package lockprovider

import (
	"fmt"

	"gitlink.org.cn/cloudream/common/utils/lo2"
	"gitlink.org.cn/cloudream/jcs-pub/client/internal/publock/types"
)

const (
	UserSpaceLockPathPrefix     = "UserSpace"
	UserSpaceStorageIDPathIndex = 1
	UserSpaceBuzyLock           = "Buzy"
	UserSpaceGCLock             = "GC"
)

type UserSpaceLock struct {
	stgLocks  map[string]*UserSpaceStorageLock
	dummyLock *UserSpaceStorageLock
}

func NewUserSpaceLock() *UserSpaceLock {
	return &UserSpaceLock{
		stgLocks:  make(map[string]*UserSpaceStorageLock),
		dummyLock: NewUserSpaceStorageLock(),
	}
}

// CanLock 判断这个锁能否锁定成功
func (l *UserSpaceLock) CanLock(lock types.Lock) error {
	nodeLock, ok := l.stgLocks[lock.Path[UserSpaceStorageIDPathIndex]]
	if !ok {
		// 不能直接返回nil，因为如果锁数据的格式不对，也不能获取锁。
		// 这里使用一个空Provider来进行检查。
		return l.dummyLock.CanLock(lock)
	}

	return nodeLock.CanLock(lock)
}

// 锁定。在内部可以不用判断能否加锁，外部需要保证调用此函数前调用了CanLock进行检查
func (l *UserSpaceLock) Lock(reqID types.RequestID, lock types.Lock) error {
	stgID := lock.Path[UserSpaceStorageIDPathIndex]

	nodeLock, ok := l.stgLocks[stgID]
	if !ok {
		nodeLock = NewUserSpaceStorageLock()
		l.stgLocks[stgID] = nodeLock
	}

	return nodeLock.Lock(reqID, lock)
}

// 解锁
func (l *UserSpaceLock) Unlock(reqID types.RequestID, lock types.Lock) error {
	stgID := lock.Path[UserSpaceStorageIDPathIndex]

	nodeLock, ok := l.stgLocks[stgID]
	if !ok {
		return nil
	}

	return nodeLock.Unlock(reqID, lock)
}

// Clear 清除内部所有状态
func (l *UserSpaceLock) Clear() {
	l.stgLocks = make(map[string]*UserSpaceStorageLock)
}

type UserSpaceStorageLock struct {
	buzyReqIDs []types.RequestID
	gcReqIDs   []types.RequestID

	lockCompatibilityTable *LockCompatibilityTable
}

func NewUserSpaceStorageLock() *UserSpaceStorageLock {
	compTable := &LockCompatibilityTable{}

	sdLock := UserSpaceStorageLock{
		lockCompatibilityTable: compTable,
	}

	compTable.
		Column(UserSpaceBuzyLock, func() bool { return len(sdLock.buzyReqIDs) > 0 }).
		Column(UserSpaceGCLock, func() bool { return len(sdLock.gcReqIDs) > 0 })

	comp := LockCompatible()
	uncp := LockUncompatible()

	compTable.MustRow(comp, uncp)
	compTable.MustRow(uncp, comp)

	return &sdLock
}

// CanLock 判断这个锁能否锁定成功
func (l *UserSpaceStorageLock) CanLock(lock types.Lock) error {
	return l.lockCompatibilityTable.Test(lock)
}

// 锁定
func (l *UserSpaceStorageLock) Lock(reqID types.RequestID, lock types.Lock) error {
	switch lock.Name {
	case UserSpaceBuzyLock:
		l.buzyReqIDs = append(l.buzyReqIDs, reqID)
	case UserSpaceGCLock:
		l.gcReqIDs = append(l.gcReqIDs, reqID)
	default:
		return fmt.Errorf("unknow lock name: %s", lock.Name)
	}

	return nil
}

// 解锁
func (l *UserSpaceStorageLock) Unlock(reqID types.RequestID, lock types.Lock) error {
	switch lock.Name {
	case UserSpaceBuzyLock:
		l.buzyReqIDs = lo2.Remove(l.buzyReqIDs, reqID)
	case UserSpaceGCLock:
		l.gcReqIDs = lo2.Remove(l.gcReqIDs, reqID)
	default:
		return fmt.Errorf("unknow lock name: %s", lock.Name)
	}

	return nil
}