tablo-core 0.8.0

//! The panel's sign-up page: the [`Registrar`] trait that creates accounts, the shipped
//! [`SignUp`] form, and the `{prefix}/register` routes.

use std::{future::Future, sync::Arc};

use topcoat::{
    context::Cx,
    router::{
        Body, RouteFuture,
        request::client_ip,
        response::{IntoResponse, Response},
    },
    view::{BoxView, ViewExt},
};

use super::{
    PanelUser, infrastructure_failure, input,
    login::{NEXT_FIELD, login_url, next_from_query, safe_next},
    panel_root,
    session::{fresh_session, record},
};
use crate::{
    BoxFuture,
    auth::realm::{current_realm, hosted, panel_prefix},
    flash::set_notification,
    form::{FieldError, FieldErrors, FormInput, FormValues, parse_password, parse_scalar},
    outcome::Notification,
    schema::{Field, Schema, Source},
};

/// How a panel creates accounts from its sign-up page, installed with
/// [`Auth::registration`](super::Auth::registration).
///
/// It mirrors an [`Action`](crate::Action) with input: [`Input`](Self::Input) is the form the
/// page asks for, [`validate`](Self::validate) refuses a submission field by field, and
/// [`register`](Self::register) writes the account. Both run in one transaction the framework
/// opens, so a uniqueness probe in `validate` sees what `register` writes against.
///
/// The shipped [`PasswordSignUp`](crate::PasswordSignUp) registers an
/// [`AdminUser`](super::AdminUser) from a [`SignUp`]; an app with its own user table implements
/// it beside its [`Authenticator`](super::Authenticator), for the same user type:
///
/// ```rust
/// # use tablo_core::{FieldErrors, PanelUser, Registrar, SignUp, auth::hash_password};
/// # use topcoat::context::Cx;
/// # #[derive(Debug, Clone, toasty::Model)]
/// # struct Staff {
/// #     #[key] #[auto] id: uuid::Uuid,
/// #     #[unique] email: String,
/// #     password_hash: String,
/// #     name: String,
/// # }
/// # impl PanelUser for Staff {
/// #     fn user_id(&self) -> String { self.id.to_string() }
/// #     fn display_name(&self) -> &str { &self.name }
/// # }
/// struct StaffAuth;
///
/// impl Registrar for StaffAuth {
///     type Input = SignUp;
///     type User = Staff;
///
///     async fn validate(
///         &self,
///         _cx: &Cx,
///         sign_up: &SignUp,
///         ex: &mut dyn toasty::Executor,
///     ) -> topcoat::Result<FieldErrors> {
///         let mut errors = sign_up.password_errors();
///         let taken = Staff::filter_by_email(&sign_up.email)
///             .first()
///             .exec(ex)
///             .await?;
///         if taken.is_some() {
///             errors.add("email", "Email has already been taken");
///         }
///         Ok(errors)
///     }
///
///     async fn register(
///         &self,
///         _cx: &Cx,
///         sign_up: SignUp,
///         ex: &mut dyn toasty::Executor,
///     ) -> topcoat::Result<Staff> {
///         Ok(toasty::create!(Staff {
///             email: sign_up.email,
///             password_hash: hash_password(&sign_up.password).await?,
///             name: sign_up.name,
///         })
///         .exec(ex)
///         .await?)
///     }
/// }
/// ```
///
/// A new account that [may access the panel](PanelUser::can_access_panel) is signed in and lands
/// on the panel; one that may not, such as an account awaiting approval, lands on the login page
/// with a notification saying it was created.
pub trait Registrar: Send + Sync + 'static {
    /// What the sign-up page asks for: [`SignUp`], or the app's own
    /// [`#[derive(FormInput)]`](derive@crate::FormInput) struct. `#[form(password)]` masks a
    /// field, and `#[form(email)]` checks an address.
    type Input: FormInput;

    /// The account a sign-up creates: the type the panel's
    /// [`Authenticator`](super::Authenticator) loads, which mounting checks.
    type User: PanelUser;

    /// Refuse a submission [`register`](Self::register) should not receive, such as an email
    /// another account holds: each error names an input field's key and renders under its
    /// control. Defaults to none. A key no control renders is a declaration error: the page
    /// would show no message.
    ///
    /// It runs inside the sign-up's transaction `ex`, after the input parses and its controls'
    /// own rules pass.
    fn validate(
        &self,
        _cx: &Cx,
        _input: &Self::Input,
        _ex: &mut dyn toasty::Executor,
    ) -> impl Future<Output = topcoat::Result<FieldErrors>> + Send {
        async { Ok(FieldErrors::new()) }
    }

    /// Create the account from a validated `input` through the transaction `ex`, which commits
    /// when it returns `Ok`.
    fn register(
        &self,
        cx: &Cx,
        input: Self::Input,
        ex: &mut dyn toasty::Executor,
    ) -> impl Future<Output = topcoat::Result<Self::User>> + Send;
}

/// What a sign-up submission came to.
pub(crate) enum Outcome {
    /// The committed account.
    Registered(Arc<dyn PanelUser>),
    /// The refused submission, its values, and why. The page renders a password control empty.
    Refused {
        values: FormValues,
        errors: FieldErrors,
    },
}

/// [`Registrar`] with its input and user types erased, as the panel keeps it.
pub(crate) trait DynRegistrar: Send + Sync {
    /// The sign-up form.
    fn schema(&self) -> Schema;
    /// Parses, checks, validates and registers one submission.
    fn sign_up<'a>(
        &'a self,
        cx: &'a Cx,
        values: FormValues,
    ) -> BoxFuture<'a, topcoat::Result<Outcome>>;
}

impl<R: Registrar> DynRegistrar for R {
    fn schema(&self) -> Schema {
        R::Input::schema()
    }

    fn sign_up<'a>(
        &'a self,
        cx: &'a Cx,
        values: FormValues,
    ) -> BoxFuture<'a, topcoat::Result<Outcome>> {
        Box::pin(async move {
            let input =
                match input::parse::<R::Input>(cx, &values, &FormValues::new(), "sign-up").await? {
                    Ok(input) => input,
                    Err(errors) => return Ok(Outcome::Refused { values, errors }),
                };
            let mut db = crate::db::db(cx)?;
            let mut tx = db.transaction().await.map_err(infrastructure_failure)?;
            let errors = self.validate(cx, &input, &mut tx).await?;
            input::placed(&R::Input::schema(), &errors, "the registrar", "sign-up")?;
            if !errors.is_empty() {
                return Ok(Outcome::Refused { values, errors });
            }
            let user = self.register(cx, input, &mut tx).await?;
            tx.commit().await.map_err(infrastructure_failure)?;
            Ok(Outcome::Registered(Arc::new(user)))
        })
    }
}

/// The sign-up form [`PasswordSignUp`](crate::PasswordSignUp) registers from, and a custom
/// [`Registrar`] can take as its input: a name, an email address, and a new password typed
/// twice.
#[derive(Clone, PartialEq, Eq)]
pub struct SignUp {
    /// The display name, posted as `name`.
    pub name: String,
    /// The email address the account signs in with, posted as `email`.
    pub email: String,
    /// The new password, posted as `password`.
    pub password: String,
    /// The password typed again, posted as `password_confirmation`.
    pub password_confirmation: String,
}

impl SignUp {
    /// The refusals [`new_password_errors`] makes of this sign-up's passwords.
    pub fn password_errors(&self) -> FieldErrors {
        new_password_errors(&self.password, &self.password_confirmation)
    }
}

/// Redacts the passwords, so a sign-up logged with `?` writes none to the log.
impl std::fmt::Debug for SignUp {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        f.debug_struct("SignUp")
            .field("name", &self.name)
            .field("email", &self.email)
            .field("password", &"<redacted>")
            .field("password_confirmation", &"<redacted>")
            .finish()
    }
}

impl FormInput for SignUp {
    fn schema() -> Schema {
        let field = crate::form::required_input;
        Schema::new((
            field(Field::text_input::<String>("name").label(crate::text!("tablo-auth-name"))),
            field(
                Field::text_input::<String>("email")
                    .email()
                    .label(crate::text!("tablo-auth-email")),
            ),
            field(
                Field::text_input::<String>(PASSWORD_FIELD)
                    .password()
                    .label(crate::text!("tablo-auth-password")),
            ),
            field(
                Field::text_input::<String>(CONFIRMATION_FIELD)
                    .password()
                    .label(crate::text!("tablo-auth-confirm-password")),
            ),
        ))
    }

    fn parse(_cx: &Cx, values: &FormValues) -> Result<Self, Vec<FieldError>> {
        let mut errors = Vec::new();
        type Parse = fn(&str, &FormValues, Option<String>) -> Result<String, FieldError>;
        let mut read = |key: &str, parse: Parse| {
            parse(key, values, None)
                .map_err(|error| errors.push(error))
                .ok()
        };
        let name = read("name", parse_scalar::<String>);
        let email = read("email", parse_scalar::<String>);
        let password = read(PASSWORD_FIELD, parse_password);
        let confirmation = read(CONFIRMATION_FIELD, parse_password);
        match (name, email, password, confirmation) {
            (Some(name), Some(email), Some(password), Some(password_confirmation))
                if errors.is_empty() =>
            {
                Ok(Self {
                    name,
                    email,
                    password,
                    password_confirmation,
                })
            }
            _ => Err(errors),
        }
    }

    fn write(&self, out: &mut FormValues) {
        out.insert("name".to_string(), self.name.clone());
        out.insert("email".to_string(), self.email.clone());
    }
}

/// The key [`SignUp`]'s new password posts under.
const PASSWORD_FIELD: &str = "password";
/// The key [`SignUp`]'s repeated password posts under.
const CONFIRMATION_FIELD: &str = "password_confirmation";

/// The fewest characters a new password holds, as NIST SP 800-63B asks of a password a user
/// chooses.
pub const MIN_PASSWORD_CHARS: usize = 8;

/// Refuses a new `password` shorter than [`MIN_PASSWORD_CHARS`] under the `password` key, and a
/// `confirmation` that differs from it under `password_confirmation`: the checks a sign-up form
/// with [`SignUp`]'s password keys runs in [`Registrar::validate`].
#[must_use]
pub fn new_password_errors(password: &str, confirmation: &str) -> FieldErrors {
    let mut errors = FieldErrors::new();
    if password.chars().count() < MIN_PASSWORD_CHARS {
        errors.add(
            PASSWORD_FIELD,
            crate::text!("tablo-password-too-short", min = MIN_PASSWORD_CHARS),
        );
    }
    if password != confirmation {
        errors.add(CONFIRMATION_FIELD, crate::text!("tablo-password-mismatch"));
    }
    errors
}

/// The keys a sign-up POST carries besides its input, which no input field may post.
pub(crate) const RESERVED_KEYS: [&str; 2] = [crate::csrf::FIELD_NAME, NEXT_FIELD];

/// Where the panel's sign-up page lives: `{prefix}/register`.
pub(crate) fn register_url(cx: &Cx) -> String {
    format!("{}/register", panel_prefix(cx))
}

/// `url` with `next` in its query: how the login and sign-up pages carry it to each other.
pub(crate) fn with_next(url: String, next: &str) -> String {
    if next.is_empty() {
        return url;
    }
    let mut serializer = form_urlencoded::Serializer::new(String::new());
    serializer.append_pair(NEXT_FIELD, next);
    format!("{url}?{}", serializer.finish())
}

/// Whether the request's panel installs a [`Registrar`].
pub(crate) fn offered(cx: &Cx) -> bool {
    current_realm(cx).is_some_and(|panel| panel.auth.registrar().is_some())
}

/// `GET {prefix}/register` — the standalone sign-up page.
pub(super) fn register_page(cx: &Cx, _body: Body) -> RouteFuture<'_> {
    Box::pin(async move {
        let next = next_from_query(cx).unwrap_or_default();
        page_response(cx, &FormValues::new(), &FieldErrors::new(), next, None).await
    })
}

/// `POST {prefix}/register` — create the account, then sign it in or send it to the login page.
pub(super) fn register_post(cx: &Cx, body: Body) -> RouteFuture<'_> {
    Box::pin(async move {
        let panel = current_realm(cx).ok_or_else(topcoat::router::error::not_found)?;
        let registrar = panel
            .auth
            .registrar()
            .ok_or_else(topcoat::router::error::not_found)?;
        let form = crate::auth::input::read_form(cx, body).await?;
        crate::csrf::verify(cx, form.last(crate::csrf::FIELD_NAME))?;
        let next = form
            .last(NEXT_FIELD)
            .and_then(safe_next)
            .map(str::to_string)
            .unwrap_or_default();
        let schema = registrar.schema();
        let values = schema.read_input(cx, &form.pairs, &RESERVED_KEYS)?;
        let client = client_ip(cx);
        if !panel.auth.throttle_sign_ups().attempt("", client) {
            tracing::warn!(panel = %panel.prefix, client = ?client, "sign-up attempt throttled");
            return page_response(
                cx,
                &values,
                &FieldErrors::new(),
                next,
                Some(Alert::Throttled),
            )
            .await;
        }
        let user = match registrar.sign_up(cx, values).await {
            Ok(Outcome::Registered(user)) => user,
            Ok(Outcome::Refused { values, errors }) => {
                return page_response(cx, &values, &errors, next, None).await;
            }
            Err(error) => {
                let error = infrastructure_failure(error);
                if crate::error::TabloError::is_infrastructure(&error) {
                    return unavailable(cx, next).await;
                }
                return Err(error);
            }
        };
        if !user.can_access_panel() {
            set_notification(
                cx,
                Notification::success(crate::t!(cx, "tablo-sign-up-created"))
                    .description(crate::t!(cx, "tablo-sign-up-pending")),
            );
            return topcoat::router::error::see_other(login_url(cx)).into_response(cx);
        }
        // Rotate as a login does, so a session presented before the sign-up cannot be replayed.
        let recorded = match fresh_session(cx).await {
            Ok(session) => record(cx, &session, &*user, panel).await,
            Err(error) => Err(error),
        };
        if let Err(error) = recorded {
            // The account is committed: send it to sign in rather than to a sign-up whose retry
            // would find its email taken.
            tracing::error!(error = %infrastructure_failure(error), "sign-up session not recorded");
            set_notification(
                cx,
                Notification::success(crate::t!(cx, "tablo-sign-up-created"))
                    .description(crate::t!(cx, "tablo-sign-up-sign-in")),
            );
            return topcoat::router::error::see_other(login_url(cx)).into_response(cx);
        }
        super::verification::mail_after_sign_up(cx, &*user);
        let target = if next.is_empty() {
            panel_root(cx)
        } else {
            next
        };
        topcoat::router::error::see_other(target).into_response(cx)
    })
}

/// The sign-up page with the outage alert.
async fn unavailable(cx: &Cx, next: String) -> topcoat::Result<Response> {
    let values = FormValues::new();
    page_response(
        cx,
        &values,
        &FieldErrors::new(),
        next,
        Some(Alert::Unavailable),
    )
    .await
}

/// What the sign-up page says above its form, besides a field's error.
#[derive(Debug, Clone, Copy)]
enum Alert {
    /// The client is past its sign-up limit; answers 429.
    Throttled,
    /// The database behind sign-up could not answer; answers 503.
    Unavailable,
}

impl Alert {
    /// The message the page renders.
    fn message(self) -> &'static str {
        match self {
            Self::Throttled => "tablo-sign-up-throttled",
            Self::Unavailable => "tablo-sign-up-unavailable",
        }
    }

    fn status(self) -> http::StatusCode {
        match self {
            Self::Throttled => http::StatusCode::TOO_MANY_REQUESTS,
            Self::Unavailable => http::StatusCode::SERVICE_UNAVAILABLE,
        }
    }
}

/// The sign-up page: 422 for a refused submission, the alert's status with one, else 200.
async fn page_response(
    cx: &Cx,
    values: &FormValues,
    errors: &FieldErrors,
    next: String,
    alert: Option<Alert>,
) -> topcoat::Result<Response> {
    let status = match alert {
        Some(alert) => Some(alert.status()),
        None => (!errors.is_empty()).then_some(http::StatusCode::UNPROCESSABLE_ENTITY),
    };
    let page = render_page(cx, values, errors, next, alert, status).await?;
    page.single().await?.into_response(cx)
}

/// Renders the standalone sign-up document: the brand, the registrar's form with its errors,
/// and a link to the login page.
async fn render_page<'a>(
    cx: &'a Cx,
    values: &FormValues,
    errors: &FieldErrors,
    next: String,
    alert: Option<Alert>,
    status: Option<http::StatusCode>,
) -> topcoat::Result<BoxView<'a>> {
    let schema = current_realm(cx)
        .and_then(|panel| panel.auth.registrar())
        .map_or_else(Schema::empty, DynRegistrar::schema);
    let csrf = crate::csrf::ensure_token(cx);
    let action = register_url(cx);
    let login = with_next(login_url(cx), &next);
    let fields = schema.render(cx, Source::form(values, errors)).await?;
    let form = topcoat::view::view! {
        cx =>
        <form method="post" action=(action) class="flex flex-col gap-5">
            (crate::csrf::field(cx, &csrf))
            <input type="hidden" name=(NEXT_FIELD) value=(next)>
            if let Some(alert) = alert {
                tablo_ui::alert(
                    variant: tablo_ui::AlertVariant::Destructive,
                    attrs: topcoat::view::attributes! { role="alert" },
                    tablo_ui::alert_title((crate::t!(cx, alert.message())))
                )
            }
            (fields)
            tablo_ui::button(
                variant: tablo_ui::ButtonVariant::Primary,
                attrs: topcoat::view::attributes! { type="submit" class="w-full" },
                (crate::t!(cx, "tablo-sign-up-submit"))
            )
        </form>
    }
    .boxed();
    super::page::render(
        cx,
        super::page::AuthPage {
            title: crate::t!(cx, "tablo-sign-up-title"),
            description: crate::t!(
                cx,
                "tablo-sign-up-description",
                brand = hosted(cx)?.brand_name(cx)
            ),
            status,
            form,
            switch: Some(super::page::switch_link(
                cx,
                "tablo-sign-up-have-account",
                &login,
                "tablo-sign-up-sign-in-link",
            )),
            note: None,
        },
    )
    .await
}

/// The mistakes in a panel's [`Auth::registration`](super::Auth::registration): a registration
/// without auth, a registrar whose user is not the authenticator's, and a sign-up form field the
/// page cannot serve.
pub(super) fn declaration_errors(auth: &super::AuthConfig) -> Vec<crate::DeclarationErrorKind> {
    use super::input::FieldFault;
    use crate::{DeclarationErrorKind, declaration::SignUpFault};

    let Some(registrar) = auth.registrar.as_deref() else {
        return Vec::new();
    };
    if auth.authenticator().is_none() {
        return vec![DeclarationErrorKind::SignUp(SignUpFault::AuthDisabled)];
    }
    let mut kinds = Vec::new();
    let schema = registrar.schema();
    kinds.extend(schema.declaration_errors());
    kinds.extend(schema.empty_choices());
    kinds.extend(
        input::field_faults(&schema, &RESERVED_KEYS).map(|(fault, name)| {
            DeclarationErrorKind::SignUp(match fault {
                FieldFault::Reserved => SignUpFault::ReservedField(name),
                FieldFault::File => SignUpFault::FileField(name),
                FieldFault::Relationship => SignUpFault::RelationshipField(name),
            })
        }),
    );
    kinds
}

#[cfg(test)]
mod tests;