package timer

import (
	"context"
	"sync"
	"time"

	"daily-timer/internal/models"
)

type EventType string

const (
	EventTick           EventType = "tick"
	EventSpeakerWarning EventType = "speaker_warning"
	EventSpeakerTimeUp  EventType = "speaker_timeup"
	EventMeetingWarning EventType = "meeting_warning"
	EventMeetingTimeUp  EventType = "meeting_timeup"
	EventSpeakerChanged EventType = "speaker_changed"
	EventMeetingEnded   EventType = "meeting_ended"
)

type Event struct {
	Type  EventType          `json:"type"`
	State models.TimerState `json:"state"`
}

type Timer struct {
	mu sync.RWMutex

	running bool
	paused  bool

	meetingStartTime  time.Time
	meetingElapsed    time.Duration
	meetingLimit      time.Duration

	speakerStartTime  time.Time
	speakerElapsed    time.Duration
	speakerLimit      time.Duration

	currentSpeakerID  uint
	currentSpeaker    string
	speakingOrder     int
	queue             []models.QueuedSpeaker
	allSpeakers       []models.SpeakerInfo

	warningThreshold    time.Duration
	speakerWarned       bool
	speakerTimeUpEmitted bool
	meetingWarned       bool

	eventCh           chan Event
	ctx               context.Context
	cancel            context.CancelFunc
	pausedAt          time.Time
}

func New(meetingLimitSec, warningThresholdSec int) *Timer {
	ctx, cancel := context.WithCancel(context.Background())
	return &Timer{
		meetingLimit:     time.Duration(meetingLimitSec) * time.Second,
		warningThreshold: time.Duration(warningThresholdSec) * time.Second,
		eventCh:          make(chan Event, 100),
		ctx:              ctx,
		cancel:           cancel,
	}
}

func (t *Timer) Events() <-chan Event {
	return t.eventCh
}

func (t *Timer) SetQueue(speakers []models.QueuedSpeaker) {
	t.mu.Lock()
	defer t.mu.Unlock()
	t.queue = speakers
	
	// Initialize allSpeakers with pending status
	t.allSpeakers = make([]models.SpeakerInfo, len(speakers))
	for i, s := range speakers {
		t.allSpeakers[i] = models.SpeakerInfo{
			ID:        s.ID,
			Name:      s.Name,
			TimeLimit: s.TimeLimit,
			Order:     i + 1,
			Status:    models.SpeakerStatusPending,
		}
	}
}

func (t *Timer) Start() {
	t.mu.Lock()
	if t.running {
		t.mu.Unlock()
		return
	}

	now := time.Now()
	t.running = true
	t.paused = false
	t.meetingStartTime = now
	t.meetingElapsed = 0
	t.speakingOrder = 0
	t.speakerWarned = false
	t.meetingWarned = false

	hasSpeakers := len(t.queue) > 0
	if hasSpeakers {
		t.startNextSpeaker(now, 0)
	}
	t.mu.Unlock()

	if hasSpeakers {
		t.emit(EventSpeakerChanged)
	}

	go t.tick()
}

func (t *Timer) startNextSpeaker(now time.Time, offset time.Duration) {
	if len(t.queue) == 0 {
		return
	}

	// Mark previous speaker as done and save their time spent
	if t.currentSpeakerID != 0 {
		timeSpent := int(now.Sub(t.speakerStartTime).Seconds())
		for i := range t.allSpeakers {
			if t.allSpeakers[i].ID == t.currentSpeakerID {
				if t.allSpeakers[i].Status == models.SpeakerStatusSpeaking {
					t.allSpeakers[i].Status = models.SpeakerStatusDone
					t.allSpeakers[i].TimeSpent = timeSpent
				}
				break
			}
		}
	}

	speaker := t.queue[0]
	t.queue = t.queue[1:]
	t.currentSpeakerID = speaker.ID
	t.currentSpeaker = speaker.Name
	t.speakerLimit = time.Duration(speaker.TimeLimit) * time.Second
	t.speakerStartTime = now.Add(-offset)
	t.speakerElapsed = offset
	t.speakingOrder++
	t.speakerWarned = false
	t.speakerTimeUpEmitted = false

	// Mark current speaker as speaking
	t.updateSpeakerStatus(speaker.ID, models.SpeakerStatusSpeaking)
}

func (t *Timer) updateSpeakerStatus(id uint, status models.SpeakerStatus) {
	for i := range t.allSpeakers {
		if t.allSpeakers[i].ID == id {
			t.allSpeakers[i].Status = status
			break
		}
	}
}

func (t *Timer) moveSpeakerToEnd(id uint) {
	var speaker models.SpeakerInfo
	idx := -1
	for i := range t.allSpeakers {
		if t.allSpeakers[i].ID == id {
			speaker = t.allSpeakers[i]
			idx = i
			break
		}
	}
	if idx >= 0 {
		// Remove from current position
		t.allSpeakers = append(t.allSpeakers[:idx], t.allSpeakers[idx+1:]...)
		// Add to end
		t.allSpeakers = append(t.allSpeakers, speaker)
		// Update order numbers
		for i := range t.allSpeakers {
			t.allSpeakers[i].Order = i + 1
		}
	}
}

func (t *Timer) NextSpeaker() {
	t.mu.Lock()

	if !t.running {
		t.mu.Unlock()
		return
	}

	now := time.Now()
	if !t.paused {
		t.speakerElapsed = now.Sub(t.speakerStartTime)
	}

	var eventType EventType
	if len(t.queue) > 0 {
		t.startNextSpeaker(now, 0)
		eventType = EventSpeakerChanged
	} else {
		t.running = false
		t.paused = false
		eventType = EventMeetingEnded
	}
	t.mu.Unlock()
	t.emit(eventType)
}

func (t *Timer) SkipSpeaker() {
	t.mu.Lock()

	if !t.running || t.currentSpeakerID == 0 {
		t.mu.Unlock()
		return
	}

	// Mark current speaker as skipped in allSpeakers
	t.updateSpeakerStatus(t.currentSpeakerID, models.SpeakerStatusSkipped)

	skipped := models.QueuedSpeaker{
		ID:        t.currentSpeakerID,
		Name:      t.currentSpeaker,
		TimeLimit: int(t.speakerLimit.Seconds()),
	}
	t.queue = append(t.queue, skipped)

	// Move skipped speaker to end of allSpeakers list
	t.moveSpeakerToEnd(t.currentSpeakerID)

	now := time.Now()
	if len(t.queue) > 1 {
		t.startNextSpeaker(now, 0)
		t.mu.Unlock()
		t.emit(EventSpeakerChanged)
	} else {
		// Only skipped speaker left - they need to speak now
		t.startNextSpeaker(now, 0)
		t.mu.Unlock()
		t.emit(EventSpeakerChanged)
	}
}

func (t *Timer) RemoveFromQueue(speakerID uint) {
	t.mu.Lock()
	defer t.mu.Unlock()

	if !t.running {
		return
	}

	// Don't remove current speaker - use SkipSpeaker for that
	if speakerID == t.currentSpeakerID {
		return
	}

	// Find speaker info before removing
	var speakerInfo models.QueuedSpeaker
	for _, s := range t.queue {
		if s.ID == speakerID {
			speakerInfo = s
			break
		}
	}

	// Remove from current position in queue
	for i, s := range t.queue {
		if s.ID == speakerID {
			t.queue = append(t.queue[:i], t.queue[i+1:]...)
			break
		}
	}

	// Add to end of queue so they can speak later
	if speakerInfo.ID != 0 {
		t.queue = append(t.queue, speakerInfo)
	}

	// Mark as skipped in allSpeakers and move to end
	t.updateSpeakerStatus(speakerID, models.SpeakerStatusSkipped)
	t.moveSpeakerToEnd(speakerID)
}

// SwitchToSpeaker moves the specified speaker to front of queue and starts them
// If speaker is already done, resumes their timer from accumulated time
func (t *Timer) SwitchToSpeaker(speakerID uint) {
	t.mu.Lock()

	if !t.running {
		t.mu.Unlock()
		return
	}

	// First, find speaker in allSpeakers to get their info and status
	var speakerInfo *models.SpeakerInfo
	var speakerInfoIdx int
	for i := range t.allSpeakers {
		if t.allSpeakers[i].ID == speakerID {
			speakerInfo = &t.allSpeakers[i]
			speakerInfoIdx = i
			break
		}
	}

	if speakerInfo == nil {
		t.mu.Unlock()
		return
	}

	// Don't switch to currently speaking speaker
	if speakerInfo.Status == models.SpeakerStatusSpeaking {
		t.mu.Unlock()
		return
	}

	// Calculate offset for resuming (0 for pending/skipped, timeSpent for done)
	var offset time.Duration
	if speakerInfo.Status == models.SpeakerStatusDone {
		offset = time.Duration(speakerInfo.TimeSpent) * time.Second
	}

	// Save current speaker time
	now := time.Now()
	if t.currentSpeakerID != 0 {
		timeSpent := int(now.Sub(t.speakerStartTime).Seconds())
		for i := range t.allSpeakers {
			if t.allSpeakers[i].ID == t.currentSpeakerID {
				if t.allSpeakers[i].Status == models.SpeakerStatusSpeaking {
					t.allSpeakers[i].Status = models.SpeakerStatusDone
					t.allSpeakers[i].TimeSpent = timeSpent
				}
				break
			}
		}
	}

	// Find speaker in queue (pending/skipped) or create new entry (done)
	foundIdx := -1
	for i, s := range t.queue {
		if s.ID == speakerID {
			foundIdx = i
			break
		}
	}

	// Create QueuedSpeaker from SpeakerInfo
	queuedSpeaker := models.QueuedSpeaker{
		ID:        speakerInfo.ID,
		Name:      speakerInfo.Name,
		TimeLimit: speakerInfo.TimeLimit,
		Order:     speakerInfo.Order,
	}

	if foundIdx >= 0 {
		// Remove from current position in queue
		t.queue = append(t.queue[:foundIdx], t.queue[foundIdx+1:]...)
	}
	// Insert at front of queue
	t.queue = append([]models.QueuedSpeaker{queuedSpeaker}, t.queue...)

	// Move the selected speaker in allSpeakers to position after last done/speaking
	insertPos := 0
	for i, s := range t.allSpeakers {
		if s.Status == models.SpeakerStatusDone || s.Status == models.SpeakerStatusSpeaking {
			insertPos = i + 1
		}
	}

	if speakerInfoIdx >= 0 && speakerInfoIdx != insertPos {
		// Save speaker info before removing
		savedInfo := *speakerInfo
		// Remove from current position
		t.allSpeakers = append(t.allSpeakers[:speakerInfoIdx], t.allSpeakers[speakerInfoIdx+1:]...)
		// Adjust insert position if needed
		if speakerInfoIdx < insertPos {
			insertPos--
		}
		// Insert at new position
		t.allSpeakers = append(t.allSpeakers[:insertPos], append([]models.SpeakerInfo{savedInfo}, t.allSpeakers[insertPos:]...)...)
		// Update order numbers
		for i := range t.allSpeakers {
			t.allSpeakers[i].Order = i + 1
		}
	}

	// Start this speaker with offset (0 for new speakers, accumulated time for done)
	t.startNextSpeaker(now, offset)
	t.mu.Unlock()
	t.emit(EventSpeakerChanged)
}

func (t *Timer) Pause() {
	t.mu.Lock()

	if !t.running || t.paused {
		t.mu.Unlock()
		return
	}

	now := time.Now()
	t.paused = true
	t.pausedAt = now
	t.speakerElapsed = now.Sub(t.speakerStartTime)
	t.meetingElapsed = now.Sub(t.meetingStartTime)
	t.mu.Unlock()
	t.emit(EventTick)
}

func (t *Timer) Resume() {
	t.mu.Lock()

	if !t.running || !t.paused {
		t.mu.Unlock()
		return
	}

	pauseDuration := time.Since(t.pausedAt)
	t.speakerStartTime = t.speakerStartTime.Add(pauseDuration)
	t.meetingStartTime = t.meetingStartTime.Add(pauseDuration)
	t.paused = false
	t.mu.Unlock()
	t.emit(EventTick)
}

func (t *Timer) Stop() {
	t.mu.Lock()

	if !t.running {
		t.mu.Unlock()
		return
	}
	// Mark current speaker as done and save their time spent
	if t.currentSpeakerID != 0 {
		now := time.Now()
		timeSpent := int(now.Sub(t.speakerStartTime).Seconds())
		for i := range t.allSpeakers {
			if t.allSpeakers[i].ID == t.currentSpeakerID {
				t.allSpeakers[i].Status = models.SpeakerStatusDone
				t.allSpeakers[i].TimeSpent = timeSpent
				break
			}
		}
	}
	t.running = false
	t.paused = false
	t.mu.Unlock()
	t.emit(EventMeetingEnded)
}

func (t *Timer) GetState() models.TimerState {
	t.mu.RLock()
	defer t.mu.RUnlock()
	return t.buildState()
}

func (t *Timer) buildState() models.TimerState {
	speakerElapsed := t.speakerElapsed
	meetingElapsed := t.meetingElapsed

	if t.running && !t.paused {
		now := time.Now()
		speakerElapsed = now.Sub(t.speakerStartTime)
		meetingElapsed = now.Sub(t.meetingStartTime)
	}

	speakerOvertime := speakerElapsed > t.speakerLimit
	meetingOvertime := meetingElapsed > t.meetingLimit
	warning := !speakerOvertime && (t.speakerLimit-speakerElapsed) <= t.warningThreshold

	// Copy allSpeakers to avoid data race and calculate total speakers time
	allSpeakers := make([]models.SpeakerInfo, len(t.allSpeakers))
	copy(allSpeakers, t.allSpeakers)
	
	totalSpeakersTime := 0
	for _, s := range t.allSpeakers {
		totalSpeakersTime += s.TimeLimit
	}

	return models.TimerState{
		Running:           t.running,
		Paused:            t.paused,
		CurrentSpeakerID:  t.currentSpeakerID,
		CurrentSpeaker:    t.currentSpeaker,
		SpeakerElapsed:    int(speakerElapsed.Seconds()),
		SpeakerLimit:      int(t.speakerLimit.Seconds()),
		MeetingElapsed:    int(meetingElapsed.Seconds()),
		MeetingLimit:      int(t.meetingLimit.Seconds()),
		SpeakerOvertime:   speakerOvertime,
		MeetingOvertime:   meetingOvertime,
		Warning:           warning,
		WarningSeconds:    int(t.warningThreshold.Seconds()),
		TotalSpeakersTime: totalSpeakersTime,
		SpeakingOrder:     t.speakingOrder,
		TotalSpeakers:     len(t.allSpeakers),
		RemainingQueue:    t.queue,
		AllSpeakers:       allSpeakers,
	}
}

func (t *Timer) tick() {
	ticker := time.NewTicker(100 * time.Millisecond)
	defer ticker.Stop()

	for {
		select {
		case <-t.ctx.Done():
			return
		case <-ticker.C:
			t.mu.Lock()
			if !t.running {
				t.mu.Unlock()
				return
			}
			if t.paused {
				t.mu.Unlock()
				continue
			}

			now := time.Now()
			speakerElapsed := now.Sub(t.speakerStartTime)
			meetingElapsed := now.Sub(t.meetingStartTime)

			remaining := t.speakerLimit - speakerElapsed
			if !t.speakerWarned && remaining <= t.warningThreshold && remaining > 0 {
				t.speakerWarned = true
				t.mu.Unlock()
				t.emit(EventSpeakerWarning)
				continue
			}

			if !t.speakerTimeUpEmitted && speakerElapsed >= t.speakerLimit {
				t.speakerTimeUpEmitted = true
				t.mu.Unlock()
				t.emit(EventSpeakerTimeUp)
				continue
			}

			meetingRemaining := t.meetingLimit - meetingElapsed
			if !t.meetingWarned && meetingRemaining <= t.warningThreshold && meetingRemaining > 0 {
				t.meetingWarned = true
				t.mu.Unlock()
				t.emit(EventMeetingWarning)
				continue
			}

			t.mu.Unlock()
			t.emit(EventTick)
		}
	}
}

func (t *Timer) emit(eventType EventType) {
	t.mu.RLock()
	state := t.buildState()
	t.mu.RUnlock()

	select {
	case t.eventCh <- Event{Type: eventType, State: state}:
	default:
	}
}

func (t *Timer) Close() {
	t.cancel()
	close(t.eventCh)
}