package main

import (
	"log"
	"os"
	"path/filepath"
	"sync"
	"time"

	"github.com/robfig/cron/v3"
)

// -----------------------------------------------------------------------------
// TTL 清理器
// -----------------------------------------------------------------------------

var cleanerOnce sync.Once

func startCleaner() {
	cleanerOnce.Do(func() {
		if err := os.MkdirAll(*uploadDir, 0o755); err != nil {
			log.Fatalf("create upload dir failed: %v", err)
		}
		c := cron.New()
		_, err := c.AddFunc("@every "+scanEvery.String(), func() {
			now := time.Now()
			removed := 0
			var removedBytes int64
			_ = filepath.Walk(*uploadDir, func(path string, info os.FileInfo, err error) error {
				if err != nil || info.IsDir() {
					return nil
				}
				if now.Sub(info.ModTime()) > *fileTTL {
					if rmErr := os.Remove(path); rmErr != nil {
						log.Printf("[cleaner] remove failed: %s err=%v", path, rmErr)
					} else {
						log.Printf("[cleaner] removed: %s (age=%v, size=%s)", path, now.Sub(info.ModTime()), formatSize(info.Size()))
						removed++
						removedBytes += info.Size()
					}
				}
				return nil
			})
			quotaSub(removedBytes)
			// 漂移修正: 每小时一次 rescan 校正任何来源不明的字节数偏差
			rescanQuota()
			log.Printf("[cleaner] scan done, removed=%d (%s), quota used now=%s",
				removed, formatSize(removedBytes), formatSize(quotaUsedSnapshot()))
		})
		if err != nil {
			log.Fatalf("add cron job failed: %v", err)
		}
		c.Start()
		// 分片目录独立清理: 复用同一周期, 清掉孤儿分片并释放预留配额
		go func() {
			cleanupChunks(*fileTTL) // 启动先清一轮, 处理上次进程遗留
			ticker := time.NewTicker(*scanEvery)
			defer ticker.Stop()
			for range ticker.C {
				cleanupChunks(*fileTTL)
			}
		}()
		log.Printf("[cleaner] started, schedule=@every %s dir=%s ttl=%s",
			scanEvery, *uploadDir, *fileTTL)
	})
}