package distributedlock

import (
	"context"
	"errors"
	"fmt"
	"strings"
	"sync"
	"time"

	constants "modelRT/distributedlock/constant"
	luascript "modelRT/distributedlock/luascript"
	"modelRT/logger"

	uuid "github.com/gofrs/uuid"
	"github.com/redis/go-redis/v9"
	"go.uber.org/zap"
)

const (
	internalLockLeaseTime = uint64(30 * 1000)
	unlockMessage         = 0
)

// RedissionLockConfig define redission lock config
type RedissionLockConfig struct {
	LockLeaseTime uint64
	Token         string
	Prefix        string
	ChanPrefix    string
	TimeoutPrefix string
	Key           string
	NeedRefresh   bool
}

type redissionLocker struct {
	lockLeaseTime   uint64
	Token           string
	Key             string
	waitChanKey     string
	needRefresh     bool
	refreshExitChan chan struct{}
	subExitChan     chan struct{}
	client          *redis.Client
	refreshOnce     *sync.Once
}

func (rl *redissionLocker) Lock(ctx context.Context, timeout ...time.Duration) error {
	if rl.refreshExitChan == nil {
		rl.refreshExitChan = make(chan struct{})
	}
	result := rl.tryLock(ctx).(*constants.RedisResult)
	if result.Code == constants.UnknownInternalError {
		logger.Error(ctx, result.OutputResultMessage())
		return fmt.Errorf("get lock failed:%w", result)
	}

	if (result.Code == constants.LockSuccess) && rl.needRefresh {
		rl.refreshOnce.Do(func() {
			// async refresh lock timeout unitl receive exit singal
			go rl.refreshLockTimeout(ctx)
		})
		return nil
	}

	subMsg := make(chan struct{}, 1)
	defer close(subMsg)
	sub := rl.client.Subscribe(ctx, rl.waitChanKey)
	defer sub.Close()
	go rl.subscribeLock(ctx, sub, subMsg)

	if len(timeout) > 0 && timeout[0] > 0 {
		acquireTimer := time.NewTimer(timeout[0])
		for {
			select {
			case _, ok := <-subMsg:
				if !ok {
					err := errors.New("failed to read the lock waiting for for the channel message")
					logger.Error(ctx, "failed to read the lock waiting for for the channel message")
					return err
				}

				resultErr := rl.tryLock(ctx).(*constants.RedisResult)
				if (resultErr.Code == constants.LockFailure) || (resultErr.Code == constants.UnknownInternalError) {
					logger.Info(ctx, resultErr.OutputResultMessage())
					continue
				}

				if resultErr.Code == constants.LockSuccess {
					logger.Info(ctx, resultErr.OutputResultMessage())
					return nil
				}
			case <-acquireTimer.C:
				err := errors.New("the waiting time for obtaining the lock operation has timed out")
				logger.Info(ctx, "the waiting time for obtaining the lock operation has timed out")
				return err
			}
		}
	}
	return fmt.Errorf("lock the redis lock failed:%w", result)
}

func (rl *redissionLocker) subscribeLock(ctx context.Context, sub *redis.PubSub, subMsgChan chan struct{}) {
	if sub == nil || subMsgChan == nil {
		return
	}
	logger.Info(ctx, "lock: enter sub routine", zap.String("token", rl.Token))

	for {
		select {
		case <-rl.subExitChan:
			close(subMsgChan)
			return
		case <-sub.Channel():
			// 这里只会收到真正的数据消息
			subMsgChan <- struct{}{}
		default:
		}
	}
}

/*
KEYS[1]:锁的键名（key）,通常是锁的唯一标识。
ARGV[1]:锁的过期时间（lockLeaseTime）,单位为秒。
ARGV[2]:当前客户端的唯一标识（token）,用于区分不同的客户端。
*/
func (rl *redissionLocker) refreshLockTimeout(ctx context.Context) {
	logger.Info(ctx, "lock refresh by key and token", zap.String("token", rl.Token), zap.String("key", rl.Key))

	lockTime := time.Duration(rl.lockLeaseTime/3) * time.Millisecond
	timer := time.NewTimer(lockTime)
	defer timer.Stop()

	for {
		select {
		case <-timer.C:
			// extend key lease time
			res := rl.client.Eval(ctx, luascript.RefreshLockScript, []string{rl.Key}, rl.lockLeaseTime, rl.Token)
			val, err := res.Int()
			if err != redis.Nil && err != nil {
				logger.Info(ctx, "lock refresh failed", "token", rl.Token, "key", rl.Key, "error", err)
				return
			}

			if constants.RedisCode(val) == constants.RefreshLockFailure {
				logger.Error(ctx, "lock refreash failed,can not find the lock by key and token", "token", rl.Token, "key", rl.Key)
				break
			}

			if constants.RedisCode(val) == constants.RefreshLockSuccess {
				logger.Info(ctx, "lock refresh success by key and token", "token", rl.Token, "key", rl.Key)
			}
			timer.Reset(lockTime)
		case <-rl.refreshExitChan:
			return
		}
	}
}

func (rl *redissionLocker) cancelRefreshLockTime() {
	if rl.refreshExitChan != nil {
		close(rl.refreshExitChan)
		rl.refreshOnce = &sync.Once{}
	}
}

func (rl *redissionLocker) closeSub(ctx context.Context, sub *redis.PubSub, noticeChan chan struct{}) {
	if sub != nil {
		err := sub.Close()
		if err != nil {
			logger.Error(ctx, "close sub failed", "token", rl.Token, "key", rl.Key, "error", err)
		}
	}

	if noticeChan != nil {
		close(noticeChan)
	}
}

/*
KEYS[1]:锁的键名（key）,通常是锁的唯一标识。
ARGV[1]:锁的过期时间（lockLeaseTime）,单位为秒。
ARGV[2]:当前客户端的唯一标识（token）,用于区分不同的客户端。
*/
func (rl *redissionLocker) tryLock(ctx context.Context) error {
	lockType := constants.LockType
	res := rl.client.Eval(ctx, luascript.LockScript, []string{rl.Key}, rl.lockLeaseTime, rl.Token)
	val, err := res.Int()
	if err != redis.Nil && err != nil {
		return constants.NewRedisResult(constants.UnknownInternalError, lockType, err.Error())
	}
	return constants.NewRedisResult(constants.RedisCode(val), lockType, "")
}

/*
KEYS[1]:锁的键名（key）,通常是锁的唯一标识。
KEYS[2]:锁的释放通知频道（chankey）,用于通知其他客户端锁已释放。
ARGV[1]:解锁消息（unlockMessage）,用于通知其他客户端锁已释放。
ARGV[2]:当前客户端的唯一标识（token）,用于区分不同的客户端。
*/
func (rl *redissionLocker) UnLock(ctx context.Context) error {
	res := rl.client.Eval(ctx, luascript.UnLockScript, []string{rl.Key, rl.waitChanKey}, unlockMessage, rl.Token)
	val, err := res.Int()
	if err != redis.Nil && err != nil {
		logger.Info(ctx, "unlock lock failed", zap.String("token", rl.Token), zap.String("key", rl.Key), zap.Error(err))
		return fmt.Errorf("unlock lock failed:%w", constants.NewRedisResult(constants.UnknownInternalError, constants.UnLockType, err.Error()))
	}

	if constants.RedisCode(val) == constants.UnLockSuccess {
		if rl.needRefresh {
			rl.cancelRefreshLockTime()
		}

		logger.Info(ctx, "unlock lock success", zap.String("token", rl.Token), zap.String("key", rl.Key))
		return nil
	}

	if constants.RedisCode(val) == constants.UnLocakFailureWithLockOccupancy {
		logger.Info(ctx, "unlock lock failed", zap.String("token", rl.Token), zap.String("key", rl.Key))
		return fmt.Errorf("unlock lock failed:%w", constants.NewRedisResult(constants.UnLocakFailureWithLockOccupancy, constants.UnLockType, ""))
	}
	return nil
}

// TODO 优化 panic
func GetLocker(client *redis.Client, ops *RedissionLockConfig) *redissionLocker {
	if ops.Token == "" {
		token, err := uuid.NewV4()
		if err != nil {
			panic(err)
		}
		ops.Token = token.String()
	}

	if len(ops.Prefix) <= 0 {
		ops.Prefix = "redission-lock"
	}

	if len(ops.ChanPrefix) <= 0 {
		ops.ChanPrefix = "redission-lock-channel"
	}

	if ops.LockLeaseTime == 0 {
		ops.LockLeaseTime = internalLockLeaseTime
	}

	r := &redissionLocker{
		Token:           ops.Token,
		Key:             strings.Join([]string{ops.Prefix, ops.Key}, ":"),
		waitChanKey:     strings.Join([]string{ops.ChanPrefix, ops.Key, "wait"}, ":"),
		needRefresh:     ops.NeedRefresh,
		client:          client,
		refreshExitChan: make(chan struct{}),
	}
	return r
}