package media

import (
	"context"
	"fmt"
	"io"
	"os"
	"path/filepath"
	"strings"
)

// LocalStorage saves uploads under a directory on disk and serves them via
// a static file route (mounted by main.go at /uploads when this driver is
// active).
type LocalStorage struct {
	dir     string
	baseURL string
}

func NewLocalStorage(dir, baseURL string) (*LocalStorage, error) {
	if err := os.MkdirAll(dir, 0o755); err != nil {
		return nil, fmt.Errorf("create upload dir: %w", err)
	}
	return &LocalStorage{dir: dir, baseURL: strings.TrimRight(baseURL, "/")}, nil
}

func (s *LocalStorage) Save(_ context.Context, key string, reader io.Reader, _ int64, _ string) (string, error) {
	// key is always a freshly generated UUID-based name (see service.go),
	// never derived from user input, so path traversal is not reachable here.
	dest := filepath.Join(s.dir, filepath.Base(key))

	f, err := os.OpenFile(dest, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0o644)
	if err != nil {
		return "", fmt.Errorf("create file: %w", err)
	}
	defer f.Close()

	if _, err := io.Copy(f, reader); err != nil {
		return "", fmt.Errorf("write file: %w", err)
	}

	return s.baseURL + "/" + filepath.Base(key), nil
}

func (s *LocalStorage) Delete(_ context.Context, key string) error {
	err := os.Remove(filepath.Join(s.dir, filepath.Base(key)))
	if err != nil && !os.IsNotExist(err) {
		return fmt.Errorf("delete file: %w", err)
	}
	return nil
}