package bot

import (
	"sort"

	"worktimeBot/internal/db"
)

type State int

const (
	StateIdle State = iota
	StateWorking
	StateOnBreak
)

// DailyTotals holds aggregated times for a single day.
type DailyTotals struct {
	TotalSeconds int64
	BreakSeconds int64
	PairCount    int
}

// ComputeDailyTotals pairs events with break inference.
// Multi‑out sequences: first out ends work, second out starts break,
// next in ends break, next out ends work, etc.
func ComputeDailyTotals(events []db.Event) 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
	})

	var workTotal, breakTotal int64
	var workStart, breakStart int64
	pairs := 0
	state := StateIdle

	for _, e := range sorted {
		switch {
		case e.EventType == "in":
			switch state {
			case StateIdle, StateOnBreak:
				if state == StateOnBreak {
					breakTotal += e.OccurredAt - breakStart
					breakStart = 0
				}
				workStart = e.OccurredAt
				state = StateWorking
			// Working → ignore duplicate in (shouldn't happen)
			case StateWorking:
				// already working, ignore
			}
		case e.EventType == "out":
			switch state {
			case StateWorking:
				// End of work period
				workTotal += e.OccurredAt - workStart
				workStart = 0
				pairs++
				state = StateIdle
			case StateIdle:
				// Second consecutive out → break start
				breakStart = e.OccurredAt
				state = StateOnBreak
			case StateOnBreak:
				// Duplicate break start – ignore
			}
		}
	}

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