package main

import (
	"context"
	"encoding/json"
	"errors"
	"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 appConfig AppConfig

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

	// 初始化日志框架、读取配置
	logger = initLog()
	theAppConfig, 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)
	}
	appConfig = theAppConfig

	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.Infof("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(appConfig.WatchingConfig.UploadFileInterval) * time.Second)
			notifyChan <- "<timer>"
		}
	}()

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

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

	minioClient, err := minio.New(appConfig.MinIoConfig.Addr, &minio.Options{
		Creds:  credentials.NewStaticV4(appConfig.MinIoConfig.AccessKeyID, appConfig.MinIoConfig.SecretAccessKey, ""),
		Secure: appConfig.UseSSL,
	})
	if err != nil {
		logger.Errorf("MinIO Client init error: %s", err)
		return
	}
	logger.Println("MinIO Client初始化成功")

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

	// Upload files
	for _, entry := range entries {
		if entry.IsDir() {
			// Upload files in the folder
			localPath := filepath.Join(appConfig.WatchingConfig.Dir, entry.Name())
			objPath := entry.Name()
			fullyUploaded, err := uploadOneStreamFolder(localPath, objPath, minioClient)
			if err != nil {
				logger.Error(err)
				continue
			}
			if fullyUploaded {
				// Remove the uploaded folder
				logger.Infof("fully uploaded, removing folder: %s", localPath)
				err := os.RemoveAll(localPath)
				if err != nil {
					logger.Error(err)
				}
			} else {
				logger.Infof("not fully uploaded, keeping folder: %s", localPath)
			}
		}
	}

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

func uploadOneStreamFolder(localPath string, objPath string, minioClient *minio.Client) (fullyUploaded bool, err error) {
	ctx := context.Background()
	bucket := appConfig.MinIoConfig.Bucket

	fullyUploaded = true

	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"`
		}

		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
		}

		return nil
	}

	// NOTE: We need to check metadata file before obtaining the list of files
	//       to prevent TOCTOU issues.
	if fullyUploaded {
		err := checkMetadataFile(localPath)
		if err != nil {
			return false, 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 := objPath + "/"
	_, err = minioClient.PutObject(ctx, bucket, objFolderPath, nil, 0, minio.PutObjectOptions{})
	if err != nil {
		return false, fmt.Errorf("create folder `%s` error: %w", objPath, err)
	}

	// Upload files
	// NOTE: We overwrite the existing files in the minio bucket
	for _, entry := range entries {
		// 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
			_, err := minioClient.FPutObject(ctx, bucket,
				objFolderPath+entry.Name(), innerLocalPath,
				minio.PutObjectOptions{ContentType: "application/octet-stream"})
			if err != nil {
				return false, fmt.Errorf("upload file `%s` error: %w", entry.Name(), err)
			}
			logger.Infof("uploaded file `%s`", entry.Name())

			// 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)
				}
			}
		}
	}

	return fullyUploaded, nil
}

func monitorDirAndNotify(notifyChan chan string) {
	scanFn := func() {
		// Create new watcher.
		watcher, err := fsnotify.NewWatcher()
		if err != nil {
			logger.Error(err)
		}
		defer watcher.Close()

		// Add a path.
		dir := appConfig.WatchingConfig.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.Infof("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", appConfig.WatchingConfig.UploadFileInterval)

		// sleep
		time.Sleep(time.Duration(appConfig.WatchingConfig.UploadFileInterval) * time.Second)
	}
}

func initLog() *logrus.Logger {
	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
	}
	logger := logrus.New()
	// logger.Out = log
	logger.Out = io.MultiWriter(os.Stdout, log)
	return logger
}

func loadConfig() (AppConfig, error) {
	configFilePath := "./config/application.yaml"

	if !util.FileExists(configFilePath) {
		return AppConfig{}, errors.New("找不到配置文件")
	}

	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!!! 最新的Global.Source这个字段的值为 %s:", e.Name, viper.GetString("Global.Source"))
	})
	err := viper.ReadInConfig()
	if err != nil {
		panic(fmt.Errorf("error reading config: %s", 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 failed, err:%s\n", err)
	}

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

	return config, nil
}

// func old_main() {
// 	// 初始化日志框架、读取配置
// 	logger = initLog()
// 	appConfig, err := loadConfig()
// 	if err != nil {
// 		logger.Error(err)
// 		logger.Errorf("无法加载配置，程序退出")
// 		os.Exit(1)
// 	}

// 	// upload file from tmp to minio
// 	go uploadFileToMinIo(appConfig)

// 	// Create new watcher.
// 	watcher, err := fsnotify.NewWatcher()
// 	if err != nil {
// 		logger.Error(err)
// 	}
// 	defer watcher.Close()

// 	// Start listening for events.
// 	go func() {
// 		for {
// 			select {
// 			case event, ok := <-watcher.Events:
// 				if !ok {
// 					return
// 				}
// 				if event.Has(fsnotify.Create) && strings.HasSuffix(event.Name, "sync") {
// 					logger.Printf("copy file:%s from src:%s to:%s", event.Name,
// 						appConfig.WatchingConfig.Dir, appConfig.WatchingConfig.TmpDir)

// 					// create hard link
// 					srcFilePath := strings.ReplaceAll(strings.TrimSuffix(event.Name, ".sync")+".zst",
// 						"\\", "/")
// 					dstFilePath := strings.ReplaceAll(srcFilePath, appConfig.WatchingConfig.Dir, appConfig.WatchingConfig.TmpDir)
// 					err := util.CreateHardLink(srcFilePath, dstFilePath)
// 					if err != nil {
// 						logger.Errorf("拷贝文件失败, src:%s dst:%s", srcFilePath, dstFilePath)
// 					}
// 				} else if event.Has(fsnotify.Create) {
// 					stat, err := os.Stat(event.Name)
// 					if err != nil {
// 						logger.Error(err)
// 					}
// 					if stat.IsDir() {
// 						logger.Println("开始监听: ", event.Name)
// 						err = watcher.Add(event.Name)
// 						if err != nil {
// 							logger.Errorf("监听目录失败, dir:%s e:%s", event.Name, err)
// 						}
// 					}
// 				}
// 			case err, ok := <-watcher.Errors:
// 				if !ok {
// 					return
// 				}
// 				logger.Errorf("error: %s", err)
// 			}
// 		}
// 	}()

// 	// Add a path.
// 	err = addWatchPath(appConfig.WatchingConfig.Dir, watcher)
// 	if err != nil {
// 		logger.Error(err)
// 	}

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

// // 递归添加监控目录
// func addWatchPath(dir string, watcher *fsnotify.Watcher) error {
// 	entries, err := os.ReadDir(dir)
// 	if err != nil {
// 		return fmt.Errorf("读取目录error: %w", err)
// 	}

// 	logger.Println("开始监听目录:", dir)
// 	err = watcher.Add(dir)
// 	if err != nil {
// 		return err
// 	}

// 	if len(entries) > 0 {
// 		// 递归子目录
// 		for _, entry := range entries {
// 			if entry.IsDir() {
// 				err := addWatchPath(filepath.Join(dir, entry.Name()), watcher)
// 				if err != nil {
// 					return err
// 				}
// 			}
// 		}
// 	}
// 	return nil
// }

// // 每隔一定时间上传文件
// func uploadFileToMinIo(appConfig AppConfig) {
// 	// minioClient
// 	minioClient, err := minio.New(appConfig.MinIoConfig.Addr, &minio.Options{
// 		Creds:  credentials.NewStaticV4(appConfig.MinIoConfig.AccessKeyID, appConfig.MinIoConfig.SecretAccessKey, ""),
// 		Secure: appConfig.UseSSL,
// 	})
// 	if err != nil {
// 		logger.Errorf("MinIO Client init error: %s", err)
// 		return
// 	}
// 	logger.Println("MinIO Client初始化成功")

// 	for {
// 		err := uploadFiles(appConfig.TmpDir, minioClient, appConfig.MinIoConfig.Bucket)
// 		if err != nil {
// 			logger.Errorf("upload files error, e: %s", err)
// 		}

// 		time.Sleep(time.Duration(appConfig.WatchingConfig.UploadFileInterval) * time.Second)
// 	}
// }

// func uploadFiles(dir string, minioClient *minio.Client, bucket string) error {
// 	entries, err := os.ReadDir(dir)
// 	if err != nil {
// 		return fmt.Errorf("上传文件, 读取目录. err: %w", err)
// 	}

// 	// uploadFiles
// 	if len(entries) > 0 {
// 		for _, entry := range entries {
// 			if entry.IsDir() {
// 				// 递归处理子文件夹
// 				subfolder := filepath.Join(dir, entry.Name())
// 				err := uploadFiles(subfolder, minioClient, bucket)
// 				if err != nil {
// 					logger.Errorf("上传文件失败 err:%s\n", err)
// 				}

// 				// 删除空文件夹
// 				err = util.RemoveEmptyDir(subfolder)
// 				if err != nil {
// 					logger.Errorf("上传文件失败 err:%s\n", err)
// 				}
// 			} else {
// 				filePath := filepath.Join(dir, entry.Name())

// 				// 将文件上传至桶中对应文件夹
// 				_, err = minioClient.FPutObject(context.Background(), bucket,
// 					strings.ReplaceAll(filePath, "\\", "/"), dir,
// 					minio.PutObjectOptions{ContentType: "application/octet-stream"})
// 				if err != nil {
// 					logger.Errorf("上传文件失败, filePath: %s err:%s\n", filePath, err)
// 				}

// 				// 删除文件
// 				err := os.Remove(filePath)
// 				if err != nil {
// 					logger.Errorf("删除备份文件失败, filePath: %s err:%s\n", filePath, err)
// 				}
// 			}
// 		}
// 	}
// 	return nil
// }