import json
from typing import List, Optional, Dict, Any
from datetime import datetime, UTC
import logging
from sqlalchemy.ext.asyncio import AsyncSession, create_async_engine
from sqlalchemy.orm import sessionmaker, declarative_base
from sqlalchemy import Column, String, Index, select, text
from sqlalchemy.dialects.postgresql import JSONB

from .base_database import BaseDatabase
from ..models.documents import Document
from ..models.auth import AuthContext

logger = logging.getLogger(__name__)
Base = declarative_base()


class DocumentModel(Base):
    """SQLAlchemy model for document metadata."""

    __tablename__ = "documents"

    external_id = Column(String, primary_key=True)
    owner = Column(JSONB)
    content_type = Column(String)
    filename = Column(String, nullable=True)
    doc_metadata = Column(JSONB, default=dict)
    storage_info = Column(JSONB, default=dict)
    system_metadata = Column(JSONB, default=dict)
    additional_metadata = Column(JSONB, default=dict)
    access_control = Column(JSONB, default=dict)
    chunk_ids = Column(JSONB, default=list)

    # Create indexes
    __table_args__ = (
        Index("idx_owner_id", "owner", postgresql_using="gin"),
        Index("idx_access_control", "access_control", postgresql_using="gin"),
        Index("idx_system_metadata", "system_metadata", postgresql_using="gin"),
    )


def _serialize_datetime(obj: Any) -> Any:
    """Helper function to serialize datetime objects to ISO format strings."""
    if isinstance(obj, datetime):
        return obj.isoformat()
    elif isinstance(obj, dict):
        return {key: _serialize_datetime(value) for key, value in obj.items()}
    elif isinstance(obj, list):
        return [_serialize_datetime(item) for item in obj]
    return obj


class PostgresDatabase(BaseDatabase):
    """PostgreSQL implementation for document metadata storage."""

    def __init__(
        self,
        uri: str,
    ):
        """Initialize PostgreSQL connection for document storage."""
        self.engine = create_async_engine(uri)
        self.async_session = sessionmaker(self.engine, class_=AsyncSession, expire_on_commit=False)

    async def initialize(self):
        """Initialize database tables and indexes."""
        try:
            async with self.engine.begin() as conn:
                await conn.run_sync(Base.metadata.create_all)

                # Create caches table if it doesn't exist
                await conn.execute(
                    text(
                        """
                    CREATE TABLE IF NOT EXISTS caches (
                        name TEXT PRIMARY KEY,
                        metadata JSONB NOT NULL,
                        created_at TIMESTAMP WITH TIME ZONE DEFAULT CURRENT_TIMESTAMP,
                        updated_at TIMESTAMP WITH TIME ZONE DEFAULT CURRENT_TIMESTAMP
                    )
                """
                    )
                )

            logger.info("PostgreSQL tables and indexes created successfully")
            return True

        except Exception as e:
            logger.error(f"Error creating PostgreSQL tables and indexes: {str(e)}")
            return False

    async def store_document(self, document: Document) -> bool:
        """Store document metadata."""
        try:
            doc_dict = document.model_dump()

            # Rename metadata to doc_metadata
            if "metadata" in doc_dict:
                doc_dict["doc_metadata"] = doc_dict.pop("metadata")
            doc_dict["doc_metadata"]["external_id"] = doc_dict["external_id"]
            # Ensure system metadata
            if "system_metadata" not in doc_dict:
                doc_dict["system_metadata"] = {}
            doc_dict["system_metadata"]["created_at"] = datetime.now(UTC)
            doc_dict["system_metadata"]["updated_at"] = datetime.now(UTC)

            # Serialize datetime objects to ISO format strings
            doc_dict = _serialize_datetime(doc_dict)

            async with self.async_session() as session:
                doc_model = DocumentModel(**doc_dict)
                session.add(doc_model)
                await session.commit()
            return True

        except Exception as e:
            logger.error(f"Error storing document metadata: {str(e)}")
            return False

    async def get_document(self, document_id: str, auth: AuthContext) -> Optional[Document]:
        """Retrieve document metadata by ID if user has access."""
        try:
            async with self.async_session() as session:
                # Build access filter
                access_filter = self._build_access_filter(auth)

                # Query document
                query = (
                    select(DocumentModel)
                    .where(DocumentModel.external_id == document_id)
                    .where(text(f"({access_filter})"))
                )

                result = await session.execute(query)
                doc_model = result.scalar_one_or_none()

                if doc_model:
                    # Convert doc_metadata back to metadata
                    doc_dict = {
                        "external_id": doc_model.external_id,
                        "owner": doc_model.owner,
                        "content_type": doc_model.content_type,
                        "filename": doc_model.filename,
                        "metadata": doc_model.doc_metadata,
                        "storage_info": doc_model.storage_info,
                        "system_metadata": doc_model.system_metadata,
                        "additional_metadata": doc_model.additional_metadata,
                        "access_control": doc_model.access_control,
                        "chunk_ids": doc_model.chunk_ids,
                    }
                    return Document(**doc_dict)
                return None

        except Exception as e:
            logger.error(f"Error retrieving document metadata: {str(e)}")
            return None

    async def get_documents(
        self,
        auth: AuthContext,
        skip: int = 0,
        limit: int = 10000,
        filters: Optional[Dict[str, Any]] = None,
    ) -> List[Document]:
        """List documents the user has access to."""
        try:
            async with self.async_session() as session:
                # Build query
                access_filter = self._build_access_filter(auth)
                metadata_filter = self._build_metadata_filter(filters)

                query = select(DocumentModel).where(text(f"({access_filter})"))
                if metadata_filter:
                    query = query.where(text(metadata_filter))

                query = query.offset(skip).limit(limit)

                result = await session.execute(query)
                doc_models = result.scalars().all()

                return [
                    Document(
                        external_id=doc.external_id,
                        owner=doc.owner,
                        content_type=doc.content_type,
                        filename=doc.filename,
                        metadata=doc.doc_metadata,
                        storage_info=doc.storage_info,
                        system_metadata=doc.system_metadata,
                        additional_metadata=doc.additional_metadata,
                        access_control=doc.access_control,
                        chunk_ids=doc.chunk_ids,
                    )
                    for doc in doc_models
                ]

        except Exception as e:
            logger.error(f"Error listing documents: {str(e)}")
            return []

    async def update_document(
        self, document_id: str, updates: Dict[str, Any], auth: AuthContext
    ) -> bool:
        """Update document metadata if user has write access."""
        try:
            if not await self.check_access(document_id, auth, "write"):
                return False

            # Update system metadata
            updates.setdefault("system_metadata", {})
            updates["system_metadata"]["updated_at"] = datetime.now(UTC)

            # Serialize datetime objects to ISO format strings
            updates = _serialize_datetime(updates)

            async with self.async_session() as session:
                result = await session.execute(
                    select(DocumentModel).where(DocumentModel.external_id == document_id)
                )
                doc_model = result.scalar_one_or_none()

                if doc_model:
                    for key, value in updates.items():
                        setattr(doc_model, key, value)
                    await session.commit()
                    return True
                return False

        except Exception as e:
            logger.error(f"Error updating document metadata: {str(e)}")
            return False

    async def delete_document(self, document_id: str, auth: AuthContext) -> bool:
        """Delete document if user has admin access."""
        try:
            if not await self.check_access(document_id, auth, "admin"):
                return False

            async with self.async_session() as session:
                result = await session.execute(
                    select(DocumentModel).where(DocumentModel.external_id == document_id)
                )
                doc_model = result.scalar_one_or_none()

                if doc_model:
                    await session.delete(doc_model)
                    await session.commit()
                    return True
                return False

        except Exception as e:
            logger.error(f"Error deleting document: {str(e)}")
            return False

    async def find_authorized_and_filtered_documents(
        self, auth: AuthContext, filters: Optional[Dict[str, Any]] = None
    ) -> List[str]:
        """Find document IDs matching filters and access permissions."""
        try:
            async with self.async_session() as session:
                # Build query
                access_filter = self._build_access_filter(auth)
                metadata_filter = self._build_metadata_filter(filters)

                logger.debug(f"Access filter: {access_filter}")
                logger.debug(f"Metadata filter: {metadata_filter}")
                logger.debug(f"Original filters: {filters}")

                query = select(DocumentModel.external_id).where(text(f"({access_filter})"))
                if metadata_filter:
                    query = query.where(text(metadata_filter))

                logger.debug(f"Final query: {query}")

                result = await session.execute(query)
                doc_ids = [row[0] for row in result.all()]
                logger.debug(f"Found document IDs: {doc_ids}")
                return doc_ids

        except Exception as e:
            logger.error(f"Error finding authorized documents: {str(e)}")
            return []

    async def check_access(
        self, document_id: str, auth: AuthContext, required_permission: str = "read"
    ) -> bool:
        """Check if user has required permission for document."""
        try:
            async with self.async_session() as session:
                result = await session.execute(
                    select(DocumentModel).where(DocumentModel.external_id == document_id)
                )
                doc_model = result.scalar_one_or_none()

                if not doc_model:
                    return False

                # Check owner access
                owner = doc_model.owner
                if owner.get("type") == auth.entity_type and owner.get("id") == auth.entity_id:
                    return True

                # Check permission-specific access
                access_control = doc_model.access_control
                permission_map = {"read": "readers", "write": "writers", "admin": "admins"}
                permission_set = permission_map.get(required_permission)

                if not permission_set:
                    return False

                return auth.entity_id in access_control.get(permission_set, [])

        except Exception as e:
            logger.error(f"Error checking document access: {str(e)}")
            return False

    def _build_access_filter(self, auth: AuthContext) -> str:
        """Build PostgreSQL filter for access control."""
        filters = [
            f"owner->>'id' = '{auth.entity_id}'",
            f"access_control->'readers' ? '{auth.entity_id}'",
            f"access_control->'writers' ? '{auth.entity_id}'",
            f"access_control->'admins' ? '{auth.entity_id}'",
        ]

        if auth.entity_type == "DEVELOPER" and auth.app_id:
            # Add app-specific access for developers
            filters.append(f"access_control->'app_access' ? '{auth.app_id}'")

        return " OR ".join(filters)

    def _build_metadata_filter(self, filters: Dict[str, Any]) -> str:
        """Build PostgreSQL filter for metadata."""
        if not filters:
            return ""

        filter_conditions = []
        for key, value in filters.items():
            # Convert boolean values to string 'true' or 'false'
            if isinstance(value, bool):
                value = str(value).lower()
            filter_conditions.append(f"doc_metadata->>'{key}' = '{value}'")

        return " AND ".join(filter_conditions)

    async def store_cache_metadata(self, name: str, metadata: Dict[str, Any]) -> bool:
        """Store metadata for a cache in PostgreSQL.

        Args:
            name: Name of the cache
            metadata: Cache metadata including model info and storage location

        Returns:
            bool: Whether the operation was successful
        """
        try:
            async with self.async_session() as session:
                await session.execute(
                    text(
                        """
                        INSERT INTO caches (name, metadata, updated_at)
                        VALUES (:name, :metadata, CURRENT_TIMESTAMP)
                        ON CONFLICT (name)
                        DO UPDATE SET
                            metadata = :metadata,
                            updated_at = CURRENT_TIMESTAMP
                        """
                    ),
                    {"name": name, "metadata": json.dumps(metadata)},
                )
                await session.commit()
                return True
        except Exception as e:
            logger.error(f"Failed to store cache metadata: {e}")
            return False

    async def get_cache_metadata(self, name: str) -> Optional[Dict[str, Any]]:
        """Get metadata for a cache from PostgreSQL.

        Args:
            name: Name of the cache

        Returns:
            Optional[Dict[str, Any]]: Cache metadata if found, None otherwise
        """
        try:
            async with self.async_session() as session:
                result = await session.execute(
                    text("SELECT metadata FROM caches WHERE name = :name"), {"name": name}
                )
                row = result.first()
                return row[0] if row else None
        except Exception as e:
            logger.error(f"Failed to get cache metadata: {e}")
            return None