// This file is part of Desktop App Toolkit,
// a set of libraries for developing nice desktop applications.
//
// For license and copyright information please follow this link:
// https://github.com/desktop-app/legal/blob/master/LEGAL
//
#include "ui/style/style_core_font.h"

#include "base/algorithm.h"
#include "base/debug_log.h"
#include "base/variant.h"
#include "base/base_file_utilities.h"
#include "ui/integration.h"

#include <QtCore/QMap>
#include <QtCore/QVector>
#include <QtGui/QFontInfo>
#include <QtGui/QFontDatabase>
#include <QtWidgets/QApplication>

void style_InitFontsResource() {
#ifdef Q_OS_MAC // Use resources from the .app bundle on macOS.

	base::RegisterBundledResources(u"lib_ui.rcc"_q);

#else // Q_OS_MAC

#ifndef LIB_UI_USE_PACKAGED_FONTS
	Q_INIT_RESOURCE(fonts);
#endif // !LIB_UI_USE_PACKAGED_FONTS
#ifdef Q_OS_WIN
	Q_INIT_RESOURCE(win);
#endif // Q_OS_WIN

#endif // Q_OS_MAC
}

namespace style {
namespace {

CustomFont Custom;

} // namespace

void SetCustomFont(const CustomFont &font) {
	Custom = font;
}

namespace internal {
namespace {

#ifndef LIB_UI_USE_PACKAGED_FONTS
const auto FontTypes = std::array{
	std::make_pair(u"OpenSans-Regular"_q, FontFlags()),
	std::make_pair(u"OpenSans-Italic"_q, FontItalic),
	std::make_pair(u"OpenSans-SemiBold"_q, FontSemibold),
	std::make_pair(u"OpenSans-SemiBoldItalic"_q, FontFlags(FontSemibold | FontItalic)),
};
const auto PersianFontTypes = std::array{
	std::make_pair(u"Vazirmatn-UI-NL-Regular"_q, FontFlags()),
	std::make_pair(u"Vazirmatn-UI-NL-SemiBold"_q, FontSemibold),
};
#endif // !LIB_UI_USE_PACKAGED_FONTS

bool Started = false;
QString FontOverride;

QMap<QString, int> fontFamilyMap;
QVector<QString> fontFamilies;
QMap<uint32, FontData*> fontsMap;

uint32 fontKey(int size, uint32 flags, int family) {
	return (((uint32(family) << 12) | uint32(size)) << 6) | flags;
}

bool ValidateFont(const QString &familyName, int flags = 0) {
	QFont checkFont(familyName);
	checkFont.setWeight(((flags & FontBold) || (flags & FontSemibold))
		? QFont::DemiBold
		: QFont::Normal);
	checkFont.setItalic(flags & FontItalic);
	checkFont.setUnderline(flags & FontUnderline);
	checkFont.setStrikeOut(flags & FontStrikeOut);
	auto realFamily = QFontInfo(checkFont).family();
	if (!realFamily.trimmed().startsWith(familyName, Qt::CaseInsensitive)) {
		LOG(("Font Error: could not resolve '%1' font, got '%2'.").arg(familyName, realFamily));
		return false;
	}

	auto metrics = QFontMetrics(checkFont);
	if (!metrics.height()) {
		LOG(("Font Error: got a zero height in '%1'.").arg(familyName));
		return false;
	}

	return true;
}

#ifndef LIB_UI_USE_PACKAGED_FONTS
bool LoadCustomFont(const QString &filePath, const QString &familyName, int flags = 0) {
	auto regularId = QFontDatabase::addApplicationFont(filePath);
	if (regularId < 0) {
		LOG(("Font Error: could not add '%1'.").arg(filePath));
		return false;
	}

	const auto found = [&] {
		for (auto &family : QFontDatabase::applicationFontFamilies(regularId)) {
			LOG(("Font: from '%1' loaded '%2'").arg(filePath, family));
			if (family.trimmed().startsWith(familyName, Qt::CaseInsensitive)) {
				return true;
			}
		}
		return false;
	}();
	if (!found) {
		LOG(("Font Error: could not locate '%1' font in '%2'.").arg(familyName, filePath));
		return false;
	}

	return ValidateFont(familyName, flags);
}
#endif // !LIB_UI_USE_PACKAGED_FONTS

[[nodiscard]] QString SystemMonospaceFont() {
	const auto type = QFontDatabase::FixedFont;
	return QFontDatabase::systemFont(type).family();
}

[[nodiscard]] QString ManualMonospaceFont() {
	const auto kTryFirst = std::initializer_list<QString>{
		u"Cascadia Mono"_q,
		u"Consolas"_q,
		u"Liberation Mono"_q,
		u"Menlo"_q,
		u"Courier"_q,
	};
	for (const auto &family : kTryFirst) {
		const auto resolved = QFontInfo(QFont(family)).family();
		if (resolved.trimmed().startsWith(family, Qt::CaseInsensitive)) {
			return family;
		}
	}
	return QString();
}

[[nodiscard]] QString MonospaceFont() {
	static const auto family = [&]() -> QString {
		const auto manual = ManualMonospaceFont();
		const auto system = SystemMonospaceFont();

#ifdef Q_OS_WIN
		// Prefer our monospace font.
		const auto useSystem = manual.isEmpty();
#else // Q_OS_WIN
		// Prefer system monospace font.
		const auto metrics = QFontMetrics(QFont(system));
		const auto useSystem = manual.isEmpty()
			|| (metrics.horizontalAdvance(QChar('i')) == metrics.horizontalAdvance(QChar('W')));
#endif // Q_OS_WIN
		return useSystem ? system : manual;
	}();

	return family;
}

[[nodiscard]] int ComputePixelSize(QFont font, uint32 flags, int size) {
	const auto family = font.family();
	const auto basic = GetFontOverride(flags);
	if (family == basic) {
		return size;
	}
	auto copy = font;
	copy.setFamily(basic);
	const auto desired = QFontMetricsF(copy).capHeight();
	if (desired < 1.) {
		return size;
	}
	font.setPixelSize(size);
	auto current = QFontMetricsF(font).capHeight();
	constexpr auto kMaxSizeShift = 4;
	if (current < 1. || std::abs(current - desired) < 0.2) {
		return size;
	} else if (current < desired) {
		for (auto i = 0; i != kMaxSizeShift; ++i) {
			const auto shift = i + 1;
			font.setPixelSize(size + shift);
			const auto now = QFontMetricsF(font).capHeight();
			if (now > desired) {
				return (now - desired * 2 < desired - current)
					? (size + shift)
					: (size + shift - 1);
			}
			current = now;
		}
		return size + kMaxSizeShift;
	} else {
		for (auto i = 0; i != kMaxSizeShift; ++i) {
			const auto shift = i + 1;
			font.setPixelSize(size - shift);
			const auto now = QFontMetricsF(font).capHeight();
			if (now < desired) {
				return (desired - now * 2 < current - desired)
					? (size - shift)
					: (size - shift + 1);
			}
			current = now;
		}
		return size - kMaxSizeShift;
	}
}

[[nodiscard]] QFont ResolveFont(
		const QString &familyOverride,
		uint32 flags,
		int size) {
	auto result = QFont();
	if (!familyOverride.isEmpty()) {
		result.setFamily(familyOverride);
	} else if (flags & FontMonospace) {
		result.setFamily(MonospaceFont());
	} else if (const auto name = std::get_if<QString>(&Custom)) {
		result.setFamily(*name);
	} else if (!v::is<SystemFont>(Custom)) {
		result.setFamily(GetFontOverride(flags));
#if QT_VERSION >= QT_VERSION_CHECK(6, 7, 0)
		result.setFeature("ss03", true);
#endif // Qt >= 6.7.0
	}
	result.setWeight(((flags & FontBold) || (flags & FontSemibold))
		? QFont::DemiBold
		: QFont::Normal);
	result.setItalic(flags & FontItalic);
	result.setUnderline(flags & FontUnderline);
	result.setStrikeOut(flags & FontStrikeOut);
	result.setPixelSize(familyOverride.isEmpty()
		? ComputePixelSize(result, flags, size)
		: size);
	return result;
}

} // namespace

void StartFonts() {
	if (Started) {
		return;
	}
	Started = true;

	style_InitFontsResource();

#ifndef LIB_UI_USE_PACKAGED_FONTS
	//[[maybe_unused]] auto badFlags = std::optional<int>();
	const auto base = u":/gui/fonts/"_q;
	const auto name = u"Open Sans"_q;
	const auto persianFallback = u"Vazirmatn UI NL"_q;

	for (const auto &[file, flags] : FontTypes) {
		if (!LoadCustomFont(base + file + u".ttf"_q, name, flags)) {
			//badFlags = flags;
		}
	}

	for (const auto &[file, flags] : PersianFontTypes) {
		LoadCustomFont(base + file + u".ttf"_q, persianFallback, flags);
	}
	QFont::insertSubstitution(name, persianFallback);

#ifdef Q_OS_WIN
	// Attempt to workaround a strange font bug with Open Sans Semibold not loading.
	// See https://github.com/telegramdesktop/tdesktop/issues/3276 for details.
	// Crash happens on "options.maxh / _t->_st->font->height" with "division by zero".
	// In that place "_t->_st->font" is "semiboldFont" is "font(13 "Open Sans Semibold").
	//const auto fallback = u"Segoe UI"_q;
	//if (badFlags && ValidateFont(fallback, *badFlags)) {
	//	FontOverride = fallback;
	//	LOG(("Fonts Info: Using '%1' instead of '%2'.").arg(fallback, name));
	//}
	// Disable default fallbacks to Segoe UI, see:
	// https://github.com/telegramdesktop/tdesktop/issues/5368
	//
	//QFont::insertSubstitution(name, fallback);
#endif // Q_OS_WIN

#ifdef Q_OS_MAC
	const auto list = QStringList{
		u"STIXGeneral"_q,
		u".SF NS Text"_q,
		u"Helvetica Neue"_q,
		u"Lucida Grande"_q,
	};
	QFont::insertSubstitutions(name, list);
#endif // Q_OS_MAC
#endif // !LIB_UI_USE_PACKAGED_FONTS

	auto appFont = QApplication::font();
	appFont.setStyleStrategy(QFont::PreferQuality);
	QApplication::setFont(appFont);
}

QString GetFontOverride(int32 flags) {
	return FontOverride.isEmpty() ? u"Open Sans"_q : FontOverride;
}

void destroyFonts() {
	for (auto fontData : std::as_const(fontsMap)) {
		delete fontData;
	}
	fontsMap.clear();
}

int registerFontFamily(const QString &family) {
	auto result = fontFamilyMap.value(family, -1);
	if (result < 0) {
		result = fontFamilies.size();
		fontFamilyMap.insert(family, result);
		fontFamilies.push_back(family);
	}
	return result;
}

FontData::FontData(int size, uint32 flags, int family, Font *other)
: f(ResolveFont(family ? fontFamilies[family] : QString(), flags, size))
, _m(f)
, _size(size)
, _flags(flags)
, _family(family) {
	if (other) {
		memcpy(_modified, other, sizeof(_modified));
	}
	_modified[_flags] = Font(this);

	height = int(base::SafeRound(_m.height()));
	ascent = int(base::SafeRound(_m.ascent()));
	descent = int(base::SafeRound(_m.descent()));
	spacew = width(QLatin1Char(' '));
	elidew = width("...");
}

Font FontData::bold(bool set) const {
	return otherFlagsFont(FontBold, set);
}

Font FontData::italic(bool set) const {
	return otherFlagsFont(FontItalic, set);
}

Font FontData::underline(bool set) const {
	return otherFlagsFont(FontUnderline, set);
}

Font FontData::strikeout(bool set) const {
	return otherFlagsFont(FontStrikeOut, set);
}

Font FontData::semibold(bool set) const {
	return otherFlagsFont(FontSemibold, set);
}

Font FontData::monospace(bool set) const {
	return otherFlagsFont(FontMonospace, set);
}

int FontData::size() const {
	return _size;
}

uint32 FontData::flags() const {
	return _flags;
}

int FontData::family() const {
	return _family;
}

Font FontData::otherFlagsFont(uint32 flag, bool set) const {
	int32 newFlags = set ? (_flags | flag) : (_flags & ~flag);
	if (!_modified[newFlags].v()) {
		_modified[newFlags] = Font(_size, newFlags, _family, _modified);
	}
	return _modified[newFlags];
}

Font::Font(int size, uint32 flags, const QString &family) {
	if (fontFamilyMap.isEmpty()) {
		for (uint32 i = 0, s = fontFamilies.size(); i != s; ++i) {
			fontFamilyMap.insert(fontFamilies.at(i), i);
		}
	}

	auto i = fontFamilyMap.constFind(family);
	if (i == fontFamilyMap.cend()) {
		fontFamilies.push_back(family);
		i = fontFamilyMap.insert(family, fontFamilies.size() - 1);
	}
	init(size, flags, i.value(), 0);
}

Font::Font(int size, uint32 flags, int family) {
	init(size, flags, family, 0);
}

Font::Font(int size, uint32 flags, int family, Font *modified) {
	init(size, flags, family, modified);
}

void Font::init(int size, uint32 flags, int family, Font *modified) {
	uint32 key = fontKey(size, flags, family);
	auto i = fontsMap.constFind(key);
	if (i == fontsMap.cend()) {
		i = fontsMap.insert(key, new FontData(size, flags, family, modified));
	}
	ptr = i.value();
}

} // namespace internal
} // namespace style