// 最小堆存放数据项
// 并实现了一个时序队列，支持添加、删除、修改等操作
// 修改时间：2024-12-26
package smallheap

import (
	"container/heap"
	"context"
	"leafstalk/log"
	"leafstalk/otherutils/snowflake"
	"sync"
	"time"
)

type SortItem interface {
	SetIndex(index int)
	GetIndex() int
	GetSortKey() int64
	GetUniqueKey() int64
}

type SmallHeap[T SortItem] struct {
	Items      []T
	QueryTable map[int64]T
	sequence   *snowflake.Node //1MS生成400万个,不分节点
}

func (h SmallHeap[T]) Len() int {
	return len(h.Items)
}

func (h SmallHeap[T]) Less(i, j int) bool {
	return h.Items[i].GetSortKey() < h.Items[j].GetSortKey()
}

func (h SmallHeap[T]) Swap(i, j int) {
	h.Items[i], h.Items[j] = h.Items[j], h.Items[i]
	h.Items[i].SetIndex(i)
	h.Items[j].SetIndex(j)
}

func (h *SmallHeap[T]) Push(x interface{}) {
	v, ok := x.(T)
	if ok {
		v.SetIndex(len(h.Items))
		h.Items = append(h.Items, v)
	}
}

func (h *SmallHeap[T]) Pop() interface{} {
	n := len(h.Items)
	x := h.Items[n-1]
	h.Items = h.Items[:n-1]
	return x
}

func NewSmallHeap[T SortItem]() *SmallHeap[T] {
	sh := new(SmallHeap[T])
	sh.Items = make([]T, 0, 16)
	sh.QueryTable = make(map[int64]T)

	seq, err := snowflake.NewMsNode(0, 0)
	if err != nil {
		panic("NewSmallHeap init sequence error")
		return nil
	}

	sh.sequence = seq
	heap.Init(sh)

	return sh
}

func (h *SmallHeap[T]) Clear() {
	h.Items = make([]T, 0)
	h.QueryTable = make(map[int64]T)
}

// 使用接口
// 添加
func (h *SmallHeap[T]) Add(it T) {
	heap.Push(h, it)

	k := it.GetUniqueKey()
	h.QueryTable[k] = it
}

// 删除
func (h *SmallHeap[T]) Remove(index int) T {
	if index < 0 || index >= h.Len() {
		var t T
		return t
	}

	it := heap.Remove(h, index)
	v, ok := it.(T)
	if ok {
		v.SetIndex(-1)
		delete(h.QueryTable, v.GetUniqueKey())
		return v
	}
	var t T
	return t
}

func (h *SmallHeap[T]) RemoveByUniqueKey(uniqueKey int64) T {
	v, ok := h.QueryTable[uniqueKey]
	if !ok {
		var t T
		return t
	}
	return h.Remove(v.GetIndex())
}

// 修改
func (h *SmallHeap[T]) Update(t1 T) bool {
	old, ok := h.GetByUniqueKey(t1.GetUniqueKey())
	if ok {
		heap.Fix(h, old.GetIndex())
		return true
	}
	return false
}

// 查看第一个
func (h *SmallHeap[T]) Get(index int) T {
	if index >= 0 && index < h.Len() {
		return h.Items[index]
	}
	var t T
	return t
}

func (h *SmallHeap[T]) GetByUniqueKey(uniqueKey int64) (T, bool) {
	v, ok := h.QueryTable[uniqueKey]
	return v, ok
}

// 生成唯一ID，1MS生成400万个
func (h *SmallHeap[T]) NewId() int64 {
	return h.sequence.Generate().Int64()
}

// 排序、唯一KEY都是int64
type Int64SortObject[T any] struct {
	index     int
	SortKey   int64
	uniqueKey int64
	val       T
}

func (t *Int64SortObject[T]) GetSortKey() int64 {
	return t.SortKey
}

func (t *Int64SortObject[T]) SetIndex(index int) {
	t.index = index
}

func (t *Int64SortObject[T]) GetIndex() int {
	return t.index
}

func (t *Int64SortObject[T]) GetUniqueKey() int64 {
	return t.uniqueKey
}

// 时序队列
type TimeOrderQueue[T2 any] struct {
	allObjects *SmallHeap[*Int64SortObject[T2]]
	callBack   func(t T2)
	wg         sync.WaitGroup
	cancel     context.CancelFunc
}

func NewTimeOrderQueue[T2 any](checkPeriod time.Duration, callBack func(t T2)) *TimeOrderQueue[T2] {
	df := new(TimeOrderQueue[T2])
	df.allObjects = NewSmallHeap[*Int64SortObject[T2]]()

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

	df.callBack = callBack

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

		df.checkOnTime(ctx, checkPeriod)
	}()

	return df
}

func (d *TimeOrderQueue[T2]) Stop() {

	// 关闭存储协程
	if d.cancel != nil {
		d.cancel()
		d.cancel = nil
	}
	d.wg.Wait()
}

func (d *TimeOrderQueue[T2]) GetAll() map[int64]T2 {
	res := make(map[int64]T2)
	for k, v := range d.allObjects.QueryTable {
		res[k] = v.val
	}
	return res
}

func (d *TimeOrderQueue[T2]) NewId() int64 {
	return d.allObjects.NewId()
}

// 添加定时触发对象
// 要求objId运行期间必须唯一
func (d *TimeOrderQueue[T2]) AddTimeOrderObject(delay int64, obj T2, objId int64) int64 {
	ct := time.Now().Unix()
	ct += delay

	if objId == 0 {
		objId = d.NewId()
	}

	it := new(Int64SortObject[T2])
	it.SortKey = ct
	it.val = obj
	it.uniqueKey = objId

	d.allObjects.Add(it)
	return objId
}

func (d *TimeOrderQueue[T2]) RemoveTimeOrderObject(id int64) T2 {
	t := d.allObjects.RemoveByUniqueKey(id)
	return t.val
}

// 更新延迟时间，从调用函数时开始计算
func (d *TimeOrderQueue[T2]) UpdateDelayTime(id int64, delay int64) bool {
	it, ok := d.allObjects.GetByUniqueKey(id)
	if !ok {
		return ok
	}

	ct := time.Now().Unix()
	ct += delay
	it.SortKey = ct

	return d.allObjects.Update(it)
}

func (d *TimeOrderQueue[T2]) checkOnTime(ctx context.Context, period time.Duration) {

	safeCall := func(t T2) {
		if d.callBack == nil {
			return
		}

		defer func() {
			if err := recover(); err != nil {
				log.Warnf("checkTimeout safeCall error. %v", err)
			}
		}()

		d.callBack(t)
	}

	if period < time.Millisecond {
		period = 50 * time.Millisecond
	}
	ticker := time.NewTicker(period)
	for {

		var ct time.Time
		select {
		case <-ctx.Done():
			ticker.Stop()
			log.Warnf("checkTimeout exit.")
			return
		case ct = <-ticker.C:
		}

		cst := ct.Unix()
		for {
			// 是否到时间
			t := d.allObjects.Get(0)
			if t == nil {
				break
			}

			if t.SortKey > cst {
				break
			}

			// 取第一个
			d.allObjects.Remove(0)

			safeCall(t.val)
		}
	}
}