package store

import (
	"crypto/rand"
	"encoding/hex"
	"fmt"
	"io"
	"os"
	"path/filepath"
)

type Store struct {
	dir string
}

func New() (*Store, error) {
	dir := filepath.Join(os.TempDir(), "aroll-uploads")
	if err := os.MkdirAll(dir, 0755); err != nil {
		return nil, fmt.Errorf("create upload dir: %w", err)
	}
	return &Store{dir: dir}, nil
}

// Save streams r into a new file in the store and returns its key.
func (s *Store) Save(r io.Reader, ext string) (string, error) {
	key := "video-" + NewID() + ext
	path := filepath.Join(s.dir, key)
	f, err := os.Create(path)
	if err != nil {
		return "", fmt.Errorf("create file: %w", err)
	}
	defer f.Close()
	if _, err := io.Copy(f, r); err != nil {
		os.Remove(path)
		return "", fmt.Errorf("write file: %w", err)
	}
	return key, nil
}

// Path returns the absolute path for a key, if the file exists.
func (s *Store) Path(key string) (string, bool) {
	path := filepath.Join(s.dir, key)
	if _, err := os.Stat(path); err != nil {
		return "", false
	}
	return path, true
}

// Allocate returns a path for a new key without creating the file.
// Used by ExportHandler so ffmpeg can write directly to the store.
func (s *Store) Allocate(key string) string {
	return filepath.Join(s.dir, key)
}

// Delete removes the file for a key.
func (s *Store) Delete(key string) {
	os.Remove(filepath.Join(s.dir, key))
}

func NewID() string {
	b := make([]byte, 16)
	rand.Read(b)
	return hex.EncodeToString(b)
}