use anyhow::Result;
use rmcp::{
    ServerHandler, ServiceExt,
    handler::server::{router::tool::ToolRouter, wrapper::Parameters},
    model::{ServerCapabilities, ServerInfo},
    schemars, tool, tool_handler, tool_router,
    transport::stdio,
};
use tracing_subscriber::{self, EnvFilter};

// --- Calculator types ---

#[derive(Debug, serde::Deserialize, schemars::JsonSchema)]
pub struct SumRequest {
    #[schemars(description = "the left hand side number")]
    pub a: i32,
    pub b: i32,
}

#[derive(Debug, serde::Deserialize, schemars::JsonSchema)]
pub struct SubRequest {
    #[schemars(description = "the left hand side number")]
    pub a: i32,
    #[schemars(description = "the right hand side number")]
    pub b: i32,
}

// --- Calculator server ---

#[derive(Debug, Clone)]
pub struct Calculator {
    tool_router: ToolRouter<Self>,
}

#[tool_router]
impl Calculator {
    pub fn new() -> Self {
        Self {
            tool_router: Self::tool_router(),
        }
    }

    #[tool(description = "Calculate the sum of two numbers")]
    fn sum(&self, Parameters(SumRequest { a, b }): Parameters<SumRequest>) -> String {
        (a + b).to_string()
    }

    #[tool(description = "Calculate the difference of two numbers")]
    fn sub(&self, Parameters(SubRequest { a, b }): Parameters<SubRequest>) -> String {
        (a - b).to_string()
    }
}

#[tool_handler]
impl ServerHandler for Calculator {
    fn get_info(&self) -> ServerInfo {
        ServerInfo::new(ServerCapabilities::builder().enable_tools().build())
            .with_instructions("A simple calculator".to_string())
    }
}

// --- Main ---

#[tokio::main]
async fn main() -> Result<()> {
    tracing_subscriber::fmt()
        .with_env_filter(EnvFilter::from_default_env().add_directive(tracing::Level::DEBUG.into()))
        .with_writer(std::io::stderr)
        .with_ansi(false)
        .init();

    tracing::info!("Starting Calculator MCP server");

    let service = Calculator::new().serve(stdio()).await.inspect_err(|e| {
        tracing::error!("serving error: {:?}", e);
    })?;

    service.waiting().await?;
    Ok(())
}