"""只用 sys + json，从零实现一个 MCP Server
提供 calculate_bmi(height, weight) 工具。
"""

import sys
import json

def process(request):
    if request.get("method") == "ping":
        result = {
            "jsonrpc": "2.0",
            "id": request.get("id"),
            "result": "pong"
        }
        return result
    if request.get("method") == "tools/list":
        result = {
            "jsonrpc": "2.0",
            "id": 1,
            "result": {
                "tools": [
                {
                    "name": "calculate_bmi",
                    "description": "Calculate BMI from height and weight",
                    "inputSchema": {
                    "type": "object",
                    "properties": {
                        "height": {
                        "type": "number"
                        },
                        "weight": {
                        "type": "number"
                        }
                    },
                    "required": [
                        "height",
                        "weight"
                    ]
                    }
                }
                ]
            }
        }
        return result
    if request.get("method") == "tools/call":
        name = request.get("params", {}).get("name")
        arguments = request.get("params", {}).get("arguments", {})
        if name == "calculate_bmi":
            height = arguments.get("height")
            weight = arguments.get("weight")
            if height is not None and weight is not None:
                bmi = weight / (height ** 2)
                result = {
                    "jsonrpc": "2.0",
                    "id": request.get("id"),
                    "result": {
                        "resultType": "complete",
                        "content": [
                            {
                                "type": "text",
                                "text": str(bmi)
                            }
                        ],
                        "isError": False
                    }
                }
                return result
        
    return None

for line in sys.stdin:
    request = json.loads(line)

    output = process(request)
    if output is not None:
        print(json.dumps(output, ensure_ascii=False), flush=True)