package main

import (
	"context"
	"log"
	"math"
	"sync"

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

// The personal boundary decides one thing: is this question about him. It used
// to decide it by matching possession words, and that was the whole defect
// behind Vikunja #495. "что я говорил про бэкапы?" is his data by definition —
// nothing outside the box has ever heard him say anything — and it carried no
// possession word, so it walked past the boundary into SearXNG and came back
// answered out of a Habr article about somebody else's backups.
//
// The first fix was one more marker class, `я говорил|сказал|писал|…`, plus a
// carve-out so "как я говорил, почему небо синее" stayed a world question. Both
// halves are a lexicon, and a lexicon is the wrong instrument here: Russian
// gives every verb a dozen surface forms, the preamble list has no end, and
// every utterance the list misses is one that reaches the world. It also drifts
// silently — a missing verb looks exactly like no bug.
//
// So the boundary asks the embedder instead. Two frozen seed sets — questions
// about him, questions about the world — are embedded once, and the turn's own
// query vector, already computed by queryEmbed upstream, is scored against
// both. Nearest side wins. Word order, verb form and unseen phrasing stop
// mattering, which is exactly what a lexicon could not do.
//
// Measured 03-08-2026 against multilingual-e5-small on 19 held-out utterances,
// none of them a seed: 19 right (TestONNXPersonalBoundary). A 20th, "as i said,
// what is the population of india", missed by +0.008 during the first pass and
// is a world seed now, which is why it is not in the held-out set. True
// positives clear the world side by +0.014 to +0.089 and the nearest true
// negative sits at -0.005, so the gate is the sign of the difference and
// nothing tighter: the margins are too thin to justify a threshold, and the
// asymmetry favours claiming anyway. A false claim costs one honest "не знаю";
// a false pass sends his life to an upstream engine.
//
// The embedder is the one model CLAUDE.md pins to homesrv permanently, and it
// is what makes this affordable: no llama-server call, no network, one cosine
// per seed against a vector the turn already has.

// personalSeeds — questions about him. Frozen: they are scoring data, so
// editing one moves the boundary and must be re-measured, not eyeballed. Cover
// both classes the boundary owns, possession and first-person speech, in both
// languages.
var personalSeeds = []string{
	"что я говорил про это",
	"я тебе рассказывал об этом?",
	"что я записал про врача",
	"я упоминал эту тему?",
	"что у меня сегодня",
	"когда моя встреча",
	"what did i say about this",
	"did i mention this to you",
}

// worldSeeds — questions the world can answer, including the two shapes that
// look personal and are not: a first-person preamble on a world question ("как
// я говорил, ..."), and first person without possession ("что я могу
// посмотреть вечером"). Refusing those is the opposite mistake and the older
// comment on personalMarkers already named it.
var worldSeeds = []string{
	"почему небо синее",
	"какая столица франции",
	"как сварить борщ",
	"кто написал эту книгу",
	"what is the capital of france",
	"how do i boil an egg",
	"как я говорил, почему небо синее",
	"as i said, why is the sky blue",
	"as i said, what is the population of india",
	"что я могу посмотреть вечером",
	"что мне почитать про историю",
	"что я должен знать про питон",
	"what can i watch tonight",
	// A third shape that looks personal and is not: asking when something
	// happens (Vikunja #553). "во сколько закат сегодня" scored personal,
	// because "что у меня сегодня" and "когда моя встреча" put that frame on
	// the personal side and nothing here answered it. The sunset is the one
	// thing on his list that is the same for everybody standing outside.
	// "сегодня" is carried on purpose. Without it these caught nothing: the
	// day word is most of what pulls the frame personal, because "что у меня
	// сегодня" is a personal seed and the day word is the half it shares.
	"во сколько сегодня открывается магазин",
	"когда сегодня начинается матч",
	"во сколько сегодня восход солнца",
	// The other frame a day word carries, and the same story: "что у меня
	// сегодня" is a personal seed, so "какой сегодня праздник" and "что
	// интересного произошло сегодня в мире" were refused as his after the
	// topic seeds had already let them past the weather source.
	"какой сегодня курс валют",
	"что сегодня происходит в мире",
	// The narrative shape (Vikunja #554). "расскажи про Байкал" was refused as
	// his by 0.0052, and nothing here was phrased as an order rather than a
	// question: every world seed above opens with an interrogative. So a world
	// question that names its subject and asks for prose landed nearer "я тебе
	// рассказывал об этом?", which is the same verb about his own words.
	"расскажи про байкал",
	"расскажи про древний рим",
	"объясни как работает двигатель",
	"tell me about the roman empire",
}

// personalBoundary holds the embedded seeds. Zero value is usable and means
// "not loaded yet"; a handler built without an embedder never loads and the
// boundary falls back to personalMarkers.
type personalBoundary struct {
	once     sync.Once
	personal [][]float32
	world    [][]float32
	loaded   bool
}

// load embeds both seed sets, once per process. Seeds are embedded on the QUERY
// side, like the utterance they are compared with — a question against a
// question. Mixing sides would measure the e5 prefix, not the meaning.
func (b *personalBoundary) load(ctx context.Context, emb router.Embedder) {
	b.once.Do(func() {
		if emb == nil {
			return
		}
		embedAll := func(ss []string) [][]float32 {
			out := make([][]float32, 0, len(ss))
			for _, s := range ss {
				v, err := router.EmbedQuery(ctx, emb, s)
				if err != nil {
					log.Printf("voice: personal boundary seeds unavailable (%v); falling back to possession markers", err)
					return nil
				}
				out = append(out, v)
			}
			return out
		}
		p, w := embedAll(personalSeeds), embedAll(worldSeeds)
		if p == nil || w == nil {
			return
		}
		b.personal, b.world, b.loaded = p, w, true
	})
}

// score returns the best similarity to each side. ok is false when the seeds
// are not loaded, which is the caller's signal to use the markers instead.
func (b *personalBoundary) score(vec []float32) (personal, world float64, ok bool) {
	if !b.loaded || len(vec) == 0 {
		return 0, 0, false
	}
	best := func(seeds [][]float32) float64 {
		m := -1.0
		for _, s := range seeds {
			if c := cosine(vec, s); c > m {
				m = c
			}
		}
		return m
	}
	return best(b.personal), best(b.world), true
}

// cosine — same math as internal/router and internal/memory, small enough that
// importing one of them for it would be the larger coupling.
func cosine(a, b []float32) float64 {
	if len(a) != len(b) {
		return 0
	}
	var dot, na, nb float64
	for i := range a {
		dot += float64(a[i]) * float64(b[i])
		na += float64(a[i]) * float64(a[i])
		nb += float64(b[i]) * float64(b[i])
	}
	if na == 0 || nb == 0 {
		return 0
	}
	return dot / (math.Sqrt(na) * math.Sqrt(nb))
}