From 37222c3fa2f558df5f7ef420ad583ba403ceda62 Mon Sep 17 00:00:00 2001
From: frosch <frosch@openttd.org>
Date: Sun, 11 Apr 2021 17:28:47 +0200
Subject: [PATCH] Change: treat languages as finished, if translations are 75%
 completed. Unfinished translations are not auto-picked from the locale. In
 release builds, unfinished translations are not offered in the GUI.
 Unfinished translations are available in non-release builds, or by editing
 openttd.cfg.

---
 src/language.h       |  1 +
 src/settings_gui.cpp |  2 ++
 src/strings.cpp      | 13 +++++++++++++
 3 files changed, 16 insertions(+)

diff --git a/src/language.h b/src/language.h
index faac595613..9d2499068b 100644
--- a/src/language.h
+++ b/src/language.h
@@ -58,6 +58,7 @@ struct LanguagePackHeader {
 	char cases[MAX_NUM_CASES][CASE_GENDER_LEN];     ///< the cases used by this translation
 
 	bool IsValid() const;
+	bool IsReasonablyFinished() const;
 
 	/**
 	 * Get the index for the given gender.
diff --git a/src/settings_gui.cpp b/src/settings_gui.cpp
index 1e3bdb7d7d..f5872c648f 100644
--- a/src/settings_gui.cpp
+++ b/src/settings_gui.cpp
@@ -218,6 +218,8 @@ struct GameOptionsWindow : Window {
 
 			case WID_GO_LANG_DROPDOWN: { // Setup interface language dropdown
 				for (uint i = 0; i < _languages.size(); i++) {
+					bool hide_language = IsReleasedVersion() && !_languages[i].IsReasonablyFinished();
+					if (hide_language) continue;
 					bool hide_percentage = IsReleasedVersion() || _languages[i].missing < _settings_client.gui.missing_strings_threshold;
 					auto item = new DropDownListParamStringItem(hide_percentage ? STR_JUST_RAW_STRING : STR_GAME_OPTIONS_LANGUAGE_PERCENTAGE, i, false);
 					if (&_languages[i] == _current_language) {
diff --git a/src/strings.cpp b/src/strings.cpp
index aeea7c071a..d533db1fce 100644
--- a/src/strings.cpp
+++ b/src/strings.cpp
@@ -1716,6 +1716,15 @@ bool LanguagePackHeader::IsValid() const
 	       StrValid(this->digit_decimal_separator,        lastof(this->digit_decimal_separator));
 }
 
+/**
+ * Check whether a translation is sufficiently finished to offer it to the public.
+ */
+bool LanguagePackHeader::IsReasonablyFinished() const
+{
+	/* "Less than 25% missing" is "sufficiently finished". */
+	return 4 * this->missing < LANGUAGE_TOTAL_STRINGS;
+}
+
 /**
  * Read a particular language.
  * @param lang The metadata about the language.
@@ -1969,6 +1978,10 @@ void InitializeLanguagePacks()
 		}
 
 		if (strcmp (lng.isocode, "en_GB") == 0) en_GB_fallback    = &lng;
+
+		/* Only auto-pick finished translations */
+		if (!lng.IsReasonablyFinished()) continue;
+
 		if (strncmp(lng.isocode, lang, 5) == 0) chosen_language   = &lng;
 		if (strncmp(lng.isocode, lang, 2) == 0) language_fallback = &lng;
 	}