package main

import (
	"context"
	"log"
	"math/rand"
	"strings"
	"time"

	"github.com/kami/maven/internal/dialogue"
	"github.com/kami/maven/internal/router"
)

// clarifyTTL — how long a parked question stays answerable. Same 90s as the
// confirm gate, for the same reason: an answer is a same-breath gesture, and a
// stale question must not eat an unrelated later utterance.
const clarifyTTL = 90 * time.Second

// wantedSlots — what each intent needs before she can act on it. First entry is
// the one she asks about this turn; the rest are asked about on later turns, one
// per turn, as each answer lands (see askRemainingGap).
//
// Intents not listed here are never worth a question: note and query act on the
// raw utterance, chat and system have nothing to fill in. For those a clarify
// decision keeps the canned "не поняла" reply — inventing a question for noise
// is worse than admitting she missed it.
// A reminder wants BOTH what to remind about and when. Subject first: "напомни
// в 11" has a time and nothing to say at 11, and a reminder with no subject is
// not worth setting. Order here is the order she asks in.
var wantedSlots = map[router.Intent][]dialogue.Slot{
	router.IntentReminder: {dialogue.SlotText, dialogue.SlotTime},
	router.IntentFact:     {dialogue.SlotKey},
	router.IntentAct:      {dialogue.SlotFn},
}

// clarifyQuestions — one short question per missing slot.
//
// These are fixed templates, not model output. The resident model is a 0.8B; it
// would wander, and a question whose wording changes every time is harder to
// answer than a blunt one that always reads the same. They are infinitive
// questions, so there is no gender agreement to get wrong; the feminine
// self-reference lives in the reply she gives when she drops the request.
var clarifyQuestions = map[dialogue.Slot]string{
	dialogue.SlotTime: "Когда?",
	dialogue.SlotText: "О чём напомнить?",
	dialogue.SlotKey:  "Что записать?",
	dialogue.SlotFn:   "Что сделать?",
}

// clarifyGaveUp — she is out of questions and still does not have the slot. She
// says so out loud: dropping the request in silence would leave him thinking it
// landed. Feminine self-reference ("поняла"), as everywhere.
const clarifyGaveUp = "Прости, я не поняла. Скажи, пожалуйста, по-другому."

// clarifyExpiredVariants — his answer came after the TTL, so the parked request
// is already gone. Same tone as clarifyGaveUp, different reason: too much time
// passed, not "I did not understand". Feminine self-reference ("ждала",
// "отпустила"); he is addressed with a plain imperative.
//
// Five phrasings, not one. This is the line he hears whenever he walks off
// mid-request, so it is the line that repeats most — and the same sentence every
// time is what makes a house assistant sound like a kiosk. They all carry the
// same two facts (the old request is gone; say it again if it still matters),
// because the wording may vary and the meaning may not.
//
// Fixed templates rather than model output, for the same reason as
// clarifyQuestions: this text has to be right every time, and it is not worth a
// generation to say something this small.
var clarifyExpiredVariants = []string{
	"Прости, я слишком долго ждала ответа и отпустила прошлую просьбу. Если она ещё нужна, скажи заново.",
	"Кажется, прошлая просьба уже не важна — я её отпустила. Если я ошибаюсь, повтори.",
	"Ты как-то резко замолчал, и я не стала ждать дальше. Если та просьба ещё нужна, скажи заново.",
	"Я не дождалась ответа и убрала прошлую просьбу. Повтори, если она всё ещё нужна.",
	"Столько времени прошло, что я отпустила прошлую просьбу. Скажи заново, если она в силе.",
}

// clarifyExpiredLine picks one of them at random.
func clarifyExpiredLine() string {
	return clarifyExpiredVariants[rand.Intn(len(clarifyExpiredVariants))]
}

// isClarifyExpired reports whether s opens with any of the expiry lines. The
// notice is glued in front of this turn's reply (see withNotice), so a caller
// checking for it has to match a prefix, not the whole string.
func isClarifyExpired(s string) bool {
	for _, v := range clarifyExpiredVariants {
		if strings.HasPrefix(s, v) {
			return true
		}
	}
	return false
}

// trimClarifyExpired strips a leading expiry notice, leaving this turn's actual
// reply. "" ⇒ the notice was the whole thing.
func trimClarifyExpired(s string) string {
	for _, v := range clarifyExpiredVariants {
		if strings.HasPrefix(s, v) {
			return strings.TrimSpace(strings.TrimPrefix(s, v))
		}
	}
	return strings.TrimSpace(s)
}

// clarifyExpiredNotice returns that line when a parked question had just timed
// out, and "" when nothing was parked. Call it right after
// resolveClarifyAnswer: a live question is answered there, an expired one is
// only reported here — the words themselves still go on to be routed fresh.
func (h *reactiveHandler) clarifyExpiredNotice() string {
	if h.clarifyStore == nil {
		return ""
	}
	if !h.clarifyStore.TakeExpired(voiceDialogueID, h.now()) {
		return ""
	}
	log.Printf("voice: clarify — parked question expired, telling him and routing the words fresh")
	return clarifyExpiredLine()
}

// withNotice glues the expiry notice in front of this turn's reply. One turn
// carries one reply on the wire, so the notice cannot be a message of its own —
// but neither the notice nor the fresh answer may be dropped.
func withNotice(notice, reply string) string {
	if notice == "" {
		return reply
	}
	if reply == "" {
		return notice
	}
	return notice + " " + reply
}

// missingFor returns the slots a decision still needs, most important first.
// Empty ⇒ there is nothing identifiable to ask about.
func missingFor(dec router.Decision) []dialogue.Slot {
	return dialogue.StillMissing(wantedSlots[dec.Intent], toDialogueSlots(dec.Slots))
}

// clarifyQuestion picks the one question to ask for a clarify decision. Returns
// ("", false) when she has no idea what is missing.
//
// One question about one thing: if two slots are missing she asks about the
// first only. Two questions in one breath is an interrogation. The second gap
// is picked up on the turn after the first one is answered (askRemainingGap).
func clarifyQuestion(dec router.Decision) (dialogue.Slot, string, bool) {
	missing := missingFor(dec)
	if len(missing) == 0 {
		return "", "", false
	}
	q, ok := clarifyQuestions[missing[0]]
	if !ok {
		return "", "", false
	}
	return missing[0], q, true
}

// askClarify parks the request and returns the question to ask instead of the
// canned "не поняла". Returns ("", false) when there is nothing to ask about, so
// the caller falls back to the canned reply.
func (h *reactiveHandler) askClarify(dec router.Decision) (string, bool) {
	if h.clarifyStore == nil {
		return "", false
	}
	slot, question, ok := clarifyQuestion(dec)
	if !ok {
		return "", false
	}
	h.clarifyStore.Put(voiceDialogueID, &dialogue.PendingQuestion{
		Intent:      dialogue.Intent(dec.Intent),
		Slots:       toDialogueSlots(dec.Slots),
		Missing:     []dialogue.Slot{slot},
		Utterance:   dec.Utterance,
		Asked:       h.now(),
		TTL:         clarifyTTL,
		Attempts:    1, // this ask
		MaxAttempts: h.clarifyMaxAttempts,
	})
	log.Printf("voice: clarify — asked about %s for intent=%s", slot, dec.Intent)
	return question, true
}

// resolveClarifyAnswer reads an utterance as the answer to a parked question.
// Returns ("", false) when no live question is parked (or it expired), so the
// caller routes the utterance normally as a fresh request. Sibling of
// resolveConfirm and checked in the same place.
//
// The answer is parsed with the same extractor the router uses, for the intent
// she parked — no second parser. If it still does not fill the gap she asks
// again, up to MaxAttempts; after that she says out loud that she did not
// understand. She never drops the request in silence.
func (h *reactiveHandler) resolveClarifyAnswer(ctx context.Context, text string) (string, bool) {
	if h.clarifyStore == nil {
		return "", false
	}
	q := h.clarifyStore.Get(voiceDialogueID, h.now())
	if q == nil {
		return "", false
	}

	intent := router.Intent(q.Intent)
	answer := h.extractor.Extract(ctx, intent, text, h.now())
	merged := q.Answer(text, toDialogueSlots(answer))
	// Fold a newly answered subject into the raw utterance. Downstream actions
	// phrase from Utterance, not from the text slot — actionReminder stores it
	// as the reminder payload — so a reminder clarified out of a bare "напомни"
	// would fire at 11:00 saying "напомни" and nothing else.
	q.Utterance = foldAnswerIntoUtterance(q.Utterance, merged.Text)
	if len(dialogue.StillMissing(q.Missing, merged)) > 0 {
		return h.reaskOrGiveUp(q, merged, text), true
	}
	h.clarifyStore.Delete(voiceDialogueID)

	// One gap filled is not the same as a complete request. askClarify parks
	// only the first gap, because one question per turn is the rule, but a
	// reminder wants both a subject and a time. "напомни" with neither used to
	// ask "О чём напомнить?", accept "позвонить маме", and then hand applyAction
	// a reminder with no time, which answered "не получилось разобрать время
	// напоминания." — an error for a request she never finished asking about.
	// Re-enter the loop instead, one question at a time as before.
	if reply, asked := h.askRemainingGap(q, intent, merged); asked {
		return reply, true
	}

	// Rebuild the decision as if it had routed cleanly, then run it down the
	// normal path. Clarify is deliberately false and the intent is unchanged:
	// filling in an argument never grants authority, so the completed decision
	// still meets the allowlist and the destructive-act confirm gate in
	// applyAction exactly like any other decision.
	dec := router.Decision{
		Utterance: q.Utterance,
		Stage:     2,
		Intent:    intent,
		Slots:     applyDialogueSlots(answer, merged),
	}
	return h.finishClarified(ctx, dec), true
}

// foldAnswerIntoUtterance appends an answered subject to the original words,
// unless they already carry it. "напомни" + "позвонить маме" reads as the
// request he would have made in one breath. Nothing is appended when the
// subject is empty or already present, so re-asking the same question twice
// cannot grow the utterance.
func foldAnswerIntoUtterance(utterance, subject string) string {
	subject = strings.TrimSpace(subject)
	if subject == "" || strings.Contains(utterance, subject) {
		return utterance
	}
	if strings.TrimSpace(utterance) == "" {
		return subject
	}
	return strings.TrimSpace(utterance) + " " + subject
}

// askRemainingGap re-parks the request when the answer closed one gap and
// wantedSlots still names another. Returns ("", false) when the request is
// complete, when there is no question for what is left, or when she is out of
// attempts — in all three the caller runs the decision as it stands, which for
// the out-of-attempts case is the old behaviour and is the right one: she has
// already asked enough.
//
// The attempt budget is shared with the re-ask path on purpose. A second gap
// costs a question exactly like a second try at the first one does, so the cap
// still bounds how many times she can speak before acting or letting go.
func (h *reactiveHandler) askRemainingGap(q *dialogue.PendingQuestion, intent router.Intent, merged dialogue.Slots) (string, bool) {
	remaining := dialogue.StillMissing(wantedSlots[intent], merged)
	if len(remaining) == 0 {
		return "", false
	}
	question, ok := clarifyQuestions[remaining[0]]
	if !ok || !q.CanAsk() {
		return "", false
	}
	h.clarifyStore.Put(voiceDialogueID, &dialogue.PendingQuestion{
		Intent:      q.Intent,
		Slots:       merged,
		Missing:     []dialogue.Slot{remaining[0]},
		Utterance:   q.Utterance,
		Asked:       h.now(),
		TTL:         clarifyTTL,
		Attempts:    q.Attempts + 1,
		MaxAttempts: q.MaxAttempts,
	})
	log.Printf("voice: clarify — one gap filled, still missing %s for intent=%s, asking again (attempt %d)", remaining[0], intent, q.Attempts+1)
	return question, true
}

// reaskOrGiveUp handles an answer that left the gap open: ask the same question
// again while she has attempts left, otherwise say she did not understand and
// let the request go. Never returns "" — a mute give-up reads as "done".
func (h *reactiveHandler) reaskOrGiveUp(q *dialogue.PendingQuestion, merged dialogue.Slots, text string) string {
	question := ""
	if len(q.Missing) > 0 {
		question = clarifyQuestions[q.Missing[0]]
	}
	if question == "" || !q.CanAsk() {
		h.clarifyStore.Delete(voiceDialogueID)
		log.Printf("voice: clarify — gave up on %v after %d question(s), answer was %q", q.Missing, q.Attempts, text)
		return clarifyGaveUp
	}
	// Re-park with whatever the answer DID give, the clock restarted and one
	// more question spent.
	q.Slots = merged
	q.Attempts++
	q.Asked = h.now()
	h.clarifyStore.Put(voiceDialogueID, q)
	log.Printf("voice: clarify — answer %q did not fill %v, asking again (attempt %d)", text, q.Missing, q.Attempts)
	return question
}

// finishClarified runs a completed decision through the same steps a freshly
// routed one takes: remember the turn, act, then phrase.
func (h *reactiveHandler) finishClarified(ctx context.Context, dec router.Decision) string {
	if h.dialogueSessions != nil {
		now := h.now()
		prev := h.dialogueSessions.Get(voiceDialogueID, now)
		dec = followUpMerge(prev, dec, now)
		h.rememberTurn(prev, dec, now)
	}
	reply := h.applyAction(ctx, dec)
	if reply == "" {
		reply = h.replier.Reply(dec)
	}
	if reply == "" {
		// Belt: an empty reply here would be a silent drop.
		reply = clarifyGaveUp
	}
	return reply
}

// rememberTurn stores this turn as the dialogue session the next follow-up
// inherits from, carrying up to 4 prior turns of history for anaphora. Capped so
// one long conversation can't grow the session unboundedly.
func (h *reactiveHandler) rememberTurn(prev *dialogue.Session, dec router.Decision, now time.Time) {
	var history []dialogue.Turn
	if prev != nil {
		history = append(history, dialogue.Turn{
			Intent: prev.Intent,
			Slots:  prev.Slots,
			Text:   prev.Slots.Text,
		})
		maxHist := len(prev.History)
		if maxHist > 3 {
			maxHist = 3
		}
		history = append(history, prev.History[:maxHist]...)
	}
	ttl := time.Duration(0) // use the store default (2 min)
	if dec.Intent == router.IntentChat {
		ttl = 15 * time.Minute // conversational turns should last longer
	}
	h.dialogueSessions.Put(voiceDialogueID, &dialogue.Session{
		Intent:    dialogue.Intent(dec.Intent),
		Slots:     toDialogueSlots(dec.Slots),
		Timestamp: now,
		TTL:       ttl,
		History:   history,
	})
}