// SPDX-FileCopyrightText: 2017 Konstantinos Sideris <siderisk@auth.gr>
// SPDX-FileCopyrightText: 2021 Nheko Contributors
//
// SPDX-License-Identifier: GPL-3.0-or-later

#include <QInputDialog>
#include <QLabel>
#include <QMetaType>
#include <QPainter>
#include <QStyleOption>
#include <QTimer>
#include <QtMath>

#include <mtx/responses/register.hpp>
#include <mtx/responses/well-known.hpp>
#include <mtxclient/http/client.hpp>

#include "Config.h"
#include "Logging.h"
#include "MainWindow.h"
#include "MatrixClient.h"
#include "RegisterPage.h"
#include "ui/FlatButton.h"
#include "ui/RaisedButton.h"
#include "ui/TextField.h"

#include "dialogs/FallbackAuth.h"
#include "dialogs/ReCaptcha.h"

Q_DECLARE_METATYPE(mtx::user_interactive::Unauthorized)
Q_DECLARE_METATYPE(mtx::user_interactive::Auth)

RegisterPage::RegisterPage(QWidget *parent)
  : QWidget(parent)
{
        qRegisterMetaType<mtx::user_interactive::Unauthorized>();
        qRegisterMetaType<mtx::user_interactive::Auth>();
        top_layout_ = new QVBoxLayout();

        back_layout_ = new QHBoxLayout();
        back_layout_->setSpacing(0);
        back_layout_->setContentsMargins(5, 5, -1, -1);

        back_button_ = new FlatButton(this);
        back_button_->setMinimumSize(QSize(30, 30));

        QIcon icon;
        icon.addFile(":/icons/icons/ui/angle-pointing-to-left.png");

        back_button_->setIcon(icon);
        back_button_->setIconSize(QSize(32, 32));

        back_layout_->addWidget(back_button_, 0, Qt::AlignLeft | Qt::AlignVCenter);
        back_layout_->addStretch(1);

        QIcon logo;
        logo.addFile(":/logos/register.png");

        logo_ = new QLabel(this);
        logo_->setPixmap(logo.pixmap(128));

        logo_layout_ = new QHBoxLayout();
        logo_layout_->setMargin(0);
        logo_layout_->addWidget(logo_, 0, Qt::AlignHCenter);

        form_wrapper_ = new QHBoxLayout();
        form_widget_  = new QWidget();
        form_widget_->setMinimumSize(QSize(350, 300));

        form_layout_ = new QVBoxLayout();
        form_layout_->setSpacing(20);
        form_layout_->setContentsMargins(0, 0, 0, 40);
        form_widget_->setLayout(form_layout_);

        form_wrapper_->addStretch(1);
        form_wrapper_->addWidget(form_widget_);
        form_wrapper_->addStretch(1);

        username_input_ = new TextField();
        username_input_->setLabel(tr("Username"));
        username_input_->setRegexp(QRegularExpression("[a-z0-9._=/-]+"));
        username_input_->setToolTip(tr("The username must not be empty, and must contain only the "
                                       "characters a-z, 0-9, ., _, =, -, and /."));

        password_input_ = new TextField();
        password_input_->setLabel(tr("Password"));
        password_input_->setRegexp(QRegularExpression("^.{8,}$"));
        password_input_->setEchoMode(QLineEdit::Password);
        password_input_->setToolTip(tr("Please choose a secure password. The exact requirements "
                                       "for password strength may depend on your server."));

        password_confirmation_ = new TextField();
        password_confirmation_->setLabel(tr("Password confirmation"));
        password_confirmation_->setEchoMode(QLineEdit::Password);

        server_input_ = new TextField();
        server_input_->setLabel(tr("Homeserver"));
        server_input_->setRegexp(QRegularExpression(".+"));
        server_input_->setToolTip(
          tr("A server that allows registration. Since matrix is decentralized, you need to first "
             "find a server you can register on or host your own."));

        error_username_label_ = new QLabel(this);
        error_username_label_->setWordWrap(true);
        error_username_label_->hide();

        error_password_label_ = new QLabel(this);
        error_password_label_->setWordWrap(true);
        error_password_label_->hide();

        error_password_confirmation_label_ = new QLabel(this);
        error_password_confirmation_label_->setWordWrap(true);
        error_password_confirmation_label_->hide();

        error_server_label_ = new QLabel(this);
        error_server_label_->setWordWrap(true);
        error_server_label_->hide();

        form_layout_->addWidget(username_input_, Qt::AlignHCenter);
        form_layout_->addWidget(error_username_label_, Qt::AlignHCenter);
        form_layout_->addWidget(password_input_, Qt::AlignHCenter);
        form_layout_->addWidget(error_password_label_, Qt::AlignHCenter);
        form_layout_->addWidget(password_confirmation_, Qt::AlignHCenter);
        form_layout_->addWidget(error_password_confirmation_label_, Qt::AlignHCenter);
        form_layout_->addWidget(server_input_, Qt::AlignHCenter);
        form_layout_->addWidget(error_server_label_, Qt::AlignHCenter);

        button_layout_ = new QHBoxLayout();
        button_layout_->setSpacing(0);
        button_layout_->setMargin(0);

        error_label_ = new QLabel(this);
        error_label_->setWordWrap(true);

        register_button_ = new RaisedButton(tr("REGISTER"), this);
        register_button_->setMinimumSize(350, 65);
        register_button_->setFontSize(conf::btn::fontSize);
        register_button_->setCornerRadius(conf::btn::cornerRadius);

        button_layout_->addStretch(1);
        button_layout_->addWidget(register_button_);
        button_layout_->addStretch(1);

        top_layout_->addLayout(back_layout_);
        top_layout_->addLayout(logo_layout_);
        top_layout_->addLayout(form_wrapper_);
        top_layout_->addStretch(1);
        top_layout_->addLayout(button_layout_);
        top_layout_->addWidget(error_label_, 0, Qt::AlignHCenter);
        top_layout_->addStretch(1);
        setLayout(top_layout_);

        connect(back_button_, SIGNAL(clicked()), this, SLOT(onBackButtonClicked()));
        connect(register_button_, SIGNAL(clicked()), this, SLOT(onRegisterButtonClicked()));

        connect(username_input_, SIGNAL(returnPressed()), register_button_, SLOT(click()));
        connect(username_input_, &TextField::editingFinished, this, &RegisterPage::checkUsername);
        connect(password_input_, SIGNAL(returnPressed()), register_button_, SLOT(click()));
        connect(password_input_, &TextField::editingFinished, this, &RegisterPage::checkPassword);
        connect(password_confirmation_, SIGNAL(returnPressed()), register_button_, SLOT(click()));
        connect(password_confirmation_,
                &TextField::editingFinished,
                this,
                &RegisterPage::checkPasswordConfirmation);
        connect(server_input_, SIGNAL(returnPressed()), register_button_, SLOT(click()));
        connect(server_input_, &TextField::editingFinished, this, &RegisterPage::checkServer);

        connect(
          this,
          &RegisterPage::serverError,
          this,
          [this](const QString &msg) {
                  server_input_->setValid(false);
                  showError(error_server_label_, msg);
          },
          Qt::QueuedConnection);

        connect(this, &RegisterPage::wellKnownLookup, this, &RegisterPage::doWellKnownLookup);
        connect(this, &RegisterPage::versionsCheck, this, &RegisterPage::doVersionsCheck);
        connect(this, &RegisterPage::registration, this, &RegisterPage::doRegistration);
        connect(this, &RegisterPage::UIA, this, &RegisterPage::doUIA);
        connect(
          this, &RegisterPage::registrationWithAuth, this, &RegisterPage::doRegistrationWithAuth);
}

void
RegisterPage::onBackButtonClicked()
{
        emit backButtonClicked();
}

void
RegisterPage::showError(const QString &msg)
{
        emit errorOccurred();
        auto rect  = QFontMetrics(font()).boundingRect(msg);
        int width  = rect.width();
        int height = rect.height();
        error_label_->setFixedHeight(qCeil(width / 200.0) * height);
        error_label_->setText(msg);
}

void
RegisterPage::showError(QLabel *label, const QString &msg)
{
        emit errorOccurred();
        auto rect  = QFontMetrics(font()).boundingRect(msg);
        int width  = rect.width();
        int height = rect.height();
        label->setFixedHeight((int)qCeil(width / 200.0) * height);
        label->setText(msg);
        label->show();
}

bool
RegisterPage::checkOneField(QLabel *label, const TextField *t_field, const QString &msg)
{
        if (t_field->isValid()) {
                label->hide();
                return true;
        } else {
                showError(label, msg);
                return false;
        }
}

bool
RegisterPage::checkUsername()
{
        return checkOneField(error_username_label_,
                             username_input_,
                             tr("The username must not be empty, and must contain only the "
                                "characters a-z, 0-9, ., _, =, -, and /."));
}

bool
RegisterPage::checkPassword()
{
        return checkOneField(
          error_password_label_, password_input_, tr("Password is not long enough (min 8 chars)"));
}

bool
RegisterPage::checkPasswordConfirmation()
{
        if (password_input_->text() == password_confirmation_->text()) {
                error_password_confirmation_label_->hide();
                password_confirmation_->setValid(true);
                return true;
        } else {
                showError(error_password_confirmation_label_, tr("Passwords don't match"));
                password_confirmation_->setValid(false);
                return false;
        }
}

bool
RegisterPage::checkServer()
{
        // This doesn't check that the server is reachable,
        // just that the input is not obviously wrong.
        return checkOneField(error_server_label_, server_input_, tr("Invalid server name"));
}

void
RegisterPage::onRegisterButtonClicked()
{
        if (checkUsername() && checkPassword() && checkPasswordConfirmation() && checkServer()) {
                auto server = server_input_->text().toStdString();

                http::client()->set_server(server);
                http::client()->verify_certificates(
                  !UserSettings::instance()->disableCertificateValidation());

                // This starts a chain of `emit`s which ends up doing the
                // registration. Signals are used rather than normal function
                // calls so that the dialogs used in UIA work correctly.
                //
                // The sequence of events looks something like this:
                //
                // dowellKnownLookup
                //   v
                // doVersionsCheck
                //   v
                // doRegistration
                //   v
                // doUIA <-----------------+
                //   v					   | More auth required
                // doRegistrationWithAuth -+
                //                         | Success
                // 						   v
                //                     registering

                emit wellKnownLookup();

                emit registering();
        }
}

void
RegisterPage::doWellKnownLookup()
{
        http::client()->well_known(
          [this](const mtx::responses::WellKnown &res, mtx::http::RequestErr err) {
                  if (err) {
                          if (err->status_code == 404) {
                                  nhlog::net()->info("Autodiscovery: No .well-known.");
                                  // Check that the homeserver can be reached
                                  emit versionsCheck();
                                  return;
                          }

                          if (!err->parse_error.empty()) {
                                  emit serverError(
                                    tr("Autodiscovery failed. Received malformed response."));
                                  nhlog::net()->error(
                                    "Autodiscovery failed. Received malformed response.");
                                  return;
                          }

                          emit serverError(tr("Autodiscovery failed. Unknown error when "
                                              "requesting .well-known."));
                          nhlog::net()->error("Autodiscovery failed. Unknown error when "
                                              "requesting .well-known. {} {}",
                                              err->status_code,
                                              err->error_code);
                          return;
                  }

                  nhlog::net()->info("Autodiscovery: Discovered '" + res.homeserver.base_url + "'");
                  http::client()->set_server(res.homeserver.base_url);
                  // Check that the homeserver can be reached
                  emit versionsCheck();
          });
}

void
RegisterPage::doVersionsCheck()
{
        // Make a request to /_matrix/client/versions to check the address
        // given is a Matrix homeserver.
        http::client()->versions(
          [this](const mtx::responses::Versions &, mtx::http::RequestErr err) {
                  if (err) {
                          if (err->status_code == 404) {
                                  emit serverError(
                                    tr("The required endpoints were not found. Possibly "
                                       "not a Matrix server."));
                                  return;
                          }

                          if (!err->parse_error.empty()) {
                                  emit serverError(
                                    tr("Received malformed response. Make sure the homeserver "
                                       "domain is valid."));
                                  return;
                          }

                          emit serverError(tr("An unknown error occured. Make sure the "
                                              "homeserver domain is valid."));
                          return;
                  }

                  // Attempt registration without an `auth` dict
                  emit registration();
          });
}

void
RegisterPage::doRegistration()
{
        // These inputs should still be alright, but check just in case
        if (checkUsername() && checkPassword() && checkPasswordConfirmation()) {
                auto username = username_input_->text().toStdString();
                auto password = password_input_->text().toStdString();
                http::client()->registration(username, password, registrationCb());
        }
}

void
RegisterPage::doRegistrationWithAuth(const mtx::user_interactive::Auth &auth)
{
        // These inputs should still be alright, but check just in case
        if (checkUsername() && checkPassword() && checkPasswordConfirmation()) {
                auto username = username_input_->text().toStdString();
                auto password = password_input_->text().toStdString();
                http::client()->registration(username, password, auth, registrationCb());
        }
}

mtx::http::Callback<mtx::responses::Register>
RegisterPage::registrationCb()
{
        // Return a function to be used as the callback when an attempt at
        // registration is made.
        return [this](const mtx::responses::Register &res, mtx::http::RequestErr err) {
                if (!err) {
                        http::client()->set_user(res.user_id);
                        http::client()->set_access_token(res.access_token);
                        emit registerOk();
                        return;
                }

                // The server requires registration flows.
                if (err->status_code == 401) {
                        if (err->matrix_error.unauthorized.flows.empty()) {
                                nhlog::net()->warn("failed to retrieve registration flows: "
                                                   "status_code({}), matrix_error({}) ",
                                                   static_cast<int>(err->status_code),
                                                   err->matrix_error.error);
                                showError(QString::fromStdString(err->matrix_error.error));
                                return;
                        }

                        // Attempt to complete a UIA stage
                        emit UIA(err->matrix_error.unauthorized);
                        return;
                }

                nhlog::net()->error("failed to register: status_code ({}), matrix_error({})",
                                    static_cast<int>(err->status_code),
                                    err->matrix_error.error);

                showError(QString::fromStdString(err->matrix_error.error));
        };
}

void
RegisterPage::doUIA(const mtx::user_interactive::Unauthorized &unauthorized)
{
        auto completed_stages = unauthorized.completed;
        auto flows            = unauthorized.flows;
        auto session =
          unauthorized.session.empty() ? http::client()->generate_txn_id() : unauthorized.session;

        nhlog::ui()->info("Completed stages: {}", completed_stages.size());

        if (!completed_stages.empty()) {
                // Get rid of all flows which don't start with the sequence of
                // stages that have already been completed.
                flows.erase(
                  std::remove_if(flows.begin(),
                                 flows.end(),
                                 [completed_stages](auto flow) {
                                         if (completed_stages.size() > flow.stages.size())
                                                 return true;
                                         for (size_t f = 0; f < completed_stages.size(); f++)
                                                 if (completed_stages[f] != flow.stages[f])
                                                         return true;
                                         return false;
                                 }),
                  flows.end());
        }

        if (flows.empty()) {
                nhlog::ui()->error("No available registration flows!");
                showError(tr("No supported registration flows!"));
                return;
        }

        auto current_stage = flows.front().stages.at(completed_stages.size());

        if (current_stage == mtx::user_interactive::auth_types::recaptcha) {
                auto captchaDialog = new dialogs::ReCaptcha(QString::fromStdString(session), this);

                connect(captchaDialog,
                        &dialogs::ReCaptcha::confirmation,
                        this,
                        [this, session, captchaDialog]() {
                                captchaDialog->close();
                                captchaDialog->deleteLater();
                                doRegistrationWithAuth(mtx::user_interactive::Auth{
                                  session, mtx::user_interactive::auth::Fallback{}});
                        });

                connect(
                  captchaDialog, &dialogs::ReCaptcha::cancel, this, &RegisterPage::errorOccurred);

                QTimer::singleShot(1000, this, [captchaDialog]() { captchaDialog->show(); });

        } else if (current_stage == mtx::user_interactive::auth_types::dummy) {
                doRegistrationWithAuth(
                  mtx::user_interactive::Auth{session, mtx::user_interactive::auth::Dummy{}});

        } else if (current_stage == mtx::user_interactive::auth_types::registration_token) {
                bool ok;
                QString token =
                  QInputDialog::getText(this,
                                        tr("Registration token"),
                                        tr("Please enter a valid registration token."),
                                        QLineEdit::Normal,
                                        QString(),
                                        &ok);

                if (ok) {
                        emit registrationWithAuth(mtx::user_interactive::Auth{
                          session,
                          mtx::user_interactive::auth::RegistrationToken{token.toStdString()}});
                } else {
                        emit errorOccurred();
                }
        } else {
                // use fallback
                auto dialog = new dialogs::FallbackAuth(
                  QString::fromStdString(current_stage), QString::fromStdString(session), this);

                connect(
                  dialog, &dialogs::FallbackAuth::confirmation, this, [this, session, dialog]() {
                          dialog->close();
                          dialog->deleteLater();
                          emit registrationWithAuth(mtx::user_interactive::Auth{
                            session, mtx::user_interactive::auth::Fallback{}});
                  });

                connect(dialog, &dialogs::FallbackAuth::cancel, this, &RegisterPage::errorOccurred);

                dialog->show();
        }
}

void
RegisterPage::paintEvent(QPaintEvent *)
{
        QStyleOption opt;
        opt.init(this);
        QPainter p(this);
        style()->drawPrimitive(QStyle::PE_Widget, &opt, &p, this);
}
