// 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.
package main

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

var ruWeekdays = []string{
	"воскресенье", "понедельник", "вторник", "среда",
	"четверг", "пятница", "суббота",
}

var ruMonths = []string{
	"января", "февраля", "марта", "апреля", "мая", "июня",
	"июля", "августа", "сентября", "октября", "ноября", "декабря",
}

// 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.
var notPlaceAfterV = map[string]bool{
	"данный": true, "данную": true, "этот": true, "эту": true,
	"котором": true, "какое": true, "какой": true, "который": true,
	"общем": true, "точности": true, "курсе": true, "сутках": true,
	"часах": true, "минутах": true, "секундах": true, "неделе": true,
}

// 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."

// dayWords — day references the calendar parser cannot resolve. A weekday name
// or a "через …" phrase means he asked about a specific other day.
var dayWords = []string{
	"понедельник", "вторник", "сред", "четверг", "пятниц", "суббот", "воскресен",
	"через", "monday", "tuesday", "wednesday", "thursday", "friday", "saturday", "sunday",
}

// 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.
func mentionsUnknownDay(u string) bool {
	for _, w := range dayWords {
		if strings.Contains(u, w) {
			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 := ruPlural(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, ruPlural(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"
}

func ruPlural(n int, one, two, many string) string {
	n = n % 100
	if n > 10 && n < 20 {
		return many
	}
	n = n % 10
	switch n {
	case 1:
		return one
	case 2, 3, 4:
		return two
	default:
		return many
	}
}

// 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()
	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:
		return fmt.Sprintf("%d минут назад", int(diff.Minutes()))
	case diff < 2*time.Hour:
		return "час назад"
	case diff < 24*time.Hour:
		return fmt.Sprintf("%d часа назад", int(diff.Hours()))
	default:
		return t.Format("2 января 15:04")
	}
}