//! # Authentication middleware

use std::future::{ready, Future, Ready};
use std::pin::Pin;
use std::rc::Rc;

use actix_identity::RequestIdentity;
use actix_web::body::EitherBody;
use actix_web::http::{header, Method};
use actix_web::{
    dev::{forward_ready, Service, ServiceRequest, ServiceResponse, Transform},
    web, Error, HttpResponse,
};
use askama::Template;

use crate::constants::{ADMIN_ROUTES, AUTHENTICATED_ROUTES};
use crate::controllers::base_controller::redirect_user_for_login;
use crate::data::app_config::AppConfig;
use crate::data::session_identity::{SessionIdentity, SessionIdentityData, SessionStatus};

// There are two steps in middleware processing.
// 1. Middleware initialization, middleware factory gets called with
//    next service in chain as parameter.
// 2. Middleware's call method gets called with normal request.
pub struct AuthMiddleware;

// Middleware factory is `Transform` trait
// `S` - type of the next service
// `B` - type of response's body
impl<S, B> Transform<S, ServiceRequest> for AuthMiddleware
where
    S: Service<ServiceRequest, Response = ServiceResponse<B>, Error = Error> + 'static,
    S::Future: 'static,
    B: 'static,
{
    type Response = ServiceResponse<EitherBody<B>>;
    type Error = Error;
    type Transform = AuthInnerMiddleware<S>;
    type InitError = ();
    type Future = Ready<Result<Self::Transform, Self::InitError>>;

    fn new_transform(&self, service: S) -> Self::Future {
        ready(Ok(AuthInnerMiddleware {
            service: Rc::new(service),
        }))
    }
}

#[derive(Debug)]
enum ConnStatus {
    SignedOut,
    RegularUser,
    Admin,
}

impl ConnStatus {
    pub fn is_auth(&self) -> bool {
        !matches!(self, ConnStatus::SignedOut)
    }

    pub fn is_admin(&self) -> bool {
        matches!(self, ConnStatus::Admin)
    }
}

#[derive(Template)]
#[template(path = "access_denied.html")]
struct AccessDeniedTemplate {}

pub struct AuthInnerMiddleware<S> {
    service: Rc<S>,
}

impl<S, B> Service<ServiceRequest> for AuthInnerMiddleware<S>
where
    S: Service<ServiceRequest, Response = ServiceResponse<B>, Error = Error> + 'static,
    S::Future: 'static,
    B: 'static,
{
    type Response = ServiceResponse<EitherBody<B>>;
    type Error = Error;

    #[allow(clippy::type_complexity)]
    type Future = Pin<Box<dyn Future<Output = Result<Self::Response, Self::Error>>>>;

    forward_ready!(service);

    fn call(&self, req: ServiceRequest) -> Self::Future {
        let service = Rc::clone(&self.service);

        // Forward request
        Box::pin(async move {
            let config: &web::Data<AppConfig> = req.app_data().expect("AppData undefined!");

            // Check if POST request comes from another website (block invalid origins)
            let origin = req.headers().get(header::ORIGIN);
            if req.method() == Method::POST {
                if let Some(o) = origin {
                    if !o.to_str().unwrap_or("bad").eq(&config.website_origin) {
                        log::warn!(
                            "Blocked POST request from invalid origin! Origin given {:?}",
                            o
                        );
                        return Ok(req.into_response(
                            HttpResponse::Unauthorized()
                                .body("POST request from invalid origin!")
                                .map_into_right_body(),
                        ));
                    }
                }
            }

            if req.path().starts_with("/.git") {
                return Ok(req.into_response(
                    HttpResponse::Unauthorized()
                        .body("Hey don't touch this!")
                        .map_into_right_body(),
                ));
            }

            let session = match SessionIdentity::deserialize_session_data(req.get_identity()) {
                Some(SessionIdentityData {
                    status: SessionStatus::SignedIn,
                    is_admin: true,
                    ..
                }) => ConnStatus::Admin,
                Some(SessionIdentityData {
                    status: SessionStatus::SignedIn,
                    ..
                }) => ConnStatus::RegularUser,
                _ => ConnStatus::SignedOut,
            };

            // Redirect user to login page
            if !session.is_auth()
                && (req.path().starts_with(ADMIN_ROUTES)
                    || req.path().starts_with(AUTHENTICATED_ROUTES))
            {
                let path = req.path().to_string();
                return Ok(req
                    .into_response(redirect_user_for_login(path))
                    .map_into_right_body());
            }

            // Restrict access to admin pages
            if !session.is_admin() && req.path().starts_with(ADMIN_ROUTES) {
                return Ok(req
                    .into_response(
                        HttpResponse::Unauthorized()
                            .body(AccessDeniedTemplate {}.render().unwrap()),
                    )
                    .map_into_right_body());
            }

            service
                .call(req)
                .await
                .map(ServiceResponse::map_into_left_body)
        })
    }
}