// Package bot implements the Telegram bot logic: message routing, time tracking,
// calendar rendering, Excel export, and inline editing of events.
package bot

import (
	"sort"

	"worktimeBot/internal/db"
)

// State represents the current tracking state during daily totals computation.
type State int

const (
	// StateIdle indicates no active work session.
	StateIdle State = iota
	// StateWorking indicates an active work session.
	StateWorking
	// StateOnBreak indicates an active break session.
	StateOnBreak
)

// DailyTotals holds the computed total work and break seconds for a single day.
type DailyTotals struct {
	TotalSeconds int64
	BreakSeconds int64
}

// ComputeDailyTotals calculates the total work and break time from a list of events.
// It sorts events chronologically, inserts synthetic start/end events when needed,
// and tracks state transitions between idle, working, and on-break.
func ComputeDailyTotals(events []db.Event, minBreakThreshold int64, dayStart, dayEnd int64) DailyTotals {
	if len(events) == 0 {
		return DailyTotals{}
	}
	sorted := make([]db.Event, len(events))
	copy(sorted, events)
	sort.Slice(sorted, func(i, j int) bool {
		return sorted[i].OccurredAt < sorted[j].OccurredAt
	})

	if dayStart > 0 && len(sorted) > 0 && sorted[0].EventType == "out" {
		first := db.Event{EventType: "in", OccurredAt: dayStart}
		sorted = append([]db.Event{first}, sorted...)
	}
	if dayEnd > 0 && len(sorted) > 0 && sorted[len(sorted)-1].EventType == "in" {
		last := db.Event{EventType: "out", OccurredAt: dayEnd}
		sorted = append(sorted, last)
	}

	var workTotal, breakTotal int64
	var workStart, breakStart int64
	state := StateIdle

	for _, e := range sorted {
		switch e.EventType {
		case "in":
			switch state {
			case StateIdle:
				workStart = e.OccurredAt
				state = StateWorking
			case StateOnBreak:
				breakDuration := e.OccurredAt - breakStart
				if minBreakThreshold > 0 && breakDuration <= minBreakThreshold {
					workStart = breakStart
				} else {
					breakTotal += breakDuration
					workStart = e.OccurredAt
				}
				state = StateWorking
			}
		case "out":
			switch state {
			case StateWorking:
				workTotal += e.OccurredAt - workStart
				workStart = 0
				breakStart = e.OccurredAt
				state = StateOnBreak
			case StateIdle:
				breakStart = e.OccurredAt
				state = StateOnBreak
			case StateOnBreak:
				breakStart = e.OccurredAt
			}
		}
	}

	return DailyTotals{
		TotalSeconds: workTotal,
		BreakSeconds: breakTotal,
	}
}