//
// This file is part of Kepka,
// an unofficial desktop version of Telegram messaging app,
// see https://github.com/procxx/kepka
//
// Kepka is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// It is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// In addition, as a special exception, the copyright holders give permission
// to link the code of portions of this program with the OpenSSL library.
//
// Full license: https://github.com/procxx/kepka/blob/master/LICENSE
// Copyright (c) 2014-2017 John Preston, https://desktop.telegram.org
// Copyright (c) 2017- Kepka Contributors, https://github.com/procxx
//
#pragma once

#include "base/observer.h"
#include "base/weak_unique_ptr.h"
#include "core/basic_types.h"
#include "core/utils.h"
#include "lang_auto.h"
#include "scheme.h"

namespace Lang {

constexpr auto kLegacyLanguageNone = -2;
constexpr auto kLegacyCustomLanguage = -1;
constexpr auto kLegacyDefaultLanguage = 0;

constexpr str_const kLegacyLanguages[] = {
    "en", "it", "es", "de", "nl", "pt_BR", "ko",
};

inline QString ConvertLegacyLanguageId(const QString &languageId) {
	return languageId.toLower().replace('_', '-');
}

QString DefaultLanguageId();

class Instance;
Instance &Current();

class Instance {
public:
	Instance() {
		fillDefaults();
	}
	void switchToId(const QString &id);
	void switchToCustomFile(const QString &filePath);

	Instance(const Instance &other) = delete;
	Instance &operator=(const Instance &other) = delete;
	Instance(Instance &&other) = delete;
	Instance &operator=(Instance &&other) = delete;

	QString systemLangCode() const;
	QString cloudLangCode() const;

	QString id() const {
		return _id;
	}
	bool isCustom() const {
		return (_id == qstr("custom") || _id == qstr("TEST_X") || _id == qstr("TEST_0"));
	}
	int version() const {
		return _version;
	}

	QByteArray serialize() const;
	void fillFromSerialized(const QByteArray &data);
	void fillFromLegacy(int legacyId, const QString &legacyPath);

	void applyDifference(const MTPDlangPackDifference &difference);
	static std::map<LangKey, QString> ParseStrings(const MTPVector<MTPLangPackString> &strings);
	base::Observable<void> &updated() {
		return _updated;
	}

	QString getValue(LangKey key) {
		Expects(key >= 0 && key < kLangKeysCount);
		Expects(_values.size() == kLangKeysCount);
		return _values[key];
	}
	bool isNonDefaultPlural(LangKey key) {
		Expects(key >= 0 && key < kLangKeysCount);
		Expects(_nonDefaultSet.size() == kLangKeysCount);
		return _nonDefaultSet[key] || _nonDefaultSet[key + 1] || _nonDefaultSet[key + 2] || _nonDefaultSet[key + 3] ||
		       _nonDefaultSet[key + 4] || _nonDefaultSet[key + 5];
	}

private:
	// SetCallback takes two QByteArrays: key, value.
	// It is called for all key-value pairs in string.
	// ResetCallback takes one QByteArray: key.
	template <typename SetCallback, typename ResetCallback>
	static void HandleString(const MTPLangPackString &mtpString, SetCallback setCallback, ResetCallback resetCallback);

	// Writes each key-value pair in the result container.
	template <typename Result>
	static LangKey ParseKeyValue(const QByteArray &key, const QByteArray &value, Result &result);

	void applyValue(const QByteArray &key, const QByteArray &value);
	void resetValue(const QByteArray &key);
	void reset();
	void fillDefaults();
	void fillFromCustomFile(const QString &filePath);
	void loadFromContent(const QByteArray &content);
	void loadFromCustomContent(const QString &absolutePath, const QString &relativePath, const QByteArray &content);
	void updatePluralRules();

	QString _id;
	int _legacyId = kLegacyLanguageNone;
	QString _customFilePathAbsolute;
	QString _customFilePathRelative;
	QByteArray _customFileContent;
	int _version = 0;
	base::Observable<void> _updated;

	mutable QString _systemLanguage;

	std::vector<QString> _values;
	std::vector<uchar> _nonDefaultSet;
	std::map<QByteArray, QByteArray> _nonDefaultValues;
};

} // namespace Lang