package daemon

import (
	"log"
	"path/filepath"

	"github.com/fsnotify/fsnotify"
)

// Watcher watches for configuration file changes
type Watcher struct {
	configPath   string
	onReloadFunc func() error
}

// NewWatcher creates a new config file watcher
func NewWatcher(configPath string, onReload func() error) *Watcher {
	return &Watcher{
		configPath:   configPath,
		onReloadFunc: onReload,
	}
}

// Watch starts watching for changes to the configuration file
func (w *Watcher) Watch() error {
	watcher, err := fsnotify.NewWatcher()
	if err != nil {
		return err
	}
	defer watcher.Close()

	// Watch the parent directory since file operations might replace the file
	configDir := filepath.Dir(w.configPath)
	if err := watcher.Add(configDir); err != nil {
		return err
	}

	log.Printf("Watching for changes to %s", w.configPath)

	for {
		select {
		case event, ok := <-watcher.Events:
			if !ok {
				return nil
			}
			// Check if the event is for our config file
			if event.Name == w.configPath && (event.Op&fsnotify.Write == fsnotify.Write || event.Op&fsnotify.Create == fsnotify.Create) {
				log.Printf("Configuration file changed: %s", event.Op.String())
				// Call reload callback if provided
				if w.onReloadFunc != nil {
					if err := w.onReloadFunc(); err != nil {
						log.Printf("Failed to reload devices: %v", err)
					}
				}
			}
		case err, ok := <-watcher.Errors:
			if !ok {
				return nil
			}
			log.Printf("File watcher error: %v", err)
		}
	}
}