use super::{api, OIDCError, OIDCErrorType, Request};
use crate::{client::ClientExt, config, schema, server::session::SessionHelper};
use microrm::prelude::*;

fn do_code_authorize<'l, 's>(
    config: &config::Config,
    realm: &microrm::Stored<schema::Realm>,
    client: &microrm::Stored<schema::Client>,
    user: &microrm::Stored<schema::User>,
    scopes: impl Iterator<Item = &'l str>,
    redirect_uri: String,
    state: Option<&'s str>,
) -> Result<tide::Response, OIDCError<'s>> {
    let expiry =
        std::time::SystemTime::now() + std::time::Duration::from_secs(config.auth_code_expiry);

    let rng = ring::rand::SystemRandom::new();
    let raw_auth_code: [u8; 32] = ring::rand::generate(&rng)
        .map_err(|_| {
            OIDCError(
                OIDCErrorType::ServerError,
                "failed to generate auth code".into(),
                state,
            )
        })?
        .expose();
    let encoded_auth_code = base64::encode_config(raw_auth_code, base64::URL_SAFE_NO_PAD);

    realm.auth_codes.insert(schema::AuthCode {
        realm: realm.id(),
        client: client.id(),
        user: user.id(),
        scopes: scopes
            .map(|x| x.to_owned())
            .collect::<Vec<_>>()
            .into_serialized(),
        expiry: expiry.into(),
        redirect_uri: redirect_uri.clone(),
        code: encoded_auth_code.clone(),
    })?;

    let new_params = [
        ("response_type", "code"),
        ("code", encoded_auth_code.as_str()),
    ]
    .into_iter()
    .chain(state.map(|v| ("state", v)));

    Ok(tide::Redirect::temporary(
        tide::http::Url::parse_with_params(redirect_uri.as_str(), new_params).map_err(|e| {
            OIDCError(
                OIDCErrorType::InvalidRequest,
                format!("could not parse redirect_uri as a URL: {e}").into(),
                None,
            )
        })?,
    )
    .into())
}

pub(super) fn do_authorize(
    request: Request,
    state: Option<&str>,
) -> Result<tide::Response, OIDCError> {
    let shelper = SessionHelper::new(&request);
    let realm = shelper.get_realm().map_err(|_| {
        OIDCError(
            OIDCErrorType::InvalidRequest,
            "No such realm!".into(),
            state,
        )
    })?;

    let make_redirect = || {
        let mut login_url = request.url().join("../v1/session/login").unwrap();
        login_url
            .query_pairs_mut()
            .clear()
            .append_pair("redirect", request.url().as_str());
        Ok(tide::Redirect::new(login_url).into())
    };

    let qp: api::AuthorizationRequestQuery = request
        .query()
        .map_err(|x| OIDCError(OIDCErrorType::InvalidRequest, x.to_string().into(), state))?;

    // collect session authentication info

    let potential_sauth = shelper
        .get_session(&request)
        .and_then(|session| shelper.get_auth_for_session(realm.id(), &session));

    let Some(user_id) = potential_sauth.and_then(|v| v.user) else {
        // if we don't have any relevant auth info, redirect to login
        return make_redirect();
    };

    let Ok(Some(user)) = realm.users.with_id(user_id).first().get() else {
        return Err(OIDCError(
            OIDCErrorType::ServerError,
            "Internal state error!".into(),
            state,
        ));
    };

    // verify the client_id refers to an extant client
    let client = realm
        .clients
        .with(schema::Client::Shortname, &qp.client_id)
        .first()
        .get()
        .ok()
        .flatten()
        .ok_or_else(|| {
            OIDCError(
                OIDCErrorType::UnauthorizedClient,
                "client does not exist".into(),
                state,
            )
        })?;

    let scopes = qp.scope.as_deref().unwrap_or("").split_whitespace();

    // check that redirect URI matches
    match client.check_redirect(qp.redirect_uri.as_str()) {
        Ok(true) => (),
        Ok(false) => {
            return Err(OIDCError(
                OIDCErrorType::InvalidRequest,
                "invalid redirect URI".into(),
                state,
            ))
        }
        Err(_) => {
            return Err(OIDCError(
                OIDCErrorType::ServerError,
                "invalid stored redirect uri".into(),
                state,
            ))
        }
    }

    if qp.response_type == "code" {
        do_code_authorize(
            &request.state().core.config,
            &realm,
            &client,
            &user,
            scopes,
            qp.redirect_uri,
            state,
        )
    } else if qp.response_type == "token" {
        let rhelper = request.state().core.realms.get_helper(realm.id()).unwrap();

        let token = rhelper
            .generate_access_token(&client, &user, scopes)
            .map_err(|e| {
                OIDCError(
                    OIDCErrorType::ServerError,
                    format!("could not generate token: {e}").into(),
                    state,
                )
            })?;

        Ok(tide::Response::builder(200)
            .content_type(tide::http::mime::JSON)
            .body(
                serde_json::to_vec(&api::TokenResponse {
                    token_type: "bearer",
                    access_token: token.as_str(),
                    refresh_token: None,
                    scope: None,
                })
                .unwrap(),
            )
            .build())
    } else {
        Err(OIDCError(
            OIDCErrorType::UnsupportedResponseType,
            "only 'code' and 'token' are understood".into(),
            state,
        ))
    }
}