"""Minimal scripted MCP client for the Arcade eval.

Headless auth (confirmed from Arcade docs, see ../LIVE-POC.md):
  Authorization: Bearer <ARCADE_API_KEY>
  Arcade-User-ID: <user_id>      (any stable string; an email works)

`auth_headers` is pure (no deps) so it unit-tests offline. The `mcp` SDK is imported
lazily inside the async helpers so this module loads even before deps are installed.
"""
from __future__ import annotations


def auth_headers(api_key: str, user_id: str) -> dict[str, str]:
    """Build the headless MCP auth headers for a given Arcade user_id."""
    return {"Authorization": f"Bearer {api_key}", "Arcade-User-ID": user_id}


async def connect_and_list(mcp_url: str, headers: dict[str, str]) -> list[dict]:
    """Connect to an MCP gateway over streamable HTTP and return the tool list."""
    from mcp import ClientSession
    from mcp.client.streamable_http import streamablehttp_client

    async with streamablehttp_client(mcp_url, headers=headers) as (read, write, _):
        async with ClientSession(read, write) as session:
            await session.initialize()
            result = await session.list_tools()
            return [t.model_dump() for t in result.tools]


async def call_tool(mcp_url: str, headers: dict[str, str], name: str, args: dict) -> dict:
    """Invoke a single tool through an MCP gateway and return the result payload."""
    from mcp import ClientSession
    from mcp.client.streamable_http import streamablehttp_client

    async with streamablehttp_client(mcp_url, headers=headers) as (read, write, _):
        async with ClientSession(read, write) as session:
            await session.initialize()
            result = await session.call_tool(name, args)
            return result.model_dump()