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# index.mk
#
#> Index Gemini site content
#>
#> This Makefile builds content indicies for a Gemini site.
#>
#
# Allowing posts to be m4 files introduces complexity without clear benefit.
# Thus we are
#
# Strategy:
#   1. Mark all *.gmi files as posts.
#   2. Limit macros to:
#      a. Section index
#      b. Tagged index
#      c. Header
#      d. Footer
#   4. Create index entries for each *.gmi file.
#   5. Build the full list of tags.
#   6. Generate the post as `cat footer.gmi post.gmi footer.gmi`.
#   7. Build the tagged index files from the list of tags.
#   8. Build index.gmi from tag list.
#
# The key challenge is step 7. We do not know how to build this until we
# completed step 5. Two possible approaches:
#   1. Create a macro
#   2. Recurse into another Makefile.
#
# © 2023 Andrew Stryker <axs@sdf.org>
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#-----------------------------------------------------------------------------#
#
# Configuration
#
#-----------------------------------------------------------------------------#

# Record the name of this Makefile
self ::= $(lastword ${MAKEFILE_LIST})

# Load environment variables if needed--not the case when this is called from
# the main Makefile
ifndef ENV_LOADED

  # Assume the base directory is two levels up if not defined
  MAKO_DIR ?= ../..

  include ${MAKO_DIR}/environment.mk

endif

# Define using the same definition as in the main Makefile
build_date_msg ?= This page was built on $$(date).

# Define special files
index_template ::= index.gmi.m4
index ::= ${STAGING_SECTION}/index.gmi

header_template ::= header.gmi.m4
header ::= ${WORKING_SECTION}/header.gmi

footer_template ::= footer.gmi.m4
footer ::= ${WORKING_SECTION}/footer.gmi

# Capture all posts as Gemtext files that begin with an ISO formatted date
posts_gmi ::= $(shell ls *.gmi | grep "[[:digit:]]\{4\}\(-[[:digit:]]\{2\}\)\{2\}")
posts ::= $(addprefix ${STAGING_SECTION}/, ${posts_gmi})
entries ::= $(addprefix ${WORKING_SECTION}/, ${posts_gmi:.gmi=.lnk})

TAG_LIST ::= ${WORKING_SECTION}/tag-list
export TAG_LIST

# Create list of potential dependencies of *.gmi.m4 templates
template_depends ::= $(notdir $(filter-out %.gmi.m4 _% %~, $(wildcard *)))

#-----------------------------------------------------------------------------#
#
# User interface
#
#> This makefile supports the following targets:
#>
#-----------------------------------------------------------------------------#

.PHONY: default build clean show help create

# define the default target explicitly
default: create

create: #> Create a new post (default)
	@if [ -z $${EDITOR} ]; then \
		python3 create-post.py; \
		else \
		python3 create-post.py --edit; \
		fi

build: ${index} #> Build the site (default)
	@echo "✓ Completed processing ${content_section}"
	@echo

show: #> Show enironment variables with values
	@echo staging area: ${STAGING}
	@echo workspace: ${WORKSPACE}
	@echo post_index: ${post_index}
	@echo ${build_date_msg}
	@echo targets: ${post_targets}
	@echo header: ${header}
	@echo footer: ${footer}
	@echo tag list: ${TAG_LIST}

clean: #> Delete generated files
	@rm -rf ${STAGING} ${WORKSPACE}
	@echo "\t✓ Deleted intermediate files"
	@echo "\t✓ Deleted all posts in ${STAGING}"

help: #> Display this help message
	@awk -f ${AWKHELP} ${self}

#-----------------------------------------------------------------------------#
#
# File system interface
#
#-----------------------------------------------------------------------------#

${header} ${footer}: ${WORKING_SECTION}/%: % ${template_depends}
	@mkdir -p ${WORKING_SECTION}
	@m4 --include=${MAKO_DIR} $< > $@
	@echo "\t✓ Created: $@"

${posts}: ${STAGING_SECTION}/%: % ${header} ${footer}
	@mkdir -p ${STAGING_SECTION}
	@cat ${header} $< ${footer} > $@
	@echo "${build_date_msg}" >> $@
	@echo "\t✓ Created   $@"

${entries}: ${WORKING_SECTION}/%.lnk: ${MAKO_DIR}/create-index-entry.awk %.gmi
	@mkdir -p ${WORKING_SECTION}
	@awk -f $^ > $@
	@echo "\t✓ Created: $@"

${TAG_LIST}: ${entries}
	@cat $^ | sort --unique | \
	       	sed -e '/^---/ d; s/^\([a-zA-Z0-09]\+\).*/=> \1.gmi \1/' > $@
	@echo "\t✓ Created the tags list"

${index}: ${index_template} ${header} ${footer} ${posts} ${TAG_LIST}
	@${MAKE} -f ${TAG_MAKE} build
	@m4 --include=.. \
		--define=TAGS=${tags_list} \
		--define=POSTS=${post_entry} \
		--define=HEADER=${header} \
		--define=FOOTER=${footer} \
		$< > $@
	@echo "✓ Created: $@"

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