package logger

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

// Logger 全局日志实例
var Logger *log.Logger
var logFile *os.File
var logFileName string
var mu sync.Mutex

// InitLogger 初始化日志，创建 /data/logs 目录并按天命名文件
func InitLogger() error {
	mu.Lock()
	defer mu.Unlock()

	// 创建 /data/logs 目录
	logDir := "/data/logs"
	if err := os.MkdirAll(logDir, 0755); err != nil {
		return err
	}

	// 按天生成日志文件名：20260102.log
	logFileName = filepath.Join(logDir, time.Now().Format("20060102")+".log")
	file, err := os.OpenFile(logFileName, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644)
	if err != nil {
		return err
	}
	logFile = file
	Logger = log.New(file, "", log.LstdFlags)

	// 每天凌晨检查是否需要切换日志文件
	go func() {
		for {
			// 每天检查一次（凌晨 00:05 执行）
			now := time.Now()
			next := time.Date(now.Year(), now.Month(), now.Day()+1, 0, 5, 0, 0, now.Location())
			time.Sleep(time.Until(next))

			mu.Lock()
			newFileName := filepath.Join(logDir, time.Now().Format("20060102")+".log")
			if newFileName != logFileName {
				newFile, err := os.OpenFile(newFileName, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644)
				if err != nil {
					log.Printf("Failed to switch the log file: %v", err)
					mu.Unlock()
					continue
				}
				logFile.Close()
				logFile = newFile
				logFileName = newFileName
				Logger = log.New(newFile, "", log.LstdFlags)
				Logger.Println("The log file has been switched:", newFileName)
			}
			mu.Unlock()
		}
	}()
	return nil
}

// CloseLogger 关闭日志文件
func CloseLogger() {
	mu.Lock()
	defer mu.Unlock()
	if logFile != nil {
		logFile.Close()
		logFile = nil
	}
}

// CleanupOldLogs 删除超过30天的日志文件
func CleanupOldLogs() {
	logDir := "/data/logs"
	files, err := os.ReadDir(logDir)
	if err != nil {
		if Logger != nil {
			Logger.Printf("Read the log directory %s Error: %v", logDir, err)
		}
		return
	}
	const maxAge = 30 * 24 * time.Hour // 30天
	for _, file := range files {
		if file.IsDir() {
			continue
		}
		info, err := file.Info()
		if err != nil {
			if Logger != nil {
				Logger.Printf("Obtain file information %s Error: %v", file.Name(), err)
			}
			continue
		}
		if time.Since(info.ModTime()) > maxAge {
			filePath := filepath.Join(logDir, file.Name())
			if err := os.Remove(filePath); err != nil {
				if Logger != nil {
					Logger.Printf("Delete the old log files %s Error:  %v", filePath, err)
				}
			} else {
				if Logger != nil {
					Logger.Printf("Delete the old log files %s succeed", filePath)
				}
			}
		}
	}
}