/**
 * @file MultiSettings.cpp
 * @brief Implementation of multi-settings dialog
 */

#include "MultiSettings.h"
#include "JS8MessageBox.h"
#include "JS8_Include/SettingsGroup.h"
#include "JS8_Include/pimpl_impl.h"
#include "qt_helpers.h"

#include <QAction>
#include <QActionGroup>
#include <QApplication>
#include <QComboBox>
#include <QDialog>
#include <QDialogButtonBox>
#include <QDir>
#include <QFont>
#include <QFormLayout>
#include <QLabel>
#include <QLineEdit>
#include <QList>
#include <QMainWindow>
#include <QMenu>
#include <QMetaObject>
#include <QObject>
#include <QPushButton>
#include <QRegularExpression>
#include <QRegularExpressionValidator>
#include <QSettings>
#include <QStandardPaths>
#include <QString>
#include <QStringList>
#include <QVBoxLayout>

#include <stdexcept>

namespace {
char const *default_string = QT_TRANSLATE_NOOP("MultiSettings", "Default");
char const *multi_settings_root_group = "MultiSettings";
char const *multi_settings_current_group_key =
    "CurrentMultiSettingsConfiguration";
char const *multi_settings_current_name_key = "CurrentName";
char const *multi_settings_place_holder_key = "MultiSettingsPlaceHolder";

QString unescape_ampersands(QString s) { return s.replace("&&", "&"); }

// calculate a useable and unique settings file path
QString settings_path() {
    auto const &config_directory =
        QStandardPaths::writableLocation(QStandardPaths::ConfigLocation);
    QDir config_path{
        config_directory}; // will be "." if config_directory is empty
    if (!config_path.mkpath(".")) {
        throw std::runtime_error{"Cannot find a usable configuration path \"" +
                                 config_path.path().toStdString() + '"'};
    }
    return config_path.absoluteFilePath(QApplication::applicationName() +
                                        ".ini");
}

//
// Dialog to get a valid new configuration name
//
class NameDialog final : public QDialog {
    Q_OBJECT

  public:
    explicit NameDialog(QString const &current_name,
                        QStringList const &current_names,
                        QWidget *parent = nullptr)
        : QDialog{parent} {
        setWindowTitle(tr("New Configuration Name"));

        auto form_layout = new QFormLayout();
        form_layout->addRow(tr("Old name:"), &old_name_label_);
        old_name_label_.setText(current_name);
        form_layout->addRow(tr("&New name:"), &name_line_edit_);

        auto main_layout = new QVBoxLayout(this);
        main_layout->addLayout(form_layout);

        auto button_box = new QDialogButtonBox{QDialogButtonBox::Ok |
                                               QDialogButtonBox::Cancel};
        button_box->button(QDialogButtonBox::Ok)->setEnabled(false);
        main_layout->addWidget(button_box);

        auto name_validator = new QRegularExpressionValidator{
            QRegularExpression{R"([^/\\]+)"}, this};
        name_line_edit_.setValidator(name_validator);

        connect(&name_line_edit_, &QLineEdit::textChanged,
                [current_names, button_box](QString const &name) {
                    bool valid{!current_names.contains(name.trimmed())};
                    button_box->button(QDialogButtonBox::Ok)->setEnabled(valid);
                });
        connect(button_box, &QDialogButtonBox::accepted, this,
                &QDialog::accept);
        connect(button_box, &QDialogButtonBox::rejected, this,
                &QDialog::reject);
    }

    QString new_name() const { return name_line_edit_.text().trimmed(); }

  private:
    QLabel old_name_label_;
    QLineEdit name_line_edit_;
};

//
// Dialog to get a valid new existing name
//
class ExistingNameDialog final : public QDialog {
    Q_OBJECT

  public:
    explicit ExistingNameDialog(QStringList const &current_names,
                                QWidget *parent = nullptr)
        : QDialog{parent} {
        setWindowTitle(tr("Configuration to Clone From"));

        name_combo_box_.addItems(current_names);

        auto form_layout = new QFormLayout();
        form_layout->addRow(tr("&Source Configuration Name:"),
                            &name_combo_box_);

        auto main_layout = new QVBoxLayout(this);
        main_layout->addLayout(form_layout);

        auto button_box = new QDialogButtonBox{QDialogButtonBox::Ok |
                                               QDialogButtonBox::Cancel};
        main_layout->addWidget(button_box);

        connect(button_box, &QDialogButtonBox::accepted, this,
                &QDialog::accept);
        connect(button_box, &QDialogButtonBox::rejected, this,
                &QDialog::reject);
    }

    QString name() const { return name_combo_box_.currentText(); }

  private:
    QComboBox name_combo_box_;
};
} // namespace

class MultiSettings::impl final : public QObject {
    Q_OBJECT

  public:
    explicit impl(MultiSettings const *parent, QString const &config_name);
    bool reposition();
    void create_menu_actions(QMainWindow *main_window, QMenu *menu);
    bool exit();

    QSettings settings_;
    QString current_;

    // switch to this configuration
    void select_configuration(QString const &target_name);

  private:
    using Dictionary = QVariantMap;

    // create a configuration maintenance sub menu
    QMenu *create_sub_menu(QMenu *parent, QString const &menu_title,
                           QActionGroup * = nullptr);

    // extract all settings from the current QSettings group
    Dictionary get_settings() const;

    // write the settings values from the dictionary to the current group
    void load_from(Dictionary const &, bool add_placeholder = true);

    // clone this configuration
    void clone_configuration(QMenu *, QMenu const *);

    // update this configuration from another
    void clone_into_configuration(QMenu const *);

    // reset configuration to default values
    void reset_configuration(QMenu const *);

    // change configuration name
    void rename_configuration(QMenu *);

    // remove a configuration
    void delete_configuration(QMenu *);

    // action to take on restart
    enum class RepositionType { unchanged, replace, save_and_replace };
    void restart(RepositionType);

    MultiSettings const *parent_; // required for emitting signals
    QMainWindow *main_window_;
    bool name_change_emit_pending_; // delayed until menu built

    QFont original_font_;

    RepositionType reposition_type_;
    Dictionary new_settings_;
    bool exit_flag_; // false means loop around with new
                     // configuration
    QActionGroup *configurations_group_;
};

#include "MultiSettings.moc"
#include "moc_MultiSettings.cpp"

MultiSettings::MultiSettings(QString const &config_name)
    : m_{this, config_name} {}

MultiSettings::~MultiSettings() {}

QSettings *MultiSettings::settings() { return &m_->settings_; }

QVariant MultiSettings::common_value(QString const &key,
                                     QVariant const &default_value) const {
    QVariant value;
    QSettings *mutable_settings{const_cast<QSettings *>(&m_->settings_)};
    auto const &current_group = mutable_settings->group();
    if (current_group.size())
        mutable_settings->endGroup();
    {
        SettingsGroup alternatives{mutable_settings, multi_settings_root_group};
        value = mutable_settings->value(key, default_value);
    }
    if (current_group.size())
        mutable_settings->beginGroup(current_group);
    return value;
}

void MultiSettings::set_common_value(QString const &key,
                                     QVariant const &value) {
    auto const &current_group = m_->settings_.group();
    if (current_group.size())
        m_->settings_.endGroup();
    {
        SettingsGroup alternatives{&m_->settings_, multi_settings_root_group};
        m_->settings_.setValue(key, value);
    }
    if (current_group.size())
        m_->settings_.beginGroup(current_group);
}

void MultiSettings::remove_common_value(QString const &key) {
    if (!key.size())
        return; // we don't allow global delete as it
                // would break this classes data model
    auto const &current_group = m_->settings_.group();
    if (current_group.size())
        m_->settings_.endGroup();
    {
        SettingsGroup alternatives{&m_->settings_, multi_settings_root_group};
        m_->settings_.remove(key);
    }
    if (current_group.size())
        m_->settings_.beginGroup(current_group);
}

void MultiSettings::create_menu_actions(QMainWindow *main_window, QMenu *menu) {
    m_->create_menu_actions(main_window, menu);
}

void MultiSettings::select_configuration(QString const &name) {
    m_->select_configuration(name);
}

QString MultiSettings::configuration_name() const { return m_->current_; }

bool MultiSettings::exit() { return m_->exit(); }

MultiSettings::impl::impl(MultiSettings const *parent,
                          QString const &config_name)
    : settings_{settings_path(), QSettings::IniFormat}, parent_{parent},
      main_window_{nullptr}, name_change_emit_pending_{true},
      reposition_type_{RepositionType::unchanged}, exit_flag_{true},
      configurations_group_{new QActionGroup{this}} {
    if (!settings_.isWritable()) {
        throw std::runtime_error{QString{"Cannot access \"%1\" for writing"}
                                     .arg(settings_.fileName())
                                     .toStdString()};
    }

    // deal with transient, now defunct, settings key
    if (settings_.contains(multi_settings_current_group_key)) {
        current_ = settings_.value(multi_settings_current_group_key).toString();
        settings_.remove(multi_settings_current_group_key);
        if (current_.size()) {
            {
                SettingsGroup alternatives{&settings_,
                                           multi_settings_root_group};
                {
                    SettingsGroup source_group{&settings_, current_};
                    new_settings_ = get_settings();
                }
                settings_.setValue(multi_settings_current_name_key,
                                   tr(default_string));
            }
            reposition_type_ = RepositionType::save_and_replace;
            reposition();
        } else {
            SettingsGroup alternatives{&settings_, multi_settings_root_group};
            settings_.setValue(multi_settings_current_name_key,
                               tr(default_string));
        }
    }

    // bootstrap
    QStringList available_configurations;
    {
        SettingsGroup alternatives{&settings_, multi_settings_root_group};
        available_configurations = settings_.childGroups();
        // use last selected configuration
        current_ = settings_.value(multi_settings_current_name_key).toString();
        if (!current_.size()) {
            // no configurations so use default name
            current_ = tr(default_string);
            settings_.setValue(multi_settings_current_name_key, current_);
        }
    }

    if (config_name.size() && available_configurations.contains(config_name) &&
        config_name != current_) {
        // switch to specified configuration
        {
            SettingsGroup alternatives{&settings_, multi_settings_root_group};
            // save the target settings
            SettingsGroup target_group{&settings_, config_name};
            new_settings_ = get_settings();
        }
        current_ = config_name;
        reposition_type_ = RepositionType::save_and_replace;
        reposition();
    }
    settings_.sync();
}

// do actions that can only be done once all the windows are closed
bool MultiSettings::impl::reposition() {
    auto const &current_group = settings_.group();
    if (current_group.size())
        settings_.endGroup();
    switch (reposition_type_) {
    case RepositionType::save_and_replace: {
        // save the current settings with the other alternatives
        Dictionary saved_settings{get_settings()};
        SettingsGroup alternatives{&settings_, multi_settings_root_group};
        // get the current configuration name
        auto const &previous_group_name =
            settings_.value(multi_settings_current_name_key, tr(default_string))
                .toString();
        SettingsGroup save_group{&settings_, previous_group_name};
        load_from(saved_settings);
    }
        // fall through
    case RepositionType::replace:
        // and purge current settings
        for (auto const &key : settings_.allKeys()) {
            if (!key.contains(multi_settings_root_group)) {
                settings_.remove(key);
            }
        }
        // insert the new settings
        load_from(new_settings_, false);
        if (!new_settings_.size()) {
            // if we are clearing the current settings then we must
            // reset the application font and the font in the
            // application style sheet, this is necessary since the
            // application instance is not recreated
            qApp->setFont(original_font_);
            qApp->setStyleSheet(qApp->styleSheet() + "* {" +
                                font_as_stylesheet(original_font_) + '}');
        }
        // now we have set up the new current we can safely purge it
        // from the alternatives
        {
            SettingsGroup alternatives{&settings_, multi_settings_root_group};
            {
                SettingsGroup purge_group{&settings_, current_};
                settings_.remove(QString{}); // purge entire group
            }
            // switch to the specified configuration name
            settings_.setValue(multi_settings_current_name_key, current_);
        }
        settings_.sync();
        // fall through
    case RepositionType::unchanged:
        new_settings_.clear();
        break;
    }
    if (current_group.size())
        settings_.beginGroup(current_group);

    reposition_type_ = RepositionType::unchanged; // reset
    bool exit{exit_flag_};
    exit_flag_ = true; // reset exit flag so normal exit works

    return exit;
}

// populate a pop up menu with the configurations sub-menus for
// maintenance including select, clone, clone from, delete, rename
// and, reset
void MultiSettings::impl::create_menu_actions(QMainWindow *main_window,
                                              QMenu *menu) {
    main_window_ = main_window;
    auto const &current_group = settings_.group();
    if (current_group.size())
        settings_.endGroup();
    SettingsGroup alternatives{&settings_, multi_settings_root_group};
    // get the current configuration name
    auto const &current_configuration_name =
        settings_.value(multi_settings_current_name_key, tr(default_string))
            .toString();
    // add the default configuration sub menu
    QMenu *default_menu = create_sub_menu(menu, current_configuration_name,
                                          configurations_group_);
    // and set as the current configuration
    default_menu->menuAction()->setChecked(true);

    // get the existing alternatives
    auto const &available_configurations = settings_.childGroups();

    // add all the other configurations
    for (auto const &configuration_name : available_configurations) {
        create_sub_menu(menu, configuration_name, configurations_group_);
    }

    if (current_group.size())
        settings_.beginGroup(current_group);

    if (name_change_emit_pending_) {
        Q_EMIT parent_->configurationNameChanged(unescape_ampersands(current_));
        name_change_emit_pending_ = false;
    }
}

// call this at the end of the main program loop to determine if the
// main window really wants to quit or to run again with a new configuration
bool MultiSettings::impl::exit() {
    // ensure that configuration name changed signal gets fired on restart
    name_change_emit_pending_ = true;

    // do any configuration swap required and return exit flag
    return reposition();
}

QMenu *MultiSettings::impl::create_sub_menu(QMenu *parent_menu,
                                            QString const &menu_title,
                                            QActionGroup *action_group) {
    auto sub_menu = parent_menu->addMenu(menu_title);
    if (action_group)
        action_group->addAction(sub_menu->menuAction());
    sub_menu->menuAction()->setCheckable(true);

    // populate sub-menu actions before showing
    connect(sub_menu, &QMenu::aboutToShow, [this, parent_menu, sub_menu]() {
        // depopulate before populating and showing because on Mac OS X
        // there is an issue with depopulating in QMenu::aboutToHide()
        // with connections being disconnected before they are actioned
        while (!sub_menu->actions().isEmpty()) {
            sub_menu->removeAction(sub_menu->actions().last());
        }

        bool is_current{sub_menu->menuAction()->text() == current_};
        if (!is_current) {
            auto select_action = new QAction{tr("&Switch To"), this};
            sub_menu->addAction(select_action);
            connect(select_action, &QAction::triggered, [this, sub_menu](bool) {
                select_configuration(sub_menu->title());
            });
            sub_menu->addSeparator();
        }

        auto clone_action = new QAction{tr("&Clone"), this};
        sub_menu->addAction(clone_action);
        connect(clone_action, &QAction::triggered,
                [this, parent_menu, sub_menu](bool) {
                    clone_configuration(parent_menu, sub_menu);
                });

        auto const &current_group = settings_.group();
        if (current_group.size())
            settings_.endGroup();
        SettingsGroup alternatives{&settings_, multi_settings_root_group};
        if (settings_.childGroups().size()) {
            auto clone_into_action = new QAction{tr("Clone &Into ..."), this};
            sub_menu->addAction(clone_into_action);
            connect(
                clone_into_action, &QAction::triggered,
                [this, sub_menu](bool) { clone_into_configuration(sub_menu); });
        }
        if (current_group.size())
            settings_.beginGroup(current_group);
        auto reset_action = new QAction{tr("R&eset"), this};
        sub_menu->addAction(reset_action);
        connect(reset_action, &QAction::triggered,
                [this, sub_menu](bool) { reset_configuration(sub_menu); });

        auto rename_action = new QAction{tr("&Rename ..."), this};
        sub_menu->addAction(rename_action);
        connect(rename_action, &QAction::triggered,
                [this, sub_menu](bool) { rename_configuration(sub_menu); });

        if (!is_current) {
            auto delete_action = new QAction{tr("&Delete"), this};
            sub_menu->addAction(delete_action);
            connect(delete_action, &QAction::triggered,
                    [this, sub_menu](bool) { delete_configuration(sub_menu); });
        }
    });

    return sub_menu;
}

auto MultiSettings::impl::get_settings() const -> Dictionary {
    Dictionary settings;
    for (auto const &key : settings_.allKeys()) {
        // filter out multi settings group and empty settings
        // placeholder
        if (!key.contains(multi_settings_root_group) &&
            !key.contains(multi_settings_place_holder_key)) {
            settings[key] = settings_.value(key);
        }
    }
    return settings;
}

void MultiSettings::impl::load_from(Dictionary const &dictionary,
                                    bool add_placeholder) {
    if (dictionary.size()) {
        for (Dictionary::const_iterator iter = dictionary.constBegin();
             iter != dictionary.constEnd(); ++iter) {
            settings_.setValue(iter.key(), iter.value());
        }
    } else if (add_placeholder) {
        // add a placeholder key to stop the alternative configuration
        // name from disappearing
        settings_.setValue(multi_settings_place_holder_key, QVariant{});
    }
    settings_.sync();
}

void MultiSettings::impl::select_configuration(QString const &target_name) {
    if (main_window_ && target_name != current_) {
        bool changed{false};
        {
            auto const &current_group = settings_.group();
            if (current_group.size())
                settings_.endGroup();
            // position to the alternative settings
            SettingsGroup alternatives{&settings_, multi_settings_root_group};
            if (settings_.childGroups().contains(target_name)) {
                changed = true;
                // save the target settings
                SettingsGroup target_group{&settings_, target_name};
                new_settings_ = get_settings();
            }
            if (current_group.size())
                settings_.beginGroup(current_group);
        }
        if (changed) {
            // and set up the restart
            current_ = target_name;
            Q_EMIT parent_->configurationNameChanged(
                unescape_ampersands(current_));
            restart(RepositionType::save_and_replace);
        }
    }
}

void MultiSettings::impl::clone_configuration(QMenu *parent_menu,
                                              QMenu const *menu) {
    auto const &current_group = settings_.group();
    if (current_group.size())
        settings_.endGroup();
    auto const &source_name = menu->title();

    // settings to clone
    Dictionary source_settings;
    if (source_name == current_) {
        // grab the data to clone from the current settings
        source_settings = get_settings();
    }
    SettingsGroup alternatives{&settings_, multi_settings_root_group};
    if (source_name != current_) {
        SettingsGroup source_group{&settings_, source_name};
        source_settings = get_settings();
    }

    // find a new unique name
    QString new_name_root{source_name + " - Copy"};
    ;
    QString new_name{new_name_root};
    unsigned index{0};
    do {
        if (index++)
            new_name = new_name_root + '(' + QString::number(index) + ')';
    } while (settings_.childGroups().contains(new_name) ||
             new_name == current_);
    SettingsGroup new_group{&settings_, new_name};
    load_from(source_settings);

    // insert the new configuration sub menu in the parent menu
    create_sub_menu(parent_menu, new_name, configurations_group_);
    if (current_group.size())
        settings_.beginGroup(current_group);
}

void MultiSettings::impl::clone_into_configuration(QMenu const *menu) {
    Q_ASSERT(main_window_);
    if (!main_window_)
        return;

    auto const &current_group = settings_.group();
    if (current_group.size())
        settings_.endGroup();
    auto const &target_name = menu->title();

    // get the current configuration name
    QString current_group_name;
    QStringList sources;
    {
        SettingsGroup alternatives{&settings_, multi_settings_root_group};
        current_group_name =
            settings_.value(multi_settings_current_name_key).toString();

        {
            // get the source configuration name for the clone
            sources = settings_.childGroups();
            sources << current_group_name;
            sources.removeOne(target_name);
        }
    }

    // pick a source configuration
    ExistingNameDialog dialog{sources, main_window_};
    if (sources.size() &&
        (1 == sources.size() || QDialog::Accepted == dialog.exec())) {
        QString source_name{1 == sources.size() ? sources.at(0)
                                                : dialog.name()};
        if (main_window_ &&
            JS8MessageBox::Yes ==
                JS8MessageBox::query_message(
                    main_window_, tr("Clone Into Configuration"),
                    tr("Confirm overwrite of all values for configuration "
                       "\"%1\" with values from \"%2\"?")
                        .arg(unescape_ampersands(target_name))
                        .arg(unescape_ampersands(source_name)))) {
            // grab the data to clone from
            if (source_name == current_group_name) {
                // grab the data to clone from the current settings
                new_settings_ = get_settings();
            } else {
                SettingsGroup alternatives{&settings_,
                                           multi_settings_root_group};
                SettingsGroup source_group{&settings_, source_name};
                new_settings_ = get_settings();
            }

            // purge target settings and replace
            if (target_name == current_) {
                // restart with new settings
                restart(RepositionType::replace);
            } else {
                SettingsGroup alternatives{&settings_,
                                           multi_settings_root_group};
                SettingsGroup target_group{&settings_, target_name};
                settings_.remove(QString{}); // purge entire group
                load_from(new_settings_);
                new_settings_.clear();
            }
        }
    }
    if (current_group.size())
        settings_.beginGroup(current_group);
}

void MultiSettings::impl::reset_configuration(QMenu const *menu) {
    Q_ASSERT(main_window_);
    if (!main_window_)
        return;

    auto const &target_name = menu->title();

    if (!main_window_ ||
        JS8MessageBox::Yes !=
            JS8MessageBox::query_message(
                main_window_, tr("Reset Configuration"),
                tr("Confirm reset to default values for configuration \"%1\"?")
                    .arg(unescape_ampersands(target_name)))) {
        return;
    }

    if (target_name == current_) {
        // restart with default settings
        new_settings_.clear();
        restart(RepositionType::replace);
    } else {
        auto const &current_group = settings_.group();
        if (current_group.size())
            settings_.endGroup();
        SettingsGroup alternatives{&settings_, multi_settings_root_group};
        SettingsGroup target_group{&settings_, target_name};
        settings_.remove(QString{}); // purge entire group
        // add a placeholder to stop alternative configuration name
        // being lost
        settings_.setValue(multi_settings_place_holder_key, QVariant{});
        settings_.sync();
        if (current_group.size())
            settings_.beginGroup(current_group);
    }
}

void MultiSettings::impl::rename_configuration(QMenu *menu) {
    Q_ASSERT(main_window_);
    if (!main_window_)
        return;

    auto const &current_group = settings_.group();
    if (current_group.size())
        settings_.endGroup();
    auto const &target_name = menu->title();

    // gather names we cannot use
    SettingsGroup alternatives{&settings_, multi_settings_root_group};
    auto invalid_names = settings_.childGroups();
    invalid_names
        << settings_.value(multi_settings_current_name_key).toString();

    // get the new name
    NameDialog dialog{target_name, invalid_names, main_window_};
    if (QDialog::Accepted == dialog.exec()) {
        if (target_name == current_) {
            settings_.setValue(multi_settings_current_name_key,
                               dialog.new_name());
            settings_.sync();
            current_ = dialog.new_name();
            Q_EMIT parent_->configurationNameChanged(
                unescape_ampersands(current_));
        } else {
            // switch to the target group and fetch the configuration data
            Dictionary target_settings;
            {
                // grab the target configuration settings
                SettingsGroup target_group{&settings_, target_name};
                target_settings = get_settings();
                // purge the old configuration data
                settings_.remove(QString{}); // purge entire group
            }
            // load into new configuration group name
            SettingsGroup target_group{&settings_, dialog.new_name()};
            load_from(target_settings);
        }
        // change the action text in the menu
        menu->setTitle(dialog.new_name());
    }
    if (current_group.size())
        settings_.beginGroup(current_group);
}

void MultiSettings::impl::delete_configuration(QMenu *menu) {
    Q_ASSERT(main_window_);
    auto const &target_name = menu->title();

    if (target_name == current_) {
        return; // suicide not allowed here
    } else {
        if (!main_window_ ||
            JS8MessageBox::Yes !=
                JS8MessageBox::query_message(
                    main_window_, tr("Delete Configuration"),
                    tr("Confirm deletion of configuration \"%1\"?")
                        .arg(unescape_ampersands(target_name)))) {
            return;
        }
        auto const &current_group = settings_.group();
        if (current_group.size())
            settings_.endGroup();
        SettingsGroup alternatives{&settings_, multi_settings_root_group};
        SettingsGroup target_group{&settings_, target_name};
        // purge the configuration data
        settings_.remove(QString{}); // purge entire group
        settings_.sync();
        if (current_group.size())
            settings_.beginGroup(current_group);
    }
    // update the menu
    menu->deleteLater();
}

void MultiSettings::impl::restart(RepositionType type) {
    Q_ASSERT(main_window_);
    reposition_type_ = type;
    exit_flag_ = false;
    main_window_->close();
    main_window_ = nullptr;
}