package handlers

import (
	"context"
	"encoding/json"
	"io"
	"net/http"
	"path/filepath"

	"aroll/store"
)

// UploadHandler reads the video into memory and stores it in Redis under a
// random key. The key is returned to the frontend as "filename".
// Nothing is written to disk — the file lives only in Redis with a TTL.
func UploadHandler(st *store.Store) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		if r.Method != http.MethodPost {
			http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
			return
		}

		r.Body = http.MaxBytesReader(w, r.Body, 4<<30)
		if err := r.ParseMultipartForm(64 << 20); err != nil {
			http.Error(w, "parse form: "+err.Error(), http.StatusBadRequest)
			return
		}

		file, header, err := r.FormFile("video")
		if err != nil {
			http.Error(w, "missing 'video' field", http.StatusBadRequest)
			return
		}
		defer file.Close()

		data, err := io.ReadAll(file)
		if err != nil {
			http.Error(w, "read file: "+err.Error(), http.StatusInternalServerError)
			return
		}

		ext := filepath.Ext(header.Filename)
		if ext == "" {
			ext = ".mp4"
		}

		// Key format: "video-<id><ext>"  e.g.  "video-a3f9...2b.mp4"
		key := "video-" + store.NewID() + ext

		if err := st.Set(context.Background(), key, data); err != nil {
			http.Error(w, "store: "+err.Error(), http.StatusInternalServerError)
			return
		}

		w.Header().Set("Content-Type", "application/json")
		json.NewEncoder(w).Encode(map[string]string{"filename": key})
	}
}