"""
Chat Sessions Repository for managing chat session data.

Provides CRUD operations for the chat_sessions table in the project's
checkpoint database.
"""

import json
import logging
from datetime import datetime
from typing import Any, Dict, List, Optional
from uuid import UUID

import aiosqlite

log = logging.getLogger(__name__)


class ChatSession:
    """Chat session model."""

    def __init__(
        self,
        id: Optional[int] = None,
        thread_id: str = "",
        user_id: str = "",
        project_id: str = "",
        title: str = "New Conversation",
        message_count: int = 0,
        llm_calls_count: int = 0,
        input_tokens: int = 0,
        output_tokens: int = 0,
        total_tokens: int = 0,
        last_message_at: Optional[str] = None,
        created_at: Optional[str] = None,
        updated_at: Optional[str] = None,
        metadata: str = "{}",
        stats: str = "{}",
        pinned: bool = False
    ):
        self.id = id
        self.thread_id = thread_id
        self.user_id = user_id
        self.project_id = project_id
        self.title = title
        self.message_count = message_count
        self.llm_calls_count = llm_calls_count
        self.input_tokens = input_tokens
        self.output_tokens = output_tokens
        self.total_tokens = total_tokens
        self.last_message_at = last_message_at
        self.created_at = created_at
        self.updated_at = updated_at
        self.metadata = metadata
        self.stats = stats
        self.pinned = pinned

    def to_dict(self) -> Dict[str, Any]:
        """Convert to dictionary."""
        return {
            "id": self.id,
            "thread_id": self.thread_id,
            "user_id": self.user_id,
            "project_id": self.project_id,
            "title": self.title,
            "message_count": self.message_count,
            "llm_calls_count": self.llm_calls_count,
            "input_tokens": self.input_tokens,
            "output_tokens": self.output_tokens,
            "total_tokens": self.total_tokens,
            "last_message_at": self.last_message_at,
            "created_at": self.created_at,
            "updated_at": self.updated_at,
            "metadata": json.loads(self.metadata) if self.metadata else {},
            "stats": json.loads(self.stats) if self.stats else {},
            "pinned": self.pinned,
        }


class ChatSessionsRepository:
    """
    Repository for managing chat sessions in the checkpoint database.
    """

    def __init__(self, conn: aiosqlite.Connection):
        """
        Initialize repository with a database connection.

        Args:
            conn: aiosqlite connection to the checkpoint database
        """
        self.conn = conn

    async def create_session(
        self,
        thread_id: str,
        user_id: str,
        project_id: str,
        title: str = "New Conversation"
    ) -> ChatSession:
        """
        Create a new chat session.

        Args:
            thread_id: Unique thread identifier
            user_id: User ID
            project_id: Project ID
            title: Session title

        Returns:
            Created ChatSession
        """
        now = datetime.utcnow().isoformat()
        cursor = await self.conn.execute(
            """
            INSERT INTO chat_sessions (
                thread_id, user_id, project_id, title,
                created_at, updated_at
            ) VALUES (?, ?, ?, ?, ?, ?)
            """,
            (thread_id, user_id, project_id, title, now, now)
        )
        await self.conn.commit()

        session_id = cursor.lastrowid
        log.info("Created chat session: id=%s, thread_id=%s", session_id, thread_id)

        return await self.get_session_by_id(session_id)

    async def get_session_by_id(self, session_id: int) -> Optional[ChatSession]:
        """
        Get a session by its database ID.

        Args:
            session_id: Database row ID

        Returns:
            ChatSession or None
        """
        cursor = await self.conn.execute(
            "SELECT * FROM chat_sessions WHERE id = ?",
            (session_id,)
        )
        row = await cursor.fetchone()

        if row:
            return self._row_to_session(row)
        return None

    async def get_session_by_thread(self, thread_id: str) -> Optional[ChatSession]:
        """
        Get a session by thread_id.

        Args:
            thread_id: Thread identifier

        Returns:
            ChatSession or None
        """
        cursor = await self.conn.execute(
            "SELECT * FROM chat_sessions WHERE thread_id = ?",
            (thread_id,)
        )
        row = await cursor.fetchone()

        if row:
            return self._row_to_session(row)
        return None

    async def list_sessions(
        self,
        user_id: Optional[str] = None,
        project_id: Optional[str] = None,
        limit: int = 100
    ) -> List[ChatSession]:
        """
        List sessions with optional filters.

        Args:
            user_id: Filter by user ID
            project_id: Filter by project ID
            limit: Maximum number of sessions to return

        Returns:
            List of ChatSession
        """
        query = "SELECT * FROM chat_sessions"
        params = []

        conditions = []
        if user_id:
            conditions.append("user_id = ?")
            params.append(user_id)
        if project_id:
            conditions.append("project_id = ?")
            params.append(project_id)

        if conditions:
            query += " WHERE " + " AND ".join(conditions)

        # Sort by pinned status first, then by updated_at
        query += " ORDER BY pinned DESC, updated_at DESC LIMIT ?"
        params.append(limit)

        cursor = await self.conn.execute(query, params)
        rows = await cursor.fetchall()

        return [self._row_to_session(row) for row in rows]

    async def update_session(
        self,
        thread_id: str,
        title: Optional[str] = None,
        message_count: Optional[int] = None,
        llm_calls_count: Optional[int] = None,
        input_tokens: Optional[int] = None,
        output_tokens: Optional[int] = None,
        total_tokens: Optional[int] = None,
        last_message_at: Optional[str] = None
    ) -> Optional[ChatSession]:
        """
        Update a session.

        Args:
            thread_id: Thread identifier
            title: New title
            message_count: Increment message count
            llm_calls_count: Increment LLM call count
            input_tokens: Add to input tokens
            output_tokens: Add to output tokens
            total_tokens: Add to total tokens
            last_message_at: Last message timestamp

        Returns:
            Updated ChatSession or None
        """
        updates = []
        params = []

        now = datetime.utcnow().isoformat()

        if title is not None:
            updates.append("title = ?")
            params.append(title)

        if message_count is not None:
            updates.append("message_count = message_count + ?")
            params.append(message_count)

        if llm_calls_count is not None:
            updates.append("llm_calls_count = llm_calls_count + ?")
            params.append(llm_calls_count)

        if input_tokens is not None:
            updates.append("input_tokens = input_tokens + ?")
            params.append(input_tokens)

        if output_tokens is not None:
            updates.append("output_tokens = output_tokens + ?")
            params.append(output_tokens)

        if total_tokens is not None:
            updates.append("total_tokens = total_tokens + ?")
            params.append(total_tokens)

        if last_message_at is not None:
            updates.append("last_message_at = ?")
            params.append(last_message_at)

        if not updates:
            return await self.get_session_by_thread(thread_id)

        updates.append("updated_at = ?")
        params.append(now)
        params.append(thread_id)

        query = f"UPDATE chat_sessions SET {', '.join(updates)} WHERE thread_id = ?"

        await self.conn.execute(query, params)
        await self.conn.commit()

        log.debug("Updated chat session: thread_id=%s", thread_id)
        return await self.get_session_by_thread(thread_id)

    async def delete_session(self, thread_id: str) -> bool:
        """
        Delete a session by thread_id.

        Args:
            thread_id: Thread identifier

        Returns:
            True if deleted, False if not found
        """
        # First, delete the checkpoint data
        await self.conn.execute(
            "DELETE FROM checkpoints WHERE thread_id = ?",
            (thread_id,)
        )

        # Then delete the session
        cursor = await self.conn.execute(
            "DELETE FROM chat_sessions WHERE thread_id = ?",
            (thread_id,)
        )
        await self.conn.commit()

        deleted = cursor.rowcount > 0
        if deleted:
            log.info("Deleted chat session and checkpoints: thread_id=%s", thread_id)

        return deleted

    async def delete_all_sessions(self, project_id: str) -> int:
        """
        Delete all sessions for a project.

        Args:
            project_id: Project ID

        Returns:
            Number of sessions deleted
        """
        # Get all thread_ids for this project
        cursor = await self.conn.execute(
            "SELECT thread_id FROM chat_sessions WHERE project_id = ?",
            (project_id,)
        )
        rows = await cursor.fetchall()
        thread_ids = [row[0] for row in rows]

        # Delete checkpoints and sessions
        for thread_id in thread_ids:
            await self.conn.execute(
                "DELETE FROM checkpoints WHERE thread_id = ?",
                (thread_id,)
            )

        cursor = await self.conn.execute(
            "DELETE FROM chat_sessions WHERE project_id = ?",
            (project_id,)
        )
        await self.conn.commit()

        deleted_count = cursor.rowcount
        if deleted_count > 0:
            log.info("Deleted %d sessions for project: %s", deleted_count, project_id)

        return deleted_count

    async def pin_session(self, thread_id: str, pinned: bool = True) -> Optional[ChatSession]:
        """
        Pin or unpin a session.

        Args:
            thread_id: Thread identifier
            pinned: True to pin, False to unpin

        Returns:
            Updated ChatSession or None
        """
        now = datetime.utcnow().isoformat()
        await self.conn.execute(
            "UPDATE chat_sessions SET pinned = ?, updated_at = ? WHERE thread_id = ?",
            (1 if pinned else 0, now, thread_id)
        )
        await self.conn.commit()

        log.debug("Session pin status updated: thread_id=%s, pinned=%s", thread_id, pinned)
        return await self.get_session_by_thread(thread_id)

    def _row_to_session(self, row) -> ChatSession:
        """Convert database row to ChatSession object."""
        return ChatSession(
            id=row[0],
            thread_id=row[1],
            user_id=row[2],
            project_id=row[3],
            title=row[4],
            message_count=row[5],
            llm_calls_count=row[6],
            input_tokens=row[7],
            output_tokens=row[8],
            total_tokens=row[9],
            last_message_at=row[10],
            created_at=row[11],
            updated_at=row[12],
            metadata=row[13],
            stats=row[14],
            pinned=bool(row[15]) if len(row) > 15 else False,
        )