package storage

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

type LocalStore struct {
	rootDir string
	baseURL string
}

func NewLocalStore(rootDir, baseURL string) (*LocalStore, error) {
	if err := os.MkdirAll(rootDir, 0755); err != nil {
		return nil, fmt.Errorf("create storage dir: %w", err)
	}
	return &LocalStore{rootDir: rootDir, baseURL: baseURL}, nil
}

func (s *LocalStore) Upload(ctx context.Context, tenantID string, file *File) (*StoredFile, error) {
	now := time.Now()
	dir := filepath.Join(s.rootDir, tenantID, now.Format("2006/01/02"))
	if err := os.MkdirAll(dir, 0755); err != nil {
		return nil, fmt.Errorf("create upload dir: %w", err)
	}

	ext := filepath.Ext(file.Name)
	key := generateKey(ext)
	destPath := filepath.Join(dir, key)

	dest, err := os.Create(destPath)
	if err != nil {
		return nil, fmt.Errorf("create file: %w", err)
	}
	defer dest.Close()

	written, err := io.Copy(dest, file.Reader)
	if err != nil {
		os.Remove(destPath)
		return nil, fmt.Errorf("write file: %w", err)
	}

	relKey := filepath.Join(tenantID, now.Format("2006/01/02"), key)
	return &StoredFile{
		Key:  relKey,
		URL:  s.URL(relKey),
		Size: written,
	}, nil
}

func (s *LocalStore) Delete(ctx context.Context, key string) error {
	path := filepath.Join(s.rootDir, key)
	if err := os.Remove(path); err != nil && !os.IsNotExist(err) {
		return fmt.Errorf("delete file: %w", err)
	}
	return nil
}

func (s *LocalStore) Exists(ctx context.Context, key string) (bool, error) {
	path := filepath.Join(s.rootDir, key)
	_, err := os.Stat(path)
	if err == nil {
		return true, nil
	}
	if os.IsNotExist(err) {
		return false, nil
	}
	return false, err
}

func (s *LocalStore) URL(key string) string {
	return fmt.Sprintf("%s/uploads/%s", s.baseURL, key)
}

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