package main

import (
	"encoding/json"
	"fmt"
	"io"
	"os"
	"os/exec"
	"path/filepath"
	"strings"
	"sync"
	"time"
	"watch-daemon/util"

	"github.com/fsnotify/fsnotify"
	"github.com/minio/minio-go/v7"
	"github.com/minio/minio-go/v7/pkg/credentials"
	"github.com/natefinch/lumberjack"
	"github.com/sirupsen/logrus"
	"github.com/spf13/viper"
)

var logger *logrus.Logger
var statLogger *logrus.Logger
var gAppConfig *AppConfig

func main() {
	fmt.Println("Starting watch-daemon...")

	// 初始化日志框架、读取配置
	logger = initLog()
	initLoadConfig()

	notifyChan := make(chan string)

	// // Start a goroutine to monitor dir and notify
	// go monitorDirAndNotify(notifyChan)

	// Start a goroutine to do full scan and upload
	go func() {
		for {
			notify, ok := <-notifyChan
			if !ok {
				return
			}
			logger.Debugf("received notify: %s", notify)

			// Drain the channel (debounce)
			_ = util.DrainChannelBuffer(notifyChan)

			doFullScanAndUpload()
		}
	}()

	// Initiate the first full scan and upload
	notifyChan <- "<start>"

	// Set a timer for notifying full scan and upload
	go func() {
		for {
			time.Sleep(time.Duration(gAppConfig.Watching.UploadFileIntervalSeconds) * time.Second)
			notifyChan <- "<timer>"
		}
	}()

	// Block main goroutine forever.
	<-make(chan struct{})
}

func doFullScanAndUpload() {
	logger.Debugln("begin to do full scan and upload")

	var minioCreds *credentials.Credentials
	if gAppConfig.Minio.AccessKeyID != "" && gAppConfig.Minio.SecretAccessKey != "" {
		minioCreds = credentials.NewStaticV4(gAppConfig.Minio.AccessKeyID, gAppConfig.Minio.SecretAccessKey, "")
	} else {
		// Make anonymous client
		minioCreds = credentials.NewStaticV4("", "", "")
	}

	minioClient, err := minio.New(gAppConfig.Minio.Addr, &minio.Options{
		Creds:  minioCreds,
		Secure: gAppConfig.Minio.UseSSL,
	})
	if err != nil {
		logger.Errorf("MinIO Client init error: %s", err)
		return
	}
	logger.Debugln("MinIO Client初始化成功")

	// Make sure `.trash` folder exists in local
	trashFolder := filepath.Join(gAppConfig.Watching.Dir, ".trash")
	if !util.FileExists(trashFolder) {
		err := os.Mkdir(trashFolder, 0777)
		if err != nil {
			logger.Errorf("create trash folder error: %v", err)
			// return
		}
	}

	// Enumerate all files in the folder
	entries, err := os.ReadDir(gAppConfig.Watching.Dir)
	if err != nil {
		logger.Error(err)
		return
	}

	// Upload files
	for _, entry := range entries {
		if strings.HasPrefix(entry.Name(), ".") {
			// Skip hidden files
			continue
		}

		if entry.IsDir() {
			// Upload the folder stream first
			localPath := filepath.Join(gAppConfig.Watching.Dir, entry.Name())
			objPath := entry.Name()
			fullyUploaded, err := uploadOneStreamFolder(localPath, objPath, minioClient)
			if err != nil {
				logger.Errorf("upload folder `%s` error: %v", localPath, err)
			} else {
				if fullyUploaded {
					// Remove the uploaded folder
					logger.Infof("fully uploaded, removing folder: %s", localPath)
					err := os.RemoveAll(localPath)
					if err != nil {
						logger.Errorf("remove folder `%s` error: %v", localPath, err)
					}
				} else {
					logger.Infof("not fully uploaded, keeping folder: %s", localPath)
				}
			}

			// Then remove folder if it is too old
			if gAppConfig.Watching.DeleteFileAfterMinutes > 0 {
				info, err := entry.Info()
				if err != nil {
					logger.Errorf("get info for folder `%s` error: %v", localPath, err)
					continue
				}
				entryModTime := info.ModTime()
				entryAgeMinutes := time.Since(entryModTime).Minutes()
				if entryAgeMinutes > float64(gAppConfig.Watching.DeleteFileAfterMinutes) {
					logger.Infof("removing folder `%s` because it is too old (last modified: %v, %v minutes ago)",
						localPath, util.FmtMyTime(entryModTime), entryAgeMinutes)
					err := os.RemoveAll(localPath)
					if err != nil {
						logger.Errorf("remove folder `%s` error: %v", localPath, err)
					}
				}
			}
		}
	}

	logger.Debugln("full scan and upload done")
}

func uploadOneStreamFolder(localPath string, objPath string, minioClient *minio.Client) (fullyUploaded bool, err error) {
	type StreamObjectUploadStatistics struct {
		StartTime time.Time
		EndTime   time.Time
		Name      string
		Succeeded bool
		Msg       string
	}
	type StreamUploadStatistics struct {
		StartTime       time.Time
		EndTime         time.Time
		MetaPartsCount  int
		MetaPointsCount int
		Objects         map[string]StreamObjectUploadStatistics
		Msg             string
	}
	streamUploadStatistics := StreamUploadStatistics{
		Objects: make(map[string]StreamObjectUploadStatistics),
	}
	streamUploadStatistics.StartTime = time.Now()
	defer func() {
		streamUploadStatistics.EndTime = time.Now()
		okCount := 0
		failCount := 0
		totalCount := 0
		objDetailsMsg := ""
		for _, obj := range streamUploadStatistics.Objects {
			totalCount++
			if obj.Succeeded {
				okCount++
				objDetailsMsg += fmt.Sprintf("\n{%s: OK (t: %v ~ %v, duration: %v)}",
					obj.Name, util.FmtMyTime(obj.StartTime), util.FmtMyTime(obj.EndTime), obj.EndTime.Sub(obj.StartTime))
			} else {
				failCount++
				objDetailsMsg += fmt.Sprintf("\n{%s: FAIL (Reason: %s) (t: %v ~ %v, duration: %v)}",
					obj.Name, obj.Msg, util.FmtMyTime(obj.StartTime), util.FmtMyTime(obj.EndTime), obj.EndTime.Sub(obj.StartTime))
			}
		}
		statLogger.Infof("upload folder `%s` took %v (%v ~ %v); is fully uploaded: %v; metadata-reported parts & points count: %d & %d;"+
			" ok / fail / total: %d / %d / %d; details:%s",
			localPath, streamUploadStatistics.EndTime.Sub(streamUploadStatistics.StartTime),
			util.FmtMyTime(streamUploadStatistics.StartTime), util.FmtMyTime(streamUploadStatistics.EndTime),
			fullyUploaded, streamUploadStatistics.MetaPartsCount, streamUploadStatistics.MetaPointsCount,
			okCount, failCount, totalCount, objDetailsMsg)
	}()

	bucket := gAppConfig.Minio.Bucket

	fullyUploaded = true

	streamDateStr := util.FmtMyDate(time.Now())

	checkMetadataFile := func(localPath string) error {
		// Check for JSON metadata file. If its `total_points` is 0,
		// then the producer has not yet finished writing the stream, so we
		// should not delete the folder.

		metaFilePath := filepath.Join(localPath, "metadata.json")
		// Read metadata file
		metaFile, err := os.Open(metaFilePath)
		if err != nil {
			return fmt.Errorf("open metadata file `%s` error: %w", metaFilePath, err)
		}
		defer metaFile.Close()

		var metadata struct {
			TotalPoints     int   `json:"total_points"`
			PartsCount      int   `json:"parts_count"`
			TimestampOffset int64 `json:"timestamp_offset"` // In milliseconds
		}

		if err := json.NewDecoder(metaFile).Decode(&metadata); err != nil {
			return fmt.Errorf("decode metadata file `%s` error: %w", metaFilePath, err)
		}

		if metadata.TotalPoints == 0 {
			logger.Infof("metadata file `%s` indicates not fully uploaded because total_points is 0", metaFilePath)
			fullyUploaded = false
		}

		streamUploadStatistics.MetaPartsCount = metadata.PartsCount
		streamUploadStatistics.MetaPointsCount = metadata.TotalPoints
		streamDateStr = util.FmtMyDate(time.Unix(metadata.TimestampOffset/1000, 0))

		return nil
	}

	// NOTE: We need to check metadata file before obtaining the list of files
	//       to prevent TOCTOU issues.
	if fullyUploaded {
		if !util.FileExists(filepath.Join(localPath, "metadata.json")) {
			logger.Infof("metadata file not found in folder `%s`, skipping", localPath)
			return false, nil
		}
		err := checkMetadataFile(localPath)
		if err != nil {
			return false, fmt.Errorf("check metadata file error: %w", err)
		}
	}

	// Enumerate all files in the folder
	entries, err := os.ReadDir(localPath)
	if err != nil {
		return false, fmt.Errorf("read dir `%s` error: %w", localPath, err)
	}

	// Create folder in minio
	objFolderPath := streamDateStr + "/" + objPath + "/"
	err = util.MinioCreateFolderIfNotExists(minioClient, bucket, objFolderPath)
	if err != nil {
		return false, fmt.Errorf("create minio folder `%s` error: %w", objFolderPath, err)
	}

	// Upload metadata file
	_, err = util.MinioUploadFileIfChanged(minioClient, bucket,
		objFolderPath+"metadata.json", filepath.Join(localPath, "metadata.json"))
	if err != nil {
		return false, fmt.Errorf("upload metadata file error: %w", err)
	}

	// Upload files
	for _, entry := range entries {
		// Skip hidden files
		if strings.HasPrefix(entry.Name(), ".") {
			continue
		}

		// Skip metadata file
		if entry.Name() == "metadata.json" {
			continue
		}

		// Skip partial files
		if strings.HasSuffix(entry.Name(), ".part") {
			logger.Infof("skipping partial file `%s`", entry.Name())
			fullyUploaded = false
			continue
		}

		innerLocalPath := filepath.Join(localPath, entry.Name())

		if entry.IsDir() {
			// Upload files in the folder
			// logger.Warnf("stream folder contains subfolder `%s`, ignoring", entry.Name())
			innerObjPath := objPath + "/" + entry.Name()
			fullyUploadedInner, err := uploadOneStreamFolder(innerLocalPath, innerObjPath, minioClient)
			if err != nil {
				return false, err
			}
			if !fullyUploadedInner {
				fullyUploaded = false
			}
		} else {
			// Upload the file
			objStat := StreamObjectUploadStatistics{
				StartTime: time.Now(),
				Name:      entry.Name(),
			}

			_, err := util.MinioUploadFile(minioClient, bucket,
				objFolderPath+entry.Name(), innerLocalPath, true)
			objStat.EndTime = time.Now()
			if err != nil {
				objStat.Succeeded = false
				objStat.Msg = err.Error()

				// return false, fmt.Errorf("upload file `%s` error: %w", entry.Name(), err)
				logger.Errorf("upload file `%s` of stream `%s` error: %v, took %v",
					entry.Name(), objPath, err, objStat.EndTime.Sub(objStat.StartTime))
			} else {
				objStat.Succeeded = true

				logger.Infof("uploaded file `%s`, took %v", entry.Name(), objStat.EndTime.Sub(objStat.StartTime))

				// Remove *.zst files early
				if strings.HasSuffix(entry.Name(), ".zst") {
					err := os.Remove(innerLocalPath)
					if err != nil {
						logger.Errorf("remove file `%s` error: %v", entry.Name(), err)
					}
				}
			}

			streamUploadStatistics.Objects[entry.Name()] = objStat
		}
	}

	return fullyUploaded, nil
}

func monitorDirAndNotify(notifyChan chan string) {
	scanFn := func() {
		// Create new watcher.
		watcher, err := fsnotify.NewWatcher()
		if err != nil {
			logger.Errorf("unable to create watcher: %s", err)
		}
		defer watcher.Close()

		// Add a path.
		dir := gAppConfig.Watching.Dir
		if err := watcher.Add(dir); err != nil {
			logger.Errorf("unable to watch dir `%s`: %s", dir, err)
			return
		}

		var wg sync.WaitGroup
		wg.Add(2)

		// Start listening for events.
		go func() {
			defer wg.Done()

			for event := range watcher.Events {
				logger.Debugf("received event: %v", event)

				// Notify
				notifyChan <- "<FSNOTIFY: " + event.Name + ">"
			}
		}()

		// Start listening for errors.
		go func() {
			defer wg.Done()

			for err := range watcher.Errors {
				logger.Errorf("fsnotify error: %s", err)
			}
		}()

		wg.Wait()
	}

	for {
		// scan
		scanFn()

		logger.Errorf("scan task stopped unexpectedly, will retry in %d seconds", gAppConfig.Watching.UploadFileIntervalSeconds)

		// sleep
		time.Sleep(time.Duration(gAppConfig.Watching.UploadFileIntervalSeconds) * time.Second)
	}
}

func initLog() *logrus.Logger {
	// 主日志文件
	log := &lumberjack.Logger{
		Filename:   "./log/watch-daemon.log", // 日志文件的位置
		MaxSize:    50,                       // 文件最大尺寸（以MB为单位）
		MaxBackups: 5,                        // 保留的最大旧文件数量
		MaxAge:     28,                       // 保留旧文件的最大天数
		Compress:   true,                     // 是否压缩/归档旧文件
		LocalTime:  true,                     // 使用本地时间创建时间戳
	}
	// 错误日志文件
	errorLog := &lumberjack.Logger{
		Filename:   "./log/watch-daemon.error.log", // 错误日志文件的位置
		MaxSize:    50,                             // 文件最大尺寸（以MB为单位）
		MaxBackups: 5,                              // 保留的最大旧文件数量
		MaxAge:     28,                             // 保留旧文件的最大天数
		Compress:   true,                           // 是否压缩/归档旧文件
		LocalTime:  true,                           // 使用本地时间创建时间戳
	}
	// 统计日志文件
	statLog := &lumberjack.Logger{
		Filename:   "./log/watch-daemon.stat.log", // 统计日志文件的位置
		MaxSize:    50,                            // 文件最大尺寸（以MB为单位）
		MaxBackups: 5,                             // 保留的最大旧文件数量
		MaxAge:     28,                            // 保留旧文件的最大天数
		Compress:   true,                          // 是否压缩/归档旧文件
		LocalTime:  true,                          // 使用本地时间创建时间戳
	}

	logger := logrus.New()
	if strings.ToLower(os.Getenv("LOG_LEVEL")) == "trace" {
		logger.SetLevel(logrus.TraceLevel)
	} else {
		logger.SetLevel(logrus.DebugLevel)
	}
	logger.Out = log

	// logger.Out = io.MultiWriter(os.Stdout, log)

	// 设置错误级别日志输出到额外的文件
	logger.AddHook(&ErrorHook{
		Writer: errorLog,
		LogLevels: []logrus.Level{
			logrus.ErrorLevel,
			logrus.FatalLevel,
			logrus.PanicLevel,
		},
	})

	statLogger = logrus.New()
	statLogger.SetLevel(logrus.InfoLevel)
	statLogger.Out = statLog

	return logger
}

// ErrorHook 用于将错误级别的日志输出到额外的文件
type ErrorHook struct {
	Writer    io.Writer
	LogLevels []logrus.Level
}

func (hook *ErrorHook) Fire(entry *logrus.Entry) error {
	line, err := entry.String()
	if err != nil {
		return err
	}
	_, err = hook.Writer.Write([]byte(line))
	return err
}

func (hook *ErrorHook) Levels() []logrus.Level {
	return hook.LogLevels
}

func initLoadConfig() {
	gAppConfig = &AppConfig{}

	configFilePath := "./config/application.yaml"

	viper.SetDefault("watching.uploadFileIntervalSeconds", 3)
	viper.SetDefault("watching.deleteFileAfterMinutes", 60)

	viper.SetConfigFile(configFilePath)

	// 热更新
	viper.WatchConfig()
	viper.OnConfigChange(func(e fsnotify.Event) {
		fmt.Printf("配置文件 %s 发生了更改!!!\n", e.Name)

		// 重新加载配置
		err := loadConfig()
		if err != nil {
			fmt.Printf("load config `%s` failed, err: %s\n", configFilePath, err)
		}
	})

	err := loadConfig()
	if err != nil {
		logger.Error(err)
		logger.Errorf("无法加载配置，程序退出")
		fmt.Println("无法加载配置，程序退出")
		os.Exit(1)
	}
}

func loadConfig() error {
	err := viper.ReadInConfig()
	if err != nil {
		return err
	}

	//把读取到的配置信息反序列化到 config 变量中
	var config AppConfig
	if err := viper.Unmarshal(&config); err != nil {
		fmt.Printf("viper Unmarshal config failed, err: %s\n", err)
		return err
	}

	if strings.Contains(config.Minio.Addr, "$") {
		// Start a shell to expand the environment variables
		cmd := exec.Command("sh", "-c", "echo "+config.Minio.Addr)
		out, err := cmd.Output()
		if err == nil {
			config.Minio.Addr = strings.TrimSpace(string(out))
		}
	}

	gAppConfig = &config

	return nil
}