SIL.CoreImpl.PalasoWritingSystemManager.GetValidLangTagForNewLang C# (CSharp) Method

		public string GetValidLangTagForNewLang(string langName)
		{
			string nameD = langName.Normalize(NormalizationForm.FormD); // Get the name in NFD format
			StringBuilder builder = new StringBuilder(nameD.ToLowerInvariant());
			int index = 0;
			while (index < builder.Length)
			{
				char c = builder[index];
				bool charValid = (c >= 'A' && c <= 'Z') || (c >= 'a' && c <= 'z');
				if (!charValid)
				{
					// Found an invalid character, so remove it.
					builder.Remove(index, 1);
					continue;
				}
				index++;
			}

			string isoCode = builder.ToString().Substring(0, Math.Min(3, builder.Length));
			if (LangTagUtils.IsLanguageCodeValid(isoCode) && !LangTagInUse("qaa-x-" + isoCode))
				return isoCode; // The generated code is valid and not in use by the local or global store

			// We failed to generate a valid, unused language tag from the language name so
			// find one that isn't taken starting with 'aaa' and incrementing ('aab', 'aac', etc.)
			builder.Remove(0, builder.Length); // Clear the builder
			builder.Append("aaa");
			while (LangTagInUse("qaa-x-" + builder))
			{
				char newCharLast = (char)(builder[2] + 1);
				if (newCharLast > 'z')
				{
					// Incremented the last letter too far so reset it back to 'a' and increment the middle letter
					newCharLast = 'a';
					char newCharMiddle = (char)(builder[1] + 1);
					if (newCharMiddle > 'z')
					{
						// Incremented the middle letter too far so reset it back to 'a' and increment the first letter
						// Assume we won't ever have more then 4096 (26^3) custom writing systems
						newCharMiddle = 'a';
						builder[0] = (char)(builder[0] + 1);
					}
					builder[1] = newCharMiddle;
				}
				builder[2] = newCharLast;
			}
			return builder.ToString();
		}

        public void GetValidLangCodeForNewLang()
        {
            string storePath       = PrepareTempStore("Store");
            string globalStorePath = PrepareTempStore("GlobalStore");

            EnsureDirectoryIsEmpty(storePath);
            EnsureDirectoryIsEmpty(globalStorePath);

            var globalStore = new GlobalFileWritingSystemStore(globalStorePath);
            var wsManager   = new PalasoWritingSystemManager(
                new LocalFileWritingSystemStore(storePath, globalStore), globalStore);

            Assert.AreEqual("qip", wsManager.GetValidLangTagForNewLang("Qipkey"));
            Assert.AreEqual("sn", wsManager.GetValidLangTagForNewLang("Sn"));
            Assert.AreEqual("eba", wsManager.GetValidLangTagForNewLang("\u00CBbashlish"));             // \u00CB == E with diacritic
            Assert.AreEqual("eee", wsManager.GetValidLangTagForNewLang("\u00CB\u00CB\u00CBlish"));
            // \u00CB == E with diacritic
            Assert.AreEqual("aaa", wsManager.GetValidLangTagForNewLang("U"));

            LanguageSubtag subtag = new LanguageSubtag("qip", "Qipkey", true, null);
            IWritingSystem newWs  = wsManager.Create(subtag, null, null, null);

            wsManager.Set(newWs);
            Assert.AreEqual("aaa", wsManager.GetValidLangTagForNewLang("Qipsing"), "code for 'qip' should already be taken");

            subtag = new LanguageSubtag("aaa", "Qipsing", true, null);
            newWs  = wsManager.Create(subtag, null, null, null);
            wsManager.Set(newWs);
            Assert.AreEqual("aab", wsManager.GetValidLangTagForNewLang("Qipwest"),
                            "code for 'qip' should already be taken twice");

            // ENHANCE: Ideally, we would want to test incrementing the middle and first character,
            // but that would require at least 677 (26^2 + 1) writing systems be created.
        }