markdown-snippets := nav.md footer.md
hypertext-snippets = $(markdown-snippets:%.md=%.html)
markdown := $(filter-out $(markdown-snippets),$(wildcard *.md */*.md */*/*.md))
hypertext = $(subst index/index,index,$(markdown:%.md=%/index.html))
graph := $(wildcard *.dot */*.dot */*/*.dot)
vectorimage-graph := $(graph:%.dot=%.svg)

sitetitle := $(shell head --lines=1 index.md \
 | grep --perl-regexp --only-matching '^\#\s*\K(\S+(\s\S+)*)+')

all: $(hypertext) $(vectorimage-graph) style.css

update: .git
	git pull
	$(MAKE) all

$(hypertext-snippets): %.html: %.md Makefile
	pandoc -f markdown -t html -o $@ $<
	sed -i -e '1i <$*>' -e '$$ a </$*>' $@

$(vectorimage-graph): %.svg: %.dot Makefile
	dot -Tsvg -o$@ $<

%.html %/index.html: %.md $(hypertext-snippets) Makefile
	$(eval title = $(shell head --lines=1 $< \
	 | grep --perl-regexp --only-matching '^\#\s*\K(\S+(\s\S+)*)+'))
	$(if $(filter-out ./,$(dir $@)),mkdir -p $(dir $@))
	$(strip pandoc -f markdown -t html5 -s \
	 --metadata lang=da \
	 $(if $(title),\
	  $(if $(filter-out $(sitetitle),$(title)),$(strip \
	   --metadata pagetitle='$(sitetitle) -- $(title)'),$(strip \
	   --metadata pagetitle='$(title)'))) \
	 -c $(shell realpath --relative-to=$(dir $@) style.css) \
	 -B nav.html \
	 -A footer.html \
	 -o $@ $<)

%.css : %.scss Makefile
	sassc --load-path /usr/share/sass --style compressed $< $@

clean:
	rm -f $(vectorimage-graph)
	find * -type f -name '*.html' -delete
	find * -type d -empty -delete
	rm -f style.css style.css.map
	rm -rf .sass-cache

MAKEFLAGS += --jobs
.NOTPARALLEL: source
.PHONY: all update clean