Refactor

.golangci.yml

@@ -0,0 +1,259 @@
+# options for analysis running
+run:
+  # timeout for analysis, e.g. 30s, 5m, default is 1m
+  timeout: 5m
+
+# output configuration options
+output:
+  # sorts results by: filepath, line and column
+  sort-results: true
+
+# all available settings of specific linters
+linters-settings:
+  cyclop:
+    # the maximal code complexity to report
+    max-complexity: 30
+    # the maximal average package complexity. If it's higher than 0.0 (float) the check is enabled (default 0.0)
+    package-average: 0.0
+    # should ignore tests (default false)
+    skip-tests: true
+
+  dogsled:
+    # checks assignments with too many blank identifiers; default is 2
+    max-blank-identifiers: 2
+
+  dupl:
+    # tokens count to trigger issue, 150 by default
+    threshold: 100
+
+  errcheck:
+    # report about not checking of errors in type assertions: `a := b.(MyStruct)`;
+    # default is false: such cases aren't reported by default.
+    check-type-assertions: true
+
+    # report about assignment of errors to blank identifier: `num, _ := strconv.Atoi(numStr)`;
+    # default is false: such cases aren't reported by default.
+    check-blank: true
+
+  errorlint:
+    # Check whether fmt.Errorf uses the %w verb for formatting errors. See the readme for caveats
+    errorf: true
+    # Check for plain type assertions and type switches
+    asserts: true
+    # Check for plain error comparisons
+    comparison: true
+
+  exhaustive:
+    # indicates that switch statements are to be considered exhaustive if a
+    # 'default' case is present, even if all enum members aren't listed in the
+    # switch
+    default-signifies-exhaustive: true
+
+  exhaustivestruct:
+    # Struct Patterns is list of expressions to match struct packages and names
+    # The struct packages have the form example.com/package.ExampleStruct
+    # The matching patterns can use matching syntax from https://pkg.go.dev/path#Match
+    # If this list is empty, all structs are tested.
+    struct-patterns:
+
+  gocognit:
+    # minimal code complexity to report, 30 by default (but we recommend 10-20)
+    min-complexity: 30
+
+  nestif:
+    # minimal complexity of if statements to report, 5 by default
+    min-complexity: 4
+
+  goconst:
+    # minimal length of string constant, 3 by default
+    min-len: 3
+    # minimal occurrences count to trigger, 3 by default
+    min-occurrences: 3
+
+  gocritic:
+    # Enable multiple checks by tags, run `GL_DEBUG=gocritic golangci-lint run` to see all tags and checks.
+    # Empty list by default. See https://github.com/go-critic/go-critic#usage -> section "Tags".
+    enabled-tags:
+      - diagnostic
+      - style
+      - performance
+    disabled-checks:
+      - paramTypeCombine
+      - commentedOutCode
+      - ifElseChain
+
+    # Settings passed to gocritic.
+    # The settings key is the name of a supported gocritic checker.
+    # The list of supported checkers can be find in https://go-critic.github.io/overview.
+    settings:
+      unnamedResult:
+        # whether to check exported functions
+        checkExported: true
+
+  gocyclo:
+    # minimal code complexity to report, 30 by default (but we recommend 10-20)
+    min-complexity: 30
+
+  godot:
+    # comments to be checked: `declarations`, `toplevel`, or `all`
+    scope: declarations
+
+    # check that each sentence starts with a capital letter
+    capital: true
+
+  gofmt:
+    # simplify code: gofmt with `-s` option, true by default
+    simplify: true
+
+  gofumpt:
+    # Choose whether or not to use the extra rules that are disabled
+    # by default
+    extra-rules: false
+
+  golint:
+    # minimal confidence for issues, default is 0.8
+    min-confidence: 0.8
+
+  gosimple:
+    # Select the Go version to target. The default is '1.13'.
+    go: "1.20"
+    # https://staticcheck.io/docs/options#checks
+    checks: ["all"]
+
+  govet:
+    # report about shadowed variables
+    check-shadowing: true
+    enable-all: true
+
+  maligned:
+    # print struct with more effective memory layout or not, false by default
+    suggest-new: true
+
+  misspell:
+    # Correct spellings using locale preferences for US or UK.
+    # Default is to use a neutral variety of English.
+    # Setting locale to US will correct the British spelling of 'colour' to 'color'.
+    locale: US
+
+  prealloc:
+    # XXX: we don't recommend using this linter before doing performance profiling.
+    # For most programs usage of prealloc will be a premature optimization.
+
+    # Report preallocation suggestions only on simple loops that have no returns/breaks/continues/gotos in them.
+    # True by default.
+    simple: true
+    range-loops: true
+    for-loops: false
+
+  nolintlint:
+    # Enable to ensure that nolint directives are all used. Default is true.
+    allow-unused: true
+    # Disable to ensure that nolint directives don't have a leading space. Default is true.
+    allow-leading-space: true
+    # Exclude following linters from requiring an explanation.  Default is [].
+    allow-no-explanation: []
+    # Enable to require an explanation of nonzero length after each nolint directive. Default is false.
+    require-explanation: true
+    # Enable to require nolint directives to mention the specific linter being suppressed. Default is false.
+    require-specific: true
+
+  staticcheck:
+    # Select the Go version to target. The default is '1.13'.
+    go: "1.20"
+    # https://staticcheck.io/docs/options#checks
+    checks: ["all"]
+
+  stylecheck:
+    # Select the Go version to target. The default is '1.13'.
+    go: "1.20"
+    # https://staticcheck.io/docs/options#checks
+    checks: ["all"]
+
+  unparam:
+    # Inspect exported functions, default is false. Set to true if no external program/library imports your code.
+    # XXX: if you enable this setting, unparam will report a lot of false-positives in text editors:
+    # if it's called for subdir of a project it can't find external interfaces. All text editor integrations
+    # with golangci-lint call it on a directory with the changed file.
+    check-exported: false
+
+  unused:
+    # Select the Go version to target. The default is '1.13'.
+    go: "1.20"
+
+  whitespace:
+    multi-if: false # Enforces newlines (or comments) after every multi-line if statement
+    multi-func: false # Enforces newlines (or comments) after every multi-line function signature
+
+  wrapcheck:
+    # An array of strings that specify substrings of signatures to ignore.
+    # If this set, it will override the default set of ignored signatures.
+    # See https://github.com/tomarrell/wrapcheck#configuration for more information.
+    ignoreSigs:
+      - .Errorf(
+      - errors.New(
+      - errors.Unwrap(
+      - .Wrap(
+      - .Wrapf(
+      - .WithMessage(
+
+linters:
+  disable:
+    # Don't check for newlines before return
+    - nlreturn
+
+    # Don't check line length
+    - lll
+    - funlen
+    - exhaustivestruct
+
+    # Don't check nested ifs
+    - nestif
+
+    # Don't check var length
+    - varnamelen
+
+    # Don't check excessive blank identifiers
+    - dogsled
+
+    # Don't check json struct field tags
+    - tagliatelle
+
+    # Absolutely useless whitespace linting
+    - wsl
+
+    # Cognitive complexity ;)
+    - gocognit
+
+    # Deprecated
+    - golint
+    - interfacer
+    - scopelint
+
+    # Don't care about this (for now)
+    - exhaustruct
+    - wrapcheck
+    - nonamedreturns
+    - gomnd
+
+  enable-all: true
+  fast: false
+
+issues:
+  # Fix found issues (if it's supported by the linter)
+  fix: true
+
+
+severity:
+  # Default value is empty string.
+  # Set the default severity for issues. If severity rules are defined and the issues
+  # do not match or no severity is provided to the rule this will be the default
+  # severity applied. Severities should match the supported severity names of the
+  # selected out format.
+  # - Code climate: https://docs.codeclimate.com/docs/issues#issue-severity
+  # -   Checkstyle: https://checkstyle.sourceforge.io/property_types.html#severity
+  # -       Github: https://help.github.com/en/actions/reference/workflow-commands-for-github-actions#setting-an-error-message
+  default-severity: error
+
+  # The default value is false.
+  # If set to true severity-rules regular expressions become case sensitive.
+  case-sensitive: false

Dockerfile

@@ -1,14 +1,23 @@
-FROM golang:1.19
+FROM golangci/golangci-lint:latest-alpine
+FROM golang:alpine
 
-RUN mkdir -p /app
+COPY --from=0 /usr/bin/golangci-lint /usr/bin/golangci-lint
+RUN apk add --no-cache gcc libc-dev
 
 WORKDIR /app
-ADD . /app
+COPY src /app/
 
-RUN rm -rf go.mod go.sum config.json cache.json; \
-    touch config.json; \
-    go mod init ecodash; \
-    go mod tidy
-RUN go build -o app .
+RUN golangci-lint run
+RUN go test ./src/...
+
+RUN CGO_ENABLED=1 go build -o app src/main.go
+
+FROM alpine:latest
+
+WORKDIR /app
+
+COPY --from=1 /app/app .
+COPY ./templates /app/templates
+RUN touch config.json
 
 CMD ["./app"]

go.mod

@@ -1,6 +1,6 @@
-module ecodash
+module git.massivebox.net/ecodash/ecodash
 
-go 1.17
+go 1.20
 
 require (
 	github.com/gofiber/fiber/v2 v2.37.1

src/api.go

@@ -1,8 +1,10 @@
 package main
 
 import (
+	"context"
 	"encoding/json"
 	"errors"
+	"fmt"
 	"io"
 	"log"
 	"math"
@@ -13,8 +15,8 @@ import (
 )
 
 type HistoryResult []struct {
-	State       string    `json:"state"`
 	LastUpdated time.Time `json:"last_updated"`
+	State       string    `json:"state"`
 }
 
 func dayStart(t time.Time) time.Time {
@@ -22,13 +24,20 @@ func dayStart(t time.Time) time.Time {
 	return t.Add(-(time.Duration(hours)*time.Hour + time.Duration(minutes)*time.Minute + time.Duration(seconds)*time.Second))
 }
 
-func (config Config) queryHistory(entityID string, startTime, endTime time.Time) (HistoryResult, error) {
+var errNon200 = errors.New("got a non-200 status code. Check the correctness of sensors IDs")
 
-	req, err := http.NewRequest("GET", config.HomeAssistant.BaseURL+
-		"/api/history/period/"+url.QueryEscape(startTime.Format(time.RFC3339))+
-		"?filter_entity_id="+entityID+
-		"&end_time="+url.QueryEscape(endTime.Format(time.RFC3339)), /*+
-		"&minimal_response",*/nil)
+func (config *Config) queryHistory(entityID string, startTime, endTime time.Time) (HistoryResult, error) {
+	ctx, cancel := context.WithTimeout(context.Background(), 1*time.Minute)
+	req, err := http.NewRequestWithContext(
+		ctx,
+		http.MethodGet,
+		config.HomeAssistant.BaseURL+
+			"/api/history/period/"+url.QueryEscape(startTime.Format(time.RFC3339))+
+			"?filter_entity_id="+entityID+
+			"&end_time="+url.QueryEscape(endTime.Format(time.RFC3339)),
+		nil,
+	)
+	cancel()
 	if err != nil {
 		return HistoryResult{}, err
 	}
@@ -42,8 +51,8 @@ func (config Config) queryHistory(entityID string, startTime, endTime time.Time)
 	}
 	defer resp.Body.Close()
 
-	if resp.StatusCode != 200 {
-		return HistoryResult{}, errors.New("got a non-200 status code. Check the correctness of sensors IDs -" + resp.Status)
+	if resp.StatusCode != http.StatusOK {
+		return HistoryResult{}, fmt.Errorf("%w - %s", errNon200, resp.Status)
 	}
 
 	body, err := io.ReadAll(resp.Body)
@@ -62,30 +71,26 @@ func (config Config) queryHistory(entityID string, startTime, endTime time.Time)
 	}
 
 	return result[0], nil
-
 }
 
 // t can be any time during the desired day.
-func (config Config) getDayHistory(entityID string, t time.Time) (HistoryResult, error) {
-
+func (config *Config) getDayHistory(entityID string, t time.Time) (HistoryResult, error) {
 	hours, minutes, seconds := t.Clock()
 	endTime := t.Add(time.Duration(23-hours)*time.Hour + time.Duration(59-minutes)*time.Minute + time.Duration(59-seconds)*time.Second)
 
 	return config.queryHistory(entityID, dayStart(t), endTime)
-
 }
 
 type DayData struct {
-	DayNumber    int
 	DayTime      time.Time
+	DayNumber    int
 	Measurements int
 	Value        float32
 	High         float32
 	Low          float32
 }
 
-func (config Config) historyAverageAndConvertToGreen(entityID string, t time.Time) (DayData, error) {
-
+func (config *Config) historyAverageAndConvertToGreen(entityID string, t time.Time) (DayData, error) {
 	history, err := config.getDayHistory(entityID, t)
 	if err != nil {
 		return DayData{}, err
@@ -94,7 +99,6 @@ func (config Config) historyAverageAndConvertToGreen(entityID string, t time.Tim
 	var day DayData
 
 	for _, historyChange := range history {
-
 		val, err := strconv.ParseFloat(historyChange.State, 32)
 		if err != nil {
 			continue
@@ -102,16 +106,13 @@ func (config Config) historyAverageAndConvertToGreen(entityID string, t time.Tim
 
 		day.Value += float32(val)
 		day.Measurements++
-
 	}
 
 	day.Value = 100 - (day.Value / float32(day.Measurements))
 	return day, nil
-
 }
 
-func (config Config) historyBulkAverageAndConvertToGreen(entityID string, startTime, endTime time.Time) ([]DayData, error) {
-
+func (config *Config) historyBulkAverageAndConvertToGreen(entityID string, startTime, endTime time.Time) ([]DayData, error) {
 	history, err := config.queryHistory(entityID, startTime, endTime)
 	if err != nil {
 		return nil, err
@@ -154,11 +155,9 @@ func (config Config) historyBulkAverageAndConvertToGreen(entityID string, startT
 	days = fillMissing(days, startTime, endTime)
 
 	return days, nil
-
 }
 
-func (config Config) historyDelta(entityID string, t time.Time) (DayData, error) {
-
+func (config *Config) historyDelta(entityID string, t time.Time) (DayData, error) {
 	history, err := config.getDayHistory(entityID, t)
 	if err != nil {
 		return DayData{}, err
@@ -167,7 +166,6 @@ func (config Config) historyDelta(entityID string, t time.Time) (DayData, error)
 	var day DayData
 
 	for _, historyChange := range history {
-
 		val, err := strconv.ParseFloat(historyChange.State, 32)
 		if err != nil {
 			continue
@@ -180,16 +178,13 @@ func (config Config) historyDelta(entityID string, t time.Time) (DayData, error)
 		if value < day.Low || day.Low == 0 {
 			day.Low = value
 		}
-
 	}
 
 	day.Value = day.High - day.Low
 	return day, nil
-
 }
 
-func (config Config) historyBulkDelta(entityID string, startTime, endTime time.Time) ([]DayData, error) {
-
+func (config *Config) historyBulkDelta(entityID string, startTime, endTime time.Time) ([]DayData, error) {
 	history, err := config.queryHistory(entityID, startTime, endTime)
 	if err != nil {
 		return nil, err
@@ -198,33 +193,34 @@ func (config Config) historyBulkDelta(entityID string, startTime, endTime time.T
 	var days []DayData
 
 	for _, historyChange := range history {
-		if historyChange.State != "off" {
-			val, err := strconv.ParseFloat(historyChange.State, 32)
-			if err != nil {
-				continue
-			}
-			value := float32(val)
-			var found bool
-			dayNo := dayStart(historyChange.LastUpdated.Local()).Day()
-			for key, day := range days {
-				if dayNo == day.DayNumber {
-					found = true
-					if value > day.High {
-						day.High = value
-					}
-					if value < day.Low || day.Low == 0 {
-						day.Low = value
-					}
-					days[key] = day
+		if historyChange.State == "off" {
+			continue
+		}
+		val, err := strconv.ParseFloat(historyChange.State, 32)
+		if err != nil {
+			continue
+		}
+		value := float32(val)
+		var found bool
+		dayNo := dayStart(historyChange.LastUpdated.Local()).Day()
+		for key, day := range days {
+			if dayNo == day.DayNumber {
+				found = true
+				if value > day.High {
+					day.High = value
 				}
+				if value < day.Low || day.Low == 0 {
+					day.Low = value
+				}
+				days[key] = day
 			}
-			if !found {
-				days = append(days, DayData{
-					DayNumber: dayNo,
-					DayTime:   dayStart(historyChange.LastUpdated.Local()),
-					Value:     value,
-				})
-			}
+		}
+		if !found {
+			days = append(days, DayData{
+				DayNumber: dayNo,
+				DayTime:   dayStart(historyChange.LastUpdated.Local()),
+				Value:     value,
+			})
 		}
 	}
 
@@ -236,11 +232,9 @@ func (config Config) historyBulkDelta(entityID string, startTime, endTime time.T
 	days = fillMissing(days, startTime, endTime)
 
 	return days, nil
-
 }
 
 func fillMissing(days []DayData, startTime, endTime time.Time) []DayData {
-
 	var (
 		previousDay   time.Time
 		defaultDay    time.Time
@@ -252,9 +246,7 @@ func fillMissing(days []DayData, startTime, endTime time.Time) []DayData {
 	expectedDaysDiff := int(math.Trunc(endTime.Sub(startTime).Hours()/24) + 1)
 
 	for key, day := range days {
-
 		if key != 0 {
-
 			if day.DayTime.Day() != previousDay.Add(24*time.Hour).Day() {
 				daysDiff := math.Trunc(day.DayTime.Sub(previousDay).Hours() / 24)
 				for i := 1; float64(i) < daysDiff; i++ {
@@ -266,13 +258,11 @@ func fillMissing(days []DayData, startTime, endTime time.Time) []DayData {
 					})
 				}
 			}
-
 		}
 
 		ret = append(ret, day)
 		previousValue = day.Value
 		previousDay = day.DayTime
-
 	}
 
 	// note that here previousDay is the last logged day
@@ -313,5 +303,4 @@ func fillMissing(days []DayData, startTime, endTime time.Time) []DayData {
 	}
 
 	return ret
-
 }

src/config.go

@@ -6,12 +6,14 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
-	"github.com/gofiber/fiber/v2"
-	_ "github.com/mattn/go-sqlite3"
 	"os"
+	"reflect"
 	"regexp"
 	"strings"
 	"time"
+
+	"github.com/gofiber/fiber/v2"
+	_ "github.com/mattn/go-sqlite3"
 )
 
 type Config struct {
@@ -23,9 +25,9 @@ type Config struct {
 }
 
 type HomeAssistant struct {
+	InstallationDate time.Time `json:"installation_date"`
 	BaseURL          string    `json:"base_url"`
 	ApiKey           string    `json:"api_key"`
-	InstallationDate time.Time `json:"installation_date"`
 }
 type Sensors struct {
 	PolledSmartEnergySummation string `json:"polled_smart_energy_summation"`
@@ -42,31 +44,28 @@ type Dashboard struct {
 	HeaderLinks []Link `json:"header_links"`
 }
 
-func formatURL(url string) (string, error) {
+var errBadHAFormat = errors.New("HomeAssistant base URL is badly formatted")
 
+func formatURL(url string) (string, error) {
 	// the URL we want is: protocol://hostname[:port] without a final /
 
 	if !strings.HasPrefix(url, "http://") && !strings.HasPrefix(url, "https://") {
 		url = "http://" + url
 	}
-	if strings.HasSuffix(url, "/") {
-		url = url[0 : len(url)-1]
-	}
+	url = strings.TrimSuffix(url, "/")
 
 	test := regexp.MustCompile(`(?m)https?:\/\/[^/]*`).ReplaceAllString(url, "")
 	if test != "" {
-		return "", errors.New("HomeAssistant base URL is badly formatted")
+		return "", errBadHAFormat
 	}
 
 	return url, nil
-
 }
 
-func loadConfig() (config Config, err error, isFirstRun bool) {
-
+func loadConfig() (config *Config, isFirstRun bool, err error) {
 	db, err := sql.Open("sqlite3", "./database.db")
 	if err != nil {
-		return Config{}, err, false
+		return &Config{}, false, err
 	}
 
 	_, err = db.Exec(`CREATE TABLE IF NOT EXISTS "cache" (
@@ -76,10 +75,10 @@ func loadConfig() (config Config, err error, isFirstRun bool) {
 		PRIMARY KEY("time")
 	);`)
 	if err != nil {
-		return Config{}, err, false
+		return &Config{}, false, err
 	}
 
-	var defaultConfig = Config{}
+	defaultConfig := &Config{}
 	defaultConfig.Dashboard.Theme = "default"
 	defaultConfig.Dashboard.Name = "EcoDash"
 	defaultConfig.Dashboard.HeaderLinks = append(defaultConfig.Dashboard.HeaderLinks, Link{
@@ -97,35 +96,41 @@ func loadConfig() (config Config, err error, isFirstRun bool) {
 	if err != nil {
 		// if the data file doesn't exist, we consider it a first run
 		if os.IsNotExist(err) {
-			return defaultConfig, nil, true
+			return defaultConfig, true, nil
 		}
-		return Config{}, err, false
+		return &Config{}, false, err
 	}
 
 	// if the data file is empty, we consider it as a first run
-	if string(data) == "" {
-		return defaultConfig, nil, true
+	if len(data) == 0 {
+		return defaultConfig, true, nil
 	}
 
-	var conf Config
+	conf := &Config{}
 	err = json.Unmarshal(data, &conf)
 	if err != nil {
-		return Config{}, err, false
+		return &Config{}, false, err
 	}
 	conf.db = db
 
-	return conf, nil, false
-
+	return conf, false, nil
 }
 
-// just a little utility function to SHA256 strings (for hashing passwords)
+// just a little utility function to SHA256 strings (for hashing passwords).
 func hash(toHash string) string {
 	return fmt.Sprintf("%x", sha256.Sum256([]byte(toHash)))
 }
 
-func (config Config) isAuthorized(c *fiber.Ctx) bool {
+func (config *Config) isAuthorized(c *fiber.Ctx) bool {
 	if config.Administrator.PasswordHash == "" {
 		return true
 	}
 	return c.Cookies("admin_username") == config.Administrator.Username && c.Cookies("admin_password_hash") == config.Administrator.PasswordHash
 }
+
+func (config *Config) equals(new *Config) bool {
+	return reflect.DeepEqual(new.HomeAssistant, config.HomeAssistant) &&
+		reflect.DeepEqual(new.Sensors, config.Sensors) &&
+		reflect.DeepEqual(new.Administrator, config.Administrator) &&
+		reflect.DeepEqual(new.Dashboard, config.Dashboard)
+}

src/database.go

@@ -2,7 +2,7 @@ package main
 
 import (
 	"errors"
-	"fmt"
+	"log"
 	"time"
 )
 
@@ -13,8 +13,7 @@ type HistoryEntry struct {
 }
 type History []HistoryEntry
 
-func (config Config) updateHistory() {
-
+func (config *Config) updateHistory() {
 	greenEnergyPercentage, err := config.historyAverageAndConvertToGreen(config.Sensors.FossilPercentage, time.Now())
 	if err != nil {
 		return
@@ -24,31 +23,34 @@ func (config Config) updateHistory() {
 		return
 	}
 
-	config.db.Exec("INSERT OR REPLACE INTO cache(time,green_energy_percentage,energy_consumption) VALUES (?,?,?);", dayStart(time.Now()).Unix(), greenEnergyPercentage.Value, historyPolledSmartEnergySummation.Value)
+	_, err = config.db.Exec("INSERT OR REPLACE INTO cache(time,green_energy_percentage,energy_consumption) VALUES (?,?,?);", dayStart(time.Now()).Unix(), greenEnergyPercentage.Value, historyPolledSmartEnergySummation.Value)
+	if err != nil {
+		log.Println("Error inserting into cache", err.Error())
+	}
 
 	cached, err := config.readHistory()
 	if err != nil {
 		return
 	}
-	if len(cached) != 8 && time.Now().Sub(config.HomeAssistant.InstallationDate) > 8*time.Hour*24 {
+	if len(cached) != 8 && time.Since(config.HomeAssistant.InstallationDate) > 8*time.Hour*24 {
 		err := config.refreshCacheFromPast(time.Now().Add(-8 * time.Hour * 24))
 		if err != nil {
-			fmt.Println("Error refreshing cache", err.Error())
+			log.Println("Error refreshing cache", err.Error())
 			return
 		}
 	}
-
 }
 
-func (config Config) refreshCacheFromInstall() error {
+func (config *Config) refreshCacheFromInstall() error {
 	return config.refreshCacheFromPast(config.HomeAssistant.InstallationDate)
 }
 
-func (config Config) refreshCacheFromPast(pastTime time.Time) error {
+var errNoInstallDate = errors.New("installation date not set")
 
+func (config *Config) refreshCacheFromPast(pastTime time.Time) error {
 	// in order to avoid querying and storing each day's data from 0001-01-01 in future versions
 	if config.HomeAssistant.InstallationDate.IsZero() {
-		return errors.New("installation date not set")
+		return errNoInstallDate
 	}
 
 	greenEnergyPercentage, err := config.historyBulkAverageAndConvertToGreen(config.Sensors.FossilPercentage, pastTime, time.Now())
@@ -61,7 +63,6 @@ func (config Config) refreshCacheFromPast(pastTime time.Time) error {
 	}
 
 	for key, day := range greenEnergyPercentage {
-
 		var action2 string
 		if greenEnergyPercentage[key].Value != 0 && historyPolledSmartEnergySummation[key].Value != 0 {
 			action2 = "REPLACE"
@@ -77,15 +78,12 @@ func (config Config) refreshCacheFromPast(pastTime time.Time) error {
 		if err != nil {
 			return err
 		}
-
 	}
 
 	return nil
-
 }
 
-func (config Config) readHistory() (History, error) {
-
+func (config *Config) readHistory() (History, error) {
 	start := dayStart(time.Now()).AddDate(0, 0, -8)
 
 	rows, err := config.db.Query("SELECT time, green_energy_percentage, energy_consumption FROM cache WHERE time > ?", start.Unix())
@@ -102,9 +100,11 @@ func (config Config) readHistory() (History, error) {
 			polledSmartEnergyConsumption float32
 		)
 		err = rows.Scan(&date, &greenEnergyPercentage, &polledSmartEnergyConsumption)
+		if err != nil {
+			return nil, err
+		}
 		ret = append(ret, HistoryEntry{date, greenEnergyPercentage, polledSmartEnergyConsumption})
 	}
 
 	return ret, nil
-
 }

src/http.go

@@ -4,13 +4,13 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
-	"github.com/gofiber/fiber/v2"
 	"html/template"
 	"math"
 	"os"
-	"reflect"
 	"strconv"
 	"time"
+
+	"github.com/gofiber/fiber/v2"
 )
 
 type Link struct {
@@ -27,7 +27,7 @@ type Warning struct {
 	IsSuccess bool
 }
 
-func (config Config) getTemplateDefaults() fiber.Map {
+func (config *Config) getTemplateDefaults() fiber.Map {
 	return fiber.Map{
 		"DashboardName": config.Dashboard.Name,
 		"HeaderLinks":   config.Dashboard.HeaderLinks,
@@ -35,16 +35,14 @@ func (config Config) getTemplateDefaults() fiber.Map {
 	}
 }
 
-func (config Config) templateDefaultsMap() fiber.Map {
+func (config *Config) templateDefaultsMap() fiber.Map {
 	return fiber.Map{
 		"Default": config.getTemplateDefaults(),
 	}
 }
 
-func (config Config) adminEndpoint(c *fiber.Ctx) error {
-
+func (config *Config) adminEndpoint(c *fiber.Ctx) error {
 	if c.Method() == "POST" {
-
 		if config.isAuthorized(c) { // here the user is submitting the form to change configuration
 			err := config.saveAdminForm(c)
 			if err != nil {
@@ -68,18 +66,15 @@ func (config Config) adminEndpoint(c *fiber.Ctx) error {
 			return config.renderAdminPanel(c)
 		}
 		return c.Render("login", fiber.Map{"Defaults": config.getTemplateDefaults(), "Failed": true}, "base")
-
 	}
 
 	if config.isAuthorized(c) {
 		return config.renderAdminPanel(c)
 	}
 	return c.Render("login", config.templateDefaultsMap(), "base")
-
 }
 
-func (config Config) renderAdminPanel(c *fiber.Ctx, warning ...Warning) error {
-
+func (config *Config) renderAdminPanel(c *fiber.Ctx, warning ...Warning) error {
 	dirs, err := os.ReadDir("./templates")
 	if err != nil {
 		return err
@@ -100,15 +95,18 @@ func (config Config) renderAdminPanel(c *fiber.Ctx, warning ...Warning) error {
 		"Themes":   dirs,
 		"Config":   config,
 	}, "base")
-
 }
 
-func (config Config) saveAdminForm(c *fiber.Ctx) error {
+var (
+	errNoChanges    = errors.New("no changes from previous config")
+	errMissingField = errors.New("required field is missing")
+)
 
+func (config *Config) saveAdminForm(c *fiber.Ctx) error {
 	requiredFields := []string{"base_url", "api_key", "polled_smart_energy_summation", "fossil_percentage", "username", "theme", "name", "installation_date"}
 	for _, requiredField := range requiredFields {
 		if c.FormValue(requiredField) == "" {
-			return errors.New("Required field is missing: " + requiredField)
+			return fmt.Errorf("%w: %s", errMissingField, requiredField)
 		}
 	}
 
@@ -117,7 +115,7 @@ func (config Config) saveAdminForm(c *fiber.Ctx) error {
 		return err
 	}
 
-	form := Config{
+	form := &Config{
 		HomeAssistant: HomeAssistant{ /*BaseURL to be filled later*/ ApiKey: c.FormValue("api_key"), InstallationDate: dayStart(parsedTime)},
 		Sensors:       Sensors{PolledSmartEnergySummation: c.FormValue("polled_smart_energy_summation"), FossilPercentage: c.FormValue("fossil_percentage")},
 		Administrator: Administrator{Username: c.FormValue("username") /*PasswordHash to be filled later*/},
@@ -136,8 +134,8 @@ func (config Config) saveAdminForm(c *fiber.Ctx) error {
 	}
 	form.HomeAssistant.BaseURL = fmtURL
 
-	if reflect.DeepEqual(form, config) {
-		return errors.New("No changes from previous config.")
+	if form.equals(config) {
+		return errNoChanges
 	}
 
 	form.db = config.db
@@ -151,8 +149,7 @@ func (config Config) saveAdminForm(c *fiber.Ctx) error {
 		return err
 	}
 
-	return os.WriteFile("config.json", js, 0666)
-
+	return os.WriteFile("config.json", js, 0o666)
 }
 
 func averageExcludingCurrentDay(data []float32) float32 {
@@ -164,12 +161,11 @@ func averageExcludingCurrentDay(data []float32) float32 {
 	for _, num := range data {
 		sum += num
 	}
-	var avg = sum / float32(len(data))
+	avg := sum / float32(len(data))
 	return float32(math.Floor(float64(avg)*100)) / 100
 }
 
-func (config Config) renderIndex(c *fiber.Ctx) error {
-
+func (config *Config) renderIndex(c *fiber.Ctx) error {
 	if config.HomeAssistant.InstallationDate.IsZero() {
 		return c.Render("config-error", fiber.Map{
 			"Defaults": config.getTemplateDefaults(),
@@ -182,12 +178,10 @@ func (config Config) renderIndex(c *fiber.Ctx) error {
 		return err
 	}
 
-	var (
-		labels                         []string
-		greenEnergyConsumptionAbsolute []float32
-		greenEnergyPercents            []float32
-		energyConsumptions             []float32
-	)
+	labels := make([]string, 0, len(data))
+	greenEnergyConsumptionAbsolute := make([]float32, 0, len(data))
+	greenEnergyPercents := make([]float32, 0, len(data))
+	energyConsumptions := make([]float32, 0, len(data))
 
 	for _, datum := range data {
 		labels = append(labels, time.Unix(datum.Date, 0).Format("02/01"))
@@ -206,21 +200,18 @@ func (config Config) renderIndex(c *fiber.Ctx) error {
 		"GreenEnergyPercent":  averageExcludingCurrentDay(greenEnergyPercents),
 		"PerDayUsage":         perDayUsage,
 	}, "base")
-
 }
 
 func templateDivide(num1, num2 float32) template.HTML {
-
 	division := float64(num1 / num2)
 
 	powerOfTen := int(math.Floor(math.Log10(division)))
 	if powerOfTen >= -2 && powerOfTen <= 2 {
-		return template.HTML(fmt.Sprintf("%s", strconv.FormatFloat(math.Round(division*100)/100, 'f', -1, 64)))
+		return template.HTML(strconv.FormatFloat(math.Round(division*100)/100, 'f', -1, 64))
 	}
 
 	preComma := division / math.Pow10(powerOfTen)
 	return template.HTML(fmt.Sprintf("%s * 10<sup>%d</sup>", strconv.FormatFloat(math.Round(preComma*100)/100, 'f', -1, 64), powerOfTen))
-
 }
 
 func templateHTMLDateFormat(date time.Time) template.HTML {

src/main.go

@@ -1,17 +1,18 @@
 package main
 
 import (
+	"log"
+	"net/http"
+	"os"
+	"time"
+
 	"github.com/gofiber/fiber/v2"
 	"github.com/gofiber/template/html"
 	"github.com/robfig/cron/v3"
-	"log"
-	"os"
-	"time"
 )
 
 func main() {
-
-	config, err, isFirstRun := loadConfig()
+	config, isFirstRun, err := loadConfig()
 	if err != nil {
 		log.Fatal(err)
 	}
@@ -59,7 +60,7 @@ func main() {
 			}()
 			return c.Render("restart", config.templateDefaultsMap(), "base")
 		}
-		return c.Redirect("./", 307)
+		return c.Redirect("./", http.StatusTemporaryRedirect)
 	})
 
 	port := os.Getenv("PORT")
@@ -67,5 +68,4 @@ func main() {
 		port = "80"
 	}
 	log.Fatal(app.Listen(":" + port))
-
 }