/*
This file is part of Telegram Desktop,
the official desktop application for the Telegram messaging service.

For license and copyright information please follow this link:
https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
*/
#include "boxes/language_box.h"

#include "lang/lang_keys.h"
#include "ui/widgets/checkbox.h"
#include "ui/widgets/buttons.h"
#include "ui/widgets/labels.h"
#include "ui/widgets/multi_select.h"
#include "ui/widgets/scroll_area.h"
#include "ui/text/text_entity.h"
#include "ui/wrap/vertical_layout.h"
#include "ui/wrap/slide_wrap.h"
#include "ui/effects/ripple_animation.h"
#include "ui/text_options.h"
#include "storage/localstorage.h"
#include "boxes/confirm_box.h"
#include "mainwidget.h"
#include "mainwindow.h"
#include "messenger.h"
#include "lang/lang_instance.h"
#include "lang/lang_cloud_manager.h"
#include "styles/style_boxes.h"
#include "styles/style_passport.h"

namespace {

using Language = Lang::Language;
using Languages = Lang::CloudManager::Languages;

class Rows : public Ui::RpWidget {
public:
	Rows(QWidget *parent, const Languages &data, const QString &chosen);

	void filter(const QString &query);

	int count() const;
	int selected() const;
	void setSelected(int selected);
	rpl::producer<int> selections() const;

	void activateSelected();
	rpl::producer<Language> activations() const;

	Ui::ScrollToRequest rowScrollRequest(int index) const;

protected:
	int resizeGetHeight(int newWidth) override;

	void paintEvent(QPaintEvent *e) override;
	void mouseMoveEvent(QMouseEvent *e) override;
	void mousePressEvent(QMouseEvent *e) override;
	void mouseReleaseEvent(QMouseEvent *e) override;
	void leaveEventHook(QEvent *e) override;

private:
	struct Row {
		Language data;
		Text title = { st::boxWideWidth / 2 };
		Text description = { st::boxWideWidth / 2 };
		int top = 0;
		int height = 0;
		mutable std::unique_ptr<Ui::RippleAnimation> ripple;
		int titleHeight = 0;
		int descriptionHeight = 0;
		QStringList keywords;
	};

	void updateSelected(int selected);
	void updatePressed(int pressed);
	Rows::Row &rowByIndex(int index);
	const Rows::Row &rowByIndex(int index) const;
	int countAvailableWidth() const;
	int countAvailableWidth(int newWidth) const;
	void repaint(int index);
	void repaint(const Row &row);
	void repaintChecked(not_null<Row*> row);
	void activateByIndex(int index);

	std::vector<Row> _rows;
	std::vector<not_null<Row*>> _filtered;
	int _selected = -1;
	int _pressed = -1;
	QString _chosen;
	QStringList _query;

	bool _mouseSelection = false;
	QPoint _globalMousePosition;

	rpl::event_stream<int> _selections;
	rpl::event_stream<Language> _activations;

};

class Content : public Ui::RpWidget {
public:
	Content(
		QWidget *parent,
		const Languages &official,
		const Languages &unofficial);

	Ui::ScrollToRequest jump(int rows);
	void filter(const QString &query);
	rpl::producer<Language> activations() const;
	void activateBySubmit();

private:
	void setupContent(
		const Languages &official,
		const Languages &unofficial);

	Fn<Ui::ScrollToRequest(int rows)> _jump;
	Fn<void(const QString &query)> _filter;
	Fn<rpl::producer<Language>()> _activations;
	Fn<void()> _activateBySubmit;

};

Rows::Rows(QWidget *parent, const Languages &data, const QString &chosen)
: RpWidget(parent)
, _chosen(chosen) {
	const auto descriptionOptions = TextParseOptions{
		TextParseMultiline,
		0,
		0,
		Qt::LayoutDirectionAuto
	};
	_rows.reserve(data.size());
	for (const auto &item : data) {
		_rows.push_back(Row{ item });
		auto &row = _rows.back();
		row.title.setText(
			st::semiboldTextStyle,
			item.nativeName,
			Ui::NameTextOptions());
		row.description.setText(
			st::defaultTextStyle,
			item.name,
			descriptionOptions);
		row.keywords = TextUtilities::PrepareSearchWords(
			item.name + ' ' + item.nativeName);
	}
	resizeToWidth(width());
	setAttribute(Qt::WA_MouseTracking);
	update();
}

void Rows::mouseMoveEvent(QMouseEvent *e) {
	const auto position = e->globalPos();
	if (!_mouseSelection && position == _globalMousePosition) {
		return;
	}
	_mouseSelection = true;
	_globalMousePosition = position;
	const auto index = [&] {
		const auto y = e->pos().y();
		if (y < 0) {
			return -1;
		}
		for (auto i = 0, till = count(); i != till; ++i) {
			const auto &row = rowByIndex(i);
			if (row.top + row.height > y) {
				return i;
			}
		}
		return -1;
	}();
	updateSelected(index);
}

void Rows::mousePressEvent(QMouseEvent *e) {
	updatePressed(_selected);
	if (_pressed >= 0) {
		auto &row = rowByIndex(_pressed);
		if (!row.ripple) {
			auto mask = Ui::RippleAnimation::rectMask({
				width(),
				row.height
				});
			row.ripple = std::make_unique<Ui::RippleAnimation>(
				st::defaultRippleAnimation,
				std::move(mask),
				[=, row = &row] { repaintChecked(row); });
		}
		row.ripple->add(e->pos() - QPoint(0, row.top));
	}
}

void Rows::mouseReleaseEvent(QMouseEvent *e) {
	const auto pressed = _pressed;
	updatePressed(-1);
	if (pressed == _selected && pressed >= 0) {
		activateByIndex(_selected);
	}
}

void Rows::activateByIndex(int index) {
	_activations.fire_copy(rowByIndex(index).data);
}

void Rows::leaveEventHook(QEvent *e) {
	updateSelected(-1);
}

void Rows::filter(const QString &query) {
	updateSelected(-1);
	updatePressed(-1);

	_query = TextUtilities::PrepareSearchWords(query);

	const auto skip = [](
			const QStringList &haystack,
			const QStringList &needles) {
		const auto find = [](
				const QStringList &haystack,
				const QString &needle) {
			for (const auto &item : haystack) {
				if (item.startsWith(needle)) {
					return true;
				}
			}
			return false;
		};
		for (const auto &needle : needles) {
			if (!find(haystack, needle)) {
				return true;
			}
		}
		return false;
	};

	if (!_query.isEmpty()) {
		_filtered.clear();
		_filtered.reserve(_rows.size());
		for (auto &row : _rows) {
			if (!skip(row.keywords, _query)) {
				_filtered.push_back(&row);
			} else {
				row.ripple = nullptr;
			}
		}
	}

	resizeToWidth(width());
	Ui::SendPendingMoveResizeEvents(this);
}

int Rows::count() const {
	return _query.isEmpty() ? _rows.size() : _filtered.size();
}

int Rows::selected() const {
	const auto limit = count();
	return (_selected >= 0 && _selected < limit) ? _selected : -1;
}

void Rows::activateSelected() {
	const auto index = selected();
	if (index >= 0) {
		activateByIndex(index);
	}
}

rpl::producer<Language> Rows::activations() const {
	return _activations.events();
}

void Rows::setSelected(int selected) {
	_mouseSelection = false;
	const auto limit = count();
	updateSelected((selected >= 0 && selected < limit) ? selected : -1);
}

rpl::producer<int> Rows::selections() const {
	return _selections.events();
}

void Rows::repaint(int index) {
	if (index >= 0) {
		repaint(rowByIndex(index));
	}
}

void Rows::repaint(const Row &row) {
	update(0, row.top, width(), row.height);
}

void Rows::repaintChecked(not_null<Row*> row) {
	const auto found = (ranges::find(_filtered, row) != end(_filtered));
	if (_query.isEmpty() || found) {
		repaint(*row);
	}
}

void Rows::updateSelected(int selected) {
	repaint(_selected);
	_selected = selected;
	repaint(_selected);
	_selections.fire_copy(_selected);
}

void Rows::updatePressed(int pressed) {
	if (_pressed >= 0) {
		if (const auto ripple = rowByIndex(_pressed).ripple.get()) {
			ripple->lastStop();
		}
	}
	_pressed = pressed;
}

Rows::Row &Rows::rowByIndex(int index) {
	Expects(index >= 0 && index < count());

	return _query.isEmpty() ? _rows[index] : *_filtered[index];
}

const Rows::Row &Rows::rowByIndex(int index) const {
	Expects(index >= 0 && index < count());

	return _query.isEmpty() ? _rows[index] : *_filtered[index];
}

Ui::ScrollToRequest Rows::rowScrollRequest(int index) const {
	const auto &row = rowByIndex(index);
	return Ui::ScrollToRequest(row.top, row.top + row.height);
}

int Rows::resizeGetHeight(int newWidth) {
	const auto availableWidth = countAvailableWidth(newWidth);
	auto result = 0;
	for (auto i = 0, till = count(); i != till; ++i) {
		auto &row = rowByIndex(i);
		row.top = result;
		row.titleHeight = row.title.countHeight(availableWidth);
		row.descriptionHeight = row.description.countHeight(availableWidth);
		row.height = st::passportRowPadding.top()
			+ row.titleHeight
			+ st::passportRowSkip
			+ row.descriptionHeight
			+ st::passportRowPadding.bottom();
		result += row.height;
	}
	return result;
}

int Rows::countAvailableWidth(int newWidth) const {
	return newWidth
		- st::passportRowPadding.left()
		- st::passportRowPadding.right()
		- st::passportRowReadyIcon.width()
		- st::passportRowIconSkip;
}

int Rows::countAvailableWidth() const {
	return countAvailableWidth(width());
}

void Rows::paintEvent(QPaintEvent *e) {
	Painter p(this);

	const auto ms = getms();
	const auto clip = e->rect();

	const auto left = st::passportRowPadding.left();
	const auto availableWidth = countAvailableWidth();
	for (auto i = 0, till = count(); i != till; ++i) {
		const auto &row = rowByIndex(i);
		if (row.top + row.height <= clip.y()) {
			continue;
		} else if (row.top >= clip.y() + clip.height()) {
			break;
		}
		p.translate(0, row.top);
		const auto guard = gsl::finally([&] { p.translate(0, -row.top); });

		const auto selected = (_selected == i);
		if (selected) {
			p.fillRect(0, 0, width(), row.height, st::windowBgOver);
		}

		if (row.ripple) {
			row.ripple->paint(p, 0, 0, width(), ms);
			if (row.ripple->empty()) {
				row.ripple.reset();
			}
		}

		auto top = st::passportRowPadding.top();

		p.setPen(st::passportRowTitleFg);
		row.title.drawLeft(p, left, top, availableWidth, width());
		top += row.titleHeight + st::passportRowSkip;

		p.setPen(selected ? st::windowSubTextFgOver : st::windowSubTextFg);
		row.description.drawLeft(p, left, top, availableWidth, width());
		top += row.descriptionHeight + st::passportRowPadding.bottom();

		if (row.data.id == _chosen) {
			const auto &icon = st::passportRowReadyIcon;
			icon.paint(
				p,
				width() - st::passportRowPadding.right() - icon.width(),
				(row.height - icon.height()) / 2,
				width());
		}
	}
}

Content::Content(
	QWidget *parent,
	const Languages &official,
	const Languages &unofficial)
: RpWidget(parent) {
	setupContent(official, unofficial);
}

void Content::setupContent(
		const Languages &official,
		const Languages &unofficial) {
	const auto current = Lang::LanguageIdOrDefault(Lang::Current().id());
	const auto content = Ui::CreateChild<Ui::VerticalLayout>(this);
	const auto primary = content->add(
		object_ptr<Ui::SlideWrap<Ui::VerticalLayout>>(
			content,
			object_ptr<Ui::VerticalLayout>(content)));
	const auto container = primary->entity();
	container->add(object_ptr<Ui::FixedHeightWidget>(
		container,
		st::boxVerticalMargin));
	const auto main = container->add(object_ptr<Rows>(
		container,
		official,
		current));
	container->add(object_ptr<Ui::FixedHeightWidget>(
		container,
		st::boxVerticalMargin));
	const auto additional = !unofficial.isEmpty()
		? content->add(object_ptr<Ui::SlideWrap<Ui::VerticalLayout>>(
			content,
			object_ptr<Ui::VerticalLayout>(content)))
		: nullptr;
	const auto inner = additional ? additional->entity() : nullptr;
	const auto divider = inner
		? inner->add(object_ptr<Ui::SlideWrap<BoxContentDivider>>(
			inner,
			object_ptr<BoxContentDivider>(inner)))
		: nullptr;
	const auto label = inner
		? inner->add(
			object_ptr<Ui::FlatLabel>(
				inner,
				Lang::Viewer(lng_languages_unofficial),
				st::passportFormHeader),
			st::passportFormHeaderPadding)
		: nullptr;
	const auto other = inner
		? inner->add(object_ptr<Rows>(inner, unofficial, current))
		: nullptr;
	if (inner) {
		inner->add(object_ptr<Ui::FixedHeightWidget>(
			inner,
			st::boxVerticalMargin));
	}
	Ui::ResizeFitChild(this, content);

	using namespace rpl::mappers;
	auto nonempty = [](Rows *rows) {
		return rows->heightValue(
		) | rpl::map(
			_1 > 0
		) | rpl::distinct_until_changed(
		);
	};
	nonempty(main) | rpl::start_with_next([=](bool nonempty) {
		primary->toggle(nonempty, anim::type::instant);
	}, main->lifetime());
	if (other) {
		nonempty(other) | rpl::start_with_next([=](bool nonempty) {
			additional->toggle(nonempty, anim::type::instant);
		}, other->lifetime());

		rpl::combine(
			nonempty(main),
			nonempty(other),
			_1 && _2
		) | rpl::start_with_next([=](bool nonempty) {
			divider->toggle(nonempty, anim::type::instant);
		}, divider->lifetime());

		const auto excludeSelections = [](Rows *a, Rows *b) {
			a->selections(
			) | rpl::filter(
				_1 >= 0
			) | rpl::start_with_next([=] {
				b->setSelected(-1);
			}, a->lifetime());
		};
		excludeSelections(main, other);
		excludeSelections(other, main);
	}

	const auto rowsCount = [=] {
		return main->count() + (other ? other->count() : 0);
	};
	const auto selectedIndex = [=] {
		if (const auto index = main->selected(); index >= 0) {
			return index;
		}
		const auto index = other ? other->selected() : -1;
		return (index >= 0) ? (main->count() + index) : -1;
	};
	const auto setSelectedIndex = [=](int index) {
		const auto count = main->count();
		if (index >= count) {
			main->setSelected(-1);
			if (other) {
				other->setSelected(index - count);
			}
		} else {
			main->setSelected(index);
			if (other) {
				other->setSelected(-1);
			}
		}
	};
	const auto selectedCoords = [=] {
		const auto coords = [=](Rows *rows, int index) {
			const auto result = rows->rowScrollRequest(index);
			const auto shift = rows->mapToGlobal({ 0, 0 }).y()
				- mapToGlobal({ 0, 0 }).y();
			return Ui::ScrollToRequest(
				result.ymin + shift,
				result.ymax + shift);
		};
		if (const auto index = main->selected(); index >= 0) {
			return coords(main, index);
		}
		const auto index = other ? other->selected() : -1;
		if (index >= 0) {
			return coords(other, index);
		}
		return Ui::ScrollToRequest(-1, -1);
	};
	_jump = [=](int rows) {
		const auto count = rowsCount();
		const auto now = selectedIndex();
		if (now >= 0) {
			const auto changed = now + rows;
			if (changed < 0) {
				setSelectedIndex((now > 0) ? 0 : -1);
			} else if (changed >= count) {
				setSelectedIndex(count - 1);
			} else {
				setSelectedIndex(changed);
			}
		} else if (rows > 0) {
			setSelectedIndex(0);
		}
		return selectedCoords();
	};
	_filter = [=](const QString &query) {
		main->filter(query);
		if (other) {
			other->filter(query);
		}
	};
	_activations = [=] {
		if (!other) {
			return main->activations();
		}
		return rpl::merge(
			main->activations(),
			other->activations()
		) | rpl::type_erased();
	};
	_activateBySubmit = [=] {
		if (selectedIndex() < 0) {
			_jump(1);
		}
		main->activateSelected();
		if (other) {
			other->activateSelected();
		}
	};
}

void Content::filter(const QString &query) {
	_filter(query);
}

rpl::producer<Language> Content::activations() const {
	return _activations();
}

void Content::activateBySubmit() {
	_activateBySubmit();
}

Ui::ScrollToRequest Content::jump(int rows) {
	return _jump(rows);
}

} // namespace

void LanguageBox::prepare() {
	addButton(langFactory(lng_box_ok), [=] { closeBox(); });

	setTitle(langFactory(lng_languages));

	const auto select = createMultiSelect();

	const auto current = Lang::LanguageIdOrDefault(Lang::Current().id());
	auto official = Lang::CurrentCloudManager().languageList();
	if (official.isEmpty()) {
		official.push_back({ "en", "English", "English" });
	}
	ranges::stable_partition(official, [&](const Language &language) {
		return (language.id == current);
	});
	ranges::stable_partition(official, [&](const Language &language) {
		return (language.id == current) || (language.id == "en");
	});
	const auto foundInOfficial = [&](const Language &language) {
		return ranges::find(official, language.id, [](const Language &v) {
			return v.id;
		}) != official.end();
	};
	auto unofficial = Local::readRecentLanguages();
	unofficial.erase(
		ranges::remove_if(
			unofficial,
			foundInOfficial),
		unofficial.end());
	ranges::stable_partition(unofficial, [&](const Language &language) {
		return (language.id == current);
	});
	if (official.front().id != current
		&& (unofficial.isEmpty() || unofficial.front().id != current)) {
		const auto name = (current == "#custom")
			? "Custom lang pack"
			: lang(lng_language_name);
		unofficial.push_back({
			current,
			QString(),
			QString(),
			name,
			lang(lng_language_name)
		});
	}

	using namespace rpl::mappers;

	const auto inner = setInnerWidget(
		object_ptr<Content>(this, official, unofficial),
		st::boxLayerScroll,
		select->height());
	inner->resizeToWidth(st::langsWidth);

	const auto max = lifetime().make_state<int>(0);
	rpl::combine(
		inner->heightValue(),
		select->heightValue(),
		_1 + _2
	) | rpl::start_with_next([=](int height) {
		accumulate_max(*max, height);
		setDimensions(st::langsWidth, qMin(*max, st::boxMaxListHeight));
	}, inner->lifetime());

	select->setSubmittedCallback([=](Qt::KeyboardModifiers) {
		inner->activateBySubmit();
	});
	select->setQueryChangedCallback([=](const QString &query) {
		inner->filter(query);
	});
	select->setCancelledCallback([=] {
		select->clearQuery();
	});

	inner->activations(
	) | rpl::start_with_next([=](const Language &language) {
		// "#custom" is applied each time it's passed to switchToLanguage().
		// So we check that the language really has changed.
		if (language.id != Lang::Current().id()) {
			Lang::CurrentCloudManager().switchToLanguage(
				language.id,
				language.pluralId,
				language.baseId);
		}
	}, inner->lifetime());

	_setInnerFocus = [=] {
		select->setInnerFocus();
	};
	_jump = [=](int rows) {
		return inner->jump(rows);
	};
}

void LanguageBox::keyPressEvent(QKeyEvent *e) {
	const auto key = e->key();
	const auto selected = [&] {
		if (key == Qt::Key_Up) {
			return _jump(-1);
		} else if (key == Qt::Key_Down) {
			return _jump(1);
		} else if (key == Qt::Key_PageUp) {
			return _jump(-rowsInPage());
		} else if (key == Qt::Key_PageDown) {
			return _jump(rowsInPage());
		}
		return Ui::ScrollToRequest(-1, -1);
	}();
	if (selected.ymin >= 0 && selected.ymax >= 0) {
		onScrollToY(selected.ymin, selected.ymax);
	}
}

int LanguageBox::rowsInPage() const {
	const auto rowHeight = st::passportRowPadding.top()
		+ st::semiboldFont->height
		+ st::passportRowSkip
		+ st::normalFont->height
		+ st::passportRowPadding.bottom();
	return std::max(height() / rowHeight, 1);
}

void LanguageBox::setInnerFocus() {
	_setInnerFocus();
}

not_null<Ui::MultiSelect*> LanguageBox::createMultiSelect() {
	const auto result = Ui::CreateChild<Ui::MultiSelect>(
		this,
		st::contactsMultiSelect,
		langFactory(lng_participant_filter));
	result->resizeToWidth(st::langsWidth);
	result->moveToLeft(0, 0);
	return result;
}

base::binary_guard LanguageBox::Show() {
	auto result = base::binary_guard();

	const auto manager = Messenger::Instance().langCloudManager();
	if (manager->languageList().isEmpty()) {
		auto guard = std::make_shared<base::binary_guard>();
		std::tie(result, *guard) = base::make_binary_guard();
		auto alive = std::make_shared<std::unique_ptr<base::Subscription>>(
			std::make_unique<base::Subscription>());
		**alive = manager->languageListChanged().add_subscription([=] {
			const auto show = guard->alive();
			*alive = nullptr;
			if (show) {
				Ui::show(Box<LanguageBox>());
			}
		});
	} else {
		Ui::show(Box<LanguageBox>());
	}
	manager->requestLanguageList();

	return result;
}