// 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 "spellcheck/spellcheck_utils.h"
#include "spellcheck/platform/platform_spellcheck.h"

#include <QtCore/QStringList>
#include <QTextBoundaryFinder>

namespace Spellchecker {
namespace {

struct SubtagScript {
	const char *subtag;
	QChar::Script script;
};

// https://chromium.googlesource.com/chromium/src/+/refs/heads/master/third_party/blink/renderer/platform/text/locale_to_script_mapping.cc

std::vector<QChar::Script> SupportedScripts;
rpl::event_stream<> SupportedScriptsEventStream;

constexpr auto kFactor = 1000;

constexpr auto kAcuteAccentChars = {
	QChar(769),	QChar(833),	// QChar(180),
	QChar(714),	QChar(779),	QChar(733),
	QChar(758),	QChar(791),	QChar(719),
};

constexpr auto kUnspellcheckableScripts = {
	QChar::Script_Katakana,
	QChar::Script_Han,
};

constexpr SubtagScript kLocaleScriptList[] = {
	{"aa", QChar::Script_Latin},     {"ab", QChar::Script_Cyrillic},
	{"ady", QChar::Script_Cyrillic}, {"aeb", QChar::Script_Arabic},
	{"af", QChar::Script_Latin},     {"ak", QChar::Script_Latin},
	{"am", QChar::Script_Ethiopic},  {"ar", QChar::Script_Arabic},
	{"arq", QChar::Script_Arabic},   {"ary", QChar::Script_Arabic},
	{"arz", QChar::Script_Arabic},   {"as", QChar::Script_Bengali},
	{"ast", QChar::Script_Latin},    {"av", QChar::Script_Cyrillic},
	{"ay", QChar::Script_Latin},     {"az", QChar::Script_Latin},
	{"azb", QChar::Script_Arabic},   {"ba", QChar::Script_Cyrillic},
	{"bal", QChar::Script_Arabic},   {"be", QChar::Script_Cyrillic},
	{"bej", QChar::Script_Arabic},   {"bg", QChar::Script_Cyrillic},
	{"bi", QChar::Script_Latin},     {"bn", QChar::Script_Bengali},
	{"bo", QChar::Script_Tibetan},   {"bqi", QChar::Script_Arabic},
	{"brh", QChar::Script_Arabic},   {"bs", QChar::Script_Latin},
	{"ca", QChar::Script_Latin},     {"ce", QChar::Script_Cyrillic},
	{"ceb", QChar::Script_Latin},    {"ch", QChar::Script_Latin},
	{"chk", QChar::Script_Latin},    {"cja", QChar::Script_Arabic},
	{"cjm", QChar::Script_Arabic},   {"ckb", QChar::Script_Arabic},
	{"cs", QChar::Script_Latin},     {"cy", QChar::Script_Latin},
	{"da", QChar::Script_Latin},     {"dcc", QChar::Script_Arabic},
	{"de", QChar::Script_Latin},     {"doi", QChar::Script_Arabic},
	{"dv", QChar::Script_Thaana},    {"dyo", QChar::Script_Arabic},
	{"dz", QChar::Script_Tibetan},   {"ee", QChar::Script_Latin},
	{"efi", QChar::Script_Latin},    {"el", QChar::Script_Greek},
	{"en", QChar::Script_Latin},     {"es", QChar::Script_Latin},
	{"et", QChar::Script_Latin},     {"eu", QChar::Script_Latin},
	{"fa", QChar::Script_Arabic},    {"fi", QChar::Script_Latin},
	{"fil", QChar::Script_Latin},    {"fj", QChar::Script_Latin},
	{"fo", QChar::Script_Latin},     {"fr", QChar::Script_Latin},
	{"fur", QChar::Script_Latin},    {"fy", QChar::Script_Latin},
	{"ga", QChar::Script_Latin},     {"gaa", QChar::Script_Latin},
	{"gba", QChar::Script_Arabic},   {"gbz", QChar::Script_Arabic},
	{"gd", QChar::Script_Latin},     {"gil", QChar::Script_Latin},
	{"gl", QChar::Script_Latin},     {"gjk", QChar::Script_Arabic},
	{"gju", QChar::Script_Arabic},   {"glk", QChar::Script_Arabic},
	{"gn", QChar::Script_Latin},     {"gsw", QChar::Script_Latin},
	{"gu", QChar::Script_Gujarati},  {"ha", QChar::Script_Latin},
	{"haw", QChar::Script_Latin},    {"haz", QChar::Script_Arabic},
	{"he", QChar::Script_Hebrew},    {"hi", QChar::Script_Devanagari},
	{"hil", QChar::Script_Latin},    {"hnd", QChar::Script_Arabic},
	{"hno", QChar::Script_Arabic},   {"ho", QChar::Script_Latin},
	{"hr", QChar::Script_Latin},     {"ht", QChar::Script_Latin},
	{"hu", QChar::Script_Latin},     {"hy", QChar::Script_Armenian},
	{"id", QChar::Script_Latin},     {"ig", QChar::Script_Latin},
	{"ii", QChar::Script_Yi},        {"ilo", QChar::Script_Latin},
	{"inh", QChar::Script_Cyrillic}, {"is", QChar::Script_Latin},
	{"it", QChar::Script_Latin},     {"iu", QChar::Script_CanadianAboriginal},
	{"ja", QChar::Script_Katakana},  // or Script_Hiragana.
	{"jv", QChar::Script_Latin},     {"ka", QChar::Script_Georgian},
	{"kaj", QChar::Script_Latin},    {"kam", QChar::Script_Latin},
	{"kbd", QChar::Script_Cyrillic}, {"kha", QChar::Script_Latin},
	{"khw", QChar::Script_Arabic},   {"kk", QChar::Script_Cyrillic},
	{"kl", QChar::Script_Latin},     {"km", QChar::Script_Khmer},
	{"kn", QChar::Script_Kannada},   {"ko", QChar::Script_Hangul},
	{"kok", QChar::Script_Devanagari}, {"kos", QChar::Script_Latin},
	{"kpe", QChar::Script_Latin},    {"krc", QChar::Script_Cyrillic},
	{"ks", QChar::Script_Arabic},    {"ku", QChar::Script_Arabic},
	{"kum", QChar::Script_Cyrillic}, {"kvx", QChar::Script_Arabic},
	{"kxp", QChar::Script_Arabic},   {"ky", QChar::Script_Cyrillic},
	{"la", QChar::Script_Latin},     {"lah", QChar::Script_Arabic},
	{"lb", QChar::Script_Latin},     {"lez", QChar::Script_Cyrillic},
	{"lki", QChar::Script_Arabic},   {"ln", QChar::Script_Latin},
	{"lo", QChar::Script_Lao},       {"lrc", QChar::Script_Arabic},
	{"lt", QChar::Script_Latin},     {"luz", QChar::Script_Arabic},
	{"lv", QChar::Script_Latin},     {"mai", QChar::Script_Devanagari},
	{"mdf", QChar::Script_Cyrillic}, {"mfa", QChar::Script_Arabic},
	{"mg", QChar::Script_Latin},     {"mh", QChar::Script_Latin},
	{"mi", QChar::Script_Latin},     {"mk", QChar::Script_Cyrillic},
	{"ml", QChar::Script_Malayalam}, {"mn", QChar::Script_Cyrillic},
	{"mr", QChar::Script_Devanagari},{"ms", QChar::Script_Latin},
	{"mt", QChar::Script_Latin},     {"mvy", QChar::Script_Arabic},
	{"my", QChar::Script_Myanmar},   {"myv", QChar::Script_Cyrillic},
	{"mzn", QChar::Script_Arabic},   {"na", QChar::Script_Latin},
	{"nb", QChar::Script_Latin},     {"ne", QChar::Script_Devanagari},
	{"niu", QChar::Script_Latin},    {"nl", QChar::Script_Latin},
	{"nn", QChar::Script_Latin},     {"nr", QChar::Script_Latin},
	{"nso", QChar::Script_Latin},    {"ny", QChar::Script_Latin},
	{"oc", QChar::Script_Latin},     {"om", QChar::Script_Latin},
	{"or", QChar::Script_Oriya},     {"os", QChar::Script_Cyrillic},
	{"pa", QChar::Script_Gurmukhi},  {"pag", QChar::Script_Latin},
	{"pap", QChar::Script_Latin},    {"pau", QChar::Script_Latin},
	{"pl", QChar::Script_Latin},     {"pon", QChar::Script_Latin},
	{"prd", QChar::Script_Arabic},   {"prs", QChar::Script_Arabic},
	{"ps", QChar::Script_Arabic},    {"pt", QChar::Script_Latin},
	{"qu", QChar::Script_Latin},     {"rm", QChar::Script_Latin},
	{"rmt", QChar::Script_Arabic},   {"rn", QChar::Script_Latin},
	{"ro", QChar::Script_Latin},     {"ru", QChar::Script_Cyrillic},
	{"rw", QChar::Script_Latin},     {"sa", QChar::Script_Devanagari},
	{"sah", QChar::Script_Cyrillic}, {"sat", QChar::Script_Latin},
	{"sd", QChar::Script_Arabic},    {"sdh", QChar::Script_Arabic},
	{"se", QChar::Script_Latin},     {"sg", QChar::Script_Latin},
	{"shi", QChar::Script_Arabic},   {"si", QChar::Script_Sinhala},
	{"sid", QChar::Script_Latin},    {"sk", QChar::Script_Latin},
	{"skr", QChar::Script_Arabic},   {"sl", QChar::Script_Latin},
	{"sm", QChar::Script_Latin},     {"so", QChar::Script_Latin},
	{"sq", QChar::Script_Latin},     {"sr", QChar::Script_Cyrillic},
	{"ss", QChar::Script_Latin},     {"st", QChar::Script_Latin},
	{"su", QChar::Script_Latin},     {"sus", QChar::Script_Arabic},
	{"sv", QChar::Script_Latin},     {"sw", QChar::Script_Latin},
	{"swb", QChar::Script_Arabic},   {"syr", QChar::Script_Arabic},
	{"ta", QChar::Script_Tamil},     {"te", QChar::Script_Telugu},
	{"tet", QChar::Script_Latin},    {"tg", QChar::Script_Cyrillic},
	{"th", QChar::Script_Thai},      {"ti", QChar::Script_Ethiopic},
	{"tig", QChar::Script_Ethiopic}, {"tk", QChar::Script_Latin},
	{"tkl", QChar::Script_Latin},    {"tl", QChar::Script_Latin},
	{"tn", QChar::Script_Latin},     {"to", QChar::Script_Latin},
	{"tpi", QChar::Script_Latin},    {"tr", QChar::Script_Latin},
	{"trv", QChar::Script_Latin},    {"ts", QChar::Script_Latin},
	{"tt", QChar::Script_Cyrillic},  {"ttt", QChar::Script_Arabic},
	{"tvl", QChar::Script_Latin},    {"tw", QChar::Script_Latin},
	{"ty", QChar::Script_Latin},     {"tyv", QChar::Script_Cyrillic},
	{"udm", QChar::Script_Cyrillic}, {"ug", QChar::Script_Arabic},
	{"uk", QChar::Script_Cyrillic},  {"und", QChar::Script_Latin},
	{"ur", QChar::Script_Arabic},    {"uz", QChar::Script_Cyrillic},
	{"ve", QChar::Script_Latin},     {"vi", QChar::Script_Latin},
	{"wal", QChar::Script_Ethiopic}, {"war", QChar::Script_Latin},
	{"wo", QChar::Script_Latin},     {"xh", QChar::Script_Latin},
	{"yap", QChar::Script_Latin},    {"yo", QChar::Script_Latin},
	{"za", QChar::Script_Latin},     {"zdj", QChar::Script_Arabic},
	{"zh", QChar::Script_Han},       {"zu", QChar::Script_Latin},
	// Encompassed languages within the Chinese macrolanguage.
	// http://www-01.sil.org/iso639-3/documentation.asp?id=zho
	// http://lists.w3.org/Archives/Public/public-i18n-cjk/2016JulSep/0022.html
	// {"cdo", USCRIPT_SIMPLIFIED_HAN},
	// {"cjy", USCRIPT_SIMPLIFIED_HAN},
	// {"cmn", USCRIPT_SIMPLIFIED_HAN},
	// {"cpx", USCRIPT_SIMPLIFIED_HAN},
	// {"czh", USCRIPT_SIMPLIFIED_HAN},
	// {"czo", USCRIPT_SIMPLIFIED_HAN},
	// {"gan", USCRIPT_SIMPLIFIED_HAN},
	// {"hsn", USCRIPT_SIMPLIFIED_HAN},
	// {"mnp", USCRIPT_SIMPLIFIED_HAN},
	// {"wuu", USCRIPT_SIMPLIFIED_HAN},
	// {"hak", USCRIPT_TRADITIONAL_HAN},
	// {"lzh", USCRIPT_TRADITIONAL_HAN},
	// {"nan", USCRIPT_TRADITIONAL_HAN},
	// {"yue", USCRIPT_TRADITIONAL_HAN},
	// {"zh-cdo", USCRIPT_SIMPLIFIED_HAN},
	// {"zh-cjy", USCRIPT_SIMPLIFIED_HAN},
	// {"zh-cmn", USCRIPT_SIMPLIFIED_HAN},
	// {"zh-cpx", USCRIPT_SIMPLIFIED_HAN},
	// {"zh-czh", USCRIPT_SIMPLIFIED_HAN},
	// {"zh-czo", USCRIPT_SIMPLIFIED_HAN},
	// {"zh-gan", USCRIPT_SIMPLIFIED_HAN},
	// {"zh-hsn", USCRIPT_SIMPLIFIED_HAN},
	// {"zh-mnp", USCRIPT_SIMPLIFIED_HAN},
	// {"zh-wuu", USCRIPT_SIMPLIFIED_HAN},
	// {"zh-hak", USCRIPT_TRADITIONAL_HAN},
	// {"zh-lzh", USCRIPT_TRADITIONAL_HAN},
	// {"zh-nan", USCRIPT_TRADITIONAL_HAN},
	// {"zh-yue", USCRIPT_TRADITIONAL_HAN},
	// // Chinese with regions. Logically, regions should be handled
	// // separately, but this works for the current purposes.
	// {"zh-hk", USCRIPT_TRADITIONAL_HAN},
	// {"zh-mo", USCRIPT_TRADITIONAL_HAN},
	// {"zh-tw", USCRIPT_TRADITIONAL_HAN},
};

inline auto IsAcuteAccentChar(const QChar &c) {
	return ranges::contains(kAcuteAccentChars, c);
}

inline auto IsSpellcheckableScripts(const QChar::Script &s) {
	return !ranges::contains(kUnspellcheckableScripts, s);
}

} // namespace

QChar::Script LocaleToScriptCode(const QString &locale) {
	const auto subtag = locale.left(
		std::max(locale.indexOf('_'), locale.indexOf('-')));
	for (const auto &kv : kLocaleScriptList) {
		if (subtag == kv.subtag) {
			return kv.script;
		}
	}
	return QChar::Script_Common;
}

QChar::Script WordScript(QStringView word) {
	// Find the first letter.
	const auto firstLetter = ranges::find_if(word, [](QChar c) {
		return c.isLetter();
	});
	return firstLetter == word.end()
		? QChar::Script_Common
		: firstLetter->script();
}

bool IsWordSkippable(QStringView word, bool checkSupportedScripts) {
	if (word.size() > kMaxWordSize) {
		return true;
	}
	const auto wordScript = WordScript(word);
	if (checkSupportedScripts
		&& !ranges::contains(SupportedScripts, wordScript)) {
		return true;
	}
	return ranges::any_of(word, [&](QChar c) {
		return (c.script() != wordScript)
			&& !IsAcuteAccentChar(c)
			&& (c.unicode() != '\'') // Patched Qt to make it a non-separator.
			&& (c.unicode() != '_'); // This is not a word separator.
	});
}

void UpdateSupportedScripts(std::vector<QString> languages) {
	// It should be called at least once from Platform::Spellchecker::Init().
	SupportedScripts = ranges::views::all(
		languages
	) | ranges::views::transform(
		LocaleToScriptCode
	) | ranges::views::unique | ranges::views::filter(
		IsSpellcheckableScripts
	) | ranges::to_vector;
	SupportedScriptsEventStream.fire({});
}

rpl::producer<> SupportedScriptsChanged() {
	return SupportedScriptsEventStream.events();
}

MisspelledWords RangesFromText(
	const QString &text,
	Fn<bool(const QString &word)> filterCallback) {
	MisspelledWords ranges;

	if (text.isEmpty()) {
		return ranges;
	}

	auto finder = QTextBoundaryFinder(QTextBoundaryFinder::Word, text);

	const auto isEnd = [&] {
		return (finder.toNextBoundary() == -1);
	};

	while (finder.position() < text.length()) {
		if (!finder.boundaryReasons().testFlag(
				QTextBoundaryFinder::StartOfItem)) {
			if (isEnd()) {
				break;
			}
			continue;
		}

		const auto start = finder.position();
		const auto end = finder.toNextBoundary();
		if (end == -1) {
			break;
		}
		const auto length = end - start;
		if (length < 1) {
			continue;
		}
		if (!filterCallback(text.mid(start, length))) {
			ranges.push_back(std::make_pair(start, length));
		}

		if (isEnd()) {
			break;
		}
	}
	return ranges;
}

bool CheckSkipAndSpell(const QString &word) {
	return !IsWordSkippable(word)
		&& Platform::Spellchecker::CheckSpelling(word);
}

QLocale LocaleFromLangId(int langId) {
	if (langId < kFactor) {
		return QLocale(static_cast<QLocale::Language>(langId));
	}
	const auto l = langId / kFactor;
	const auto lang = static_cast<QLocale::Language>(l);
	const auto country = static_cast<QLocale::Country>(langId - l * kFactor);
	return QLocale(lang, country);
}

} // namespace Spellchecker