"""OAuth utilities for MCP server authentication."""

import asyncio
import json
import secrets
import time
from datetime import datetime, timedelta
from typing import TYPE_CHECKING, Callable, Optional, Tuple

from mcp.client.auth import OAuthClientProvider, TokenStorage
from mcp.shared.auth import OAuthClientInformationFull, OAuthClientMetadata, OAuthToken
from sqlalchemy import select

from letta.log import get_logger
from letta.orm.mcp_oauth import MCPOAuth, OAuthSessionStatus
from letta.schemas.mcp import MCPOAuthSessionUpdate
from letta.schemas.user import User as PydanticUser
from letta.server.db import db_registry
from letta.services.mcp.types import OauthStreamEvent

if TYPE_CHECKING:
    from letta.services.mcp_manager import MCPManager

logger = get_logger(__name__)


class DatabaseTokenStorage(TokenStorage):
    """Database-backed token storage using MCPOAuth table via mcp_manager."""

    def __init__(self, session_id: str, mcp_manager: "MCPManager", actor: PydanticUser):
        self.session_id = session_id
        self.mcp_manager = mcp_manager
        self.actor = actor

    async def get_tokens(self) -> Optional[OAuthToken]:
        """Retrieve tokens from database."""
        oauth_session = await self.mcp_manager.get_oauth_session_by_id(self.session_id, self.actor)
        if not oauth_session:
            return None

        # Read tokens directly from _enc columns
        access_token = await oauth_session.access_token_enc.get_plaintext_async() if oauth_session.access_token_enc else None
        if not access_token:
            return None

        refresh_token = await oauth_session.refresh_token_enc.get_plaintext_async() if oauth_session.refresh_token_enc else None

        return OAuthToken(
            access_token=access_token,
            refresh_token=refresh_token,
            token_type=oauth_session.token_type,
            expires_in=int(oauth_session.expires_at.timestamp() - time.time()),
            scope=oauth_session.scope,
        )

    async def set_tokens(self, tokens: OAuthToken) -> None:
        """Store tokens in database."""
        session_update = MCPOAuthSessionUpdate(
            access_token=tokens.access_token,
            refresh_token=tokens.refresh_token,
            token_type=tokens.token_type,
            expires_at=datetime.fromtimestamp(tokens.expires_in + time.time()),
            scope=tokens.scope,
            status=OAuthSessionStatus.AUTHORIZED,
        )
        await self.mcp_manager.update_oauth_session(self.session_id, session_update, self.actor)

    async def get_client_info(self) -> Optional[OAuthClientInformationFull]:
        """Retrieve client information from database."""
        oauth_session = await self.mcp_manager.get_oauth_session_by_id(self.session_id, self.actor)
        if not oauth_session or not oauth_session.client_id:
            return None

        # Read client secret directly from _enc column
        client_secret = await oauth_session.client_secret_enc.get_plaintext_async() if oauth_session.client_secret_enc else None

        return OAuthClientInformationFull(
            client_id=oauth_session.client_id,
            client_secret=client_secret,
            redirect_uris=[oauth_session.redirect_uri] if oauth_session.redirect_uri else [],
        )

    async def set_client_info(self, client_info: OAuthClientInformationFull) -> None:
        """Store client information in database."""
        session_update = MCPOAuthSessionUpdate(
            client_id=client_info.client_id,
            client_secret=client_info.client_secret,
            redirect_uri=str(client_info.redirect_uris[0]) if client_info.redirect_uris else None,
        )
        await self.mcp_manager.update_oauth_session(self.session_id, session_update, self.actor)


class MCPOAuthSession:
    """Legacy OAuth session class - deprecated, use mcp_manager directly."""

    def __init__(
        self,
        session_id: str,
        server_url: Optional[str] = None,
        server_name: Optional[str] = None,
        user_id: Optional[str] = None,
        organization_id: Optional[str] = None,
    ):
        self.session_id = session_id
        self.server_url = server_url
        self.server_name = server_name
        self.user_id = user_id
        self.organization_id = organization_id
        self.state = secrets.token_urlsafe(32) if server_url else None

    # TODO: consolidate / deprecate this in favor of mcp_manager access
    async def create_session(self) -> str:
        """Create a new OAuth session in the database."""
        async with db_registry.async_session() as session:
            oauth_record = MCPOAuth(
                id=self.session_id,
                state=self.state,
                server_url=self.server_url,
                server_name=self.server_name,
                user_id=self.user_id,
                organization_id=self.organization_id,
                status=OAuthSessionStatus.PENDING,
                created_at=datetime.now(),
                updated_at=datetime.now(),
            )
            oauth_record = await oauth_record.create_async(session, actor=None)

        return self.session_id

    async def get_session_status(self) -> OAuthSessionStatus:
        """Get the current status of the OAuth session."""
        async with db_registry.async_session() as session:
            try:
                oauth_record = await MCPOAuth.read_async(db_session=session, identifier=self.session_id, actor=None)
                return oauth_record.status
            except Exception:
                return OAuthSessionStatus.ERROR

    async def update_session_status(self, status: OAuthSessionStatus) -> None:
        """Update the session status."""
        async with db_registry.async_session() as session:
            try:
                oauth_record = await MCPOAuth.read_async(db_session=session, identifier=self.session_id, actor=None)
                oauth_record.status = status
                oauth_record.updated_at = datetime.now()
                await oauth_record.update_async(db_session=session, actor=None)
            except Exception:
                pass

    async def store_authorization_code(self, code: str, state: str) -> Optional[MCPOAuth]:
        """Store the authorization code from OAuth callback."""
        from letta.schemas.secret import Secret

        async with db_registry.async_session() as session:
            try:
                oauth_record = await MCPOAuth.read_async(db_session=session, identifier=self.session_id, actor=None)

                # Encrypt the authorization_code and store only in _enc column (async to avoid blocking event loop)
                if code is not None:
                    code_secret = await Secret.from_plaintext_async(code)
                    oauth_record.authorization_code_enc = code_secret.get_encrypted()

                oauth_record.status = OAuthSessionStatus.AUTHORIZED
                oauth_record.state = state

                return await oauth_record.update_async(db_session=session, actor=None)
            except Exception:
                return None

    async def get_authorization_url(self) -> Optional[str]:
        """Get the authorization URL for this session."""
        async with db_registry.async_session() as session:
            try:
                oauth_record = await MCPOAuth.read_async(db_session=session, identifier=self.session_id, actor=None)
                return oauth_record.authorization_url
            except Exception:
                return None

    async def set_authorization_url(self, url: str) -> None:
        """Set the authorization URL for this session."""
        async with db_registry.async_session() as session:
            try:
                oauth_record = await MCPOAuth.read_async(db_session=session, identifier=self.session_id, actor=None)
                oauth_record.authorization_url = url
                oauth_record.updated_at = datetime.now()
                await oauth_record.update_async(db_session=session, actor=None)
            except Exception:
                pass


async def create_oauth_provider(
    session_id: str,
    server_url: str,
    redirect_uri: str,
    mcp_manager: "MCPManager",
    actor: PydanticUser,
    logo_uri: Optional[str] = None,
    url_callback: Optional[Callable[[str], None]] = None,
) -> OAuthClientProvider:
    """Create an OAuth provider for MCP server authentication.

    DEPRECATED: Use ServerSideOAuth from letta.services.mcp.server_side_oauth instead.
    This function is kept for backwards compatibility but will be removed in a future version.
    """
    logger.warning("create_oauth_provider is deprecated. Use ServerSideOAuth from letta.services.mcp.server_side_oauth instead.")

    client_metadata_dict = {
        "client_name": "Letta",
        "redirect_uris": [redirect_uri],
        "grant_types": ["authorization_code", "refresh_token"],
        "response_types": ["code"],
        "token_endpoint_auth_method": "client_secret_post",
        "logo_uri": logo_uri,
    }

    # Use manager-based storage
    storage = DatabaseTokenStorage(session_id, mcp_manager, actor)

    # Extract base URL (remove /mcp endpoint if present)
    oauth_server_url = server_url.rstrip("/").removesuffix("/sse").removesuffix("/mcp")

    async def redirect_handler(authorization_url: str) -> None:
        """Handle OAuth redirect by storing the authorization URL."""
        logger.info(f"OAuth redirect handler called with URL: {authorization_url}")
        session_update = MCPOAuthSessionUpdate(authorization_url=authorization_url)
        await mcp_manager.update_oauth_session(session_id, session_update, actor)
        logger.info(f"OAuth authorization URL stored: {authorization_url}")

        # Call the callback if provided (e.g., to yield URL to SSE stream)
        if url_callback:
            url_callback(authorization_url)

    async def callback_handler() -> Tuple[str, Optional[str]]:
        """Handle OAuth callback by waiting for authorization code."""
        timeout = 300  # 5 minutes
        start_time = time.time()

        logger.info(f"Waiting for authorization code for session {session_id}")
        while time.time() - start_time < timeout:
            oauth_session = await mcp_manager.get_oauth_session_by_id(session_id, actor)
            if oauth_session and oauth_session.authorization_code_enc:
                # Read authorization code directly from _enc column
                auth_code = await oauth_session.authorization_code_enc.get_plaintext_async()
                return auth_code, oauth_session.state
            elif oauth_session and oauth_session.status == OAuthSessionStatus.ERROR:
                raise Exception("OAuth authorization failed")
            await asyncio.sleep(1)

        raise Exception(f"Timeout waiting for OAuth callback after {timeout} seconds")

    return OAuthClientProvider(
        server_url=oauth_server_url,
        client_metadata=OAuthClientMetadata.model_validate(client_metadata_dict),
        storage=storage,
        redirect_handler=redirect_handler,
        callback_handler=callback_handler,
    )


async def cleanup_expired_oauth_sessions(max_age_hours: int = 24) -> None:
    """Clean up expired OAuth sessions."""
    cutoff_time = datetime.now() - timedelta(hours=max_age_hours)

    async with db_registry.async_session() as session:
        result = await session.execute(select(MCPOAuth).where(MCPOAuth.created_at < cutoff_time))
        expired_sessions = result.scalars().all()

        for oauth_session in expired_sessions:
            await oauth_session.hard_delete_async(db_session=session, actor=None)

        if expired_sessions:
            logger.info(f"Cleaned up {len(expired_sessions)} expired OAuth sessions")


def oauth_stream_event(event: OauthStreamEvent, **kwargs) -> str:
    data = {"event": event.value}
    data.update(kwargs)
    return f"data: {json.dumps(data)}\n\n"


def drill_down_exception(exception, depth=0, max_depth=5):
    """Recursively drill down into nested exceptions to find the root cause"""
    indent = "  " * depth
    error_details = []

    error_details.append(f"{indent}Exception at depth {depth}:")
    error_details.append(f"{indent}  Type: {type(exception).__name__}")
    error_details.append(f"{indent}  Message: {str(exception)}")
    error_details.append(f"{indent}  Module: {getattr(type(exception), '__module__', 'unknown')}")

    # Check for exception groups (TaskGroup errors)
    if hasattr(exception, "exceptions") and exception.exceptions:
        error_details.append(f"{indent}  ExceptionGroup with {len(exception.exceptions)} sub-exceptions:")
        for i, sub_exc in enumerate(exception.exceptions):
            error_details.append(f"{indent}    Sub-exception {i}:")
            if depth < max_depth:
                error_details.extend(drill_down_exception(sub_exc, depth + 1, max_depth))

    # Check for chained exceptions (__cause__ and __context__)
    if hasattr(exception, "__cause__") and exception.__cause__ and depth < max_depth:
        error_details.append(f"{indent}  Caused by:")
        error_details.extend(drill_down_exception(exception.__cause__, depth + 1, max_depth))

    if hasattr(exception, "__context__") and exception.__context__ and depth < max_depth:
        error_details.append(f"{indent}  Context:")
        error_details.extend(drill_down_exception(exception.__context__, depth + 1, max_depth))

    # Add traceback info
    import traceback

    if hasattr(exception, "__traceback__") and exception.__traceback__:
        tb_lines = traceback.format_tb(exception.__traceback__)
        error_details.append(f"{indent}  Traceback:")
        for line in tb_lines[-3:]:  # Show last 3 traceback lines
            error_details.append(f"{indent}    {line.strip()}")

    error_info = "".join(error_details)
    return error_info
