From 3ead63f9ac4ff0e91b3fdf6094875c913266c6d2 Mon Sep 17 00:00:00 2001
From: yuyu <kawaiiyuyu@outlook.com>
Date: Sun, 23 Oct 2022 22:23:26 +0800
Subject: [PATCH] Handle vanilla `-lang` and `-language` CLI flags for I18n

---
 TShockAPI/I18n.cs | 24 ++++++++++++++++++++++--
 docs/changelog.md |  1 +
 2 files changed, 23 insertions(+), 2 deletions(-)

diff --git a/TShockAPI/I18n.cs b/TShockAPI/I18n.cs
index 59f812f4..5d3aef85 100644
--- a/TShockAPI/I18n.cs
+++ b/TShockAPI/I18n.cs
@@ -21,7 +21,10 @@ global using static TShockAPI.I18n;
 using System;
 using System.Globalization;
 using System.IO;
+using System.Linq;
 using GetText;
+using Terraria.Initializers;
+using Terraria.Localization;
 
 namespace TShockAPI
 {
@@ -29,8 +32,7 @@ namespace TShockAPI
 		static string TranslationsDirectory => Path.Combine(AppContext.BaseDirectory, "i18n");
 		static CultureInfo TranslationCultureInfo
 		{
-			get
-			{
+			get {
 				// cross-platform mapping of cultureinfos can be a bit screwy, so give our users
 				// the chance to explicitly spell out which translation they would like to use.
 				// this is an environment variable instead of a flag because this needs to be
@@ -39,6 +41,24 @@ namespace TShockAPI
 				{
 					return new CultureInfo(overrideLang);
 				}
+
+				static CultureInfo Redirect(CultureInfo cultureInfo)
+					=> cultureInfo.Name == "zh-Hans" ? new CultureInfo("zh-CN") : cultureInfo;
+
+				if (Terraria.Program.LaunchParameters.TryGetValue("-lang", out var langArg)
+				    && int.TryParse(langArg, out var langId)) {
+					if (GameCulture._legacyCultures.TryGetValue(langId, out var culture)) {
+						return Redirect(culture.CultureInfo);
+					}
+				}
+
+				if (Terraria.Program.LaunchParameters.TryGetValue("-language", out var languageArg)) {
+					var culture = GameCulture._legacyCultures.Values.SingleOrDefault(c => c.Name == languageArg);
+					if (culture != null) {
+						return Redirect(culture.CultureInfo);
+					}
+				}
+
 				return CultureInfo.CurrentUICulture;
 			}
 		}
diff --git a/docs/changelog.md b/docs/changelog.md
index 90100cea..344c66f2 100644
--- a/docs/changelog.md
+++ b/docs/changelog.md
@@ -69,6 +69,7 @@ Use past tense when adding new entries; sign your name off when you add or chang
 * Check loadout slots for hacked item stacks. (@drunderscore)
 * Fix players being kicked after using the Flamethrower to apply the `OnFire3` debuff for `1200` ticks. (@BashGuy10)
 * Fix being kicked for using the new sponge types on liquid. (@BashGuy10)
+* Added support of `-lang` and `-language` flags for our i18n system. (@KawaiiYuyu)
 
 ## TShock 4.5.18
 * Fixed `TSPlayer.GiveItem` not working if the player is in lava. (@PotatoCider)