krafttrainer/backend/internal/handler/image_handler.go

package handler

import (
	"fmt"
	"io"
	"net/http"
	"os"
	"path/filepath"

	"github.com/google/uuid"
)

const (
	maxImageSize = 5 << 20 // 5 MB
	uploadDir    = "uploads"
)

func (h *Handler) handleListImages(w http.ResponseWriter, r *http.Request) {
	exerciseID, err := pathID(r, "id")
	if err != nil {
		writeError(w, http.StatusBadRequest, "Ungültige ID")
		return
	}

	images, err := h.store.ListExerciseImages(exerciseID)
	if err != nil {
		writeError(w, http.StatusInternalServerError, "Fehler beim Laden der Bilder")
		return
	}
	writeJSON(w, http.StatusOK, images)
}

func (h *Handler) handleUploadImage(w http.ResponseWriter, r *http.Request) {
	exerciseID, err := pathID(r, "id")
	if err != nil {
		writeError(w, http.StatusBadRequest, "Ungültige ID")
		return
	}

	// Übung muss existieren
	exercise, err := h.store.GetExercise(exerciseID)
	if err != nil {
		writeError(w, http.StatusInternalServerError, "Fehler beim Prüfen der Übung")
		return
	}
	if exercise == nil {
		writeError(w, http.StatusNotFound, "Übung nicht gefunden")
		return
	}

	r.Body = http.MaxBytesReader(w, r.Body, maxImageSize)
	if err := r.ParseMultipartForm(maxImageSize); err != nil {
		writeError(w, http.StatusBadRequest, "Datei zu groß (max 5 MB)")
		return
	}

	file, header, err := r.FormFile("image")
	if err != nil {
		writeError(w, http.StatusBadRequest, "Kein Bild im Request")
		return
	}
	defer file.Close()

	// Content-Type prüfen
	ct := header.Header.Get("Content-Type")
	if ct != "image/jpeg" {
		writeError(w, http.StatusBadRequest, "Nur JPG-Bilder erlaubt")
		return
	}

	// Datei speichern
	filename := uuid.New().String() + ".jpg"
	destPath := filepath.Join(uploadDir, filename)

	if err := os.MkdirAll(uploadDir, 0755); err != nil {
		writeError(w, http.StatusInternalServerError, "Fehler beim Erstellen des Upload-Verzeichnisses")
		return
	}

	dst, err := os.Create(destPath)
	if err != nil {
		writeError(w, http.StatusInternalServerError, "Fehler beim Speichern der Datei")
		return
	}
	defer dst.Close()

	if _, err := io.Copy(dst, file); err != nil {
		os.Remove(destPath)
		writeError(w, http.StatusInternalServerError, "Fehler beim Schreiben der Datei")
		return
	}

	img, err := h.store.CreateExerciseImage(exerciseID, filename)
	if err != nil {
		os.Remove(destPath)
		writeError(w, http.StatusInternalServerError, "Fehler beim Speichern des Bildes")
		return
	}
	writeJSON(w, http.StatusCreated, img)
}

func (h *Handler) handleDeleteImage(w http.ResponseWriter, r *http.Request) {
	imageID, err := pathID(r, "imageId")
	if err != nil {
		writeError(w, http.StatusBadRequest, "Ungültige Bild-ID")
		return
	}

	filename, err := h.store.DeleteExerciseImage(imageID)
	if err != nil {
		writeError(w, http.StatusNotFound, "Bild nicht gefunden")
		return
	}

	// Datei vom Dateisystem löschen
	os.Remove(filepath.Join(uploadDir, filename))

	w.WriteHeader(http.StatusNoContent)
}

// RegisterImageRoutes registriert die Bild-spezifischen Routen und den statischen File-Server.
func (h *Handler) RegisterImageRoutes(mux *http.ServeMux) {
	mux.HandleFunc("GET /api/v1/exercises/{id}/images", h.handleListImages)
	mux.HandleFunc("POST /api/v1/exercises/{id}/images", h.handleUploadImage)
	mux.HandleFunc("DELETE /api/v1/exercises/{id}/images/{imageId}", h.handleDeleteImage)

	// Bilder statisch servieren
	mux.Handle("GET /uploads/", http.StripPrefix("/uploads/",
		http.FileServer(http.Dir(uploadDir))))

	// uploads-Verzeichnis sicherstellen
	os.MkdirAll(uploadDir, 0755)

	fmt.Println("Bild-Upload konfiguriert:", uploadDir)
}