package domain

import "sort"

// ComputeDailyTotals calculates the total work and break time from a list of events.
func ComputeDailyTotals(events []Event, minBreakThreshold int64, dayStart, dayEnd int64) DailyTotals {
	if len(events) == 0 {
		return DailyTotals{}
	}

	sorted := make([]Event, len(events))
	copy(sorted, events)
	sort.Slice(sorted, func(i, j int) bool {
		return sorted[i].OccurredAt < sorted[j].OccurredAt
	})

	var totalWork, totalBreak int64
	state := StateIdle
	var workStart, breakStart int64

	if dayStart > 0 {
		state = StateWorking
		workStart = dayStart
	} else if sorted[0].EventType == "out" {
		state = StateOnBreak
	}

	for _, e := range sorted {
		switch {
		case e.EventType == "in" && state == StateIdle:
			state = StateWorking
			workStart = e.OccurredAt
		case e.EventType == "in" && state == StateOnBreak:
			breakElapsed := e.OccurredAt - breakStart
			if breakElapsed >= minBreakThreshold {
				totalBreak += breakElapsed
			} else {
				totalWork += breakElapsed
			}
			state = StateWorking
			workStart = e.OccurredAt
		case e.EventType == "in" && state == StateWorking:
		case e.EventType == "out" && state == StateWorking:
			totalWork += e.OccurredAt - workStart
			state = StateOnBreak
			breakStart = e.OccurredAt
		case e.EventType == "out" && state == StateOnBreak:
			breakStart = e.OccurredAt
		case e.EventType == "out" && state == StateIdle:
			state = StateOnBreak
			breakStart = e.OccurredAt
		}
	}

	if state == StateWorking && dayEnd > 0 {
		totalWork += dayEnd - workStart
	}
	if state == StateOnBreak && dayEnd > 0 {
		breakElapsed := dayEnd - breakStart
		if breakElapsed >= minBreakThreshold {
			totalBreak += breakElapsed
		} else {
			totalWork += breakElapsed
		}
	}

	return DailyTotals{TotalSeconds: totalWork, BreakSeconds: totalBreak}
}