package dbserver

import (
	"container/heap"
	"fmt"
	"sync"
)

type SaveItem interface {
	TableName() string
	GetUniqueKey() string
}

type SaveCallBack func()

type SortItem struct {
	value      SaveItem
	tick       int64
	index      int
	chEndEvent chan struct{}
}

type SortQueue struct {
	sync.Mutex
	heap     []*SortItem
	itemsMap map[string]*SortItem
}

// 接口

func (sq *SortQueue) Len() int {
	return len(sq.heap)
}

// 根最小
func (sq *SortQueue) Less(i, j int) bool {
	return sq.heap[i].tick < sq.heap[j].tick
}

func (sq *SortQueue) Swap(i, j int) {
	sq.heap[i], sq.heap[j] = sq.heap[j], sq.heap[i]
	sq.heap[i].index = i
	sq.heap[j].index = j
}

// 元素放在队列尾部
func (sq *SortQueue) Push(x interface{}) {
	n := len(sq.heap)
	item := x.(*SortItem)
	item.index = n
	sq.heap = append(sq.heap, item)
}

// 弹出最后一个元素
func (sq *SortQueue) Pop() interface{} {

	n := len(sq.heap)
	item := sq.heap[n-1]
	item.index = -1
	sq.heap = sq.heap[0 : n-1]

	return item
}

// 使用
func NewSortQueue(len int) *SortQueue {

	sq := new(SortQueue)
	sq.heap = make([]*SortItem, 0, len)
	heap.Init(sq)

	sq.itemsMap = make(map[string]*SortItem)

	return sq
}

func CalcUniqueKey(item SaveItem) string {
	tab := item.TableName()
	id := item.GetUniqueKey()
	return fmt.Sprintf("%s.%s", tab, id)
}

// 插入一条记录
func (sq *SortQueue) Set(si SaveItem, tick int64, needEndEvent bool) chan struct{} {

	sq.Lock()
	defer sq.Unlock()

	key := CalcUniqueKey(si)
	if v, ok := sq.itemsMap[key]; ok {
		v.value = si
		if needEndEvent {
			if v.chEndEvent == nil {
				v.chEndEvent = make(chan struct{})
			}
		}
		if v.tick > tick {
			v.tick = tick
			heap.Fix(sq, v.index)
		}
		return v.chEndEvent
	}

	item := new(SortItem)
	item.value = si
	item.tick = tick
	if needEndEvent {
		if item.chEndEvent == nil {
			item.chEndEvent = make(chan struct{})
		}
	}
	heap.Push(sq, item)
	sq.itemsMap[key] = item
	return item.chEndEvent
}

// 插入一条记录
func (sq *SortQueue) SetUtil(si SaveItem, tick int64, needEndEvent bool) chan struct{} {

	sq.Lock()
	defer sq.Unlock()

	key := CalcUniqueKey(si)
	if v, ok := sq.itemsMap[key]; ok {
		if needEndEvent {
			if v.chEndEvent == nil {
				v.chEndEvent = make(chan struct{})
			}
		}
		if v.tick > tick {
			v.tick = tick
			heap.Fix(sq, v.index)
		}
		return v.chEndEvent
	}

	return nil
}

// 移除最小值记录
func (sq *SortQueue) PopItem() (SaveItem, chan struct{}) {
	sq.Lock()
	defer sq.Unlock()

	if len(sq.heap) == 0 {
		return nil, nil
	}

	it := heap.Pop(sq).(*SortItem)
	key := CalcUniqueKey(it.value)
	delete(sq.itemsMap, key)
	return it.value, it.chEndEvent
}

// 移除指定记录
func (sq *SortQueue) RemoveItem(item SaveItem) SaveItem {
	sq.Lock()
	defer sq.Unlock()

	if len(sq.heap) == 0 {
		return nil
	}

	key := CalcUniqueKey(item)
	if v, ok := sq.itemsMap[key]; ok {
		heap.Remove(sq, v.index)
		delete(sq.itemsMap, key)
		return v.value
	}
	return nil
}

// 查看二叉树根记录，就是最小值记录
func (sq *SortQueue) First() (SaveItem, int64) {
	sq.Lock()
	defer sq.Unlock()

	if len(sq.heap) == 0 {
		return nil, 0
	}

	item := sq.heap[0]
	return item.value, item.tick
}

// 查看二叉树最后节点信息，不一定是最大值
func (sq *SortQueue) Last() (SaveItem, int64) {
	sq.Lock()
	defer sq.Unlock()

	cnt := sq.Len()
	if cnt == 0 {
		return nil, 0
	}

	item := sq.heap[cnt-1]
	return item.value, item.tick
}

func example() {
	// saveSq := NewSortQueue(100)

	// for i := 0; i < 10; i += 1 {
	// 	it := new(NewYearFifteen)
	// 	it.PlayerId = 1 + int64(i)

	// 	rd := rand.Int63n(1000)

	// 	saveSq.Set(it, rd, nil)
	// }

	// fmt.Println(saveSq.First())
	// fmt.Println(saveSq.Last())

	// for _, v := range saveSq.heap {
	// 	fmt.Println(v.tick, v.value.GetUniqueKey())
	// }

	// cnt := saveSq.Len()
	// for i := 0; i < cnt; i += 1 {
	// 	fmt.Println(saveSq.PopItem().GetUniqueKey())
	// }
}