//! Sign in, sign out and registration (hub spec §5.1).

use super::{Error, Page, Shell};

use crate::auth::{self, totp, Viewer};

use crate::db::{self, accounts};

use crate::Shared;

use askama::Template;

use axum::extract::{Form, Query, State};

use axum::http::header;

use axum::response::{IntoResponse, Redirect, Response};

use serde::Deserialize;

#[derive(Template)]

#[template(path = "login.html")]

pub struct LoginPage {

    shell: Shell,

    error: Option<String>,

    next: String,

    /// Second step: the password was right, a one-time code is needed.

    totp_for: Option<String>,

}

#[derive(Deserialize)]

pub struct NextQuery {

    next: Option<String>,

}

fn safe_next(next: Option<String>) -> String {

    match next {

        Some(n) if n.starts_with('/') && !n.starts_with("//") => n,

        _ => "/".into(),

    }

}

pub async fn login_form(State(app): State<Shared>, viewer: Viewer, Query(q): Query<NextQuery>) -> Response {

    if viewer.signed_in() {

        return Redirect::to(&safe_next(q.next)).into_response();

    }

    Page(LoginPage { shell: Shell::new(&app, "/login", &viewer), error: None, next: safe_next(q.next), totp_for: None }).into_response()

}

#[derive(Deserialize)]

pub struct LoginForm {

    username: String,

    password: String,

    #[serde(default)]

    code: String,

    #[serde(default)]

    next: String,

}

pub async fn login(State(app): State<Shared>, viewer: Viewer, Form(f): Form<LoginForm>) -> Result<Response, Error> {

    let shell = Shell::new(&app, "/login", &viewer);

    let next = safe_next(Some(f.next.clone()));

    let fail = |msg: &str, totp_for: Option<String>| {

        Page(LoginPage { shell: shell.clone(), error: Some(msg.into()), next: next.clone(), totp_for }).into_response()

    };

    let username = f.username.trim().to_string();

    let account = accounts::account_by_name(&app.db, &username).await.map_err(|e| Error::from_db(shell.clone(), e))?;

    let Some(account) = account.filter(|a| auth::verify_password(&a.password_hash, &f.password)) else {

        accounts::audit(&app.db, None, "login.failed", &username, "").await.ok();

        return Ok(fail("Wrong username or password.", None));

    };

    if account.banned {

        return Ok(fail("This account is banned.", None));

    }

    if let Some(secret) = &account.totp_secret {

        if f.code.trim().is_empty() {

            return Ok(fail("Enter the code from your authenticator app.", Some(username)));

        }

        let now = (db::now_ms() / 1000) as u64;

        if !totp::verify(secret, &f.code, now) {

            match totp::use_recovery_code(&account.recovery_codes, &f.code) {

                Some(rest) => {

                    accounts::set_totp(&app.db, account.id, Some(secret), &rest).await.map_err(|e| Error::from_db(shell.clone(), e))?

                }

                None => {

                    accounts::audit(&app.db, Some(&account), "login.totp_failed", &username, "").await.ok();

                    return Ok(fail("That code is not right.", Some(username)));

                }

            }

        }

    }

    accounts::audit(&app.db, Some(&account), "login", &username, "").await.ok();

    Ok(signed_in(&app, &account, &next))

}

/// A redirect that sets the session cookie.

pub fn signed_in(app: &Shared, account: &accounts::Account, to: &str) -> Response {

    let value = auth::session_value(&app.cookie_key, &account.username, &account.session_salt);

    let secure = if app.config.base_url().starts_with("https://") { "; Secure" } else { "" };

    let cookie = format!("{}={value}; Path=/; HttpOnly; SameSite=Lax; Max-Age=2592000{secure}", auth::SESSION_COOKIE);

    ([(header::SET_COOKIE, cookie)], Redirect::to(to)).into_response()

}

#[derive(Deserialize)]

pub struct CsrfForm {

    #[serde(rename = "_csrf")]

    pub csrf: String,

}

pub async fn logout(State(app): State<Shared>, viewer: Viewer, Form(f): Form<CsrfForm>) -> Response {

    if !viewer.csrf_ok(&f.csrf) {

        return Redirect::to("/").into_response();

    }

    if let Some(a) = viewer.account() {

        accounts::audit(&app.db, Some(a), "logout", &a.username, "").await.ok();

    }

    let cookie = format!("{}=; Path=/; HttpOnly; SameSite=Lax; Max-Age=0", auth::SESSION_COOKIE);

    ([(header::SET_COOKIE, cookie)], Redirect::to("/")).into_response()

}

#[derive(Template)]

#[template(path = "register.html")]

pub struct RegisterPage {

    shell: Shell,

    error: Option<String>,

    mode: String,

    first: bool,

    invite: String,

}

/// The registration mode: the settings table overrides `hub.toml`.

pub async fn registration_mode(app: &Shared) -> String {

    accounts::setting(&app.db, "registration_mode").await.ok().flatten().unwrap_or_else(|| app.config.registration.mode.clone())

}

#[derive(Deserialize)]

pub struct InviteQuery {

    invite: Option<String>,

}

pub async fn register_form(State(app): State<Shared>, viewer: Viewer, Query(q): Query<InviteQuery>) -> Result<Response, Error> {

    if viewer.signed_in() {

        return Ok(Redirect::to("/").into_response());

    }

    let shell = Shell::new(&app, "/register", &viewer);

    let first = accounts::account_count(&app.db).await.map_err(|e| Error::from_db(shell.clone(), e))? == 0;

    Ok(Page(RegisterPage { shell, error: None, mode: registration_mode(&app).await, first, invite: q.invite.unwrap_or_default() })

        .into_response())

}

#[derive(Deserialize)]

pub struct RegisterForm {

    username: String,

    email: String,

    password: String,

    #[serde(default)]

    invite: String,

}

pub async fn register(State(app): State<Shared>, viewer: Viewer, Form(f): Form<RegisterForm>) -> Result<Response, Error> {

    let shell = Shell::new(&app, "/register", &viewer);

    let first = accounts::account_count(&app.db).await.map_err(|e| Error::from_db(shell.clone(), e))? == 0;

    let mode = registration_mode(&app).await;

    let fail = |msg: &str| {

        Page(RegisterPage { shell: shell.clone(), error: Some(msg.into()), mode: mode.clone(), first, invite: f.invite.clone() })

            .into_response()

    };

    let username = f.username.trim().to_string();

    if !crate::repos::names::valid_owner(&username) {

        return Ok(fail("A username is letters, digits, dots, dashes and underscores, and is not a reserved word."));

    }

    if let Err(e) = auth::password_ok(&f.password) {

        return Ok(fail(e));

    }

    if !first {

        match mode.as_str() {

            "open" => {}

            "invite" => {

                let ok = !f.invite.trim().is_empty()

                    && accounts::invitation_unused(&app.db, f.invite.trim()).await.map_err(|e| Error::from_db(shell.clone(), e))?;

                if !ok {

                    return Ok(fail("Registration needs a valid invitation code."));

                }

            }

            _ => return Ok(fail("Registration is closed.")),

        }

    }

    if accounts::account_by_name(&app.db, &username).await.map_err(|e| Error::from_db(shell.clone(), e))?.is_some()

        || accounts::org_by_name(&app.db, &username).await.map_err(|e| Error::from_db(shell.clone(), e))?.is_some()

    {

        return Ok(fail("That name is taken."));

    }

    let hash = auth::hash_password(&f.password).map_err(|e| Error::bad(shell.clone(), e.to_string()))?;

    let account = accounts::create_account(&app.db, &username, f.email.trim(), &hash, &auth::random_hex(16), first)

        .await

        .map_err(|e| Error::from_db(shell.clone(), e))?;

    if !first && mode == "invite" {

        accounts::use_invitation(&app.db, f.invite.trim(), account.id).await.ok();

    }

    accounts::audit(&app.db, Some(&account), "register", &username, if first { "first account: administrator" } else { "" }).await.ok();

    Ok(signed_in(&app, &account, "/"))

}