package tasksch

import (
	"errors"
	"sync"
	"time"

	"git.rosy.net.cn/baseapi/utils"
	"git.rosy.net.cn/jx-callback/business/jxutils"
)

const (
	TaskStatusBegin     = 0
	TaskStatusWorking   = 0
	TaskStatusCanceling = 1

	TaskStatusEndBegin = 2
	TaskStatusFinished = 2
	TaskStatusCanceled = 3
	TaskStatusFailed   = 4
	TaskStatusEnd      = 4
)

type WorkFunc func(batchItemList []interface{}, params ...interface{}) (retVal interface{}, err error)
type ResultHandlerFunc func(taskName string, result []interface{}, err error)

type Task struct {
	ID                string    `json:"id"`
	Name              string    `json:"name"`
	CreatedBy         string    `json:"createdBy"`
	CreatedAt         time.Time `json:"createdAt"`
	UpdatedAt         time.Time `json:"updatedAt"`
	TerminatedAt      time.Time `json:"terminatedAt"`
	ParallelCount     int       `json:"parallelCount"`
	TotalItemCount    int       `json:"totalItemCount"`
	TotalJobCount     int       `json:"totalJobCount"`
	FinishedItemCount int       `json:"finishedItemCount"`
	FinishedJobCount  int       `json:"finishedJobCount"`
	Status            int       `json:"status"`

	C <-chan int `json:"-"`

	taskChan      chan []interface{}
	quitChan      chan int
	subFinishChan chan interface{}
	finishChan    chan int

	locker sync.RWMutex
	result []interface{}
	err    error
}

type TaskList []*Task

func (s TaskList) Len() int {
	return len(s)
}

func (s TaskList) Less(i, j int) bool {
	return s[i].CreatedAt.Sub(s[j].CreatedAt) < 0
}

func (s TaskList) Swap(i, j int) {
	tmp := s[i]
	s[i] = s[j]
	s[j] = tmp
}

var (
	ErrTaskNotFinished = errors.New("任务还未完成")
	ErrTaskIsCanceled  = errors.New("任务被取消了")
)

func RunTask(taskName string, worker WorkFunc, resultHandler ResultHandlerFunc, parallelCount, batchSize int, userName string, itemList interface{}, params ...interface{}) *Task {
	realItemList := utils.Interface2Slice(itemList)
	jobList := jxutils.SplitSlice(realItemList, batchSize)
	task := &Task{
		ID:             utils.GetUUID(),
		Name:           taskName,
		CreatedAt:      time.Now(),
		CreatedBy:      userName,
		UpdatedAt:      time.Now(),
		TotalJobCount:  len(jobList),
		TotalItemCount: len(realItemList),
		ParallelCount:  parallelCount,
		taskChan:       make(chan []interface{}, parallelCount*100),
		quitChan:       make(chan int, parallelCount),
		subFinishChan:  make(chan interface{}, parallelCount),
		finishChan:     make(chan int, 2),
		Status:         TaskStatusWorking,
	}
	task.C = task.finishChan
	go func() {
		for i := 0; i < parallelCount; i++ {
			go func() {
				var chanRetVal interface{}
				retVal := make([]interface{}, 0)
				for {
					select {
					case <-task.quitChan:
						goto end
					case job := <-task.taskChan:
						if job == nil {
							chanRetVal = retVal
							goto end
						} else {
							if result, err := worker(job, params...); err == nil {
								task.finishedOneJob(len(job))
								if result != nil {
									retVal = append(retVal, utils.Interface2Slice(result)...)
								}
							} else {
								chanRetVal = err
								task.Cancel()
							}
						}
					}
				}
			end:
				task.subFinishChan <- chanRetVal
			}()
		}
		for _, job := range jobList {
			task.taskChan <- job
		}
		for i := 0; i < parallelCount; i++ {
			task.taskChan <- nil
		}

		taskResult := make([]interface{}, 0)
		var taskErr error
		for i := 0; i < parallelCount; i++ {
			result := <-task.subFinishChan
			if err2, ok := result.(error); ok {
				taskResult = nil
				taskErr = err2
				break
			} else if result != nil {
				resultList := result.([]interface{})
				taskResult = append(taskResult, resultList...)
			}
		}

		task.locker.Lock()
		if taskErr != nil { // 如果有错误，肯定就是失败了
			task.Status = TaskStatusFailed
		} else {
			if len(task.taskChan) > 0 {
				taskErr = ErrTaskIsCanceled
				task.Status = TaskStatusCanceled
			} else {
				task.Status = TaskStatusFinished
			}
		}
		task.err = taskErr
		task.result = taskResult
		task.TerminatedAt = time.Now()

		task.locker.Unlock()

		close(task.finishChan)
		close(task.subFinishChan)
		close(task.quitChan)

		if resultHandler != nil {
			resultHandler(taskName, task.result, task.err)
		}
	}()
	return task
}

func (t *Task) GetResult(duration time.Duration) (retVal []interface{}, err error) {
	if t.GetStatus() >= TaskStatusEndBegin {
		return t.result, t.err
	}
	if duration == 0 {
		duration = time.Hour * 10000 // duration为0表示无限等待
	}
	timer := time.NewTimer(duration)
	select {
	case <-t.finishChan:
		timer.Stop()
		t.locker.RLock()
		defer t.locker.RUnlock()

		return t.result, t.err
	case <-timer.C:
	}
	return nil, ErrTaskNotFinished
}

func (t *Task) Cancel() {
	if t.GetStatus() < TaskStatusEndBegin {
		for i := 0; i < t.ParallelCount; i++ {
			t.quitChan <- 0
		}
		t.setStatus(TaskStatusCanceling)
	}
}

func (t *Task) GetTotalItemCount() int {
	return t.TotalItemCount
}

func (t *Task) GetFinishedItemCount() int {
	t.locker.RLock()
	defer t.locker.RUnlock()

	return t.FinishedItemCount
}

func (t *Task) GetTotalJobCount() int {
	return t.TotalJobCount
}

func (t *Task) GetFinishedJobCount() int {
	t.locker.RLock()
	defer t.locker.RUnlock()

	return t.FinishedJobCount
}

func (t *Task) GetStatus() int {
	t.locker.RLock()
	defer t.locker.RUnlock()

	return t.Status
}

/////////

func (t *Task) finishedOneJob(itemCount int) {
	t.locker.Lock()
	defer t.locker.Unlock()

	t.UpdatedAt = time.Now()
	t.FinishedItemCount += itemCount
	t.FinishedJobCount++
}

func (t *Task) setStatus(status int) {
	t.locker.Lock()
	defer t.locker.Unlock()

	t.Status = status
}