package router

import (
	"strings"

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

// AmbiguousFragmentGrammar refuses an utterance which only points at context
// that is not present. The statistical heads usually catch these, but a missed
// refusal is the dangerous direction: "ну это" must not become a confident
// chat answer, and "сделай это" must not become an act.
//
// This is a structural whole-utterance rule. Demonstratives inside a sentence
// remain ordinary language: "это резервный ключ" names a subject and does not
// match. Only filler plus unresolved-reference words can reach this lane.
func AmbiguousFragmentGrammar() Grammar {
	return Grammar{Name: "ambiguous-fragment", Decide: ambiguousFragmentDecision}
}

func ambiguousFragmentDecision(utterance string) (Decision, bool) {
	if !thinReferenceFragment(utterance) {
		return Decision{}, false
	}
	return Decision{
		Stage:      3,
		Intent:     IntentChat,
		Confidence: 0,
		Clarify:    true,
	}, true
}

// thinReferenceFragment reports whether every content word merely points at
// something omitted. It requires at least one reference word so a politeness
// utterance such as "пожалуйста" stays social rather than becoming a refusal.
func thinReferenceFragment(utterance string) bool {
	tokens := planTokens(strings.TrimSpace(utterance))
	if len(tokens) == 0 {
		return false
	}
	references := lexicon.UnresolvedReferences()
	hasReference := false
	for _, token := range tokens {
		if lexicon.IsFillerParticle(token) {
			continue
		}
		if hasExactWord(references, token) {
			hasReference = true
			continue
		}
		return false
	}
	return hasReference
}

func hasExactWord(words []string, token string) bool {
	for _, word := range words {
		if token == word {
			return true
		}
	}
	return false
}