JAVA                  ?= /usr/bin/java
JS_MINIFY_FILTER_IN   ?= sed 's/console\.[a-z]\+([^)]\+) *;//g'
JS_SRC                ?= $(filter-out %.min.js,$(wildcard *.js))
JS_GENERATED          ?= $(patsubst %.js,%.min.js,$(JS_SRC))
JS_EXTRA_EXTERNS      ?=
JS_EXTERNS_DIRS       ?= /opt/closure-compiler/share/externs
JS_EXTERNS            ?= $(sort $(JS_EXTRA_EXTERNS) jquery-3.3.js)
JS_EXTERN_PATHS       ?= $(wildcard $(foreach d,$(JS_EXTERNS_DIRS),$(addprefix $d/,$(JS_EXTERNS))))
JS_MINIFY_OPTS        ?= $(addprefix --externs ,$(JS_EXTERN_PATHS)) --compilation_level ADVANCED --strict_mode_input
JS_MINIFY_EXE         ?= $(JAVA) -jar $(firstword $(wildcard \
	$(CVS_PROJ_DIR)/closure-compiler/contrib/closure-compiler/install-root/usr/share/java/closure-compiler.jar \
	/usr/share/java/closure-compiler.jar \
	))
JS_MINIFY             ?= $(JS_MINIFY_EXE) $(JS_MINIFY_OPTS)

# This is not nice. It requires install-files to be included from elsewhere,
# which is not obvious. OTOH, if it isn't, SOURCE_FILES doesn't do any harm,
# either.
SOURCE_FILES           += $(JS_GENERATED)

all: $(JS_GENERATED)
clean: minify.clean

%.min.js: %.js
	cat $< | $(JS_MINIFY_FILTER_IN) > $@.filtered
	$(JS_MINIFY) $@.filtered > $@.tmp
	mv $@.tmp $@

minify.clean:
	rm -f $(JS_GENERATED) *.tmp *.filtered