// 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 "ui/ui_log.h"

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

void style_InitFontsResource() {
	Q_INIT_RESOURCE(fonts);
#ifdef Q_OS_WIN
	Q_INIT_RESOURCE(win);
#elif defined Q_OS_MAC // Q_OS_WIN
	Q_INIT_RESOURCE(mac);
#else // Q_OS_WIN || Q_OS_MAC
	Q_INIT_RESOURCE(linux);
#endif // Q_OS_WIN || Q_OS_MAC || Q_OS_LINUX
}

namespace style {
namespace internal {
namespace {

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

uint32 fontKey(int size, uint32 flags, int family) {
	return (((uint32(family) << 10) | uint32(size)) << 4) | flags;
}

bool ValidateFont(const QString &familyName, int flags = 0) {
	QFont checkFont(familyName);
	checkFont.setPixelSize(13);
	checkFont.setBold(flags & style::internal::FontBold);
	checkFont.setItalic(flags & style::internal::FontItalic);
	checkFont.setUnderline(flags & style::internal::FontUnderline);
	checkFont.setStyleStrategy(QFont::PreferQuality);
	auto realFamily = QFontInfo(checkFont).family();
	if (realFamily.trimmed().compare(familyName, Qt::CaseInsensitive)) {
		UI_LOG(("Font Error: could not resolve '%1' font, got '%2'.").arg(familyName).arg(realFamily));
		return false;
	}

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

	return true;
}

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

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

	return ValidateFont(familyName, flags);
}

bool Started = false;
QString OpenSansOverride;
QString OpenSansSemiboldOverride;

} // namespace

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

	style_InitFontsResource();

	auto regular = LoadCustomFont(":/gui/fonts/OpenSans-Regular.ttf", "Open Sans");
	auto bold = LoadCustomFont(":/gui/fonts/OpenSans-Bold.ttf", "Open Sans", style::internal::FontBold);
	auto semibold = LoadCustomFont(":/gui/fonts/OpenSans-Semibold.ttf", "Open Sans Semibold");

#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").
	if (!regular || !bold) {
		if (ValidateFont("Segoe UI") && ValidateFont("Segoe UI", style::internal::FontBold)) {
			OpenSansOverride = "Segoe UI";
			UI_LOG(("Fonts Info: Using Segoe UI instead of Open Sans."));
		}
	}
	if (!semibold) {
		if (ValidateFont("Segoe UI Semibold")) {
			OpenSansSemiboldOverride = "Segoe UI Semibold";
			UI_LOG(("Fonts Info: Using Segoe UI Semibold instead of Open Sans Semibold."));
		}
	}
	// Disable default fallbacks to Segoe UI, see:
	// https://github.com/telegramdesktop/tdesktop/issues/5368
	//
	//QFont::insertSubstitution("Open Sans", "Segoe UI");
	//QFont::insertSubstitution("Open Sans Semibold", "Segoe UI Semibold");
#elif defined Q_OS_MAC // Q_OS_WIN
	auto list = QStringList();
	list.append(".SF NS Text");
	list.append("Helvetica Neue");
	list.append("Lucida Grande");
	QFont::insertSubstitutions("Open Sans", list);
	QFont::insertSubstitutions("Open Sans Semibold", list);
#endif // Q_OS_WIN || Q_OS_MAC
}

QString GetFontOverride(const QString &familyName) {
	if (familyName == qstr("Open Sans")) {
		return OpenSansOverride.isEmpty() ? familyName : OpenSansOverride;
	} else if (familyName == qstr("Open Sans Semibold")) {
		return OpenSansSemiboldOverride.isEmpty() ? familyName : OpenSansSemiboldOverride;
	}
	return familyName;
}

void destroyFonts() {
	for (auto fontData : 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(GetFontOverride(fontFamilies[family]))
, m(f)
, _size(size)
, _flags(flags)
, _family(family) {
	if (other) {
		memcpy(modified, other, sizeof(modified));
	} else {
		memset(modified, 0, sizeof(modified));
	}
	modified[_flags] = Font(this);

	f.setPixelSize(size);
	if (_flags & FontBold) {
		f.setBold(true);
	//} else if (fontFamilies[family] == "Open Sans Semibold") {
	//	f.setWeight(QFont::DemiBold);
	}
	f.setItalic(_flags & FontItalic);
	f.setUnderline(_flags & FontUnderline);
	f.setStrikeOut(_flags & FontStrikeOut);
	f.setStyleStrategy(QFont::PreferQuality);

	m = QFontMetrics(f);
	height = m.height();
	ascent = m.ascent();
	descent = 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);
}

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