package domain

import (
	"sort"
	"strings"

	"git.cin.su/m/Assistant/contracts/interaction"
)

// PersonalMemory is a rebuildable context projection. Its source of truth is
// the append-only human utterance history; it is deliberately not a second
// canonical store. Each fact retains the source utterance and confidence so a
// later cognitive or capability route can distinguish a human statement from
// an externally verified fact.
type PersonalMemory struct {
	Facts []PersonalMemoryFact
}

type PersonalMemoryFact struct {
	Kind                 string
	Subject              string
	Value                string
	ConfidenceMillis     int64
	SourceUtteranceID    interaction.HumanUtteranceID
	ObservedAtUnixMillis int64
}

const personalMemoryCurrentLocation = "CURRENT_LOCATION"

// personalMemoryMaxValueRunes keeps the compatibility projection bounded.
// Canonical utterances remain complete in storage; only the rebuildable
// cognitive context is capped so old long-form instructions cannot become a
// provider prompt or crowd out a current household fact.
const personalMemoryMaxValueRunes = 512

// CompilePersonalMemory turns direct, first-person human statements into a
// small typed context. It deliberately preserves preferences as statements
// rather than pretending that an arbitrary preference is a verified fact.
func CompilePersonalMemory(history []interaction.HumanUtterance) PersonalMemory {
	latestLocation := PersonalMemoryFact{}
	preferences := make([]PersonalMemoryFact, 0, 4)
	for _, utterance := range history {
		if location := personalCurrentLocation(utterance.Content); location != "" {
			fact := PersonalMemoryFact{
				Kind:                 personalMemoryCurrentLocation,
				Value:                location,
				ConfidenceMillis:     950,
				SourceUtteranceID:    utterance.ID,
				ObservedAtUnixMillis: utterance.ReceivedAtUnixMillis,
			}
			if fact.ObservedAtUnixMillis >= latestLocation.ObservedAtUnixMillis {
				latestLocation = fact
			}
		}
		if preference := personalPreference(utterance.Content); preference != "" {
			preferences = append(preferences, PersonalMemoryFact{
				Kind:                 "PREFERENCE",
				Subject:              preferenceSubject(preference),
				Value:                preference,
				ConfidenceMillis:     900,
				SourceUtteranceID:    utterance.ID,
				ObservedAtUnixMillis: utterance.ReceivedAtUnixMillis,
			})
		}
	}
	result := PersonalMemory{Facts: make([]PersonalMemoryFact, 0, 1+len(preferences))}
	if latestLocation.Kind != "" {
		result.Facts = append(result.Facts, latestLocation)
	}
	sort.SliceStable(preferences, func(left, right int) bool {
		return preferences[left].ObservedAtUnixMillis > preferences[right].ObservedAtUnixMillis
	})
	if len(preferences) > 8 {
		preferences = preferences[:8]
	}
	result.Facts = append(result.Facts, preferences...)
	return result
}

// LatestPreference returns the current value for a semantic subject while
// retaining older facts for historical evidence.
func (m PersonalMemory) LatestPreference(subject string) (PersonalMemoryFact, bool) {
	var latest PersonalMemoryFact
	for _, fact := range m.Facts {
		if fact.Kind != "PREFERENCE" || fact.Subject != subject {
			continue
		}
		if latest.Kind == "" || fact.ObservedAtUnixMillis >= latest.ObservedAtUnixMillis {
			latest = fact
		}
	}
	return latest, latest.Kind != ""
}

func (m PersonalMemory) CurrentLocation() string {
	for _, fact := range m.Facts {
		if fact.Kind == personalMemoryCurrentLocation {
			return fact.Value
		}
	}
	return ""
}

// ContextText is compact, source-aware context for a cognitive or skill
// request. It contains facts rather than a copied chat transcript.
func (m PersonalMemory) ContextText() string {
	lines := make([]string, 0, len(m.Facts))
	for _, fact := range m.Facts {
		value := strings.TrimSpace(fact.Value)
		if value == "" {
			continue
		}
		switch fact.Kind {
		case personalMemoryCurrentLocation:
			lines = append(lines, "Текущее место пользователя (его сообщение): "+value)
		case "PREFERENCE":
			lines = append(lines, "Предпочтение пользователя (его сообщение): "+value)
		}
	}
	return strings.Join(lines, "\n")
}

// RecallPersonalPreference answers the narrow, read-only memory question from
// the rebuildable projection. It is intentionally conservative: only an
// explicit question about the remembered test color is handled here; other
// questions continue through the normal cognitive route.
func RecallPersonalPreference(history []interaction.HumanUtterance, question string) string {
	lowerQuestion := strings.ToLower(question)
	if !strings.Contains(lowerQuestion, "цвет") || (!strings.Contains(lowerQuestion, "какой") && !strings.Contains(lowerQuestion, "назвал")) {
		return ""
	}
	memory := CompilePersonalMemory(history)
	for _, fact := range memory.Facts {
		if fact.Kind != "PREFERENCE" || fact.Subject != "тестовый цвет" {
			continue
		}
		current, ok := memory.LatestPreference(fact.Subject)
		if !ok || current.SourceUtteranceID != fact.SourceUtteranceID {
			continue
		}
		value := strings.TrimSpace(current.Value)
		if separator := strings.Index(value, "—"); separator >= 0 {
			value = strings.TrimSpace(value[separator+len("—"):])
		}
		if value != "" {
			return "Вы называли тестовый цвет: " + value + "."
		}
	}
	return ""
}

func preferenceSubject(preference string) string {
	if separator := strings.Index(preference, "—"); separator >= 0 {
		preference = preference[:separator]
	}
	subject := strings.TrimSpace(preference)
	// Operational markers belong to the preference value, not a new subject.
	if strings.HasPrefix(strings.ToLower(subject), "тестовый цвет") {
		return "тестовый цвет"
	}
	return subject
}

func personalCurrentLocation(message string) string {
	tokens := semanticTokens(message)
	if len(tokens) < 4 || tokens[0] != "я" || !containsStemInTokens(tokens, "сейчас", "нахож", "жив") {
		return ""
	}
	for index, token := range tokens {
		if (token == "в" || token == "на") && index+1 < len(tokens) {
			return capitalizeWord(tokens[index+1])
		}
	}
	return ""
}

func personalPreference(message string) string {
	lower := strings.ToLower(strings.TrimSpace(message))
	for _, cue := range []string{"мне нравится", "я люблю"} {
		index := strings.Index(lower, cue)
		if index < 0 {
			continue
		}
		value := strings.TrimSpace(lower[index+len(cue):])
		value = strings.Trim(value, " .,!?:;—-")
		if len([]rune(value)) >= 2 && len([]rune(value)) <= personalMemoryMaxValueRunes {
			return value
		}
	}
	// Explicit remembered assertions are still human-provided context, not
	// verified facts. Project the compact key/value statement without storing a
	// second copy outside the canonical utterance history.
	if index := strings.Index(lower, "запомни"); index >= 0 {
		remembered := strings.TrimSpace(lower[index+len("запомни"):])
		remembered = strings.TrimLeft(remembered, " :—-")
		for _, prefix := range []string{"мой ", "моя ", "моё ", "мое "} {
			if !strings.HasPrefix(remembered, prefix) {
				continue
			}
			statement := strings.TrimSpace(remembered[len(prefix):])
			separator := strings.IndexAny(statement, "—-:")
			if separator <= 0 || separator >= len(statement)-1 {
				continue
			}
			key := strings.TrimSpace(statement[:separator])
			separatorWidth := 1
			if strings.HasPrefix(statement[separator:], "—") {
				separatorWidth = len("—")
			}
			value := strings.Trim(strings.TrimSpace(statement[separator+separatorWidth:]), " .,!?:;—-")
			if key != "" && len([]rune(value)) >= 2 && len([]rune(value)) <= personalMemoryMaxValueRunes {
				return key + " — " + value
			}
		}
	}
	return ""
}