package startimer

import (
	"context"
	"encoding/json"
	"errors"
	"sort"
	"sync"
	"time"
)

func NewTimer(baseDate time.Time, opts ...TimerOptions) StarTimer {
	timer := StarTimer{
		base:     baseDate,
		nextDate: time.Time{},
		mu:       new(sync.RWMutex),
	}
	for _, opt := range opts {
		var op TimerOption
		opt(&op)
		switch op.idx {
		case 3:
			timer.repeat = append(timer.repeat, &Repeats{
				Repeat: []Repeat{
					{
						Unit:  STAR_YEAR,
						Value: uint32(op.date.Year()),
					},
					{
						Unit:  STAR_MONTH,
						Value: uint32(op.date.Month()),
					},
					{
						Unit:  STAR_DAY,
						Value: uint32(op.date.Day()),
					},
					{
						Unit:  STAR_HOUR,
						Value: uint32(op.date.Hour()),
					},
					{
						Unit:  STAR_MINUTE,
						Value: uint32(op.date.Minute()),
					},
					{
						Unit:  STAR_SECOND,
						Value: uint32(op.date.Second()),
					},
				},
				Every: false,
			})
		case 4:
			timer.repeat = append(timer.repeat, &Repeats{
				Repeat: []Repeat{op.repeat},
				Every:  true,
			})
		}

		if op.repeats != nil {
			timer.repeat = append(timer.repeat, op.repeats)
		}
		if op.tasks != nil {
			timer.tasks = append(timer.tasks, op.tasks)
		}
	}
	return timer
}
func (t *StarTimer) IsRunning() bool {
	t.mu.RLock()
	defer t.mu.RUnlock()
	return t.running
}

func (t *StarTimer) AddTask(task func()) {
	t.tasks = append(t.tasks, task)
}

func (t *StarTimer) SetTasks(tasks []func()) {
	t.tasks = tasks
}

func (t *StarTimer) Stop() error {
	t.mu.Lock()
	defer t.mu.Unlock()
	if !t.running {
		return nil
	}
	t.running = false
	t.stopFn()
	if t.timer != nil {
		t.timer.Stop()
	}
	return nil
}

func (t *StarTimer) NextTimer() time.Time {
	return t.nextDate
}

func (t *StarTimer) NextTimerAfterDate(date time.Time) time.Time {
	return t.parseNextDate(date, true)
}

func (t *StarTimer) ExportRepeats() (string, error) {
	var rep []Repeats
	for _, r := range t.repeat {
		rep = append(rep, *r)
	}
	data, err := json.Marshal(rep)
	if err != nil {
		return "", err
	}
	return string(data), nil
}

func (t *StarTimer) ImportRepeats(r string) error {
	t.mu.Lock()
	defer t.mu.Unlock()
	if t.running {
		return errors.New("coonot import repeats to already running timer")
	}
	var rep []Repeats
	err := json.Unmarshal([]byte(r), &rep)
	if err != nil {
		return err
	}
	t.repeat = make([]*Repeats, 0, len(rep))
	for _, v := range rep {
		t.repeat = append(t.repeat, &v)
	}
	return nil
}

func (t *StarTimer) BaseDate() time.Time {
	return t.base
}

func (t *StarTimer) ResetWithRepeat(base time.Time, repeat []*Repeats) error {
	t.Stop()
	t.base = base
	t.repeat = repeat
	return t.Run()
}

func (t *StarTimer) Run() error {
	t.mu.Lock()
	defer t.mu.Unlock()
	if t.running {
		return nil
	}
	t.nextDate = t.parseNextDate(time.Now(), false)
	if t.nextDate.Before(time.Now()) {
		return errors.New("Invalid Timer Options,Please Check")
	}
	t.running = true
	t.stopCtx, t.stopFn = context.WithCancel(context.Background())
	go func() {
		for {
			now := time.Now()
			t.mu.Lock()
			t.timer = time.NewTimer(t.nextDate.Sub(now))
			t.mu.Unlock()
			select {
			case <-t.timer.C:
				t.nextDate = t.parseNextDate(t.nextDate, false)
				if t.nextDate.Before(now) {
					t.Stop()
				}
				for _, fn := range t.tasks {
					go fn()
				}
				if !t.running {
					return
				}
			case <-t.stopCtx.Done():
				return
			}
		}
	}()
	return nil
}

func (t *StarTimer) parseNextDate(base time.Time, isMock bool) time.Time {
	if len(t.repeat) == 0 {
		return time.Time{}
	}
	var dates []time.Time
	for _, d := range t.repeat {
		if d == nil {
			continue
		}
		if d.Every {
			dates = append(dates, t.parseEveryNextDate(base, d, isMock)...)
		} else {
			dates = append(dates, t.parseStaticNextDate(base, d))
		}
	}
	sort.SliceStable(dates, func(i, j int) bool {
		return dates[i].UnixNano() < dates[j].UnixNano()
	})
	if len(dates) == 0 {
		return time.Time{}
	}
	now := time.Now().UnixNano()
	for _, v := range dates {
		if v.UnixNano() > now {
			return v
		}
	}
	return time.Time{}
}

func (t *StarTimer) parseStaticNextDate(base time.Time, r *Repeats) time.Time {
	target := base
	if !r.Every { //固定日期
		for _, d := range r.Repeat {
			switch d.Unit {
			case STAR_SECOND:
				sub := int(d.Value) - target.Second()
				if sub < 0 {
					sub += 60
				}
				target = target.Add(time.Second * time.Duration(sub))
			case STAR_MINUTE:
				sub := int(d.Value) - target.Minute()
				if sub < 0 {
					sub += 60
				}
				target = target.Add(time.Minute * time.Duration(sub))
			case STAR_HOUR:
				sub := int(d.Value) - target.Hour()
				if sub < 0 {
					sub += 24
				}
				target = target.Add(time.Hour * time.Duration(sub))
			case STAR_DAY:
				sub := int(d.Value) - target.Day()
				if sub >= 0 {
					target = target.Add(time.Hour * 24 * time.Duration(sub))
					continue
				}
				target = time.Date(target.Year(), target.Month()+1, int(d.Value), target.Hour(), target.Minute(), target.Second(), 0, target.Location())
			case STAR_MONTH:
				sub := int(d.Value) - int(target.Month())
				if sub < 0 {
					sub += 12
				}
				target = target.AddDate(0, sub, 0)
			case STAR_YEAR:
				sub := int(d.Value) - int(target.Year())
				if sub < 0 {
					return time.Date(0, 0, 0, 0, 0, 0, 0, nil)
				}
				target = target.AddDate(sub, 0, 0)
			}
		}
	}
	if target == base {
		return time.Time{}
	}
	return target
}

func (t *StarTimer) parseEveryNextDate(target time.Time, r *Repeats, isMock bool) []time.Time {
	var res []time.Time
	if r.Every { //定期日期
		for idx, d := range r.Repeat {
			if d.baseDate.Unix() == -62135596800 {
				d.baseDate = t.base
				if !isMock {
					r.Repeat[idx] = d
				}
			}
			if d.baseDate.After(target) {
				res = append(res, d.baseDate)
				continue
			}
			switch d.Unit {
			case STAR_SECOND:
				for {
					d.baseDate = d.baseDate.Add(time.Second * time.Duration(int(d.Value)))
					if d.baseDate.After(target) {
						if !isMock {
							r.Repeat[idx] = d
						}
						break
					}
				}
				res = append(res, d.baseDate)
			case STAR_MINUTE:
				for {
					d.baseDate = d.baseDate.Add(time.Minute * time.Duration(int(d.Value)))
					if d.baseDate.After(target) {
						if !isMock {
							r.Repeat[idx] = d
						}
						break
					}
				}
				res = append(res, d.baseDate)
			case STAR_HOUR:
				for {
					d.baseDate = d.baseDate.Add(time.Hour * time.Duration(int(d.Value)))
					if d.baseDate.After(target) {
						if !isMock {
							r.Repeat[idx] = d
						}
						break
					}
				}
				res = append(res, d.baseDate)
			case STAR_DAY:
				for {
					d.baseDate = d.baseDate.Add(time.Hour * 24 * time.Duration(int(d.Value)))
					if d.baseDate.After(target) {
						if !isMock {
							r.Repeat[idx] = d
						}
						break
					}
				}
				res = append(res, d.baseDate)
			case STAR_MONTH:
				for {
					d.baseDate = d.baseDate.AddDate(0, int(d.Value), 0)
					if d.baseDate.After(target) {
						if !isMock {
							r.Repeat[idx] = d
						}
						break
					}
				}
				res = append(res, d.baseDate)
			case STAR_YEAR:
				for {
					d.baseDate = d.baseDate.AddDate(int(d.Value), 0, 0)
					if d.baseDate.After(target) {
						if !isMock {
							r.Repeat[idx] = d
						}
						break
					}
				}
				res = append(res, d.baseDate)
			}
		}
	}
	return res
}