#include "RecordPanel.h"
#include "CustomDataRole.h"
#include "Pgsql_oids.h"
#include <QEvent>
#include <QFont>
#include <QFontDatabase>
#include <QFormLayout>
#include <QHBoxLayout>
#include <QLabel>
#include <QLineEdit>
#include <QPlainTextEdit>
#include <QToolButton>
#include <QVBoxLayout>

namespace {

constexpr int CollapsedTextLines = 2;
constexpr int ExpandedTextLines = 10;

bool isLongTextType(Oid oid)
{
	switch (oid) {
		case Pgsql::text_oid:
		case Pgsql::varchar_oid:
		case Pgsql::bpchar_oid:
		case Pgsql::json_oid:
		case Pgsql::jsonb_oid:
		case Pgsql::xml_oid:
			return true;
		default:
			return false;
	}
}

int textEditHeight(const QPlainTextEdit *edit, int lines)
{
	return edit->fontMetrics().lineSpacing() * lines + 2 * edit->frameWidth() + 6;
}

QString editorText(const QWidget *editor)
{
	if (auto line = qobject_cast<const QLineEdit *>(editor))
		return line->text();
	if (auto plain = qobject_cast<const QPlainTextEdit *>(editor))
		return plain->toPlainText();
	return {};
}

} // namespace

RecordPanel::RecordPanel(QWidget *parent)
	: QScrollArea(parent)
{
	setWidgetResizable(true);
}

void RecordPanel::setModel(QAbstractItemModel *model)
{
	if (m_model)
		m_model->disconnect(this);

	m_model = model;
	if (m_model) {
		connect(m_model, &QAbstractItemModel::dataChanged, this, &RecordPanel::refresh);
		connect(m_model, &QAbstractItemModel::layoutChanged, this, &RecordPanel::refresh);
		connect(m_model, &QAbstractItemModel::rowsInserted, this, &RecordPanel::refresh);
		connect(m_model, &QAbstractItemModel::rowsRemoved, this, &RecordPanel::refresh);
		connect(m_model, &QAbstractItemModel::modelReset, this, &RecordPanel::onModelReset);
	}
	onModelReset();
}

void RecordPanel::setFirstDataColumn(int column)
{
	m_firstDataColumn = column;
	clearFields();
	refresh();
}

void RecordPanel::setCurrentRow(int row)
{
	if (m_model && row >= 0 && row < m_model->rowCount())
		m_rowIndex = QPersistentModelIndex(m_model->index(row, 0));
	else
		m_rowIndex = QPersistentModelIndex();
	refresh();
}

void RecordPanel::onModelReset()
{
	m_rowIndex = QPersistentModelIndex();
	refresh();
}

void RecordPanel::refresh()
{
	if (!m_model || !m_rowIndex.isValid()) {
		clearFields();
		return;
	}

	int columns = m_model->columnCount() - m_firstDataColumn;
	if (columns < 0)
		columns = 0;
	if (m_fields.size() != static_cast<size_t>(columns))
		rebuild();

	for (auto &field : m_fields) {
		QModelIndex index = m_model->index(m_rowIndex.row(), field.column);
		bool editable = m_model->flags(index).testFlag(Qt::ItemIsEditable);
		QVariant value = index.data(Qt::EditRole);
		QString text;
		if (value.isValid() && !value.isNull()) {
			text = value.toString();
			// An empty string is shown as '' so it can be told apart from NULL, the placeholder shows NULL
			if (text.isEmpty())
				text = QStringLiteral("''");
		}
		showValue(field, text, editable);
	}
}

void RecordPanel::clearFields()
{
	m_fields.clear();
	if (QWidget *old = takeWidget())
		old->deleteLater();
}

void RecordPanel::rebuild()
{
	clearFields();

	auto content = new QWidget;
	auto outer = new QVBoxLayout(content);
	outer->setContentsMargins(0, 0, 0, 0);
	auto form = new QWidget(content);
	auto layout = new QFormLayout(form);
	layout->setFieldGrowthPolicy(QFormLayout::AllNonFixedFieldsGrow);

	int row = m_rowIndex.row();
	for (int column = m_firstDataColumn; column < m_model->columnCount(); ++column) {
		QString header = m_model->headerData(column, Qt::Horizontal, Qt::DisplayRole).toString();
		int newline = header.indexOf('\n');
		QString name = newline < 0 ? header : header.left(newline);
		QString typeName = newline < 0 ? QString() : header.mid(newline + 1);

		auto caption = new QWidget(form);
		auto captionLayout = new QVBoxLayout(caption);
		captionLayout->setContentsMargins(0, 0, 0, 0);
		auto nameLabel = new QLabel(name, caption);
		QFont nameFont = nameLabel->font();
		nameFont.setBold(true);
		nameLabel->setFont(nameFont);
		auto typeLabel = new QLabel(typeName, caption);
		captionLayout->addWidget(nameLabel);
		captionLayout->addWidget(typeLabel);

		Oid oid = m_model->index(row, column).data(CustomDataTypeRole).toUInt();
		FieldRow field;
		field.column = column;
		QWidget *fieldWidget = nullptr;

		if (isLongTextType(oid)) {
			auto container = new QWidget(form);
			auto containerLayout = new QVBoxLayout(container);
			containerLayout->setContentsMargins(0, 0, 0, 0);

			auto edit = new QPlainTextEdit(container);
			edit->setFont(QFontDatabase::systemFont(QFontDatabase::FixedFont));
			edit->setPlaceholderText(tr("null"));
			edit->setFixedHeight(textEditHeight(edit, CollapsedTextLines));
			edit->installEventFilter(this);

			auto expand = new QToolButton(container);
			expand->setCheckable(true);
			expand->setArrowType(Qt::DownArrow);
			expand->setToolTip(tr("Expand or collapse the value"));
			connect(expand, &QToolButton::toggled, edit, [edit, expand](bool expanded) {
				edit->setFixedHeight(textEditHeight(edit, expanded ? ExpandedTextLines : CollapsedTextLines));
				expand->setArrowType(expanded ? Qt::UpArrow : Qt::DownArrow);
			});

			auto buttonRow = new QHBoxLayout;
			buttonRow->addStretch();
			buttonRow->addWidget(expand);
			containerLayout->addWidget(edit);
			containerLayout->addLayout(buttonRow);

			field.editor = edit;
			field.expandButton = expand;
			fieldWidget = container;
		}
		else {
			auto edit = new QLineEdit(form);
			edit->setPlaceholderText(tr("null"));
			connect(edit, &QLineEdit::editingFinished, this, [this, edit]() { commitEditor(edit); });

			field.editor = edit;
			fieldWidget = edit;
		}

		layout->addRow(caption, fieldWidget);
		m_fields.push_back(field);
	}

	outer->addWidget(form);
	outer->addStretch(1);

	setWidget(content);
}

void RecordPanel::showValue(FieldRow &field, const QString &text, bool editable)
{
	QWidget *editor = field.editor;
	if (auto line = qobject_cast<QLineEdit *>(editor))
		line->setReadOnly(!editable);
	else if (auto plain = qobject_cast<QPlainTextEdit *>(editor))
		plain->setReadOnly(!editable);

	// Do not replace the text while the user is typing in it
	if (editor->hasFocus())
		return;

	if (auto line = qobject_cast<QLineEdit *>(editor))
		line->setText(text);
	else if (auto plain = qobject_cast<QPlainTextEdit *>(editor))
		plain->setPlainText(text);
	field.original = text;
}

void RecordPanel::commitEditor(QWidget *editor)
{
	if (m_updating || !m_model || !m_rowIndex.isValid())
		return;

	FieldRow *field = findField(editor);
	if (!field)
		return;

	QString text = editorText(editor);
	if (text == field->original)
		return;

	QModelIndex index = m_model->index(m_rowIndex.row(), field->column);
	if (!m_model->flags(index).testFlag(Qt::ItemIsEditable))
		return;

	m_updating = true;
	m_model->setData(index, text, Qt::EditRole);
	m_updating = false;

	// The model may have rebuilt the fields while storing the value, so look the field up again
	if (FieldRow *updated = findField(editor))
		updated->original = text;
}

RecordPanel::FieldRow *RecordPanel::findField(QWidget *editor)
{
	for (auto &field : m_fields) {
		if (field.editor == editor)
			return &field;
	}
	return nullptr;
}

bool RecordPanel::eventFilter(QObject *watched, QEvent *event)
{
	if (event->type() == QEvent::FocusOut) {
		if (auto edit = qobject_cast<QPlainTextEdit *>(watched))
			commitEditor(edit);
	}
	return QScrollArea::eventFilter(watched, event);
}