"""Optional Postgres backend for memory. Requires: pip install fusionagi[memory]."""

from abc import ABC, abstractmethod
from typing import Any

from fusionagi._logger import logger


class MemoryBackend(ABC):
    """Abstract backend for persistent memory storage."""

    @abstractmethod
    def store(
        self,
        id: str,
        tenant_id: str,
        user_id: str,
        session_id: str,
        type: str,
        content: dict[str, Any],
        metadata: dict[str, Any] | None = None,
        retention_policy: str = "session",
    ) -> None:
        """Store a memory item."""
        ...

    @abstractmethod
    def get(self, id: str) -> dict[str, Any] | None:
        """Get a memory item by id."""
        ...

    @abstractmethod
    def query(
        self,
        tenant_id: str,
        user_id: str | None = None,
        session_id: str | None = None,
        type: str | None = None,
        limit: int = 100,
    ) -> list[dict[str, Any]]:
        """Query memory items."""
        ...


class InMemoryBackend(MemoryBackend):
    """In-memory implementation for development."""

    def __init__(self) -> None:
        self._store: dict[str, dict[str, Any]] = {}

    def store(
        self,
        id: str,
        tenant_id: str,
        user_id: str,
        session_id: str,
        type: str,
        content: dict[str, Any],
        metadata: dict[str, Any] | None = None,
        retention_policy: str = "session",
    ) -> None:
        self._store[id] = {
            "id": id,
            "tenant_id": tenant_id,
            "user_id": user_id,
            "session_id": session_id,
            "type": type,
            "content": content,
            "metadata": metadata or {},
            "retention_policy": retention_policy,
        }

    def get(self, id: str) -> dict[str, Any] | None:
        return self._store.get(id)

    def query(
        self,
        tenant_id: str,
        user_id: str | None = None,
        session_id: str | None = None,
        type: str | None = None,
        limit: int = 100,
    ) -> list[dict[str, Any]]:
        out = []
        for v in self._store.values():
            if v["tenant_id"] != tenant_id:
                continue
            if user_id and v["user_id"] != user_id:
                continue
            if session_id and v["session_id"] != session_id:
                continue
            if type and v["type"] != type:
                continue
            out.append(v)
            if len(out) >= limit:
                break
        return out


def create_postgres_backend(connection_string: str) -> MemoryBackend | None:
    """Create Postgres-backed MemoryBackend when psycopg is available."""
    try:
        import psycopg
    except ImportError:
        logger.debug("psycopg not installed; use pip install fusionagi[memory]")
        return None

    return PostgresMemoryBackend(connection_string)


class PostgresMemoryBackend(MemoryBackend):
    """Postgres-backed memory storage."""

    def __init__(self, connection_string: str) -> None:
        self._conn_str = connection_string
        self._init_schema()

    def _init_schema(self) -> None:
        import psycopg

        with psycopg.connect(self._conn_str) as conn:
            with conn.cursor() as cur:
                cur.execute(
                    """
                    CREATE TABLE IF NOT EXISTS memory_items (
                    id TEXT PRIMARY KEY,
                    tenant_id TEXT NOT NULL,
                    user_id TEXT NOT NULL,
                    session_id TEXT NOT NULL,
                    type TEXT NOT NULL,
                    content JSONB NOT NULL,
                    metadata JSONB DEFAULT '{}',
                    retention_policy TEXT DEFAULT 'session',
                    created_at TIMESTAMPTZ DEFAULT NOW()
                )
                """
            )
            conn.commit()

    def store(
        self,
        id: str,
        tenant_id: str,
        user_id: str,
        session_id: str,
        type: str,
        content: dict[str, Any],
        metadata: dict[str, Any] | None = None,
        retention_policy: str = "session",
    ) -> None:
        import json
        import psycopg

        with psycopg.connect(self._conn_str) as conn:
            with conn.cursor() as cur:
                cur.execute(
                    """
                    INSERT INTO memory_items (id, tenant_id, user_id, session_id, type, content, metadata, retention_policy)
                    VALUES (%s, %s, %s, %s, %s, %s, %s, %s)
                    ON CONFLICT (id) DO UPDATE SET content = EXCLUDED.content, metadata = EXCLUDED.metadata
                    """,
                    (id, tenant_id, user_id, session_id, type, json.dumps(content), json.dumps(metadata or {}), retention_policy),
                )
            conn.commit()

    def get(self, id: str) -> dict[str, Any] | None:
        import json
        import psycopg

        with psycopg.connect(self._conn_str) as conn:
            with conn.cursor() as cur:
                cur.execute(
                    "SELECT id, tenant_id, user_id, session_id, type, content, metadata, retention_policy FROM memory_items WHERE id = %s",
                    (id,),
                )
                row = cur.fetchone()
        if not row:
            return None
        return {
            "id": row[0],
            "tenant_id": row[1],
            "user_id": row[2],
            "session_id": row[3],
            "type": row[4],
            "content": json.loads(row[5]) if row[5] else {},
            "metadata": json.loads(row[6]) if row[6] else {},
            "retention_policy": row[7],
        }

    def query(
        self,
        tenant_id: str,
        user_id: str | None = None,
        session_id: str | None = None,
        type: str | None = None,
        limit: int = 100,
    ) -> list[dict[str, Any]]:
        import json
        import psycopg

        q = "SELECT id, tenant_id, user_id, session_id, type, content, metadata, retention_policy FROM memory_items WHERE tenant_id = %s"
        params: list[Any] = [tenant_id]
        if user_id:
            q += " AND user_id = %s"
            params.append(user_id)
        if session_id:
            q += " AND session_id = %s"
            params.append(session_id)
        if type:
            q += " AND type = %s"
            params.append(type)
        q += " ORDER BY created_at DESC LIMIT %s"
        params.append(limit)

        with psycopg.connect(self._conn_str) as conn:
            with conn.cursor() as cur:
                cur.execute(q, params)
                rows = cur.fetchall()
        return [
            {
                "id": r[0],
                "tenant_id": r[1],
                "user_id": r[2],
                "session_id": r[3],
                "type": r[4],
                "content": json.loads(r[5]) if r[5] else {},
                "metadata": json.loads(r[6]) if r[6] else {},
                "retention_policy": r[7],
            }
            for r in rows
        ]