Fix language codes not recognized correctly

scraper/src/gutenberg2zim/iso639.py

@@ -240,5 +240,6 @@ def language_name(code: str) -> str:
     "myn": [],
     "nai": [],
     "nah": ["nhe"],
+    "nap": ["nap"],  # Neapolitan: no ISO 639-1 code, already valid ISO 639-3
     "fur": ["fvr"],  # Friulian: IETF fur maps to ISO 639-3 fvr
 }

scraper/src/gutenberg2zim/zim.py

@@ -13,12 +13,27 @@
 
 
 def get_zim_language_metadata(languages: list[str], books: list[CatalogEntry]):
-    language_counts = {
-        zim_lang: sum(lang in book.languages for book in books)
-        for lang in languages
-        for zim_lang in ZIM_LANGUAGES_MAP.get(lang, [ISO_MATRIX.get(lang, None)])
-        if zim_lang
-    }
+    unresolved = []
+    language_counts: dict[str, int] = {}
+    for lang in languages:
+        zim_langs = ZIM_LANGUAGES_MAP.get(
+            lang,
+            # Try ISO_MATRIX (2-letter → 3-letter), fall back to
+            # ISO_MATRIX_REV to check if already a valid 3-letter code
+            [ISO_MATRIX.get(lang, lang if lang in ISO_MATRIX_REV else None)],
+        )
+        resolved = [zl for zl in zim_langs if zl]
+        if not resolved:
+            unresolved.append(lang)
+            continue
+        for zim_lang in resolved:
+            language_counts[zim_lang] = sum(lang in book.languages for book in books)
+    if unresolved:
+        logger.warning(
+            f"Could not resolve ZIM language metadata for: {', '.join(unresolved)}. "
+            "Books with these languages will still be included, but they won't appear "
+            "in ZIM language metadata."
+        )
     return sorted(language_counts, key=lambda lang: language_counts[lang], reverse=True)
 
 
@@ -123,9 +138,17 @@ def build_zimfile(
         logger.info(f"Removing existing ZIM file {zim_file}")
         zim_path.unlink(missing_ok=True)
 
+    resolved_languages = zim_languages or get_zim_language_metadata(languages, books)
+    if not resolved_languages:
+        raise ValueError(
+            f"Cannot resolve language metadata for: "
+            f"{', '.join(languages)}. "
+            "Use --zim-languages to override."
+        )
+
     Global.setup(
         filename=zim_path,
-        language=zim_languages or get_zim_language_metadata(languages, books),
+        language=resolved_languages,
         title=title,
         description=description,
         long_description=long_description,