chore: minify background image (#933)

Co-authored-by: Elias Schneider <login@eliasschneider.com>

backend/internal/bootstrap/application_images_bootstrap.go

@@ -1,9 +1,13 @@
 package bootstrap
 
 import (
+	"bytes"
+	"encoding/hex"
 	"fmt"
+	"io/fs"
+	"log/slog"
 	"os"
-	"path"
+	"path/filepath"
 	"strings"
 
 	"github.com/pocket-id/pocket-id/backend/internal/common"
@@ -13,6 +17,15 @@ import (
 
 // initApplicationImages copies the images from the images directory to the application-images directory
 func initApplicationImages() error {
+	// Images that are built into the Pocket ID binary
+	builtInImageHashes := getBuiltInImageHashes()
+
+	// Previous versions of images
+	// If these are found, they are deleted
+	legacyImageHashes := imageHashMap{
+		"background.jpg": mustDecodeHex("138d510030ed845d1d74de34658acabff562d306476454369a60ab8ade31933f"),
+	}
+
 	dirPath := common.EnvConfig.UploadPath + "/application-images"
 
 	sourceFiles, err := resources.FS.ReadDir("images")
@@ -24,15 +37,48 @@ func initApplicationImages() error {
 	if err != nil && !os.IsNotExist(err) {
 		return fmt.Errorf("failed to read directory: %w", err)
 	}
+	destinationFilesMap := make(map[string]bool, len(destinationFiles))
+	for _, f := range destinationFiles {
+		name := f.Name()
+		destFilePath := filepath.Join(dirPath, name)
+
+		h, err := utils.CreateSha256FileHash(destFilePath)
+		if err != nil {
+			return fmt.Errorf("failed to get hash for file '%s': %w", name, err)
+		}
+
+		// Check if the file is a legacy one - if so, delete it
+		if legacyImageHashes.Contains(h) {
+			slog.Info("Found legacy application image that will be removed", slog.String("name", name))
+			err = os.Remove(destFilePath)
+			if err != nil {
+				return fmt.Errorf("failed to remove legacy file '%s': %w", name, err)
+			}
+			continue
+		}
+
+		// Check if the file is a built-in one and save it in the map
+		destinationFilesMap[getImageNameWithoutExtension(name)] = builtInImageHashes.Contains(h)
+	}
 
 	// Copy images from the images directory to the application-images directory if they don't already exist
 	for _, sourceFile := range sourceFiles {
-		if sourceFile.IsDir() || imageAlreadyExists(sourceFile.Name(), destinationFiles) {
+		// Skip if it's a directory
+		if sourceFile.IsDir() {
 			continue
 		}
-		srcFilePath := path.Join("images", sourceFile.Name())
-		destFilePath := path.Join(dirPath, sourceFile.Name())
 
+		name := sourceFile.Name()
+		srcFilePath := filepath.Join("images", name)
+		destFilePath := filepath.Join(dirPath, name)
+
+		// Skip if there's already an image at the path
+		// We do not check the extension because users could have uploaded a different one
+		if imageAlreadyExists(sourceFile, destinationFilesMap) {
+			continue
+		}
+
+		slog.Info("Writing new application image", slog.String("name", name))
 		err := utils.CopyEmbeddedFileToDisk(srcFilePath, destFilePath)
 		if err != nil {
 			return fmt.Errorf("failed to copy file: %w", err)
@@ -42,25 +88,49 @@ func initApplicationImages() error {
 	return nil
 }
 
-func imageAlreadyExists(fileName string, destinationFiles []os.DirEntry) bool {
-	for _, destinationFile := range destinationFiles {
-		sourceFileWithoutExtension := getImageNameWithoutExtension(fileName)
-		destinationFileWithoutExtension := getImageNameWithoutExtension(destinationFile.Name())
+func getBuiltInImageHashes() imageHashMap {
+	return imageHashMap{
+		"background.webp": mustDecodeHex("3fc436a66d6b872b01d96a4e75046c46b5c3e2daccd51e98ecdf98fd445599ab"),
+		"favicon.ico":     mustDecodeHex("70f9c4b6bd4781ade5fc96958b1267511751e91957f83c2354fb880b35ec890a"),
+		"logo.svg":        mustDecodeHex("f1e60707df9784152ce0847e3eb59cb68b9015f918ff160376c27ebff1eda796"),
+		"logoDark.svg":    mustDecodeHex("0421a8d93714bacf54c78430f1db378fd0d29565f6de59b6a89090d44a82eb16"),
+		"logoLight.svg":   mustDecodeHex("6d42c88cf6668f7e57c4f2a505e71ecc8a1e0a27534632aa6adec87b812d0bb0"),
+	}
+}
 
-		if sourceFileWithoutExtension == destinationFileWithoutExtension {
+type imageHashMap map[string][]byte
+
+func (m imageHashMap) Contains(target []byte) bool {
+	if len(target) == 0 {
+		return false
+	}
+	for _, h := range m {
+		if bytes.Equal(h, target) {
 			return true
 		}
 	}
-
 	return false
 }
 
+func imageAlreadyExists(sourceFile fs.DirEntry, destinationFiles map[string]bool) bool {
+	sourceFileWithoutExtension := getImageNameWithoutExtension(sourceFile.Name())
+	_, ok := destinationFiles[sourceFileWithoutExtension]
+	return ok
+}
+
 func getImageNameWithoutExtension(fileName string) string {
 	idx := strings.LastIndexByte(fileName, '.')
 	if idx < 1 {
 		// No dot found, or fileName starts with a dot
 		return fileName
 	}
-
 	return fileName[:idx]
 }
+
+func mustDecodeHex(str string) []byte {
+	b, err := hex.DecodeString(str)
+	if err != nil {
+		panic(err)
+	}
+	return b
+}