package handlers

import (
	"context"
	"net/http"
	"strconv"
	"strings"

	"aroll/store"
)

// DownloadHandler fetches the exported video from Redis, streams it to the
// browser, then immediately deletes the key. One download per export.
func DownloadHandler(st *store.Store) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		key := strings.TrimPrefix(r.URL.Path, "/")

		// Only serve keys we created in ExportHandler
		if !strings.HasPrefix(key, "output-") {
			http.NotFound(w, r)
			return
		}

		ctx := context.Background()

		data, err := st.Get(ctx, key)
		if err != nil {
			http.Error(w, "file not found or already downloaded", http.StatusNotFound)
			return
		}

		// Delete from Redis now — one download only
		defer st.Delete(ctx, key)

		w.Header().Set("Content-Type", "video/mp4")
		w.Header().Set("Content-Disposition", `attachment; filename="aroll-cut.mp4"`)
		w.Header().Set("Content-Length", strconv.Itoa(len(data)))
		w.Write(data)
	}
}