package timeslice

import (
	"context"
	"fmt"
	"github.com/hashicorp/go-multierror"
	"golang.org/x/sync/errgroup"
	"time"
)

type ManagerSrv struct {
	callback func(ctx context.Context, req *Task) error
}

func NewManager(callback func(ctx context.Context, req *Task) error) *ManagerSrv {
	return &ManagerSrv{callback: callback}
}

func (m *ManagerSrv) Run(ctx context.Context, req *Manager) (int, error) {

	if req.StartTime.After(req.EndTime) {
		return 0, fmt.Errorf("start_time不能大于end_time")
	}

	totalHours := req.EndTime.Sub(req.StartTime).Hours()
	taskCount := int(totalHours / 2)

	// 如果剩余时间不足2小时，增加任务数
	if totalHours-float64(taskCount)*float64(2) > 0 {
		taskCount++
	}

	processReq := &Process{
		manager:   req,
		taskCount: taskCount,
	}

	return taskCount, m.process(ctx, processReq)
}

func (m *ManagerSrv) process(ctx context.Context, req *Process) error {

	if req.taskCount == 0 {
		return fmt.Errorf("该时间范围无可执行任务次数，请检查时间范围")
	}

	if req.manager.GoNum == 0 {
		return fmt.Errorf("协程数量不能为0")
	}
	if req.manager.GoNum > 100 {
		return fmt.Errorf("协程数量不能大于100")
	}

	// 设置最大并发任务数为 5
	eg := new(errgroup.Group)
	eg.SetLimit(req.manager.GoNum)

	errs := make([]error, 0) // 用于存储所有错误

	// 为每个任务分配开始和结束时间
	for i := 0; i < req.taskCount; i++ {

		currentStart := req.manager.StartTime.Add(time.Duration(i) * 2 * time.Hour)
		currentEnd := currentStart.Add(2 * time.Hour)

		if currentEnd.After(req.manager.EndTime) {
			currentEnd = req.manager.EndTime
		}
		taskID := i + 1

		eg.Go(func() error {

			defer func() {
				if err := recover(); err != nil {
					errs = append(errs, fmt.Errorf("panic: %v", err))
				}
			}()

			taskReq := &Task{
				CurrentStartTime: currentStart,
				CurrentEndTime:   currentEnd,
				TaskID:           taskID,
				Process:          req,
			}

			if err := m.callback(ctx, taskReq); err != nil {
				errs = append(errs, err)
			}

			return nil
		})
	}

	// 等待所有任务完成
	if err := eg.Wait(); err != nil {
		return fmt.Errorf("任务执行失败: %v", err)
	}

	var result error

	// 收集错误
	for _, err2 := range errs {
		result = multierror.Append(result, err2)
	}

	return result
}