// Package ttsnorm rewrites machine-formatted dates/times/numbers into RU text
// a TTS voice speaks naturally — so "10.07.2026" is not read as "number dot
// number dot number". Pure, deterministic; runs on reply/nudge text before synth.
package ttsnorm

import (
	"regexp"
	"strconv"
	"strings"
)

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

var (
	reDateY = regexp.MustCompile(`\b(\d{1,2})\.(\d{1,2})\.(\d{4})\b`)
	reDate  = regexp.MustCompile(`\b(\d{1,2})\.(\d{1,2})\b`)
	reTime  = regexp.MustCompile(`\b(\d{1,2}):(\d{2})\b`)
	reDots  = regexp.MustCompile(`\b\d+(?:\.\d+){2,}\b`)
)

// Speakable rewrites d.m.y, d.m, h:mm, and residual dotted-number runs.
// Order matters: dates with year first, then times, then multi-dot numbers
// (3+ parts — never valid dates), then 2-part dates.
func Speakable(s string) string {
	s = reDateY.ReplaceAllStringFunc(s, func(m string) string {
		p := reDateY.FindStringSubmatch(m)
		return spokenDate(p[1], p[2], p[3])
	})
	s = reTime.ReplaceAllStringFunc(s, func(m string) string {
		p := reTime.FindStringSubmatch(m)
		return p[1] + " часов " + p[2] + " минут"
	})
	s = reDots.ReplaceAllStringFunc(s, func(m string) string {
		return strings.Join(strings.Split(m, "."), " точка ")
	})
	s = reDate.ReplaceAllStringFunc(s, func(m string) string {
		p := reDate.FindStringSubmatch(m)
		return spokenDate(p[1], p[2], "")
	})
	return s
}

func spokenDate(dd, mm, yyyy string) string {
	mi, _ := strconv.Atoi(mm)
	if mi < 1 || mi > 12 {
		return dd + " " + mm + gap(yyyy)
	}
	day := strconv.Itoa(mustInt(dd))
	out := day + " " + months[mi]
	if yyyy != "" {
		out += " " + yyyy
	}
	return out
}

func mustInt(s string) int { n, _ := strconv.Atoi(s); return n }
func gap(y string) string  { if y == "" { return "" }; return " " + y }