From 98a1d4f734be2e1fd5d9e4f2daa0da290c96fd52 Mon Sep 17 00:00:00 2001
From: Vaxry <vaxry@vaxry.net>
Date: Sat, 8 Nov 2025 22:14:23 +0000
Subject: [PATCH] better fallbacks

---
 src/i18n/I18nEngine.cpp | 31 +++++++++++++++++++++++++++++++
 tests/i18n.cpp          |  9 +++++++++
 2 files changed, 40 insertions(+)

diff --git a/src/i18n/I18nEngine.cpp b/src/i18n/I18nEngine.cpp
index 41f76a6..446710d 100644
--- a/src/i18n/I18nEngine.cpp
+++ b/src/i18n/I18nEngine.cpp
@@ -1,5 +1,7 @@
 #include "I18nEngine.hpp"
 
+#include <algorithm>
+#include <format>
 #include <hyprutils/string/String.hpp>
 
 using namespace Hyprutils::I18n;
@@ -42,6 +44,35 @@ std::string CI18nEngine::localizeEntry(const std::string& locale, uint64_t key,
         entry = &m_impl->entries[locale][key];
 
     if (!entry || !entry->exists) {
+        // try to fall back to lang_LANG
+        if (locale.contains('_')) {
+            auto stem      = locale.substr(0, locale.find('_'));
+            auto stemUpper = stem;
+            std::ranges::transform(stemUpper, stemUpper.begin(), ::toupper);
+            auto newLocale = std::format("{}_{}", stem, stemUpper);
+            if (m_impl->entries.contains(newLocale) && m_impl->entries[newLocale].size() > key)
+                entry = &m_impl->entries[newLocale][key];
+        }
+    }
+
+    if (!entry || !entry->exists) {
+        // try to fall back to any lang prefixed with our prefix
+        if (locale.contains('_')) {
+            auto stem = locale.substr(0, locale.find('_') + 1);
+            for (const auto& [k, v] : m_impl->entries) {
+                if (k.starts_with(stem)) {
+                    if (m_impl->entries.contains(k) && m_impl->entries[k].size() > key)
+                        entry = &m_impl->entries[k][key];
+
+                    if (entry && entry->exists)
+                        break;
+                }
+            }
+        }
+    }
+
+    if (!entry || !entry->exists) {
+        // fall back to general fallback
         if (m_impl->entries.contains(m_impl->fallbackLocale) && m_impl->entries[m_impl->fallbackLocale].size() > key)
             entry = &m_impl->entries[m_impl->fallbackLocale][key];
     }
diff --git a/tests/i18n.cpp b/tests/i18n.cpp
index 8e95a24..4c3c701 100644
--- a/tests/i18n.cpp
+++ b/tests/i18n.cpp
@@ -36,6 +36,9 @@ int main(int argc, char** argv, char** envp) {
             return "Mam {count} jabłek.";
     });
 
+    engine.registerEntry("es_XX", TXT_KEY_FALLBACK, "I don't speak spanish");
+    engine.registerEntry("es_ES", TXT_KEY_FALLBACK, "I don't speak spanish here either");
+
     EXPECT(engine.localizeEntry("en_US", TXT_KEY_HELLO, {}), "Hello World!");
     EXPECT(engine.localizeEntry("pl_PL", TXT_KEY_HELLO, {}), "Witaj świecie!");
     EXPECT(engine.localizeEntry("de_DE", TXT_KEY_HELLO, {}), "Hello World!");
@@ -47,6 +50,12 @@ int main(int argc, char** argv, char** envp) {
     EXPECT(engine.localizeEntry("pl_PL", TXT_KEY_I_HAVE_APPLES, {{"count", "2"}}), "Mam 2 jabłka.");
     EXPECT(engine.localizeEntry("pl_PL", TXT_KEY_I_HAVE_APPLES, {{"count", "5"}}), "Mam 5 jabłek.");
 
+    EXPECT(engine.localizeEntry("pl_XX", TXT_KEY_I_HAVE_APPLES, {{"count", "5"}}), "Mam 5 jabłek.");
+    EXPECT(engine.localizeEntry("en_XX", TXT_KEY_I_HAVE_APPLES, {{"count", "2"}}), "I have 2 apples.");
+
+    EXPECT(engine.localizeEntry("es_YY", TXT_KEY_FALLBACK, {}), "I don't speak spanish here either");
+    EXPECT(engine.localizeEntry("es_XX", TXT_KEY_FALLBACK, {}), "I don't speak spanish");
+
     EXPECT(engine.localizeEntry("pl_PL", TXT_KEY_FALLBACK, {}), "Fallback string!");
 
     return ret;