package main

import (
	"context"
	"log"
	"sync"
	"time"

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

// turnRoute is this turn's routing, computed at most once.
//
// It exists because the arbitration was inverted (Vikunja #560): the clarify
// resolver now reads the routed decision before deciding what the utterance is,
// and the pipeline then acts on that same decision. Routing twice would cost a
// second on the resident model and — worse — could disagree with itself, which
// is exactly the class of bug this task is about.
type turnRoute struct {
	h    *reactiveHandler
	text string
	now  time.Time

	once sync.Once
	dec  router.Decision
	cont bool
	prev *dialogue.Session
	err  error

	// dropped — what she let go of this turn and must say out loud. A parked
	// request that dies without a word leaves him thinking it landed.
	dropped string

	// resume — the parked question, re-worded, to put AFTER this turn's answer
	// (Vikunja #561). A side query does not end the flow it interrupted, so the
	// reply carries two acts: the answer he asked for, then the question he
	// still owes her. Empty ⇒ nothing was suspended.
	resume string
	// suspended — a flow is parked underneath this turn. askClarify reads it to
	// decide between Put (replace the top) and Push (keep the flow and stack the
	// new question on it), because a side query that needs clarifying of its own
	// must not overwrite the thing it interrupted.
	suspended bool
}

type turnRouteKey struct{}

func (h *reactiveHandler) newTurnRoute(text string, now time.Time) *turnRoute {
	return &turnRoute{h: h, text: text, now: now}
}

func withTurnRoute(ctx context.Context, rt *turnRoute) context.Context {
	return context.WithValue(ctx, turnRouteKey{}, rt)
}

// turnRouteFrom returns the turn's memo, or nil when the caller is not inside
// runTurn — a unit test calling one resolver directly, most often.
func turnRouteFrom(ctx context.Context) *turnRoute {
	rt, _ := ctx.Value(turnRouteKey{}).(*turnRoute)
	return rt
}

// resolve does the routing exactly as step 5 of runTurn does it: an elliptical
// follow-up is answered from the previous turn, everything else goes to the
// router. One copy of that, so the pre-route the clarify resolver reads and the
// decision the pipeline acts on cannot drift apart.
func (r *turnRoute) resolve(ctx context.Context) (router.Decision, bool, *dialogue.Session, error) {
	r.once.Do(func() {
		if r.h.dialogueSessions != nil {
			r.prev = r.h.dialogueSessions.Get(dialogueIDOf(ctx), r.now)
		}
		if dec, cont := continuationDecision(r.prev, r.text, r.now); cont {
			log.Printf("voice: continuation of %s from the previous turn", dec.Intent)
			r.dec, r.cont = dec, true
			return
		}
		if r.h.router == nil {
			r.err = router.ErrNoIntents
			return
		}
		r.dec, r.err = r.h.router.Route(ctx, r.text, r.now)
	})
	return r.dec, r.cont, r.prev, r.err
}

// routeForRole gives the role classifier the turn's routed decision. The second
// return is false when there is no usable decision — no router wired, or the
// route failed — and the classifier falls back to its offline tests then. A
// turn must never break on the model, so the error is logged and swallowed
// here; step 5 reads the same memo and reports it the way it always has.
func (h *reactiveHandler) routeForRole(ctx context.Context, text string) (router.Decision, bool) {
	rt := turnRouteFrom(ctx)
	if rt == nil {
		rt = h.newTurnRoute(text, h.now())
	}
	dec, _, _, err := rt.resolve(ctx)
	if err != nil {
		log.Printf("voice: role — no route to classify against (%v), falling back to the offline tests", err)
		return router.Decision{}, false
	}
	return dec, true
}

// needsRoute reports whether classifying this utterance's role is worth a
// route. It is not: an utterance with no content of its own carries no request
// of its own, so the classifier reaches the same answer without the model. A
// call-off is the same — it is read off a closed lexicon and nothing else.
//
// This is a fast path to the SAME answer and must stay one. If it ever needs a
// rule the classifier does not have, it has become a second decision procedure
// and it is the thing V-560 deleted.
//
// A question shape is the exception and V-577 is why (measured 2026-08-06).
// "что у меня сегодня?" is an interrogative, a preposition, a particle and a day
// word, so every token of it is frame and it left no content of its own. The
// fast path called it an answer, the parked reminder read "сегодня" as its time,
// and the question he asked was never answered. Asked alone the same sentence
// routes to query at stage 0, so the route knew and was never consulted.
func needsRoute(text string) bool {
	if isCancel(text) {
		return false
	}
	return len(ownContent(text)) > 0 || router.IsQuestionShaped(text)
}