// backend\record_preview_sprite.go

package main

import (
	"net/http"
	"os"
	"path/filepath"
	"strings"
)

func recordPreviewSprite(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodGet && r.Method != http.MethodHead {
		http.Error(w, "Nur GET/HEAD", http.StatusMethodNotAllowed)
		return
	}

	// Unterstützt beide Prefixe (falls du mal testweise /api/preview-sprite/ nutzt)
	id := strings.TrimPrefix(r.URL.Path, "/api/record/preview-sprite/")
	if id == r.URL.Path {
		id = strings.TrimPrefix(r.URL.Path, "/api/preview-sprite/")
	}
	id = strings.TrimSpace(id)

	// Falls jemand versehentlich einen Slash am Ende schickt
	id = strings.Trim(id, "/")

	if id == "" {
		http.Error(w, "id fehlt", http.StatusBadRequest)
		return
	}

	var err error
	id, err = sanitizeID(id)
	if err != nil {
		http.Error(w, "ungültige id", http.StatusBadRequest)
		return
	}

	dir, err := generatedDirForID(id)
	if err != nil {
		http.Error(w, "ungültige id", http.StatusBadRequest)
		return
	}

	spritePath := filepath.Join(dir, "preview-sprite.webp")

	fi, err := os.Stat(spritePath)
	if err != nil || fi.IsDir() || fi.Size() <= 0 {
		http.NotFound(w, r)
		return
	}

	f, err := os.Open(spritePath)
	if err != nil {
		http.NotFound(w, r)
		return
	}
	defer f.Close()

	// Cachebar (du hängst im Frontend ?v=updatedAtUnix dran)
	w.Header().Set("Content-Type", "image/webp")
	w.Header().Set("Cache-Control", "private, max-age=31536000, immutable")
	w.Header().Set("X-Content-Type-Options", "nosniff")

	http.ServeContent(w, r, "preview-sprite.webp", fi.ModTime(), f)
}