package watcher

import (
	"context"
	"sync"
	"time"

	"jukebox_maker/internal/disk"
)

type DiskEvent struct {
	Info disk.DiskInfo
	Prev disk.DiskState
}

type Handler func(event DiskEvent)

type Watcher struct {
	mountPath string
	interval  time.Duration
	handler   Handler

	mu      sync.RWMutex
	current disk.DiskInfo
}

func New(mountPath string, interval time.Duration, handler Handler) *Watcher {
	return &Watcher{
		mountPath: mountPath,
		interval:  interval,
		handler:   handler,
	}
}

func (w *Watcher) CurrentDisk() disk.DiskInfo {
	w.mu.RLock()
	defer w.mu.RUnlock()
	return w.current
}

func (w *Watcher) Run(ctx context.Context) {
	ticker := time.NewTicker(w.interval)
	defer ticker.Stop()

	// probe immediately on start
	w.probe()

	for {
		select {
		case <-ctx.Done():
			return
		case <-ticker.C:
			w.probe()
		}
	}
}

func (w *Watcher) probe() {
	info, _ := disk.Probe(w.mountPath)

	w.mu.Lock()
	prev := w.current.State
	changed := prev != info.State
	w.current = info
	w.mu.Unlock()

	if changed && w.handler != nil {
		w.handler(DiskEvent{Info: info, Prev: prev})
	}
}