import json
from datetime import datetime, timezone
from typing import Any

from sqlalchemy import select
from sqlalchemy.orm import Session

from app.db.models import MemoryFact, SessionSummary, UserProfile
from app.memory.parse import normalize_text, parse_identity, texts_are_similar

DEFAULT_PROFILE: dict[str, Any] = {
    "name": "",
    "age": "",
    "timezone": "",
    "language": "ru",
    "notes": "",
}


class MemoryService:
    def __init__(self, db: Session):
        self.db = db

    def get_profile(self) -> dict[str, Any]:
        row = self.db.scalar(select(UserProfile).limit(1))
        if not row:
            return dict(DEFAULT_PROFILE)
        try:
            data = json.loads(row.data_json or "{}")
        except json.JSONDecodeError:
            data = {}
        merged = dict(DEFAULT_PROFILE)
        merged.update(data)
        return merged

    def update_profile(self, updates: dict[str, Any]) -> dict[str, Any]:
        row = self.db.scalar(select(UserProfile).limit(1))
        if not row:
            row = UserProfile(data_json="{}")
            self.db.add(row)
            self.db.flush()

        current = self.get_profile()
        for key, value in updates.items():
            if value is None:
                current.pop(key, None)
            else:
                current[key] = value

        row.data_json = json.dumps(current, ensure_ascii=False)
        row.updated_at = datetime.now(timezone.utc)
        self.db.commit()
        return {"ok": True, "profile": current}

    def _find_similar_fact(self, text: str) -> MemoryFact | None:
        for fact in self.db.scalars(
            select(MemoryFact).where(MemoryFact.active.is_(True))
        ):
            if texts_are_similar(fact.content, text):
                return fact
        return None

    def _sync_identity_to_profile(self, text: str) -> dict[str, Any] | None:
        parsed = parse_identity(text)
        if not parsed:
            return None
        return self.update_profile(parsed)

    def remember_fact(
        self,
        content: str,
        *,
        category: str = "fact",
        source: str = "user",
        session_id: int | None = None,
        importance: int = 3,
    ) -> dict[str, Any]:
        text = content.strip()
        if not text:
            raise ValueError("Пустой факт")

        profile_sync = self._sync_identity_to_profile(text)

        existing = self._find_similar_fact(text)
        if existing:
            if len(text) > len(existing.content):
                existing.content = text[:2000]
            existing.category = category or existing.category
            existing.importance = max(existing.importance, min(5, max(1, importance)))
            existing.updated_at = datetime.now(timezone.utc)
            if session_id:
                existing.session_id = session_id
            self.db.commit()
            result = {
                "ok": True,
                "action": "updated",
                "memory_id": existing.id,
                "content": existing.content,
                "category": existing.category,
            }
            if profile_sync:
                result["profile"] = profile_sync.get("profile")
            return result

        fact = MemoryFact(
            category=(category or "fact")[:64],
            content=text[:2000],
            source=source[:32],
            session_id=session_id,
            importance=min(5, max(1, importance)),
        )
        self.db.add(fact)
        self.db.commit()
        self.db.refresh(fact)
        result = {
            "ok": True,
            "action": "created",
            "memory_id": fact.id,
            "content": fact.content,
            "category": fact.category,
        }
        if profile_sync:
            result["profile"] = profile_sync.get("profile")
        return result

    def recall_memories(
        self,
        *,
        query: str | None = None,
        category: str | None = None,
        limit: int = 20,
        active_only: bool = True,
    ) -> list[dict[str, Any]]:
        stmt = select(MemoryFact).order_by(
            MemoryFact.importance.desc(),
            MemoryFact.updated_at.desc(),
        )
        if active_only:
            stmt = stmt.where(MemoryFact.active.is_(True))
        if category:
            stmt = stmt.where(MemoryFact.category == category)
        facts = self.db.scalars(stmt.limit(100)).all()
        if query:
            qnorm = normalize_text(query)
            facts = [
                f
                for f in facts
                if qnorm in normalize_text(f.content)
                or qnorm in normalize_text(f.category)
            ]
        facts = facts[: min(limit, 50)]
        return [
            {
                "id": f.id,
                "category": f.category,
                "content": f.content,
                "importance": f.importance,
                "source": f.source,
                "updated_at": f.updated_at.isoformat() if f.updated_at else None,
            }
            for f in facts
        ]

    def forget_memory(self, memory_id: int) -> dict[str, Any]:
        fact = self.db.get(MemoryFact, memory_id)
        if not fact:
            raise ValueError(f"Память #{memory_id} не найдена")
        fact.active = False
        fact.updated_at = datetime.now(timezone.utc)
        self.db.commit()
        return {"ok": True, "memory_id": memory_id, "forgotten": fact.content}

    def get_active_facts(self, limit: int = 25) -> list[MemoryFact]:
        return list(
            self.db.scalars(
                select(MemoryFact)
                .where(MemoryFact.active.is_(True))
                .order_by(MemoryFact.importance.desc(), MemoryFact.updated_at.desc())
                .limit(limit)
            ).all()
        )

    def get_session_summary(self, session_id: int) -> SessionSummary | None:
        return self.db.scalar(
            select(SessionSummary).where(SessionSummary.session_id == session_id)
        )

    def update_session_summary(
        self,
        session_id: int,
        summary: str,
        *,
        message_count: int = 0,
    ) -> dict[str, Any]:
        text = summary.strip()
        if not text:
            raise ValueError("Пустая сводка")

        row = self.get_session_summary(session_id)
        if not row:
            row = SessionSummary(session_id=session_id)
            self.db.add(row)

        row.summary = text[:4000]
        row.message_count = message_count
        row.updated_at = datetime.now(timezone.utc)
        self.db.commit()
        return {"ok": True, "session_id": session_id, "summary": row.summary}

    def snapshot(self, session_id: int | None = None) -> dict[str, Any]:
        facts = self.get_active_facts()
        summary_row = self.get_session_summary(session_id) if session_id else None
        return {
            "profile": self.get_profile(),
            "facts": [
                {
                    "id": f.id,
                    "category": f.category,
                    "content": f.content,
                    "importance": f.importance,
                }
                for f in facts
            ],
            "session_summary": summary_row.summary if summary_row else "",
            "total_facts": len(facts),
        }