import json
from collections.abc import AsyncGenerator
from typing import Any, Dict, List, Literal, Optional, Union

from fastapi import APIRouter, Body, Depends, HTTPException, Query, Request
from httpx import ConnectError, HTTPStatusError
from pydantic import BaseModel, Field
from starlette.responses import StreamingResponse

from letta.constants import DEFAULT_GENERATE_TOOL_MODEL_HANDLE, MAX_TOOL_NAME_LENGTH
from letta.errors import (
    LettaInvalidArgumentError,
    LettaInvalidMCPSchemaError,
    LettaMCPConnectionError,
    LettaMCPTimeoutError,
    LettaToolCreateError,
    LettaToolNameConflictError,
    LLMError,
)
from letta.functions.functions import derive_openai_json_schema
from letta.functions.mcp_client.exceptions import MCPTimeoutError
from letta.functions.mcp_client.types import MCPTool, SSEServerConfig, StdioServerConfig, StreamableHTTPServerConfig
from letta.helpers.decorators import deprecated
from letta.llm_api.llm_client import LLMClient
from letta.log import get_logger
from letta.orm.errors import UniqueConstraintViolationError
from letta.orm.mcp_oauth import OAuthSessionStatus
from letta.prompts.gpt_system import get_system_text
from letta.schemas.enums import AgentType, MessageRole, ToolType
from letta.schemas.letta_message import ToolReturnMessage
from letta.schemas.letta_message_content import TextContent
from letta.schemas.mcp import UpdateSSEMCPServer, UpdateStdioMCPServer, UpdateStreamableHTTPMCPServer
from letta.schemas.message import Message
from letta.schemas.pip_requirement import PipRequirement
from letta.schemas.tool import BaseTool, Tool, ToolCreate, ToolRunFromSource, ToolSearchRequest, ToolSearchResult, ToolUpdate
from letta.server.rest_api.dependencies import HeaderParams, get_headers, get_letta_server
from letta.server.rest_api.streaming_response import StreamingResponseWithStatusCode
from letta.server.server import SyncServer
from letta.services.mcp.oauth_utils import MCPOAuthSession, drill_down_exception, oauth_stream_event
from letta.services.mcp.stdio_client import AsyncStdioMCPClient
from letta.services.mcp.types import OauthStreamEvent
from letta.services.summarizer.summarizer import traceback
from letta.settings import tool_settings
from letta.utils import asyncio
from letta.validators import ToolId

router = APIRouter(prefix="/tools", tags=["tools"])

logger = get_logger(__name__)


@router.delete("/{tool_id}", operation_id="delete_tool")
async def delete_tool(
    tool_id: ToolId,
    server: SyncServer = Depends(get_letta_server),
    headers: HeaderParams = Depends(get_headers),
):
    """
    Delete a tool by name
    """
    actor = await server.user_manager.get_actor_or_default_async(actor_id=headers.actor_id)
    await server.tool_manager.delete_tool_by_id_async(tool_id=tool_id, actor=actor)


@router.get("/count", response_model=int, operation_id="count_tools")
async def count_tools(
    name: Optional[str] = None,
    names: Optional[List[str]] = Query(None, description="Filter by specific tool names"),
    tool_ids: Optional[List[str]] = Query(
        None, description="Filter by specific tool IDs - accepts repeated params or comma-separated values"
    ),
    search: Optional[str] = Query(None, description="Search tool names (case-insensitive partial match)"),
    tool_types: Optional[List[str]] = Query(None, description="Filter by tool type(s) - accepts repeated params or comma-separated values"),
    exclude_tool_types: Optional[List[str]] = Query(
        None, description="Tool type(s) to exclude - accepts repeated params or comma-separated values"
    ),
    return_only_letta_tools: Optional[bool] = Query(False, description="Count only tools with tool_type starting with 'letta_'"),
    exclude_letta_tools: Optional[bool] = Query(False, description="Exclude built-in Letta tools from the count"),
    server: SyncServer = Depends(get_letta_server),
    headers: HeaderParams = Depends(get_headers),
):
    """
    Get a count of all tools available to agents belonging to the org of the user.
    """

    # Helper function to parse tool types - supports both repeated params and comma-separated values
    def parse_tool_types(tool_types_input: Optional[List[str]]) -> Optional[List[str]]:
        if tool_types_input is None:
            return None

        # Flatten any comma-separated values and validate against ToolType enum
        flattened_types = []
        for item in tool_types_input:
            # Split by comma in case user provided comma-separated values
            types_in_item = [t.strip() for t in item.split(",") if t.strip()]
            flattened_types.extend(types_in_item)

        # Validate each type against the ToolType enum
        valid_types = []
        valid_values = [tt.value for tt in ToolType]

        for tool_type in flattened_types:
            if tool_type not in valid_values:
                raise HTTPException(status_code=400, detail=f"Invalid tool_type '{tool_type}'. Must be one of: {', '.join(valid_values)}")
            valid_types.append(tool_type)

        return valid_types if valid_types else None

    # Parse and validate tool types (same logic as list_tools)
    tool_types_str = parse_tool_types(tool_types)
    exclude_tool_types_str = parse_tool_types(exclude_tool_types)

    actor = await server.user_manager.get_actor_or_default_async(actor_id=headers.actor_id)

    # Combine single name with names list for unified processing (same logic as list_tools)
    combined_names = []
    if name is not None:
        combined_names.append(name)
    if names is not None:
        combined_names.extend(names)

    # Use None if no names specified, otherwise use the combined list
    final_names = combined_names if combined_names else None

    # Helper function to parse tool IDs - supports both repeated params and comma-separated values
    def parse_tool_ids(tool_ids_input: Optional[List[str]]) -> Optional[List[str]]:
        if tool_ids_input is None:
            return None

        # Flatten any comma-separated values
        flattened_ids = []
        for item in tool_ids_input:
            # Split by comma in case user provided comma-separated values
            ids_in_item = [id.strip() for id in item.split(",") if id.strip()]
            flattened_ids.extend(ids_in_item)

        return flattened_ids if flattened_ids else None

    # Parse tool IDs (same logic as list_tools)
    final_tool_ids = parse_tool_ids(tool_ids)

    # Get the count of tools using unified query
    return await server.tool_manager.count_tools_async(
        actor=actor,
        tool_types=tool_types_str,
        exclude_tool_types=exclude_tool_types_str,
        names=final_names,
        tool_ids=final_tool_ids,
        search=search,
        return_only_letta_tools=return_only_letta_tools,
        exclude_letta_tools=exclude_letta_tools,
        project_id=headers.project_id,
    )


@router.get("/{tool_id}", response_model=Tool, operation_id="retrieve_tool")
async def retrieve_tool(
    tool_id: ToolId,
    server: SyncServer = Depends(get_letta_server),
    headers: HeaderParams = Depends(get_headers),
):
    """
    Get a tool by ID
    """
    actor = await server.user_manager.get_actor_or_default_async(actor_id=headers.actor_id)
    tool = await server.tool_manager.get_tool_by_id_async(tool_id=tool_id, actor=actor)
    if tool is None:
        # return 404 error
        raise HTTPException(status_code=404, detail=f"Tool with id {tool_id} not found.")
    return tool


@router.get("/", response_model=List[Tool], operation_id="list_tools")
async def list_tools(
    before: Optional[str] = Query(
        None, description="Tool ID cursor for pagination. Returns tools that come before this tool ID in the specified sort order"
    ),
    after: Optional[str] = Query(
        None, description="Tool ID cursor for pagination. Returns tools that come after this tool ID in the specified sort order"
    ),
    limit: Optional[int] = Query(50, description="Maximum number of tools to return"),
    order: Literal["asc", "desc"] = Query(
        "desc", description="Sort order for tools by creation time. 'asc' for oldest first, 'desc' for newest first"
    ),
    order_by: Literal["created_at"] = Query("created_at", description="Field to sort by"),
    name: Optional[str] = Query(None, description="Filter by single tool name"),
    names: Optional[List[str]] = Query(None, description="Filter by specific tool names"),
    tool_ids: Optional[List[str]] = Query(
        None, description="Filter by specific tool IDs - accepts repeated params or comma-separated values"
    ),
    search: Optional[str] = Query(None, description="Search tool names (case-insensitive partial match)"),
    tool_types: Optional[List[str]] = Query(None, description="Filter by tool type(s) - accepts repeated params or comma-separated values"),
    exclude_tool_types: Optional[List[str]] = Query(
        None, description="Tool type(s) to exclude - accepts repeated params or comma-separated values"
    ),
    return_only_letta_tools: Optional[bool] = Query(False, description="Return only tools with tool_type starting with 'letta_'"),
    server: SyncServer = Depends(get_letta_server),
    headers: HeaderParams = Depends(get_headers),
):
    """
    Get a list of all tools available to agents.
    """

    # Helper function to parse tool types - supports both repeated params and comma-separated values
    def parse_tool_types(tool_types_input: Optional[List[str]]) -> Optional[List[str]]:
        if tool_types_input is None:
            return None

        # Flatten any comma-separated values and validate against ToolType enum
        flattened_types = []
        for item in tool_types_input:
            # Split by comma in case user provided comma-separated values
            types_in_item = [t.strip() for t in item.split(",") if t.strip()]
            flattened_types.extend(types_in_item)

        # Validate each type against the ToolType enum
        valid_types = []
        valid_values = [tt.value for tt in ToolType]

        for tool_type in flattened_types:
            if tool_type not in valid_values:
                raise HTTPException(status_code=400, detail=f"Invalid tool_type '{tool_type}'. Must be one of: {', '.join(valid_values)}")
            valid_types.append(tool_type)

        return valid_types if valid_types else None

    # Parse and validate tool types
    tool_types_str = parse_tool_types(tool_types)
    exclude_tool_types_str = parse_tool_types(exclude_tool_types)

    actor = await server.user_manager.get_actor_or_default_async(actor_id=headers.actor_id)

    # Combine single name with names list for unified processing
    combined_names = []
    if name is not None:
        combined_names.append(name)
    if names is not None:
        combined_names.extend(names)

    # Use None if no names specified, otherwise use the combined list
    final_names = combined_names if combined_names else None

    # Helper function to parse tool IDs - supports both repeated params and comma-separated values
    def parse_tool_ids(tool_ids_input: Optional[List[str]]) -> Optional[List[str]]:
        if tool_ids_input is None:
            return None

        # Flatten any comma-separated values
        flattened_ids = []
        for item in tool_ids_input:
            # Split by comma in case user provided comma-separated values
            ids_in_item = [id.strip() for id in item.split(",") if id.strip()]
            flattened_ids.extend(ids_in_item)

        return flattened_ids if flattened_ids else None

    # Parse tool IDs
    final_tool_ids = parse_tool_ids(tool_ids)

    # Get the list of tools using unified query
    return await server.tool_manager.list_tools_async(
        actor=actor,
        before=before,
        after=after,
        limit=limit,
        ascending=(order == "asc"),
        tool_types=tool_types_str,
        exclude_tool_types=exclude_tool_types_str,
        names=final_names,
        tool_ids=final_tool_ids,
        search=search,
        return_only_letta_tools=return_only_letta_tools,
        project_id=headers.project_id,
    )


@router.post("/search", response_model=List[ToolSearchResult], operation_id="search_tools")
async def search_tools(
    request: ToolSearchRequest = Body(...),
    server: SyncServer = Depends(get_letta_server),
    headers: HeaderParams = Depends(get_headers),
):
    """
    Search tools using semantic search.

    Requires tool embedding to be enabled (embed_tools=True). Uses vector search,
    full-text search, or hybrid mode to find tools matching the query.

    Returns tools ranked by relevance with their search scores.
    """
    actor = await server.user_manager.get_actor_or_default_async(actor_id=headers.actor_id)

    try:
        results = await server.tool_manager.search_tools_async(
            actor=actor,
            query_text=request.query,
            search_mode=request.search_mode,
            tool_types=request.tool_types,
            tags=request.tags,
            limit=request.limit,
        )

        return [
            ToolSearchResult(
                tool=tool,
                embedded_text=None,  # Could be populated if needed
                fts_rank=metadata.get("fts_rank"),
                vector_rank=metadata.get("vector_rank"),
                combined_score=metadata.get("combined_score", 0.0),
            )
            for tool, metadata in results
        ]
    except ValueError as e:
        raise HTTPException(status_code=400, detail=str(e))


@router.post("/", response_model=Tool, operation_id="create_tool")
async def create_tool(
    request: ToolCreate = Body(...),
    server: SyncServer = Depends(get_letta_server),
    headers: HeaderParams = Depends(get_headers),
):
    """
    Create a new tool
    """
    actor = await server.user_manager.get_actor_or_default_async(actor_id=headers.actor_id)
    tool = Tool(**request.model_dump(exclude_unset=True))
    # Set project_id from header if provided
    if headers.project_id:
        tool.project_id = headers.project_id
    modal_sandbox_enabled = bool(headers.experimental_params.modal_sandbox) if headers.experimental_params else False
    return await server.tool_manager.create_or_update_tool_async(
        pydantic_tool=tool, actor=actor, modal_sandbox_enabled=modal_sandbox_enabled
    )


@router.put("/", response_model=Tool, operation_id="upsert_tool")
async def upsert_tool(
    request: ToolCreate = Body(...),
    server: SyncServer = Depends(get_letta_server),
    headers: HeaderParams = Depends(get_headers),
):
    """
    Create or update a tool
    """
    actor = await server.user_manager.get_actor_or_default_async(actor_id=headers.actor_id)
    modal_sandbox_enabled = bool(headers.experimental_params.modal_sandbox) if headers.experimental_params else False
    tool = Tool(**request.model_dump(exclude_unset=True))
    # Set project_id from header if provided
    if headers.project_id:
        tool.project_id = headers.project_id
    tool = await server.tool_manager.create_or_update_tool_async(
        pydantic_tool=tool, actor=actor, modal_sandbox_enabled=modal_sandbox_enabled
    )
    return tool


@router.patch("/{tool_id}", response_model=Tool, operation_id="modify_tool")
async def modify_tool(
    tool_id: ToolId,
    request: ToolUpdate = Body(...),
    server: SyncServer = Depends(get_letta_server),
    headers: HeaderParams = Depends(get_headers),
):
    """
    Update an existing tool
    """
    actor = await server.user_manager.get_actor_or_default_async(actor_id=headers.actor_id)
    modal_sandbox_enabled = bool(headers.experimental_params.modal_sandbox) if headers.experimental_params else False
    tool = await server.tool_manager.update_tool_by_id_async(
        tool_id=tool_id, tool_update=request, actor=actor, modal_sandbox_enabled=modal_sandbox_enabled
    )
    return tool


@router.post("/add-base-tools", response_model=List[Tool], operation_id="add_base_tools")
async def upsert_base_tools(
    server: SyncServer = Depends(get_letta_server),
    headers: HeaderParams = Depends(get_headers),
):
    """
    Upsert base tools
    """
    actor = await server.user_manager.get_actor_or_default_async(actor_id=headers.actor_id)
    return await server.tool_manager.upsert_base_tools_async(actor=actor)


@router.post("/run", response_model=ToolReturnMessage, operation_id="run_tool_from_source")
async def run_tool_from_source(
    server: SyncServer = Depends(get_letta_server),
    request: ToolRunFromSource = Body(...),
    headers: HeaderParams = Depends(get_headers),
):
    """
    Attempt to build a tool from source, then run it on the provided arguments
    """
    actor = await server.user_manager.get_actor_or_default_async(actor_id=headers.actor_id)

    return await server.run_tool_from_source(
        tool_source=request.source_code,
        tool_source_type=request.source_type,
        tool_args=request.args,
        tool_env_vars=request.env_vars,
        tool_name=request.name,
        tool_args_json_schema=request.args_json_schema,
        tool_json_schema=request.json_schema,
        pip_requirements=request.pip_requirements,
        actor=actor,
    )


# Specific routes for MCP
@router.get(
    "/mcp/servers",
    response_model=dict[str, Union[SSEServerConfig, StdioServerConfig, StreamableHTTPServerConfig]],
    operation_id="list_mcp_servers",
)
async def list_mcp_servers(
    server: SyncServer = Depends(get_letta_server),
    headers: HeaderParams = Depends(get_headers),
):
    """
    Get a list of all configured MCP servers
    """
    if tool_settings.mcp_read_from_config:
        return await server.get_mcp_servers()
    else:
        actor = await server.user_manager.get_actor_or_default_async(actor_id=headers.actor_id)
        mcp_servers = await server.mcp_manager.list_mcp_servers(actor=actor)
        result = {}
        for mcp_server in mcp_servers:
            result[mcp_server.server_name] = await mcp_server.to_config_async(resolve_variables=False)
        return result


# NOTE: async because the MCP client/session calls are async
# TODO: should we make the return type MCPTool, not Tool (since we don't have ID)?
@router.get("/mcp/servers/{mcp_server_name}/tools", response_model=List[MCPTool], operation_id="list_mcp_tools_by_server")
async def list_mcp_tools_by_server(
    mcp_server_name: str,
    server: SyncServer = Depends(get_letta_server),
    headers: HeaderParams = Depends(get_headers),
):
    """
    Get a list of all tools for a specific MCP server
    """
    actor = await server.user_manager.get_actor_or_default_async(actor_id=headers.actor_id)
    try:
        mcp_tools = await server.mcp_manager.list_mcp_server_tools(mcp_server_name=mcp_server_name, actor=actor)
        return mcp_tools
    except (ConnectError, ConnectionError) as e:
        raise LettaMCPConnectionError(str(e), server_name=mcp_server_name)
    except HTTPStatusError as e:
        # HTTPStatusError from the MCP server likely means auth issue
        if e.response.status_code == 401:
            raise LettaMCPConnectionError(f"Authentication failed: {e}", server_name=mcp_server_name)
        else:
            raise LettaMCPConnectionError(f"HTTP error from MCP server: {e}", server_name=mcp_server_name)


@router.post("/mcp/servers/{mcp_server_name}/resync", operation_id="resync_mcp_server_tools")
async def resync_mcp_server_tools(
    mcp_server_name: str,
    server: SyncServer = Depends(get_letta_server),
    headers: HeaderParams = Depends(get_headers),
    agent_id: Optional[str] = None,
):
    """
    Resync tools for an MCP server by:
    1. Fetching current tools from the MCP server
    2. Deleting tools that no longer exist on the server
    3. Updating schemas for existing tools
    4. Adding new tools from the server

    Returns a summary of changes made.
    """
    actor = await server.user_manager.get_actor_or_default_async(actor_id=headers.actor_id)
    result = await server.mcp_manager.resync_mcp_server_tools(mcp_server_name=mcp_server_name, actor=actor, agent_id=agent_id)
    return result


@router.post("/mcp/servers/{mcp_server_name}/{mcp_tool_name}", response_model=Tool, operation_id="add_mcp_tool")
async def add_mcp_tool(
    mcp_server_name: str,
    mcp_tool_name: str,
    server: SyncServer = Depends(get_letta_server),
    headers: HeaderParams = Depends(get_headers),
):
    """
    Register a new MCP tool as a Letta server by MCP server + tool name
    """
    actor = await server.user_manager.get_actor_or_default_async(actor_id=headers.actor_id)

    if tool_settings.mcp_read_from_config:
        try:
            available_tools = await server.get_tools_from_mcp_server(mcp_server_name=mcp_server_name)
        except MCPTimeoutError as e:
            raise LettaMCPTimeoutError(str(e), server_name=mcp_server_name)

        # See if the tool is in the available list
        mcp_tool = None
        for tool in available_tools:
            if tool.name == mcp_tool_name:
                mcp_tool = tool
                break
        if not mcp_tool:
            raise LettaInvalidArgumentError(
                f"Tool {mcp_tool_name} not found in MCP server {mcp_server_name} - available tools: {', '.join([tool.name for tool in available_tools])}",
                argument_name="mcp_tool_name",
            )

        # Log warning if tool has invalid schema but allow attachment
        if mcp_tool.health and mcp_tool.health.status == "INVALID":
            logger.warning(
                f"Attaching MCP tool {mcp_tool_name} from server {mcp_server_name} with invalid schema. Reasons: {mcp_tool.health.reasons}"
            )

        tool_create = ToolCreate.from_mcp(mcp_server_name=mcp_server_name, mcp_tool=mcp_tool)
        # For config-based servers, use the server name as ID since they don't have database IDs
        mcp_server_id = mcp_server_name
        return await server.tool_manager.create_mcp_tool_async(
            tool_create=tool_create, mcp_server_name=mcp_server_name, mcp_server_id=mcp_server_id, actor=actor
        )

    else:
        return await server.mcp_manager.add_tool_from_mcp_server(mcp_server_name=mcp_server_name, mcp_tool_name=mcp_tool_name, actor=actor)


@router.put(
    "/mcp/servers",
    response_model=List[Union[StdioServerConfig, SSEServerConfig, StreamableHTTPServerConfig]],
    operation_id="add_mcp_server",
)
async def add_mcp_server_to_config(
    request: Union[StdioServerConfig, SSEServerConfig, StreamableHTTPServerConfig] = Body(...),
    server: SyncServer = Depends(get_letta_server),
    headers: HeaderParams = Depends(get_headers),
):
    """
    Add a new MCP server to the Letta MCP server config
    """
    actor = await server.user_manager.get_actor_or_default_async(actor_id=headers.actor_id)

    if tool_settings.mcp_read_from_config:
        # write to config file
        return await server.add_mcp_server_to_config(server_config=request, allow_upsert=True)
    else:
        # log to DB
        # Check if stdio servers are disabled
        if isinstance(request, StdioServerConfig) and tool_settings.mcp_disable_stdio:
            raise HTTPException(
                status_code=400,
                detail="stdio is not supported in the current environment, please use a self-hosted Letta server in order to add a stdio MCP server",
            )

        # Create MCP server and optimistically sync tools
        # The mcp_manager will handle encryption of sensitive fields
        await server.mcp_manager.create_mcp_server_from_config_with_tools(request, actor=actor)

        # TODO: don't do this in the future (just return MCPServer)
        all_servers = await server.mcp_manager.list_mcp_servers(actor=actor)
        result = []
        for mcp_server in all_servers:
            result.append(await mcp_server.to_config_async())
        return result


@router.patch(
    "/mcp/servers/{mcp_server_name}",
    response_model=Union[StdioServerConfig, SSEServerConfig, StreamableHTTPServerConfig],
    operation_id="update_mcp_server",
)
async def update_mcp_server(
    mcp_server_name: str,
    request: Union[UpdateStdioMCPServer, UpdateSSEMCPServer, UpdateStreamableHTTPMCPServer] = Body(...),
    server: SyncServer = Depends(get_letta_server),
    headers: HeaderParams = Depends(get_headers),
):
    """
    Update an existing MCP server configuration
    """
    actor = await server.user_manager.get_actor_or_default_async(actor_id=headers.actor_id)

    if tool_settings.mcp_read_from_config:
        raise HTTPException(status_code=501, detail="Update not implemented for config file mode, config files to be deprecated.")
    else:
        updated_server = await server.mcp_manager.update_mcp_server_by_name(
            mcp_server_name=mcp_server_name, mcp_server_update=request, actor=actor
        )
        return await updated_server.to_config_async()


@router.delete(
    "/mcp/servers/{mcp_server_name}",
    response_model=List[Union[StdioServerConfig, SSEServerConfig, StreamableHTTPServerConfig]],
    operation_id="delete_mcp_server",
)
async def delete_mcp_server_from_config(
    mcp_server_name: str,
    server: SyncServer = Depends(get_letta_server),
    headers: HeaderParams = Depends(get_headers),
):
    """
    Delete a MCP server configuration
    """
    if tool_settings.mcp_read_from_config:
        # write to config file
        return await server.delete_mcp_server_from_config(server_name=mcp_server_name)
    else:
        # log to DB
        actor = await server.user_manager.get_actor_or_default_async(actor_id=headers.actor_id)
        mcp_server_id = await server.mcp_manager.get_mcp_server_id_by_name(mcp_server_name, actor)
        await server.mcp_manager.delete_mcp_server_by_id(mcp_server_id, actor=actor)

        # TODO: don't do this in the future (just return MCPServer)
        all_servers = await server.mcp_manager.list_mcp_servers(actor=actor)
        result = []
        for mcp_server in all_servers:
            result.append(await mcp_server.to_config_async())
        return result


@deprecated("Deprecated in favor of /mcp/servers/connect which handles OAuth flow via SSE stream")
@router.post("/mcp/servers/test", operation_id="test_mcp_server")
async def test_mcp_server(
    request: Union[StdioServerConfig, SSEServerConfig, StreamableHTTPServerConfig] = Body(...),
    server: SyncServer = Depends(get_letta_server),
    headers: HeaderParams = Depends(get_headers),
):
    """
    Test connection to an MCP server without adding it.
    Returns the list of available tools if successful.
    """
    client = None
    try:
        actor = await server.user_manager.get_actor_or_default_async(actor_id=headers.actor_id)
        request.resolve_environment_variables()
        client = await server.mcp_manager.get_mcp_client(request, actor)

        await client.connect_to_server()
        tools = await client.list_tools()

        return {"status": "success", "tools": tools}
    except ConnectionError as e:
        raise LettaMCPConnectionError(str(e), server_name=request.server_name)
    except MCPTimeoutError as e:
        raise LettaMCPTimeoutError(f"MCP server connection timed out: {str(e)}", server_name=request.server_name)
    finally:
        if client:
            try:
                await client.cleanup()
            except Exception as cleanup_error:
                logger.warning(f"Error during MCP client cleanup: {cleanup_error}")


@router.post(
    "/mcp/servers/connect",
    response_model=None,
    responses={
        200: {
            "description": "Successful response",
            "content": {
                "text/event-stream": {"description": "Server-Sent Events stream"},
            },
        }
    },
    operation_id="connect_mcp_server",
)
async def connect_mcp_server(
    request: Union[StdioServerConfig, SSEServerConfig, StreamableHTTPServerConfig] = Body(...),
    server: SyncServer = Depends(get_letta_server),
    headers: HeaderParams = Depends(get_headers),
    http_request: Request = None,
) -> StreamingResponse:
    """
    Connect to an MCP server with support for OAuth via SSE.
    Returns a stream of events handling authorization state and exchange if OAuth is required.
    """

    async def oauth_stream_generator(
        request: Union[StdioServerConfig, SSEServerConfig, StreamableHTTPServerConfig],
        http_request: Request,
    ) -> AsyncGenerator[str, None]:
        client = None

        oauth_flow_attempted = False
        try:
            # Acknolwedge connection attempt
            yield oauth_stream_event(OauthStreamEvent.CONNECTION_ATTEMPT, server_name=request.server_name)

            actor = await server.user_manager.get_actor_or_default_async(actor_id=headers.actor_id)
            # Create MCP client with respective transport type
            try:
                request.resolve_environment_variables()
                client = await server.mcp_manager.get_mcp_client(request, actor)
            except ValueError as e:
                yield oauth_stream_event(OauthStreamEvent.ERROR, message=str(e))
                return

            # Try normal connection first for flows that don't require OAuth
            try:
                await client.connect_to_server()
                tools = await client.list_tools(serialize=True)
                yield oauth_stream_event(OauthStreamEvent.SUCCESS, tools=tools)
                return
            except ConnectionError as e:
                # Only trigger OAuth flow on explicit unauthorized failures
                unauthorized = False
                if isinstance(e.__cause__, HTTPStatusError):
                    unauthorized = e.__cause__.response.status_code == 401
                elif "401" in str(e) or "Unauthorized" in str(e):
                    unauthorized = True

                if not unauthorized:
                    yield oauth_stream_event(OauthStreamEvent.ERROR, message=f"Connection failed: {str(e)}")
                    return

                if isinstance(client, AsyncStdioMCPClient):
                    logger.warning("OAuth not supported for stdio")
                    yield oauth_stream_event(OauthStreamEvent.ERROR, message="OAuth not supported for stdio")
                    return
                # Continue to OAuth flow
                logger.info(f"Attempting OAuth flow for {request}...")
            except Exception as e:
                yield oauth_stream_event(OauthStreamEvent.ERROR, message=f"Connection failed: {str(e)}")
                return
            finally:
                if client:
                    try:
                        await client.cleanup()
                    # This is a workaround to catch the expected 401 Unauthorized from the official MCP SDK, see their streamable_http.py
                    # For SSE transport types, we catch the ConnectionError above, but Streamable HTTP doesn't bubble up the exception
                    except* HTTPStatusError:
                        oauth_flow_attempted = True
                        async for event in server.mcp_manager.handle_oauth_flow(request=request, actor=actor, http_request=http_request):
                            yield event

            # Failsafe to make sure we don't try to handle OAuth flow twice
            if not oauth_flow_attempted:
                async for event in server.mcp_manager.handle_oauth_flow(request=request, actor=actor, http_request=http_request):
                    yield event
            return
        except Exception as e:
            detailed_error = drill_down_exception(e)
            logger.error(f"Error in OAuth stream:\n{detailed_error}")
            yield oauth_stream_event(OauthStreamEvent.ERROR, message=f"Internal error: {detailed_error}")
        # TODO: investigate cancelled by cancel scope errors here during oauth exchange flow
        except asyncio.CancelledError as e:
            logger.error(f"CancelledError: {e!r}")
            tb = "".join(traceback.format_stack())
            logger.error(f"Stack trace at cancellation:\n{tb}")
        finally:
            if client:
                try:
                    await client.cleanup()
                except Exception as cleanup_error:
                    logger.warning(f"Error during temp MCP client cleanup: {cleanup_error}")

    return StreamingResponseWithStatusCode(oauth_stream_generator(request, http_request), media_type="text/event-stream")


class CodeInput(BaseModel):
    code: str = Field(..., description="Source code to parse for JSON schema")
    source_type: Optional[str] = Field("python", description="The source type of the code (python or typescript)")


@router.post("/generate-schema", response_model=Dict[str, Any], operation_id="generate_json_schema")
async def generate_json_schema(
    request: CodeInput = Body(...),
    server: SyncServer = Depends(get_letta_server),
    headers: HeaderParams = Depends(get_headers),
):
    """
    Generate a JSON schema from the given source code defining a function or class.
    Supports both Python and TypeScript source code.
    """
    if request.source_type == "typescript":
        from letta.functions.typescript_parser import derive_typescript_json_schema

        schema = derive_typescript_json_schema(source_code=request.code)
    else:
        # Default to Python for backwards compatibility
        schema = derive_openai_json_schema(source_code=request.code)
    return schema


# TODO: @jnjpng move this and other models above to appropriate file for schemas
class ToolExecuteRequest(BaseModel):
    args: Dict[str, Any] = Field(default_factory=dict, description="Arguments to pass to the tool")


@router.post("/mcp/servers/{mcp_server_name}/tools/{tool_name}/execute", operation_id="execute_mcp_tool")
async def execute_mcp_tool(
    mcp_server_name: str,
    tool_name: str,
    request: ToolExecuteRequest = Body(...),
    server: SyncServer = Depends(get_letta_server),
    headers: HeaderParams = Depends(get_headers),
):
    """
    Execute a specific MCP tool from a configured server.
    Returns the tool execution result.
    """
    client = None
    try:
        actor = await server.user_manager.get_actor_or_default_async(actor_id=headers.actor_id)

        # Get the MCP server by name
        mcp_server = await server.mcp_manager.get_mcp_server(mcp_server_name, actor)
        if not mcp_server:
            from letta.orm.errors import NoResultFound

            raise NoResultFound(f"MCP server '{mcp_server_name}' not found")

        # Create client and connect
        server_config = await mcp_server.to_config_async()
        server_config.resolve_environment_variables()
        client = await server.mcp_manager.get_mcp_client(server_config, actor)
        await client.connect_to_server()

        # Execute the tool
        result, success = await client.execute_tool(tool_name, request.args)

        return {
            "result": result,
            "success": success,
        }
    finally:
        if client:
            try:
                await client.cleanup()
            except Exception as cleanup_error:
                logger.warning(f"Error during MCP client cleanup: {cleanup_error}")


# Static OAuth callback endpoint - session is identified via state parameter
@router.get("/mcp/oauth/callback", operation_id="mcp_oauth_callback")
async def mcp_oauth_callback(
    code: Optional[str] = Query(None, description="OAuth authorization code"),
    state: Optional[str] = Query(None, description="OAuth state parameter"),
    error: Optional[str] = Query(None, description="OAuth error"),
    error_description: Optional[str] = Query(None, description="OAuth error description"),
    server: SyncServer = Depends(get_letta_server),
):
    """
    Handle OAuth callback for MCP server authentication.
    Session is identified via the state parameter instead of URL path.
    """
    try:
        if not state:
            return {"status": "error", "message": "Missing state parameter"}

        # Look up OAuth session by state parameter
        oauth_session = await server.mcp_server_manager.get_oauth_session_by_state(state)
        if not oauth_session:
            return {"status": "error", "message": "Invalid or expired state parameter"}

        if error:
            error_msg = f"OAuth error: {error}"
            if error_description:
                error_msg += f" - {error_description}"
            # Note: Using MCPOAuthSession directly because this callback is unauthenticated
            # (called by OAuth provider) and the manager's update_oauth_session requires an actor
            await MCPOAuthSession(oauth_session.id).update_session_status(OAuthSessionStatus.ERROR)
            return {"status": "error", "message": error_msg}

        if not code:
            await MCPOAuthSession(oauth_session.id).update_session_status(OAuthSessionStatus.ERROR)
            return {"status": "error", "message": "Missing authorization code"}

        # Store authorization code (using MCPOAuthSession since callback is unauthenticated)
        session_handler = MCPOAuthSession(oauth_session.id)
        success = await session_handler.store_authorization_code(code, state)
        if not success:
            await session_handler.update_session_status(OAuthSessionStatus.ERROR)
            return {"status": "error", "message": "Failed to store authorization code"}

        return {"status": "success", "message": "Authorization successful", "server_url": success.server_url}

    except Exception as e:
        logger.error(f"OAuth callback error: {e}")
        return {"status": "error", "message": f"OAuth callback failed: {str(e)}"}


class GenerateToolInput(BaseModel):
    tool_name: str = Field(..., description="Name of the tool to generate code for")
    prompt: str = Field(..., description="User prompt to generate code")
    handle: Optional[str] = Field(None, description="Handle of the tool to generate code for")
    starter_code: Optional[str] = Field(None, description="Python source code to parse for JSON schema")
    validation_errors: List[str] = Field(..., description="List of validation errors")


class GenerateToolOutput(BaseModel):
    tool: Tool = Field(..., description="Generated tool")
    sample_args: Dict[str, Any] = Field(..., description="Sample arguments for the tool")
    response: str = Field(..., description="Response from the assistant")


@router.post("/generate-tool", response_model=GenerateToolOutput, operation_id="generate_tool")
async def generate_tool_from_prompt(
    request: GenerateToolInput = Body(...),
    server: SyncServer = Depends(get_letta_server),
    headers: HeaderParams = Depends(get_headers),
):
    """
    Generate a tool from the given user prompt.
    """
    actor = await server.user_manager.get_actor_or_default_async(actor_id=headers.actor_id)
    llm_config = await server.get_llm_config_from_handle_async(actor=actor, handle=request.handle or DEFAULT_GENERATE_TOOL_MODEL_HANDLE)
    formatted_prompt = (
        f"Generate a python function named {request.tool_name} using the instructions below "
        + (f"based on this starter code: \n\n```\n{request.starter_code}\n```\n\n" if request.starter_code else "\n")
        + (f"Note the following validation errors: \n{' '.join(request.validation_errors)}\n\n" if request.validation_errors else "\n")
        + f"Instructions: {request.prompt}"
    )
    llm_client = LLMClient.create(
        provider_type=llm_config.model_endpoint_type,
        actor=actor,
    )
    assert llm_client is not None

    assistant_message_ack = "Understood, I will respond with generated python source code and sample arguments that can be used to test the functionality once I receive the user prompt. I'm ready."

    input_messages = [
        Message(role=MessageRole.system, content=[TextContent(text=get_system_text("memgpt_generate_tool"))]),
        Message(role=MessageRole.assistant, content=[TextContent(text=assistant_message_ack)]),
        Message(role=MessageRole.user, content=[TextContent(text=formatted_prompt)]),
    ]

    tool = {
        "name": "generate_tool",
        "description": "This method generates the raw source code for a custom tool that can be attached to and agent for llm invocation.",
        "parameters": {
            "type": "object",
            "properties": {
                "raw_source_code": {"type": "string", "description": "The raw python source code of the custom tool."},
                "sample_args_json": {
                    "type": "string",
                    "description": "The JSON dict that contains sample args for a test run of the python function. Key is the name of the function parameter and value is an example argument that is passed in.",
                },
                "pip_requirements_json": {
                    "type": "string",
                    "description": "Optional JSON dict that contains pip packages to be installed if needed by the source code. Key is the name of the pip package and value is the version number.",
                },
            },
            "required": ["raw_source_code", "sample_args_json", "pip_requirements_json"],
        },
    }
    request_data = llm_client.build_request_data(
        AgentType.letta_v1_agent,
        input_messages,
        llm_config,
        tools=[tool],
    )
    from letta.services.telemetry_manager import TelemetryManager

    llm_client.set_telemetry_context(
        telemetry_manager=TelemetryManager(),
        call_type="tool_generation",
    )
    response_data = await llm_client.request_async_with_telemetry(request_data, llm_config)
    response = await llm_client.convert_response_to_chat_completion(response_data, input_messages, llm_config)

    # Validate that we got a tool call response
    if not response.choices or not response.choices[0].message.tool_calls:
        error_msg = (
            response.choices[0].message.content if response.choices and response.choices[0].message.content else "No response from LLM"
        )
        raise LLMError(f"Failed to generate tool '{request.tool_name}': LLM did not return a tool call. Response: {error_msg}")

    output = json.loads(response.choices[0].message.tool_calls[0].function.arguments)
    pip_requirements = [PipRequirement(name=k, version=v or None) for k, v in json.loads(output["pip_requirements_json"]).items()]

    # Derive JSON schema from the generated source code
    try:
        json_schema = derive_openai_json_schema(source_code=output["raw_source_code"])
    except Exception as e:
        raise LettaInvalidArgumentError(
            message=f"Failed to generate JSON schema for tool '{request.tool_name}': {e}", argument_name="tool_name"
        )

    return GenerateToolOutput(
        tool=Tool(
            name=request.tool_name,
            source_type="python",
            source_code=output["raw_source_code"],
            pip_requirements=pip_requirements,
            json_schema=json_schema,
        ),
        sample_args=json.loads(output["sample_args_json"]),
        response=response.choices[0].message.content,
    )
