nls: Minify translation PO files.

To save a lot of disk space, keep only actually translated messages in
Gettext PO files.  Ignore the guix domain, which is more complicated
and is tiny.

* build-aux/keep-only-translated.scm: New file.
* Makefile.am (download-po): Run it.

Change-Id: I6442ce0ef8d62f7e48e667c766b86d0ebf9c5415

1 files changed, 13 insertions, 4 deletions

diff --git a/Makefile.am b/Makefile.am
index 19aad0042e3..b29f2dfa84a 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -1299,8 +1299,10 @@ WEBLATE_REPO = https://codeberg.org/guix/translations
 # Shallow clone the Git repository behind Weblate and copy files from it if
 # they contain at least one translation, and they are well-formed (Scheme
 # format only), warn otherwise.  Copied files are converted to a canonical
-# form.
-download-po:
+# form.  Note: The files will be minified to reduce file size, except the
+# guix domain, because they are comparatively small and it would need more
+# comprehensive PO file parsing abilities for plural forms.
+download-po: guix/build/po.go
         dir=$$(mktemp -d); \
         git clone --depth 1 "$(WEBLATE_REPO)" "$$dir/translations" && \
         for domain in po/doc po/guix po/packages; do \
@@ -1313,8 +1315,15 @@ download-po:
                 target="$$domain/$$target"; \
                 msgfmt -c "$$po"; \
                 if msgfmt -c "$$po" && [ "$$translated" != "0" ] && ([ "$$domain" != "po/doc" ] || [ "$$translated" -gt $$(($$total/10)) ] || [ -f $$target ]); then \
-                    msgconv --no-wrap -o "$$po".tmp "$$po"; \
-                    mv "$$po".tmp "$$target"; \
+                    if [ "$$domain" != "po/guix" ]; then \
+                      $(GUILE) -L "$(top_builddir)" -L "$(top_srcdir)" \
+                        --no-auto-compile \
+                        -s "$(top_srcdir)"/build-aux/keep-only-translated.scm \
+                        "$$po" > "$$po".tmp; \
+                    else ln -s "$$po" "$$po".tmp; fi; \
+                    msgconv --no-wrap -o "$$po".tmp2 "$$po".tmp; \
+                    rm "$$po".tmp; \
+                    mv "$$po".tmp2 "$$target"; \
                     echo "copied $$target."; \
                 else \
                     echo "WARN: $$target ($$translated translated messages ($$((translated/total*100))%)) was not added/updated."; \