package main

import (
	"context"
	"log"
	"slices"
	"sort"
	"strings"
	"time"
	"unicode"

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

// pendingHexisExec — a mutating Hexis capability parked awaiting a spoken
// confirm. The confirmation is bound to the resolved capability + canonical
// target entity so a later "да" can only execute exactly what was proposed
// (ecosystem invariant: protected actions require bound confirmation).
type pendingHexisExec struct {
	capabilityID string
	capName      string
	entityID     string
	displayName  string
	expiry       time.Time

	// correlationID — the id the proposing turn minted for this action. A
	// confirm arrives on a later turn with a context of its own, so without
	// carrying it here the execution recorded a fresh id and no causation at
	// all, and the resolve, the discovery and the thing they authorised sat in
	// the trace as unrelated calls. The contract mints one id per action, and
	// the action began when she asked.
	correlationID string
}

// pendingRoutineConfirm — a proposed routine awaiting a spoken y/n to become
// a recurring reminder. Set by detectPattern after creating a proposal.
type pendingRoutineConfirm struct {
	routineID int64
	action    string
	object    string
	interval  float64
	phrase    string
	expiry    time.Time
}

// pendingAct — a destructive act awaiting a spoken confirm.
type pendingAct struct {
	fn     string
	args   []string
	phrase string
	expiry time.Time
}

// confirmTTL — how long a parked destructive confirm stays answerable. Short:
// a confirm is a same-breath gesture; a stale prompt shouldn't fire on an
// unrelated later "да".
const confirmTTL = 90 * time.Second

// park stores a destructive act awaiting confirmation. Overwrites any prior
// pending (last-asked wins — single-user box).
func (h *reactiveHandler) park(fn string, args []string, phrase string) {
	h.mu.Lock()
	h.pending = &pendingAct{fn: fn, args: args, phrase: phrase, expiry: h.now().Add(confirmTTL)}
	h.mu.Unlock()
}

// resolveConfirm interprets an utterance as the answer to a parked destructive
// act OR a parked routine proposal. Returns (reply, true) when it consumed the
// utterance as a y/n answer; ("", false) when there's nothing pending (or the
// parked act expired), so the caller routes the utterance normally.
//
// An utterance that is not clearly yes or no is not an answer at all, so it is
// handed straight back and the pending stays parked until it expires (V-567).
// This resolver runs before routing and holds the most dangerous trigger on the
// box; it may only claim a turn it is certain about.
func (h *reactiveHandler) resolveConfirm(ctx context.Context, text string) (string, bool) {
	verdict := classifyConfirm(text)
	if verdict == confirmUnknown {
		return "", false
	}

	h.mu.Lock()
	defer h.mu.Unlock()

	for _, r := range h.confirmResolvers(ctx) {
		if !r.claim() {
			continue
		}
		// The slot is already cleared by claim().
		switch verdict {
		case confirmYes:
			return r.yes(), true
		default:
			return r.no(), true
		}
	}
	return "", false
}

// confirmResolver — one parked-confirm slot in the chain. claim() reports
// whether this slot holds a live pending, taking it (and dropping an expired
// one) as it goes; yes/no then run the answer. Only ever called with h.mu held.
type confirmResolver struct {
	claim func() bool
	yes   func() string
	no    func() string
}

// confirmResolvers builds the ordered chain resolveConfirm walks. Order is
// deliberate: the routine proposal is checked before the tool confirm so a
// routine confirm doesn't get eaten by a stale tool pending.
func (h *reactiveHandler) confirmResolvers(ctx context.Context) []confirmResolver {
	var pr *pendingRoutineConfirm
	var hx *pendingHexisExec
	var p *pendingAct

	return []confirmResolver{
		// Routine proposal.
		{
			claim: func() bool {
				pr, h.pendingRoutine = h.pendingRoutine, nil
				return pr != nil && !h.now().After(pr.expiry)
			},
			yes: func() string {
				// Voice does NOT accept (Vikunja #367). Accepting hands the
				// tick loop a standing new reason to speak, which is the same
				// tier as enabling a tool — and DESIGN.md § "surface caps
				// authority" says a room mic, reachable by anyone present, is
				// structurally incapable of layer 3. So a spoken "да" leaves
				// the row 'proposed' and points at the authed page, where the
				// accept button is gated at step-up. The convenience of
				// answering out loud stays; the authority does not move.
				//
				// Acceptance itself is recorded by /routines, and the tick
				// loop nudges on the interval from there (Vikunja #366).
				return phraser.C(phraser.ConfirmRoutineAuthed, nil)
			},
			no: func() string {
				if err := h.dataStore.DismissProposedRoutine(ctx, pr.routineID); err != nil {
					log.Printf("voice: dismiss proposed routine: %v", err)
				}
				return phraser.C(phraser.ConfirmRoutineNo, nil)
			},
		},
		// Hexis execution confirm. Bound to the exact capability + target that
		// was proposed; a stray "да" can only run that, nothing else.
		{
			claim: func() bool {
				hx, h.pendingHexis = h.pendingHexis, nil
				return hx != nil && !h.now().After(hx.expiry)
			},
			yes: func() string {
				execCtx := ctx
				if hx.correlationID != "" {
					execCtx = withCorrelationID(execCtx, hx.correlationID)
				}
				return h.execHexis(execCtx, hx.capabilityID, hx.capName, hx.entityID, hx.displayName)
			},
			no: func() string { return phraser.C(phraser.ConfirmCancelled, nil) },
		},
		// Tool confirm.
		{
			claim: func() bool {
				p, h.pending = h.pending, nil
				return p != nil && !h.now().After(p.expiry)
			},
			yes: func() string {
				out, err := h.tools.Exec(ctx, p.fn, p.args, true) // confirmed
				if err != nil {
					log.Printf("voice: tool %s (confirmed): %v", p.fn, err)
					if out != "" {
						return phraser.A(phraser.ActFailOut, map[string]string{"out": firstLine(out)})
					}
					return phraser.A(phraser.ActFail, nil)
				}
				if out != "" {
					return phraser.A(phraser.ActDoneOut, map[string]string{"out": firstLine(out)})
				}
				return phraser.A(phraser.ActDone, nil)
			},
			no: func() string { return phraser.C(phraser.ConfirmCancelled, nil) },
		},
	}
}

// proposeGap scaffolds a 'proposed' tool for an act whose verb isn't enabled.
// maven drafts the registration (name = the verb, provenance = the utterance);
// a human enables it on the authed surface. She suggests, never enables.
func (h *reactiveHandler) proposeGap(ctx context.Context, dec router.Decision) string {
	name := firstWord(stripWake(dec.Utterance))
	if name == "" {
		return phraser.C(phraser.ProposeNoVerb, nil)
	}
	vars := map[string]string{"name": name}
	newly, err := h.api.ProposeTool(ctx, name, dec.Utterance, "", h.now())
	if err != nil {
		log.Printf("voice: propose tool %q: %v", name, err)
		return phraser.C(phraser.ProposeFailed, vars)
	}
	if newly {
		return phraser.C(phraser.ProposeNew, vars)
	}
	return phraser.C(phraser.ProposeAlready, vars)
}

// confirmVerdict — the parse of a y/n confirm answer.
type confirmVerdict int

const (
	confirmUnknown confirmVerdict = iota
	confirmYes
	confirmNo
)

// confirmWords are the two closed sets, tokenized once and ordered
// longest-first so "не надо" is read before "нет" could claim any of it.
var (
	confirmYesPhrases = confirmPhrases(lexicon.ConfirmYes())
	confirmNoPhrases  = confirmPhrases(lexicon.ConfirmNo())
)

// confirmPhrases splits each lexicon member into tokens and sorts the result
// longest-first, so a walk that tries them in order matches the longest member
// that fits.
func confirmPhrases(words []string) [][]string {
	out := make([][]string, 0, len(words))
	for _, w := range words {
		if toks := confirmTokens(w); len(toks) > 0 {
			out = append(out, toks)
		}
	}
	sort.SliceStable(out, func(i, j int) bool { return len(out[i]) > len(out[j]) })
	return out
}

// confirmTokens splits an utterance into lowercase word tokens. Punctuation and
// spacing are separators; an apostrophe is not, because "don't" is one word.
func confirmTokens(text string) []string {
	return strings.FieldsFunc(strings.ToLower(text), func(r rune) bool {
		if r == '\'' || r == '’' {
			return false
		}
		return !unicode.IsLetter(r) && !unicode.IsDigit(r)
	})
}

// classifyConfirm reads a short ru/en yes-or-no answer to a parked confirm.
//
// The whole utterance must consist of confirmation words and filler, matched as
// whole tokens against the closed lexicon sets. Anything else is
// confirmUnknown, which leaves the confirm parked and routes the turn — see
// resolveConfirm. Both halves of that are the fix for V-567: this used to be a
// substring test over bare stems, so "погода", "дальше", "надо" and "давление"
// all read as "да", and "покажи" and "около" read as "ок". A parked destructive
// act fired on a question about the weather.
//
// Requiring the WHOLE utterance is the second half. A leading confirm word does
// not make a sentence an answer: "давай посмотрим погоду" opens a request, and
// the only safe reading of a sentence that carries its own subject is that he
// moved on. Guessing wrong here executes something; guessing wrong the other way
// asks again.
func classifyConfirm(text string) confirmVerdict {
	tokens := confirmTokens(text)
	if len(tokens) == 0 {
		return confirmUnknown
	}
	verdict := confirmUnknown
	for i := 0; i < len(tokens); {
		// Negatives first: "не надо" and "не хочу" open with a token that is
		// not itself an answer, and a yes hit must never shadow them.
		if n := matchConfirm(confirmNoPhrases, tokens[i:]); n > 0 {
			return confirmNo
		}
		if n := matchConfirm(confirmYesPhrases, tokens[i:]); n > 0 {
			verdict, i = confirmYes, i+n
			continue
		}
		if lexicon.IsFillerParticle(tokens[i]) {
			i++
			continue
		}
		// A word that is neither an answer nor filler carries a subject of its
		// own, so this utterance is not an answer to her question.
		return confirmUnknown
	}
	return verdict
}

// matchConfirm reports the length of the longest phrase matching at the head of
// tokens, or 0.
func matchConfirm(phrases [][]string, tokens []string) int {
	for _, p := range phrases {
		if len(p) > len(tokens) {
			continue
		}
		if slices.Equal(p, tokens[:len(p)]) {
			return len(p)
		}
	}
	return 0
}

// actPhrase renders "fn arg1 arg2" for the confirm prompt.
func actPhrase(fn string, args []string) string {
	if len(args) == 0 {
		return fn
	}
	return fn + " " + strings.Join(args, " ")
}