#include "CompletionPopup.h"
#include <QApplication>
#include <QPainter>
#include <QScreen>
#include <QStyledItemDelegate>

namespace {

constexpr int DetailRole = Qt::UserRole + 1;
constexpr int AmbiguousRole = Qt::UserRole + 2;

class CompletionDelegate : public QStyledItemDelegate {
public:
	using QStyledItemDelegate::QStyledItemDelegate;

	void paint(QPainter *painter, const QStyleOptionViewItem &option, const QModelIndex &index) const override
	{
		QStyleOptionViewItem opt = option;
		initStyleOption(&opt, index);
		const QString display = opt.text;
		opt.text.clear();
		const QWidget *w = opt.widget;
		(w ? w->style() : QApplication::style())->drawControl(QStyle::CE_ItemViewItem, &opt, painter, w);

		const bool selected = opt.state & QStyle::State_Selected;
		const QPalette &pal = opt.palette;
		const QString detail = index.data(DetailRole).toString();
		const bool ambiguous = index.data(AmbiguousRole).toBool();

		painter->save();
		painter->setPen(selected ? pal.highlightedText().color() : pal.text().color());
		QRect r = opt.rect.adjusted(4, 0, -4, 0);
		painter->drawText(r, Qt::AlignVCenter | Qt::AlignLeft, display);
		if (!detail.isEmpty()) {
			const int x = painter->fontMetrics().horizontalAdvance(display) + 12;
			QColor dim = selected ? pal.highlightedText().color() : pal.color(QPalette::Disabled, QPalette::Text);
			painter->setPen(dim);
			if (ambiguous) {
				QFont f = painter->font();
				f.setBold(true);
				painter->setFont(f);
			}
			painter->drawText(r.adjusted(x, 0, 0, 0), Qt::AlignVCenter | Qt::AlignLeft, QStringLiteral("\u2014 ") + detail);
		}
		painter->restore();
	}

	QSize sizeHint(const QStyleOptionViewItem &option, const QModelIndex &index) const override
	{
		QSize s = QStyledItemDelegate::sizeHint(option, index);
		const QFontMetrics fm(option.font);
		s.setWidth(fm.horizontalAdvance(index.data(Qt::DisplayRole).toString())
			+ fm.horizontalAdvance(index.data(DetailRole).toString()) + 40);
		return s;
	}
};

} // namespace

CompletionPopup::CompletionPopup(QWidget *parent)
	: QListWidget(parent)
{
	setWindowFlags(Qt::ToolTip);
	setAttribute(Qt::WA_ShowWithoutActivating);
	setFocusPolicy(Qt::NoFocus);
	setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
	setUniformItemSizes(true);
	setItemDelegate(new CompletionDelegate(this));
	connect(this, &QListWidget::itemClicked, this, [this](QListWidgetItem *item) {
		emit itemAccepted(row(item));
	});
}

void CompletionPopup::setItems(const std::vector<EditorCompletionItem> &items)
{
	clear();
	int width = 150;
	const QFontMetrics fm(font());
	for (const auto &i : items) {
		auto *item = new QListWidgetItem(i.display, this);
		item->setData(DetailRole, i.detail);
		item->setData(AmbiguousRole, i.ambiguous);
		width = std::max(width, fm.horizontalAdvance(i.display) + fm.horizontalAdvance(i.detail) + 50);
	}
	if (!items.empty())
		setCurrentRow(0);
	const int rows = static_cast<int>(std::min<size_t>(items.size(), 10));
	const int rowHeight = fm.height() + 6;
	resize(std::min(width, 600), rows * rowHeight + 2 * frameWidth() + 2);
}

void CompletionPopup::moveSelection(int delta)
{
	const int n = count();
	if (n == 0)
		return;
	int r = QListWidget::currentRow() + delta;
	r = std::clamp(r, 0, n - 1);
	setCurrentRow(r);
}

void CompletionPopup::showAt(const QPoint &globalPos)
{
	QPoint p = globalPos;
	if (auto *screen = QApplication::screenAt(globalPos)) {
		const QRect avail = screen->availableGeometry();
		if (p.x() + width() > avail.right())
			p.setX(std::max(avail.left(), avail.right() - width()));
	}
	move(p);
	show();
}