context, ProviderInfo info) {
        super.attachInfo(context, info);

        if (info.exported) {
            throw new SecurityException("Provider must not be exported");
        }
        if (!info.grantUriPermissions) {
            throw new SecurityException("Provider must grant uri permissions");
        }

        mStrategy = getPathStrategy(context, info.authority.split(";")[0]);
    }

    public static Uri getUriForFile(Context context, String authority, File file) {
        final PathStrategy strategy = getPathStrategy(context, authority);
        return strategy.getUriForFile(file);
    }

    @Override
    public Cursor query(Uri uri, String[] projection, String selection, String[] selectionArgs, String sortOrder) {
        final File file = mStrategy.getFileForUri(uri);

        if (projection == null) {
            projection = COLUMNS;
        }

        String[] cols = new String[projection.length];
        Object[] values = new Object[projection.length];
        int i = 0;
        for (String col : projection) {
            if (OpenableColumns.DISPLAY_NAME.equals(col)) {
                cols[i] = OpenableColumns.DISPLAY_NAME;
                values[i++] = file.getName();
            } else if (OpenableColumns.SIZE.equals(col)) {
                cols[i] = OpenableColumns.SIZE;
                values[i++] = file.length();
            }
        }

        cols = copyOf(cols, i);
        values = copyOf(values, i);

        final MatrixCursor cursor = new MatrixCursor(cols, 1);
        cursor.addRow(values);
        return cursor;
    }

    @Override
    public String getType(Uri uri) {
        final File file = mStrategy.getFileForUri(uri);

        final int lastDot = file.getName().lastIndexOf('.');
        if (lastDot >= 0) {
            final String extension = file.getName().substring(lastDot + 1);
            final String mime = MimeTypeMap.getSingleton().getMimeTypeFromExtension(extension);
            if (mime != null) {
                return mime;
            }
        }

        return "application/octet-stream";
    }

    @Override
    public Uri insert(Uri uri, ContentValues values) {
        throw new UnsupportedOperationException("No external inserts");
    }

    @Override
    public int update(Uri uri, ContentValues values, String selection, String[] selectionArgs) {
        throw new UnsupportedOperationException("No external updates");
    }

    @Override
    public int delete(Uri uri, String selection, String[] selectionArgs) {
        final File file = mStrategy.getFileForUri(uri);
        return file.delete() ? 1 : 0;
    }

    @Override
    public ParcelFileDescriptor openFile(Uri uri, String mode) throws FileNotFoundException {
        final File file = mStrategy.getFileForUri(uri);
        final int fileMode = modeToMode(mode);
        return ParcelFileDescriptor.open(file, fileMode);
    }

    private static PathStrategy getPathStrategy(Context context, String authority) {
        PathStrategy strat;
        synchronized (sCache) {
            strat = sCache.get(authority);
            if (strat == null) {
                strat = createPathStrategy(context, authority);
                sCache.put(authority, strat);
            }
        }
        return strat;
    }

    private static PathStrategy createPathStrategy(Context context, String authority) {
        final SimplePathStrategy strat = new SimplePathStrategy(authority);

        strat.addRoot("root_files", buildPath(DEVICE_ROOT, "."));
        strat.addRoot("internal_files", buildPath(context.getFilesDir(), "."));
        strat.addRoot("cache_files", buildPath(context.getCacheDir(), "."));
        strat.addRoot("external_files", buildPath(Environment.getExternalStorageDirectory(), "."));

        File[] externalFilesDirs = context.getExternalFilesDirs(null);
        if (externalFilesDirs.length > 0) {
            strat.addRoot("external_file_files", buildPath(externalFilesDirs[0], "."));
        }
        File[] externalCacheDirs = context.getExternalCacheDirs();
        if (externalCacheDirs.length > 0) {
            strat.addRoot("external_cache_files", buildPath(externalCacheDirs[0], "."));
        }
        File[] externalMediaDirs = context.getExternalMediaDirs();
        if (externalMediaDirs.length > 0) {
            strat.addRoot("external_media_files", buildPath(externalMediaDirs[0], "."));
        }

        return strat;
    }

    interface PathStrategy {
        Uri getUriForFile(File file);

        File getFileForUri(Uri uri);
    }

    static class SimplePathStrategy implements PathStrategy {
        private final String mAuthority;
        private final HashMap<String, File> mRoots = new HashMap<>();

        SimplePathStrategy(String authority) {
            mAuthority = authority;
        }

        void addRoot(String name, File root) {
            if (TextUtils.isEmpty(name)) {
                throw new IllegalArgumentException("Name must not be empty");
            }

            try {
                root = root.getCanonicalFile();
            } catch (IOException e) {
                throw new IllegalArgumentException(
                        "Failed to resolve canonical path for " + root, e);
            }

            mRoots.put(name, root);
        }

        @Override
        public Uri getUriForFile(File file) {
            String path;
            try {
                path = file.getCanonicalPath();
            } catch (IOException e) {
                throw new IllegalArgumentException("Failed to resolve canonical path for " + file);
            }

            Map.Entry<String, File> mostSpecific = null;
            for (Map.Entry<String, File> root : mRoots.entrySet()) {
                final String rootPath = root.getValue().getPath();
                if (path.startsWith(rootPath) && (mostSpecific == null
                        || rootPath.length() > mostSpecific.getValue().getPath().length())) {
                    mostSpecific = root;
                }
            }

            if (mostSpecific == null) {
                throw new IllegalArgumentException(
                        "Failed to find configured root that contains " + path);
            }

            final String rootPath = mostSpecific.getValue().getPath();
            if (rootPath.endsWith("/")) {
                path = path.substring(rootPath.length());
            } else {
                path = path.substring(rootPath.length() + 1);
            }

            path = Uri.encode(mostSpecific.getKey()) + '/' + Uri.encode(path, "/");
            return new Uri.Builder().scheme("content")
                    .authority(mAuthority).encodedPath(path).build();
        }

        @Override
        public File getFileForUri(Uri uri) {
            String path = uri.getEncodedPath();

            final int splitIndex = path.indexOf('/', 1);
            final String tag = Uri.decode(path.substring(1, splitIndex));
            path = Uri.decode(path.substring(splitIndex + 1));

            final File root = mRoots.get(tag);
            if (root == null) {
                throw new IllegalArgumentException("Unable to find configured root for " + uri);
            }

            File file = new File(root, path);
            try {
                file = file.getCanonicalFile();
            } catch (IOException e) {
                throw new IllegalArgumentException("Failed to resolve canonical path for " + file);
            }

            if (!file.getPath().startsWith(root.getPath())) {
                throw new SecurityException("Resolved path jumped beyond configured root");
            }

            return file;
        }
    }

    private static int modeToMode(String mode) {
        int modeBits;
        if ("r".equals(mode)) {
            modeBits = ParcelFileDescriptor.MODE_READ_ONLY;
        } else if ("w".equals(mode) || "wt".equals(mode)) {
            modeBits = ParcelFileDescriptor.MODE_WRITE_ONLY
                    | ParcelFileDescriptor.MODE_CREATE
                    | ParcelFileDescriptor.MODE_TRUNCATE;
        } else if ("wa".equals(mode)) {
            modeBits = ParcelFileDescriptor.MODE_WRITE_ONLY
                    | ParcelFileDescriptor.MODE_CREATE
                    | ParcelFileDescriptor.MODE_APPEND;
        } else if ("rw".equals(mode)) {
            modeBits = ParcelFileDescriptor.MODE_READ_WRITE
                    | ParcelFileDescriptor.MODE_CREATE;
        } else if ("rwt".equals(mode)) {
            modeBits = ParcelFileDescriptor.MODE_READ_WRITE
                    | ParcelFileDescriptor.MODE_CREATE
                    | ParcelFileDescriptor.MODE_TRUNCATE;
        } else {
            throw new IllegalArgumentException("Invalid mode: " + mode);
        }
        return modeBits;
    }

    private static File buildPath(File base, String... segments) {
        File cur = base;
        for (String segment : segments) {
            if (segment != null) {
                cur = new File(cur, segment);
            }
        }
        return cur;
    }

    private static String[] copyOf(String[] original, int newLength) {
        final String[] result = new String[newLength];
        System.arraycopy(original, 0, result, 0, newLength);
        return result;
    }

    private static Object[] copyOf(Object[] original, int newLength) {
        final Object[] result = new Object[newLength];
        System.arraycopy(original, 0, result, 0, newLength);
        return result;
    }
}