package main

import (
	"os"
	"path/filepath"
	"sort"
	"strings"
	"time"

	"lc/common/util"
)

const (
	logRetentionDays = 7
	logMaxTotalSize  = 100 * 1024 * 1024 // 100MB
)

type logFileInfo struct {
	name    string
	size    int64
	modTime time.Time
}

// removeLogFile 删除单个日志文件并返回释放的字节数
func removeLogFile(dir string, f logFileInfo) (bool, int64) {
	path := filepath.Join(dir, f.name)
	if err := os.Remove(path); err != nil {
		util.GetTagLog().Warnf("sys", "CleanLogs:删除失败:%s,err=%v", f.name, err)
		return false, 0
	}
	return true, f.size
}

// CleanLogs 定时清理日志文件：保留7天，总大小不超过100MB
func CleanLogs(args ...interface{}) interface{} {
	for {
		time.Sleep(1 * time.Hour)

		dir := util.GetPath(3) // {workdir}/log/
		entries, err := os.ReadDir(dir)
		if err != nil {
			util.GetTagLog().Warnf("sys", "CleanLogs:读取日志目录失败:%s", err)
			continue
		}

		var logFiles []logFileInfo
		var totalSize int64
		now := time.Now()

		for _, e := range entries {
			if e.IsDir() || !strings.HasSuffix(e.Name(), ".log") {
				continue
			}
			info, err := e.Info()
			if err != nil {
				continue
			}
			lf := logFileInfo{
				name:    e.Name(),
				size:    info.Size(),
				modTime: info.ModTime(),
			}
			logFiles = append(logFiles, lf)
			totalSize += lf.size
		}

		if len(logFiles) == 0 {
			continue
		}

		// 按修改时间升序排列（最旧的在前）
		sort.Slice(logFiles, func(i, j int) bool {
			return logFiles[i].modTime.Before(logFiles[j].modTime)
		})

		var deleted int
		var freed int64

		// Step 1: 删除超过7天的文件
		cutoff := now.AddDate(0, 0, -logRetentionDays)
		remaining := make([]logFileInfo, 0, len(logFiles))
		for _, f := range logFiles {
			if f.modTime.Before(cutoff) {
				if ok, sz := removeLogFile(dir, f); ok {
					deleted++
					freed += sz
					totalSize -= sz
				}
			} else {
				remaining = append(remaining, f)
			}
		}

		// Step 2: 若剩余总大小超过100MB，从最旧的文件开始删除（索引遍历避免切片复制）
		idx := 0
		for totalSize > logMaxTotalSize && idx < len(remaining) {
			if ok, sz := removeLogFile(dir, remaining[idx]); ok {
				deleted++
				freed += sz
				totalSize -= sz
			}
			idx++
		}

		if deleted > 0 {
			kept := len(remaining) - idx
			if kept < 0 {
				kept = 0
			}
			util.GetTagLog().Infof("sys", "CleanLogs:清理完成,删除%d个文件,释放%.1fKB,剩余%d个文件,总大小%.1fKB",
				deleted, float64(freed)/1024, kept, float64(totalSize)/1024)
		}
	}
}