use lambda_apigateway_response::{
    http::StatusCode,
    types::{
        Headers,
        MultiValueHeaders,
    },
    Response,
};
use lambda_runtime::{
    Error as LambdaError,
    LambdaEvent,
};
use serde_json::json;

type LambdaResult<T> = Result<T, LambdaError>;

async fn handler(
    _event: LambdaEvent<serde_json::Value>,
) -> LambdaResult<Response<serde_json::Value>> {
    let res = Response {
        status_code: StatusCode::OK,
        body: json!({
            "message": "Hello world!",
        }),
        headers: Headers::new(),
        multi_value_headers: MultiValueHeaders::new(),
        is_base64_encoded: true,
    };

    Ok(res)
}

#[tokio::main]
async fn main() -> LambdaResult<()> {
    let handler_fn = lambda_runtime::service_fn(handler);
    lambda_runtime::run(handler_fn).await?;

    Ok(())
}