use actix_web::{
    get, http::header::ContentType, middleware::Logger, post, web, App, HttpResponse, HttpServer,
    Responder,
};
use clap::Parser;
use futures::try_join;
use futures::{future::join_all, lock::Mutex};
use log::info;
use serde::{Deserialize, Serialize};
use std::{
    collections::HashMap,
    env::args,
    io::{stdin, stdout, IsTerminal},
    sync::Arc,
};
use tokio;
use tokio::task;
use uuid::Uuid;

use lambda::lambda::{eval_whnf, generate_expr, Environment};
use lambda::parser::parse;

#[derive(Debug, PartialEq, Serialize, Deserialize, Clone)]
struct Registration {
    url: String,
}

trait AppState: Send + Sync {
    fn register(&mut self, registration: &Registration) -> RegistrationResult;
}

#[derive(Debug, PartialEq, Serialize, Deserialize, Clone)]
enum RegistrationResult {
    RegistrationSuccess { id: String, url: String },
    UrlAlreadyRegistered { url: String },
}

#[derive(Debug, PartialEq, Serialize, Deserialize, Clone)]
struct Client {
    id: Uuid,
    url: String,
    grade: u8,
}

#[derive(Debug)]
struct State {
    clients: HashMap<String, Arc<Mutex<Client>>>,
}

impl State {
    fn new() -> Self {
        Self {
            clients: HashMap::new(),
        }
    }
}

impl AppState for State {
    fn register(&mut self, registration: &Registration) -> RegistrationResult {
        if self.clients.contains_key(&registration.url) {
            RegistrationResult::UrlAlreadyRegistered {
                url: registration.url.clone(),
            }
        } else {
            let id = Uuid::new_v4();
            let client = Arc::new(Mutex::new(Client {
                id,
                url: registration.url.clone(),
                grade: 1,
            }));
            let client_s = client.clone();
            self.clients.insert(registration.url.clone(), client);
            // let it run in the background
            // FIXME: should find a way to handle graceful termination
            task::spawn(async move { send_tests(client_s).await });

            RegistrationResult::RegistrationSuccess {
                id: id.to_string(),
                url: registration.url.clone(),
            }
        }
    }
}

#[post("/register")]
async fn register(
    app_state: web::Data<Arc<Mutex<dyn AppState>>>,
    registration: web::Json<Registration>,
) -> impl Responder {
    let result = app_state.lock().await.register(&registration);
    match result {
        RegistrationResult::RegistrationSuccess { .. } => HttpResponse::Ok().json(result),
        RegistrationResult::UrlAlreadyRegistered { .. } => HttpResponse::BadRequest().json(result),
    }
}

#[post("/eval")]
async fn eval(input: String) -> impl Responder {
    let mut env = Environment::new();
    match parse(&input).first() {
        Some(expr) => {
            let output = eval_whnf(expr, &mut env);
            HttpResponse::Ok().body(format!("{}", output))
        }
        None => HttpResponse::BadRequest().finish(),
    }
}

#[derive(Parser, Debug)]
struct Options {
    /// The port to listen on
    /// Defaults to 8080
    #[arg(short, long, default_value_t = 8080)]
    port: u16,
    /// The host to bind the server to
    /// Defaults to 127.0.0.1
    #[arg(long, default_value = "127.0.0.1")]
    host: String,
}

#[tokio::main]
async fn main() -> std::io::Result<()> {
    let options = Options::parse();
    let app_state = Arc::new(Mutex::new(State::new()));
    let http_state: Arc<Mutex<dyn AppState>> = app_state;
    env_logger::init();
    HttpServer::new(move || {
        App::new()
            .wrap(Logger::default())
            .app_data(web::Data::new(http_state.clone()))
            .service(register)
            .service(eval)
    })
    .bind((options.host, options.port))?
    .run()
    .await
}

async fn send_tests(client_m: Arc<Mutex<Client>>) {
    loop {
        tokio::time::sleep(std::time::Duration::from_secs(1)).await;
        let mut client = client_m.lock().await;
        let result = send_test(client.grade, &client.url).await;
        match result {
            Ok(_) => {
                client.grade += 1;
            }
            Err(_) => {
                // FIXME
            }
        }
    }
}

async fn send_test(grade: u8, url: &String) -> Result<(), String> {
    let input = generate_expr(grade.into());
    let mut env = Environment::new();
    let output = eval_whnf(&input, &mut env);
    info!("Sending {} to {}", input, url);
    let response = reqwest::Client::new()
        .post(url)
        .header("content-type", "text/plain")
        .body(format!("{}", input))
        .send()
        .await;
    match response {
        Ok(response) => {
            let body = response.text().await.unwrap();
            let vals = parse(&body);
            // FIXME: should be able to handle multiple values
            let result = eval_whnf(vals.first().unwrap(), &mut env);
            info!("Received {} from {}", body, url);
            if result == output {
                info!("Test passed {}", url);
                Ok(())
            } else {
                info!("Test failed {}", url);
                Err("Test failed".to_string())
            }
        }
        Err(e) => {
            info!("Error sending test: {}", e);
            Err("Error sending test".to_string())
        }
    }
}

#[cfg(test)]
mod app_tests {
    use std::sync::Arc;

    use actix_web::http::header::TryIntoHeaderValue;
    use actix_web::{body, http::header::ContentType, middleware::Logger, test, App};

    use super::*;

    struct DummyAppState {
        id: String,
    }

    impl DummyAppState {
        fn new(id: String) -> Self {
            Self { id }
        }
    }

    impl AppState for DummyAppState {
        fn register(&mut self, registration: &Registration) -> RegistrationResult {
            if self.id.is_empty() {
                RegistrationResult::UrlAlreadyRegistered {
                    url: registration.url.clone(),
                }
            } else {
                RegistrationResult::RegistrationSuccess {
                    id: self.id.clone(),
                    url: registration.url.clone(),
                }
            }
        }
    }

    #[actix_web::test]
    async fn post_registration_returns_success_with_unique_id() {
        let id = "0123456789abcdef0123456789abcdef".to_string();
        let dummy_state: Arc<Mutex<dyn AppState>> =
            Arc::new(Mutex::new(DummyAppState::new(id.clone())));
        // FIXME should only be called once, move to setup
        env_logger::init();

        let app = test::init_service(
            App::new()
                .wrap(Logger::default())
                .app_data(web::Data::new(dummy_state))
                .service(register),
        )
        .await;
        let url = "http://192.168.1.1".to_string();
        let req = test::TestRequest::post()
            .uri("/register")
            .set_json(Registration { url: url.clone() })
            .insert_header(ContentType::json())
            .to_request();

        let resp = test::call_service(&app, req).await;

        assert!(resp.status().is_success());

        let body = resp.into_body();
        let bytes = body::to_bytes(body).await;
        assert_eq!(
            RegistrationResult::RegistrationSuccess { id, url },
            serde_json::from_slice(&bytes.unwrap()).unwrap()
        );
    }

    #[actix_web::test]
    async fn post_registration_returns_400_when_register_fails() {
        let dummy_state: Arc<Mutex<dyn AppState>> =
            Arc::new(Mutex::new(DummyAppState::new("".to_string())));

        let app = test::init_service(
            App::new()
                .wrap(Logger::default())
                .app_data(web::Data::new(dummy_state))
                .service(register),
        )
        .await;
        let url = "http://192.168.1.1".to_string();

        let req = test::TestRequest::post()
            .uri("/register")
            .set_json(Registration { url: url.clone() })
            .insert_header(ContentType::json())
            .to_request();

        let resp = test::call_service(&app, req).await;

        assert!(resp.status().is_client_error());
        assert_eq!(
            ContentType::json().try_into_value().unwrap(),
            resp.headers().get("content-type").unwrap()
        );
    }

    #[actix_web::test]
    async fn post_expression_returns_evaluation() {
        let app = test::init_service(App::new().wrap(Logger::default()).service(eval)).await;

        let req = test::TestRequest::post()
            .uri("/eval")
            .set_payload("((lam (x y) x) 1 2)")
            .insert_header(ContentType::plaintext())
            .to_request();

        let resp = test::call_service(&app, req).await;

        assert!(resp.status().is_success());

        let body = resp.into_body();
        let bytes = body::to_bytes(body).await.unwrap();
        assert_eq!(bytes, "1".to_string().into_bytes());
    }

    #[test]
    async fn app_does_not_register_same_url_twice() {
        let mut app_state = State::new();
        let registration = Registration {
            url: "http://1.2.3.4".to_string(),
        };

        app_state.register(&registration);
        let result = app_state.register(&registration);

        assert_eq!(
            RegistrationResult::UrlAlreadyRegistered {
                url: "http://1.2.3.4".to_string()
            },
            result
        );
    }

    // #[test]
    // async fn tester_repeatedly_callback_registered_client() {
    //     let app_state = Arc::new(Mutex::new(State::new()));
    //     let send_state = app_state.clone();
    //     let client = Client {
    //         id: Uuid::new_v4(),
    //         url: "http://
    // }
}