# Makefile for Plato - The Stanford Encyclopedia of Philosophy, in ePub
# Use this to build a new version of the ePub document from remote sources.

# Document generation options.
NAME     := Stanford Encyclopedia of Philosophy
BASE_URL := https://plato.stanford.edu

# Build-time dependencies.
AWK      = $(call find-cmd,awk)
GREP     = $(call find-cmd,grep)
PANDOC   = $(call find-cmd,pandoc) $(if $(VERBOSE),--verbose)
WGET     = $(call find-cmd,wget) $(if $(VERBOSE),,--quiet)
KEPUBIFY = $(call find-cmd,kepubify) $(if $(VERBOSE),--verbose)

# Directory aliases.
ROOTDIR  := $(dir $(realpath $(firstword $(MAKEFILE_LIST))))
BUILDDIR := $(ROOTDIR)build/
TMPDIR   := $(ROOTDIR)tmp/

# Default Makefile options.
VERBOSE     :=
ENABLE_KOBO :=

## Build ePub documents via Pandoc.
build: $(addprefix $(BUILDDIR),$(addsuffix $(if $(ENABLE_KOBO),.kepub).epub,$(basename $(notdir $(wildcard $(TMPDIR)entries/*.md)))))

## Remove all temporary files.
clean:
	$Q rm --recursive --force $(if $(VERBOSE),--verbose) $(TMPDIR)

## Remove all temporary and build files.
purge:
	$Q rm --recursive --force $(if $(VERBOSE),--verbose) $(BUILDDIR) $(TMPDIR)

$(BUILDDIR)%.kepub.epub: $(BUILDDIR)%.epub
	$Q $(KEPUBIFY) --inplace --smarten-punctuation --output $@ $<

$(BUILDDIR)%.epub: $(TMPDIR)entries/%.md
	$Q install -d $(@D)
	$Q cd $(TMPDIR)entries/$* && $(PANDOC) --from markdown --to epub --mathml $< > $@

$(TMPDIR)entries/%.md: $(TMPDIR)entries/%/index.html
	$Q install -d $(@D)
	$Q $(AWK) "$$EXTRACT_ARTICLE_META" $< > $@
	$Q $(PANDOC) --from html+tex_math_single_backslash+tex_math_double_backslash --to markdown $< | $(AWK) "$$EXTRACT_ARTICLE" >> $@

$(TMPDIR)%.html:
	$Q install -d $(@D)
	$Q $(WGET) --no-clobber --page-requisites --accept html,png,jpg,jpeg,gif,svg --no-directories --directory-prefix $(@D) $(BASE_URL)/$*.html

$(TMPDIR)table-of-contents.md: $(TMPDIR)contents.html
	$Q install -d $(@D)
	$Q $(PANDOC) --from html --to markdown $< | $(AWK) "$$EXTRACT_TOC" > $@

.PHONY: build clean purge

$(TMPDIR)make.depend: $(TMPDIR)table-of-contents.md
	@printf "build: $<" > $@
	@for i in `$(GREP) -Po '\[.+?\]\(\Kentries/[^/]+' $<`; do printf " $(TMPDIR)$${i}.md"; done >> $@

# Conditional command echo control.
Q := $(if $(VERBOSE),,@)

# Find and return full path to command by name, or throw error if none can be found in PATH.
# Example use: $(call find-cmd,ls)
find-cmd = $(or $(firstword $(wildcard $(addsuffix /$(1),$(subst :, ,$(PATH))))),$(error "Command '$(1)' not found in PATH"))

# Awk script for extracting bare table-of-contents body from Markdown source.
define EXTRACT_TOC
$$0 ~ "::: {#toc-wrapper}" {s=1; next}
$$0 ~ "Projected Table of Contents" {s=0}
$$1 != ":::" && s == 1 {print}
endef
export EXTRACT_TOC

# Awk script for extracting article metadata from HTML source.
define EXTRACT_ARTICLE_META
BEGIN {FS="\""; print "---"}
$$2 == "citation_title" {printf "title: \"%s\"\n", $$4; next}
$$2 == "citation_author" {if (c==0) {print "creator:"; c=1}; printf "- role: author\n  text: \"%s\"\n", $$4; next}
END {print "publisher: \"$(NAME)\""; print "belongs-to-collection: \"$(NAME)\""; print "---"}
endef
export EXTRACT_ARTICLE_META

# Awk script for extracting bare aricle body from Markdown source.
define EXTRACT_ARTICLE
$$0 ~ "::: {#article-content}" {s=1; next}
$$0 ~ "::: {#toc}" {s=0; next}
$$0 ~ "::: {#main-text}" {s=1; next}
$$0 ~ "::: {#academic-tools}" {s=0; next}
$$1 != ":::" && s == 1 {print}
endef
export EXTRACT_ARTICLE

# Dependency includes.
include $(TMPDIR)make.depend