app.py

from fastapi import FastAPI, Request
from fastapi.responses import JSONResponse
from pydantic import BaseModel
from typing import Dict

app = FastAPI()


class MCPMessage(BaseModel):
    session: str
    id: str
    command: str
    args: Dict[str, str]


@app.post("/mcp")
async def mcp_endpoint(message: MCPMessage, request: Request):
    print(f"[MCP Server] Received: {message.command} | Args: {message.args}")

    if message.command == "mcp-negotiate":
        return {
            "id": message.id,
            "status": "ok",
            "message": "Negotiation successful",
            "session": message.session,
            "version": message.args.get("version", "1.0"),
        }

    elif message.command == "mcp-message":
        return {
            "id": message.id,
            "status": "ok",
            "message": f"Delivered to {message.args.get('to')}",
            "echo": message.args.get("body", ""),
        }

    elif message.command == "mcp-echo-upper":
        original = message.args.get("body", "")
        return {
            "id": message.id,
            "status": "ok",
            "message": "Uppercase echo",
            "original": original,
            "upper": original.upper()
        }

    return JSONResponse(status_code=400, content={
        "id": message.id,
        "status": "error",
        "message": f"Unknown command: {message.command}"
    })


@app.get("/")
def root():
    return {"message": "MCP Test Server is running"}