#
# Example makefile using mjotex and a BibTeX references database.
#

# The latex compiler. The SOURCE_DATE_EPOCH=0 prevents the creation
# and modification dates from being embedded as metadata into the
# output file; that in turn is important because it allows us to tell
# when the output stops changing (that is, when we are done). The
# variable is supported in pdftex v1.40.17 and later.
LATEX = SOURCE_DATE_EPOCH=0 pdflatex -file-line-error -halt-on-error

# The name of this document.
#
# For example, to use the name of our parent directory:
#
# PN = $(notdir $(realpath .))
#
PN = example

# A space-separated list of bib files. These must all belong to paths
# contained in your $BIBINPUTS environment variable.
#
# Leave commented if you don't use a bibliography database.
#
#BIBS = local-references.bib

# A space-separated list of the mjotex files that you use. The path to
# mjotex must be contain in your $TEXINPUTS environment variable.
#
MJOTEX  = mjotex.sty mjo.bst

# Beamer template
BEAMERMJO = beamercolorthememjo.sty beamerfontthememjo.sty
BEAMERMJO += beamerinnerthememjo.sty beamerouterthememjo.sty
BEAMERMJO += beamerthememjo.sty
BEAMERMJOPATHS = $(shell kpsewhich $(BEAMERMJO))

# Use kpsewhich (from the kpathsea suite) to find the absolute paths
# of the bibtex/mjotex files listed in in $(BIBS)/$(MJOTEX). The SRCS
# variable should contain all (Bib)TeX source files for the document.
SRCS = $(PN).tex
ifdef BIBS
BIBPATHS = $(shell kpsewhich $(BIBS))
SRCS += $(BIBPATHS)
endif
ifdef MJOTEX
MJOTEXPATHS = $(shell kpsewhich $(MJOTEX))
SRCS += $(MJOTEXPATHS)
endif

SRCS += $(BEAMERMJOPATHS)


# The first target is the default, so put the PDF document first.
#
# This voodoo is all designed to find a "fixed point" of calling
# $(LATEX). When you build a LaTeX document, it requires an unknown
# number of compilation passes. How do you know when to stop? Easy,
# stop when the output file stops changing! But how to encode that
# in a makefile?
#
# At the start of this target, we call $(LATEX) to compile $(PN).tex.
# Afterwards, we check for the existence of a "previous" file. If
# there isn't one, then this is the first time that we've built the
# PDF. In that case, we take the PDF that we've just built and make it
# the "previous" file before starting all over. If, on the other hand,
# there already *was* a "previous" file, then this is the second (or
# third...) time that we've built the PDF. We diff the newly-built PDF
# against the "previous" file; if they're the same, then we've
# succeeded and stop. Otherwise, we make the new PDF the "previous"
# one, and start all over. The end result is that we will loop until
# the newly-created PDF and the "previous" one are identical.
#
$(PN).pdf: $(SRCS) $(PN).bbl
	$(LATEX) $(PN).tex

	if [ -f $@.previous ] && cmp -s $@ $@.previous; then \
		rm $@.previous; \
	else \
		mv $@ $@.previous; \
		$(MAKE) $@; \
	fi;


$(PN).aux: $(SRCS)
	$(LATEX) $(PN).tex


ifdef INDICES
# We need to be able to build the index source files without involving
# the main $(PN).pdf rule, in order to avoid a chicken-and-egg problem.
# This is similar to the $(PN).aux rule above, except that an index is
# optional and there might be more than one of them.
$(INDEX_SRCS): $(PN).tex
	$(LATEX) $(PN).tex
endif

# The pipe below indicates an "order-only dependency" on the aux file.
# Without it, every compilation of $(PN).tex would produce a new
# $(PN).aux, and thus $(PN).bbl would be rebuilt. This in turn causes
# $(PN).pdf to appear out-of-date, which leads to a recompilation of
# $(PN).tex... and so on. The order-only dependency means we won't
# rebuild $(PN).bbl if $(PN).aux changes.
#
# As a side effect, we now need to depend on $(SRCS) here, since we
# won't pick it up transitively from $(PN).aux.
#
# If the $BIBS variable is undefined, we presume that there are no
# references and create an empty bbl file. Otherwise, we risk trying
# to run biblatex on an aux file containing no citations. If you do
# define $BIBS but don't cite anything, you'll run into a similar
# problem. Don't do that.
#
$(PN).bbl: $(SRCS) | $(PN).aux
ifdef BIBS
	bibtex $(PN).aux
else
	printf '' > $@
endif

# If the output PDF exists but the log file does not, then an attempt
# to "build the log file" (i.e. build the PDF) would do nothing. Thus
# whenever the log file does not exist, we do a fresh build.
$(PN).log: $(SRCS)
	$(MAKE) clean
	$(MAKE)

# Ensure that there are no overfull or underfull boxes in the output
# document by parsing the log for said warnings.
.PHONY: check-boxes
check-boxes: $(PN).log
	@! grep -i 'overfull\|underfull' $<

# Run chktex to find silly mistakes. There is some exit code weirdness
# (Savannah bug 53129), so we just look for empty output.
.PHONY: check-chktex
CHKTEX = chktex --localrc .chktexrc --quiet --inputfiles=0
check-chktex:
	@chktexout=$$($(CHKTEX) $(PN).tex); \
	  test -z "$${chktexout}" || { echo "$${chktexout}" 1>&2; exit 1; }

# Ensure that there are no undefined references in the document by
# parsing the log file for said warnings.
.PHONY: check-undefined
check-undefined: $(PN).log
	@! grep -i 'undefined' $<

# Run a suite of checks.
.PHONY: check
check: check-boxes check-chktex check-undefined

# Clean up leftover junk. This only looks overcomplicated because
# the *.{foo,bar} syntax supported by Bash is not POSIX, and Make
# will execute these commands using /bin/sh (which should be POSIX).
JUNK_EXTENSIONS  = aux bbl bcf blg glo ilg ist listing lof log nav out pdf
JUNK_EXTENSIONS += snm spl toc xml
.PHONY: clean
clean:
	for ext in $(JUNK_EXTENSIONS); do rm -f *.$$ext; done;