// Package main — ruwords.go holds Russian language + calendar/time formatting
// helpers used by the voice reply paths (replySystem, the reminder/routine
// phrasing, etc). Pure functions, no receivers: weekday/month name tables,
// plural agreement, clock/date rendering, and the "do I actually know this
// place/day" guards that pick an honest reply over a confidently wrong one.
// Extend this file rather than voice.go for anything in that shape.
//
// Count agreement is not here. It is say.CountWord, because there were four
// copies of the same three-way rule and two of the sites that needed it were
// spelling one form out (Vikunja #521).
package main

import (
	"fmt"
	"strconv"
	"strings"
	"time"

	"github.com/kami/maven/internal/lexicon"
	"github.com/kami/maven/internal/router"
	"github.com/kami/maven/internal/say"
)

// Weekday and month names are a closed class — the language has seven and
// twelve — so they live complete in internal/lexicon, where internal/ttsnorm
// reads the same twelve month names instead of keeping a second copy
// (Vikunja #525).

// onlyLocalTimeReply — the honest answer when the user asks the time somewhere
// other than here. She only keeps one clock, and saying so is better than
// naming the wrong city's time.
//
// There used to be a city→time-zone table here. It was removed on purpose: the
// user only ever asks for local time, so the table was a second list of cities
// to keep in step with the weather one for no gain.
const onlyLocalTimeReply = "я знаю только местное время, про другие города пока не скажу."

// notPlaceAfterV — words that follow "в" without naming a place, so
// mentionsUnknownPlace does not mistake them for a city. Closed set, kept
// complete in internal/lexicon.
var notPlaceAfterV = func() map[string]bool {
	m := map[string]bool{}
	for _, w := range lexicon.NotPlaceAfterV() {
		m[w] = true
	}
	return m
}()

// mentionsUnknownPlace reports whether the question has a "в <слово>" phrase
// that looks like a place we do not know ("который час в киеве"). Used only to
// pick the honest "local time only" reply instead of answering local time as
// if it were the city's.
func mentionsUnknownPlace(u string) bool {
	toks := strings.Fields(u)
	for i := 0; i+1 < len(toks); i++ {
		if toks[i] != "в" && toks[i] != "во" {
			continue
		}
		next := strings.Trim(toks[i+1], ".,?!")
		if next == "" || notPlaceAfterV[next] {
			continue
		}
		// A number after "в" is a clock ("в 5 часов"), not a place.
		if _, err := strconv.Atoi(strings.SplitN(next, ":", 2)[0]); err == nil {
			continue
		}
		return true
	}
	return false
}

// onlyNearDaysReply — she can work out today, tomorrow, the day after and
// yesterday, and nothing further. Said out loud instead of answering today's
// date for a day she did not understand.
const onlyNearDaysReply = "я считаю только сегодня, завтра, послезавтра и вчера — про другие дни пока не скажу."

// mentionsUnknownDay reports whether the question names a day the calendar
// parser could not resolve. Mirror of mentionsUnknownPlace: it exists only to
// pick an honest reply over a confidently wrong one.
//
// Only called after ParseCalendarDate has already failed, so "завтра" and the
// other words it does know never reach here.
//
// The weekday half was a list of STEMS matched with strings.Contains until
// V-581 — "сред", "пятниц", "суббот". That is the hand-written Russian pattern
// the sweep of 2026-08-04 took out, and it was wrong in the way such a pattern
// always is: "среди", "средство" and "средний" all contain "сред", so a question
// carrying any of them was answered with onlyNearDaysReply instead of the date.
// Whole tokens now, and the weekday itself is router.WeekdayIndex, which reads
// the lexicon and asks the dictionary about the case.
func mentionsUnknownDay(u string) bool {
	for _, tok := range quietTokens(u) {
		if tok == "через" {
			return true
		}
		if _, ok := router.WeekdayIndex(tok); ok {
			return true
		}
	}
	return false
}

// ruClock renders the clock part of the time reply: "15 часов 4 минуты".
func ruClock(t time.Time) string {
	h, m := t.Hour(), t.Minute()
	hourWord := say.CountWord(h, "час", "часа", "часов")
	if m == 0 {
		return fmt.Sprintf("%d %s ровно", h, hourWord)
	}
	return fmt.Sprintf("%d %s %d %s", h, hourWord, m, say.CountWord(m, "минута", "минуты", "минут"))
}

// dayPrefix names the day relative to now ("завтра", "вчера", …) so the date
// reply opens the way a person would say it.
func dayPrefix(now, day time.Time) string {
	base := time.Date(now.Year(), now.Month(), now.Day(), 0, 0, 0, 0, now.Location())
	switch int(day.Sub(base).Hours() / 24) {
	case -1:
		return "вчера"
	case 0:
		return "сегодня"
	case 1:
		return "завтра"
	case 2:
		return "послезавтра"
	}
	return "это"
}

// hasDurationWords checks whether u is asking about elapsed/remaining time
// rather than the current clock — guards replySystem from replying "сейчас
// X часов" to "сколько времени прошло". Mirrors the stage0.go build filter.
func hasDurationWords(u string) bool {
	s := strings.ToLower(strings.TrimSpace(u))
	// First-word duration markers (same keywords as timeQueryBuild in stage0).
	first := strings.Fields(s)
	if len(first) > 0 {
		switch first[0] {
		case "прошло", "осталось", "пройдет", "минуло", "проходит":
			return true
		}
	}
	// Broader duration keywords appearing anywhere in the utterance.
	if strings.Contains(s, "прошло") || strings.Contains(s, "осталось") {
		return true
	}
	if strings.Contains(s, " до ") {
		return true
	}
	return false
}

// formatTime returns a human-readable Russian time string for a fact timestamp.
// Used by the query handler when answering "когда я это сделал?"-style questions.
func formatTime(t time.Time) string {
	now := time.Now()
	// The argument is a fact's Ts, which the store hands back as UTC. Only the
	// last branch names a wall clock, and it named the store's until V-614: an
	// answer to "когда я это сделал?" read hours off, in the same sentence
	// shape the plan reads a day in.
	t = t.Local()
	if t.After(now.Add(-2*time.Minute)) && t.Before(now.Add(2*time.Minute)) {
		return "только что"
	}
	diff := now.Sub(t)
	switch {
	case diff < 10*time.Minute:
		return "несколько минут назад"
	case diff < 60*time.Minute:
		n := int(diff.Minutes())
		return fmt.Sprintf("%d %s назад", n, say.CountWord(n, "минуту", "минуты", "минут"))
	case diff < 2*time.Hour:
		return "час назад"
	case diff < 24*time.Hour:
		n := int(diff.Hours())
		return fmt.Sprintf("%d %s назад", n, say.CountWord(n, "час", "часа", "часов"))
	default:
		// Not t.Format("2 января …"): Go reads that as a literal, so every
		// fact older than a day used to read as January (Vikunja #507).
		return fmt.Sprintf("%d %s %s", t.Day(), lexicon.MonthGenitive(int(t.Month())), t.Format("15:04"))
	}
}