[i18n] start multilang support for webconsole

Signed-off-by: R4SAS <r4sas@i2pmail.org>

i18n/I18N.h

@@ -0,0 +1,39 @@
+/*
+* Copyright (c) 2021, The PurpleI2P Project
+*
+* This file is part of Purple i2pd project and licensed under BSD3
+*
+* See full license text in LICENSE file at top of project tree
+*/
+
+#ifndef __I18N_H__
+#define __I18N_H__
+
+namespace i2p {
+namespace i18n {
+
+	namespace russian {
+		std::string GetString (std::string arg);
+		std::string GetPlural (std::string arg, int n);
+	}
+
+	std::string translate (std::string arg)
+	{
+		return i2p::i18n::russian::GetString (arg);
+	}
+
+	template<typename inttype>
+	std::string translate (std::string arg, inttype&& n)
+	{
+		return i2p::i18n::russian::GetPlural (arg, (int) n);
+	}
+
+} // i18n
+} // i2p
+
+template<typename... TArgs>
+std::string tr (TArgs&&... args) {
+	return i2p::i18n::translate(std::forward<TArgs>(args)...);
+}
+
+#endif // __I18N_H__

i18n/russian.cpp

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+#include <map>
+#include <vector>
+#include <string>
+
+// Russian localization file
+
+namespace i2p {
+namespace i18n {
+namespace russian { // language
+
+	// See for language plural forms here:
+	// https://localization-guide.readthedocs.io/en/latest/l10n/pluralforms.html
+	int plural (int n) {
+		return n%10==1 && n%100!=11 ? 0 : n%10>=2 && n%10<=4 && (n%100<10 || n%100>=20) ? 1 : 2;
+	}
+
+	static std::map<std::string, std::string> strings
+	{
+		{"Enabled", "Включено"},
+		{"Disabled", "Выключено"}
+	};
+
+	static std::map<std::string, std::vector<std::string>> plurals
+	{
+		{"days",    {"день", "дня", "дней"}},
+		{"hours",   {"час", "часа", "часов"}},
+		{"minutes", {"минута", "минуты", "минут"}},
+		{"seconds", {"секунда", "секунды", "секунд"}}
+	};
+
+	std::string GetString (std::string arg)
+	{
+		auto it = strings.find(arg);
+		if (it == strings.end())
+		{
+			return arg;
+		} else {
+			return it->second;
+		}
+	}
+
+	std::string GetPlural (std::string arg, int n)
+	{
+		auto it = plurals.find(arg);
+		if (it == plurals.end())
+		{
+			return arg;
+		} else {
+			int form = plural(n);
+			return it->second[form];
+		}
+	}
+
+} // language
+} // i18n
+} // i2p