#include <DataSource/DataSourceWidget.h>

#include <ui_DataSourceWidget.h>

#include <DataSource/DataSourceItem.h>
#include <DataSource/DataSourceTreeWidgetHelper.h>
#include <DataSource/DataSourceTreeWidgetItem.h>

#include <QMenu>

namespace
{

/// Number of columns displayed in the tree
const auto TREE_NB_COLUMNS = 1;

/// Header labels for the tree
const auto TREE_HEADER_LABELS = QStringList { QObject::tr("Name") };

/**
 * Creates the item associated to a data source
 * @param dataSource the data source for which to create the item
 * @return the new item
 */
DataSourceTreeWidgetItem* createTreeWidgetItem(DataSourceItem* dataSource)
{
    // Creates item for the data source
    auto item = new DataSourceTreeWidgetItem { dataSource };
    // Generates items for the children of the data source
    std::for_each(dataSource->cbegin(), dataSource->cend(),
        [&item](const std::unique_ptr<DataSourceItem>& child) {
            item->addChild(createTreeWidgetItem(child.get()));
        });
    return item;
}

} // namespace

DataSourceWidget::DataSourceWidget(QWidget* parent)
        : QWidget { parent }
        , ui { new Ui::DataSourceWidget }
        , m_Root { std::make_unique<DataSourceItem>(
              DataSourceItemType::NODE, QStringLiteral("Sources")) }
{
    ui->setupUi(this);

    // Set tree properties
    ui->treeWidget->setColumnCount(TREE_NB_COLUMNS);
    ui->treeWidget->setHeaderLabels(TREE_HEADER_LABELS);
    ui->treeWidget->setContextMenuPolicy(Qt::CustomContextMenu);

    // Connection to show a menu when right clicking on the tree
    connect(ui->treeWidget, &QTreeWidget::customContextMenuRequested, this,
        &DataSourceWidget::onTreeMenuRequested);

    // Connection to filter tree
    connect(ui->filterLineEdit, &QLineEdit::textChanged, this, &DataSourceWidget::filterChanged);

    // First init
    updateTreeWidget();
}

DataSourceWidget::~DataSourceWidget() noexcept
{
    delete ui;
}

void DataSourceWidget::addDataSource(DataSourceItem* dataSource) noexcept
{
    // Merges the data source (without taking its root)
    if (dataSource)
    {
        std::for_each(std::cbegin(*dataSource), std::cend(*dataSource),
            [this](const auto& child) { this->m_Root->merge(*child.get()); });
        updateTreeWidget();
    }
}

void DataSourceWidget::updateTreeWidget() noexcept
{
    ui->treeWidget->clear();

    auto rootItem = createTreeWidgetItem(m_Root.get());
    ui->treeWidget->addTopLevelItem(rootItem);
    rootItem->setExpanded(true);

    // Sorts tree
    ui->treeWidget->setSortingEnabled(true);
    ui->treeWidget->sortByColumn(0, Qt::AscendingOrder);
}

void DataSourceWidget::filterChanged(const QString& text) noexcept
{
    auto validateItem = [&text](const DataSourceTreeWidgetItem& item) {
        auto regExp = QRegExp { text, Qt::CaseInsensitive, QRegExp::Wildcard };

        // An item is valid if any of its metadata validates the text filter
        auto itemMetadata = item.data()->data();
        auto itemMetadataEnd = itemMetadata.cend();
        auto acceptFilter
            = [&regExp](const auto& variant) { return variant.toString().contains(regExp); };

        return std::find_if(itemMetadata.cbegin(), itemMetadataEnd, acceptFilter)
            != itemMetadataEnd;
    };

    // Applies filter on tree widget
    DataSourceTreeWidgetHelper::filter(*ui->treeWidget, validateItem);
}

void DataSourceWidget::onTreeMenuRequested(const QPoint& pos) noexcept
{
    // Retrieves the selected item in the tree, and build the menu from its actions
    if (auto selectedItem = dynamic_cast<DataSourceTreeWidgetItem*>(ui->treeWidget->itemAt(pos)))
    {
        QMenu treeMenu {};
        treeMenu.addActions(selectedItem->actions());

        if (!treeMenu.isEmpty())
        {
            treeMenu.exec(QCursor::pos());
        }
    }
}