use anyhow::{anyhow, Result};
use base64::Engine;
use hyper::{Request, Response};
use hyper::body::Incoming;

use aero_user::login::ArcLoginProvider;
use aero_collections::user::User;

use super::codec::text_body;
use super::controller::HttpResponse;

type ArcUser = std::sync::Arc<User>;

pub(super) async fn auth<'a>(
    login: ArcLoginProvider,
    req: Request<Incoming>, 
    next: impl Fn(ArcUser, Request<Incoming>) -> futures::future::BoxFuture<'a, Result<HttpResponse>>,
) -> Result<HttpResponse> {
    let auth_val = match req.headers().get(hyper::header::AUTHORIZATION) {
        Some(hv) => hv.to_str()?,
        None => {
            tracing::info!("Missing authorization field");
            return Ok(Response::builder()
                .status(401)
                .header("WWW-Authenticate", "Basic realm=\"Aerogramme\"")
                .body(text_body("Missing Authorization field"))?)
        },
    };

    let b64_creds_maybe_padded = match auth_val.split_once(" ") {
        Some(("Basic", b64)) => b64,
        _ => {
            tracing::info!("Unsupported authorization field");
            return Ok(Response::builder()
                .status(400)
                .body(text_body("Unsupported Authorization field"))?)
        },
    };

    // base64urlencoded may have trailing equals, base64urlsafe has not
    // theoretically authorization is padded but "be liberal in what you accept"
    let b64_creds_clean = b64_creds_maybe_padded.trim_end_matches('=');

    // Decode base64
    let creds = base64::engine::general_purpose::STANDARD_NO_PAD.decode(b64_creds_clean)?;
    let str_creds = std::str::from_utf8(&creds)?;
    
    // Split username and password
    let (username, password) = str_creds
        .split_once(':')
        .ok_or(anyhow!("Missing colon in Authorization, can't split decoded value into a username/password pair"))?;

    // Call login provider
    let creds = match login.login(username, password).await {
        Ok(c) => c,
        Err(_) => {
            tracing::info!(user=username, "Wrong credentials");
            return Ok(Response::builder()
                .status(401)
                .header("WWW-Authenticate", "Basic realm=\"Aerogramme\"")
                .body(text_body("Wrong credentials"))?)
        },
    };

    // Build a user
    let user = User::new(username.into(), creds).await?;

    // Call router with user
    next(user, req).await
}