Makefile rule to extract gettetx/ngettext calls from Golang templates and source files

Makefile

XGETTEXT_FLAGS = --no-wrap --language=c --from-code=UTF-8 --output=- -
$(POT_FILE): $(TEMPLATES) $(filter-out $(BINDATA), $(GO_FILES))
	@cat $? \
		| grep -i gettext \
		| sed -e "s/ngettext \"\([^\"]*\)\".\"\([^\"]*\)\".\(.*\) }}/ngettext(\"\1\", \"\2\", \3) }}/g" \
		| sed -e "s/[^n]gettext \"\(.*\)\"/ gettext(\"\1\")/g" \
		| sed -e "s/NGetText(\([^\)]*\))/ ngettext(\1)  /g" \
		| sed -e "s/GetText(\([^\)]*\))/ gettext(\1)  /g" \
		| xgettext $(XGETTEXT_FLAGS) \
		| sed -e '1,20d' \
		| msguniq > $@

%.po: $(POT_FILE)
	@msgmerge -U $@ $<

.INTERMEDIATE: $(POT_FILE)
.PRECIOUS: %.po