package dbserver

import (
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"leafstalk/covenant/monitor"
	"leafstalk/log"
	slog "log"
	"os"
	"path/filepath"
	"sort"
	"sync"
	"time"

	"xorm.io/xorm"
)

type DbSaveQueue struct {
	*xorm.Engine
	name        string
	delayQueue  *SortQueue
	chSaveEvent chan struct{}
	wg          sync.WaitGroup
	cancel      context.CancelFunc
	logFile     *os.File
	logger      *slog.Logger
}

var saveQueues map[string]*DbSaveQueue

func NewDbSaveQueue(name string, eng *xorm.Engine) (*DbSaveQueue, error) {
	if saveQueues == nil {
		saveQueues = make(map[string]*DbSaveQueue)
	}
	if _, ok := saveQueues[name]; ok {
		return nil, errors.New("duplicate name")
	}
	sq, err := newDbSaveQueue(name, eng)
	if err != nil {
		return nil, err
	}
	saveQueues[name] = sq
	return sq, nil
}

func newDbSaveQueue(name string, eng *xorm.Engine) (*DbSaveQueue, error) {
	sq := new(DbSaveQueue)
	sq.name = name
	sq.delayQueue = NewSortQueue(100)
	sq.Engine = eng

	// dump文件
	removeName := fmt.Sprintf("dumpToMysql%s.*.txt", name)
	if err := RemoveMatchedFiles(removeName); err != nil {
		return nil, err
	}

	ct := time.Now()
	fileName := fmt.Sprintf("dumpToMysql%s.%s.txt", name, ct.Format("20060102150405"))
	filePath := "./" + fileName
	logFile, err := os.Create(filePath)
	if err != nil {
		return nil, err
	}
	sq.logFile = logFile
	sq.logger = slog.New(logFile, "", slog.Ldate|slog.Ltime|slog.Lshortfile)

	// 开检测协程，保存延迟数据
	sq.chSaveEvent = make(chan struct{}, 1)

	ctx, cancel := context.WithCancel(context.Background())
	sq.cancel = cancel

	sq.wg.Add(1)
	go func() {
		defer sq.wg.Done()

		sq.checkTimeout(ctx, sq.chSaveEvent)
	}()

	return sq, nil
}

// request := new(model.Letter)
//
//	request.Content = "1234"
//	letterSaveQueue.Set(request, 10, false)
//	letterSaveQueue.Set(request, 10, false)
//	dbserver.Stop()
func Stop() {

	// 关闭存储协程
	for _, sq := range saveQueues {
		sq.cancel()
		sq.wg.Wait()

		// 未存储数据需要写本地文件
		sq.FlushAll()

		sq.logFile.Close()
	}
	saveQueues = nil
}

// 列表中的记录全部存库,存储失败则写文件
func (sq *DbSaveQueue) FlushAll() error {

	for _, it := range sq.delayQueue.heap {

		// 存库
		it2, ok := it.value.(SaveDBItem)
		if !ok {
			szItem, err := json.Marshal(it.value)
			sq.logger.Print(string(szItem), err, "it.value.(SaveDBItem) error")

			if it.chEndEvent != nil {
				close(it.chEndEvent)
			}
			continue
		}
		err := sq.saveOneItem(it2)
		if err != nil {
			// 存库失败写文件
			szItem, err := json.Marshal(it2)
			sq.logger.Print(string(szItem), err)
		}

		if it.chEndEvent != nil {
			close(it.chEndEvent)
		}
	}

	return nil
}

// needEndEvent 为true时，会建立一个独有的 channel，如果创建太多通道的话，性能应该是受影响的
// 所以needEndEvent最好是不要创建的太频繁
func (sq *DbSaveQueue) Set(obj SaveDBItem, delay int, needEndEvent bool) chan struct{} {
	if delay < 0 {
		delay = 0
	}

	tick := time.Now().Unix() + int64(delay)
	ch := sq.delayQueue.Set(obj, tick, needEndEvent)
	select {
	case sq.chSaveEvent <- struct{}{}:
	default:
	}

	return ch
}

// 同步存库，存储后返回
func (sq *DbSaveQueue) Save(obj SaveDBItem) error {
	ch := sq.Set(obj, 0, true)
	<-ch
	return nil
}

// 同步，确保历史记录存库，本条记录不存库,但用到了OBJ的key
func (sq *DbSaveQueue) FlushItem(obj SaveDBItem) error {

	tick := time.Now().Unix()
	ch := sq.delayQueue.SetUtil(obj, tick, true)
	if ch == nil {
		return nil
	}

	select {
	case sq.chSaveEvent <- struct{}{}:
	default:
	}

	<-ch
	return nil
}

// 协程保存
// 开多个协程进行保存工作
// 每个协程只能处理对应种类的数据，不能两个协程保存同类型数据
// 单个协程检查超时列表，取到数据后，执行存储操作
// 数据保存失败时写日志
func (sq *DbSaveQueue) checkTimeout(ctx context.Context, chSaveEvent chan struct{}) {

	ticker := time.NewTicker(time.Second)
	for {

		var ct time.Time
		select {
		case <-ctx.Done():
			ticker.Stop()
			// log.Warnf("checkTimeout exit.")
			return
		// case <-time.After(time.Millisecond * 50):
		case ct = <-ticker.C:
		// fmt.Println(time.Now().Format("2006-01-02 15:04:05"), "ticker")

		case <-chSaveEvent:
			ct = time.Now()
		}

		// fmt.Println(time.Now().Format("2006-01-02 15:04:05"), "process")
		cst := ct.Unix()
		for {
			// 是否到时间
			ci, saveTick := sq.delayQueue.First()
			if ci == nil || saveTick > cst {
				break
			}

			// 取第一个
			it, chEndEvent := sq.delayQueue.PopItem()
			if it == nil {
				continue
			}

			dbItem, ok := it.(SaveDBItem)
			if !ok {
				// 写错误日志
				szItem, err := json.Marshal(it)
				sq.logger.Print(string(szItem), err, "it.(SaveDBItem) error")

				if chEndEvent != nil {
					close(chEndEvent)
				}
				continue
			}

			err := sq.trySaveOneItem(ctx, dbItem)
			if err != nil {
				// log.Warnf("SaveDBItem trySaveOneItem error. %v", err)
				// dumpToFile(dbItem)
				// 存库失败写文件
				szItem, err := json.Marshal(it)
				sq.logger.Print(string(szItem), err, "trySaveOneItem error")
			}
			if chEndEvent != nil {
				close(chEndEvent)
			}
		}
	}
}

// 保存成功返回nil,
// 数据库关闭返回error
// 其他错误写入日志文件
func (sq *DbSaveQueue) saveOneItem(it SaveDBItem) error {
	// fmt.Println("start save to db", it)
	defer monitor.MySqlExecTimeoutWarn(it.TableName(), it, time.Now())
	defer func() {
		if r := recover(); r != nil {
			err := r.(error)
			strItem, _ := json.Marshal(it)
			log.Errorf("saveOneItem error. %v %v", err.Error(), string(strItem))
		}
	}()

	has, err := it.QueryExist(sq.Engine)
	if err != nil {
		return err
	}

	if has {
		_, err := it.UpdateDB(sq.Engine)
		if err != nil {
			return err
		}
	} else {
		_, err := sq.Engine.Insert(it)
		if err != nil {
			return err
		}
	}
	return nil
}

// 实际的存储操作
// 当数据库关闭，保存失败后一直尝试；
// 其他失败则写日志
// 当服务关闭时，添加到队列头，然后退出
func (sq *DbSaveQueue) trySaveOneItem(ctx context.Context, it SaveDBItem) error {

	isServerStop := func() bool {
		select {
		case <-ctx.Done():
			return true
		default:
		}
		return false
	}

	var err error
	for i := 0; i < 3; i += 1 {
		err = sq.saveOneItem(it)
		if err == nil {
			return nil
		}

		if isServerStop() {
			return err
		}
		time.Sleep(time.Millisecond * 100 * time.Duration(i+1))
	}

	return err
}

// 搜索匹配文件，删除字典顺序排名靠前的文件
// fmt.Sprintf("dumpTo%s.*.txt", name)
func RemoveMatchedFiles(pattern string) error {
	// 使用filepath.Glob匹配文件
	matches, err := filepath.Glob(pattern)
	if err != nil {
		return err
	}

	// 遍历匹配到的文件路径
	var toUnlink []string
	var zeroFiles []string
	for _, path := range matches {
		// fi, err := os.Stat(path)
		// if err != nil {
		// 	continue
		// }

		fl, err := os.Lstat(path)
		if err != nil {
			continue
		}

		if fl.Mode()&os.ModeSymlink == os.ModeSymlink {
			continue
		}
		if fl.Size() == 0 {
			zeroFiles = append(zeroFiles, path)
		} else {
			toUnlink = append(toUnlink, path)
		}
	}

	sort.Strings(toUnlink)

	for _, path := range zeroFiles {
		os.Remove(path)
	}

	rotationCount := 7
	if rotationCount >= len(toUnlink) {
		return nil
	}

	toUnlink = toUnlink[:len(toUnlink)-int(rotationCount)]

	// 尝试删除文件
	for _, path := range toUnlink {
		os.Remove(path)
	}

	return nil
}