infiles := $(wildcard data/*.ttl data/*/*.ttl)
turtlefiles := $(infiles:data/%.ttl=build/%/index.ttl)
textfiles = $(turtlefiles:%.ttl=%.txt)
rdfxmlfiles = $(turtlefiles:%.ttl=%.rdf)

getbase = $(shell perl -ne '/^\@base\s+<(http.+)>/ and print $$1 and exit;' "$1")

all: $(textfiles) $(rdfxmlfiles)

clean:
	rm -rf build

$(turtlefiles): build/%/index.ttl : data/%.ttl
	mkdir -p $(dir $@)
	$(eval base = $(call getbase, $<))
	rapper $(base:%=-I "%") -i turtle -o turtle "$<" > "$@"
	perl -i -pe 's/ {4}/\t/g' "$@"

$(textfiles): %.txt : %.ttl
	ln -s $(notdir $<) $@

$(rdfxmlfiles): %.rdf : %.ttl
	$(eval base = $(call getbase, $<))
	rapper $(base:%=-I "%") -i turtle -o rdfxml-abbrev "$<" > "$@"