thoughts/src/post2html

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#!/bin/bash
# Generate HTML from post Markdown source
#
# Copyright (C) 2019 Mike Gerwitz
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
#
# This script accepts the file name rather than data on stdin because the
# filename encodes the post date.
#
# Note that the `pagetitle' is set to "ignoreme"---it is not used, but is
# needed to suppress the warning pandoc produces without suppressing all
# warnings.
#
# Pandoc is used to generate the HTML and includes a (mostly) static header
# and footer. Note that this duplicates the date logic in `post2meta',
# because that must be run on this output, but the post must also contain
# the date, and we want to do all HTML processing now.
##
declare -r srcref=https://forge.mikegerwitz.com/mikegerwitz/thoughts/commits/branch/master
set -euo pipefail
# Pandoc output format and extensions.
declare -ra ext=(
markdown
smart
footnotes
gfm_auto_identifiers
fancy_lists
startnum
tex_math_dollars
)
# Convert extensions to `+'-delimited string.
pexts()
{
local IFS=+
echo "${ext[*]}"
}
# Wrap h1 in an hgroup along with the post date.
#
# Sometimes this script is used on things that aren't posts (e.g. normal
# pages), in which case a date will be unavailable and the output will be
# unchanged.
hgroup-wrap()
{
local -r date=${1?Missing date}
local -r file=${2?Missing file}
# Abort if this is not a date prefix
[[ $date =~ [0-9]{4}-[0-9]{2}-[0-9]{2} ]] || {
cat
return
}
local -r repo_href="$srcref/$file"
local anchor
printf -vanchor '<a class="muted" href="%s">%s</a>' \
"$repo_href" \
"$date"
sed '/^<h1/{
i<hgroup>
a<h2 class="date">'"$anchor"'</h2></hgroup>
}'
}
# Pre-format Markdown files before they get to Pandoc
#
# These may be able to be implemented as Pandoc filters, but I haven't had
# the time to research that yet. This is actually a fitting real-world
# demonstration of incremental development / MVP that I'm writing about at
# the time that this comment was written (MyCustomBB Part I)!
prefmt()
{
awk '
triml {
gsub( /^ +/, "" )
triml = 0
}
# ties
{ $0 = gensub( /([^\\])~/, "\\1 ", "g" ) }
{ $0 = gensub( /\\~/, "~", "g" ) }
# TeX-style newline removal
/%$/ {
gsub( /%$/, "" )
printf "%s", $0
triml = 1
next
}
# reference to the content of the last fence (e.g. if a previous
# code block is HTML and we want to render it as an example)
/^```/ {
gather = !gather
if ( gather ) gblock = ""
}
!/^```/ && gather { gblock = gblock $0 "\n" }
!gather && /^ *@LASTFENCE@$/ { print gblock; next }
{ print }
'
}
# Generate HTML from post. Note that `pagetitle' is set just to suppress
# Pandoc warnings about it missing; it is unused.
main()
{
local -r file=${1?Missing file name}
local -r base=$( basename "$file" .md )
local -r date=${base:0:10}
pandoc -f"$( pexts )" -thtml5 \
--standalone --template src/pandoc.tpl \
--metadata pagetitle:ignoreme \
--base-header-level=1 \
-B <( src/mkheader post @__PAGE_TITLE__@ ) \
-A src/footer.tpl.htm \
< <( prefmt < "$file" ) \
| src/h12title @__PAGE_TITLE__@ \
| hgroup-wrap "$date" "$file"
}
main "$@"