// core/sync.go
package lab

import (
	"fmt"
	"io/ioutil"
	"os"
	"path/filepath"
	"time"
)

// File represents file metadata
type File struct {
	Name     string
	Path     string
	Size     int64
	Checksum string
	ModTime  time.Time
}

// Sync compares local and remote files and performs synchronization
func Sync(localRoot, remoteRoot string) error {
	// 1. Scan local files
	localFiles, err := scanFiles(localRoot)
	if err != nil {
		return fmt.Errorf("error scanning local files: %w", err)
	}

	// 2. Scan remote files (replace with actual server communication)
	remoteFiles, err := scanFiles(remoteRoot)
	if err != nil {
		return fmt.Errorf("error scanning remote files: %w", err)
	}

	// 3. Compare and synchronize
	for _, localFile := range localFiles {
		// Check if file exists remotely
		remoteFile, found := remoteFiles[localFile.Path]
		if !found {
			// Upload file
			err := uploadFile(localFile.Path, remoteRoot)
			if err != nil {
				return fmt.Errorf("error uploading file: %w", err)
			}
		} else {
			// Compare timestamps
			if localFile.ModTime.After(remoteFile.ModTime) {
				// Upload updated file
				err := uploadFile(localFile.Path, remoteRoot)
				if err != nil {
					return fmt.Errorf("error uploading file: %w", err)
				}
			}
		}
	}

	// 4. Delete files that are no longer present locally
	for _, remoteFile := range remoteFiles {
		if _, found := localFiles[remoteFile.Path]; !found {
			// Delete file remotely
			err := deleteFile(remoteFile.Path, remoteRoot)
			if err != nil {
				return fmt.Errorf("error deleting file: %w", err)
			}
		}
	}

	return nil
}

// scanFiles recursively scans a directory and returns a map of file metadata
func scanFiles(root string) (map[string]*File, error) {
	files := make(map[string]*File)
	err := filepath.Walk(root, func(path string, info os.FileInfo, err error) error {
		if err != nil {
			return err
		}
		if !info.IsDir() {
			data, err := ioutil.ReadFile(path)
			if err != nil {
				return err
			}
			checksum := calculateChecksum(data)
			files[path] = &File{
				Name:     info.Name(),
				Path:     path,
				Size:     info.Size(),
				Checksum: checksum,
				ModTime:  info.ModTime(),
			}
		}
		return nil
	})
	return files, err
}

// uploadFile uploads a file to the remote server
func uploadFile(localPath, remoteRoot string) error {
	// Implement file upload logic
	// ...
	return nil
}

// deleteFile deletes a file from the remote server
func deleteFile(remotePath, remoteRoot string) error {
	// Implement file deletion logic
	// ...
	return nil
}

// calculateChecksum calculates the checksum of a file
func calculateChecksum(data []byte) string {
	// Implement checksum calculation logic
	// ...
	return ""
}