fix: decouple images from app config service (#965)

Co-authored-by: Alessandro (Ale) Segala <43508+ItalyPaleAle@users.noreply.github.com>

backend/internal/bootstrap/app_images_bootstrap.go

@@ -0,0 +1,120 @@
+package bootstrap
+
+import (
+	"bytes"
+	"encoding/hex"
+	"fmt"
+	"log/slog"
+	"os"
+	"path"
+
+	"github.com/pocket-id/pocket-id/backend/internal/common"
+	"github.com/pocket-id/pocket-id/backend/internal/utils"
+	"github.com/pocket-id/pocket-id/backend/resources"
+)
+
+// initApplicationImages copies the images from the images directory to the application-images directory
+// and returns a map containing the detected file extensions in the application-images directory.
+func initApplicationImages() (map[string]string, error) {
+	// 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")
+	if err != nil && !os.IsNotExist(err) {
+		return nil, fmt.Errorf("failed to read directory: %w", err)
+	}
+
+	destinationFiles, err := os.ReadDir(dirPath)
+	if err != nil && !os.IsNotExist(err) {
+		return nil, fmt.Errorf("failed to read directory: %w", err)
+	}
+	dstNameToExt := make(map[string]string, len(destinationFiles))
+	for _, f := range destinationFiles {
+		if f.IsDir() {
+			continue
+		}
+		name := f.Name()
+		nameWithoutExt, ext := utils.SplitFileName(name)
+		destFilePath := path.Join(dirPath, name)
+
+		// Skip directories
+		if f.IsDir() {
+			continue
+		}
+
+		h, err := utils.CreateSha256FileHash(destFilePath)
+		if err != nil {
+			slog.Warn("Failed to get hash for file", slog.String("name", name), slog.Any("error", err))
+			continue
+		}
+
+		// 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 nil, fmt.Errorf("failed to remove legacy file '%s': %w", name, err)
+			}
+			continue
+		}
+
+		// Track existing files
+		dstNameToExt[nameWithoutExt] = ext
+	}
+
+	// Copy images from the images directory to the application-images directory if they don't already exist
+	for _, sourceFile := range sourceFiles {
+		if sourceFile.IsDir() {
+			continue
+		}
+
+		name := sourceFile.Name()
+		nameWithoutExt, ext := utils.SplitFileName(name)
+		srcFilePath := path.Join("images", name)
+		destFilePath := path.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 _, exists := dstNameToExt[nameWithoutExt]; exists {
+			continue
+		}
+
+		slog.Info("Writing new application image", slog.String("name", name))
+		err := utils.CopyEmbeddedFileToDisk(srcFilePath, destFilePath)
+		if err != nil {
+			return nil, fmt.Errorf("failed to copy file: %w", err)
+		}
+
+		// Track the newly copied file so it can be included in the extensions map later
+		dstNameToExt[nameWithoutExt] = ext
+	}
+
+	return dstNameToExt, nil
+}
+
+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 mustDecodeHex(str string) []byte {
+	b, err := hex.DecodeString(str)
+	if err != nil {
+		panic(err)
+	}
+	return b
+}