use actix_web::{http::StatusCode, web, App, HttpRequest, HttpResponse, HttpServer, ResponseError};
use http_signature_normalization_actix_extractor::{
    Algorithm, Config, ConfigGenerator, DeprecatedAlgorithm, Signed, VerifyKey,
};
use sha2::Sha256;

#[actix_web::main]
async fn main() -> std::io::Result<()> {
    HttpServer::new(|| App::new().route("/", web::post().to(protected)))
        .bind("127.0.0.1:8010")?
        .run()
        .await
}

async fn protected(signed_request: Signed<String, Cfg, Sha256, Key>) -> &'static str {
    let (value, signature) = signed_request.into_parts();

    println!("{}", value);
    println!("{:#?}", signature);

    "hewwo, mr obama"
}

pub struct Cfg;

#[derive(Debug)]
pub struct Key;

#[derive(Debug, thiserror::Error)]
pub enum VerifyError {
    #[error("Unsupported algorithm")]
    Algorithm,

    #[error("Couldn't decode signature")]
    Decode,

    #[error("Invalid key")]
    Key,
}

impl ConfigGenerator for Cfg {
    fn config() -> Config {
        Config::new().require_header("accept")
    }
}

#[async_trait::async_trait(?Send)]
impl VerifyKey for Key {
    type Error = VerifyError;

    async fn init(
        _: &HttpRequest,
        key_id: &str,
        algorithm: Option<&Algorithm>,
    ) -> Result<Self, Self::Error> {
        match algorithm {
            Some(Algorithm::Hs2019 | Algorithm::Deprecated(DeprecatedAlgorithm::RsaSha256)) => (),
            _ => return Err(VerifyError::Algorithm),
        };

        if key_id != "my-key-id" {
            return Err(VerifyError::Key);
        }

        Ok(Key)
    }

    fn verify(&mut self, signature: &str, signing_string: &str) -> Result<bool, Self::Error> {
        use subtle::ConstantTimeEq;

        let decoded = base64::decode(&signature).map_err(|_| VerifyError::Decode)?;

        Ok(decoded.ct_eq(signing_string.as_bytes()).into())
    }
}

impl ResponseError for VerifyError {
    fn status_code(&self) -> StatusCode {
        StatusCode::BAD_REQUEST
    }

    fn error_response(&self) -> HttpResponse {
        HttpResponse::BadRequest().finish()
    }
}