#!/bin/sh
set -e

usage="usage:
	./md.sh <target dir>
	./md.sh <input md> <output html>"

# input: <target dir>/src.md ./md-header ./md-footer <site root>/nav.html
# output: <target dir>/index.html
# dependencies: lowdown

# Copyright 2019-2022 DistressNetwork° <uplink@distress.network>
# 
# 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/>.


IN="$1/src.md"
OUT="$1/index.html"

[ "$2" ] && { IN="$1" ; OUT="$2" ; }

[ "$1" ] || { echo "$usage" ; exit 1 ; }

[ -f "$IN" ]			|| { printf "[err] \t%s not found\n" "$IN" ;	exit 1 ; }
[ -f md-header ] 		|| { printf "[err] \tmd-header not found\n" ;	exit 1 ; }
[ -f md-footer ] 		|| { printf "[err] \tmd-footer not found\n" ;	exit 1 ; }
[ -e "$(which lowdown)" ]	|| { printf "[err] \tlowdown not found\n" ;	exit 1 ; }

cat md-header > "$OUT"
lowdown -Thtml --html-no-owasp "$IN" >> "$OUT"
cat md-footer >> "$OUT"
printf "[ok] \tinitial assembly\n"


sedesc() {
	sed -e 's;&;\\\&;g' -e 's/;/\\\;/g'
}

unesc() {
	sed -e 's;\\\&;\&;g' -e 's/\\\;/;/g'
}


TITLE=$(grep -e '^title: ' -m 1 "$IN" | cut -f 2- -d ' ' | sedesc)
sed "s/<title>/&${TITLE} \&mdash\; DistressNetwork°/1" -i'' "$OUT"
printf "[ok] \ttitle: %s\n" "$(echo "$TITLE" | unesc)"

BOMBER=$(grep -e '^bomber: ' -m 1 "$IN" | cut -f 2- -d ' ' | sedesc)
sed "s/<div class=\"bomber\">/&${BOMBER}/1" -i'' "$OUT"
printf "[ok] \tbomber: %s\n" "$(echo "$BOMBER" | unesc)"

# format: "yyyy-mm-dd hh:mm:ss±zz:zz" (ISO 8601)
MDATE=$(stat -c '%y' "$IN" | sed -e 's/\.[0-9]* //' -e 's/\(..\)\(..\)$/\1:\2/')
# format: "yymmdd" (for humans)
DATE=$(echo "$MDATE" | cut -f 1 -d ' ' | sed -e 's/-//g' -e 's/^..//')
sed -e "s;<div class=\"ident\"><time datetime=\";&${MDATE};1" -e "s;</time>;${DATE}&;1" -i'' "$OUT"
sed "s;<meta http-equiv=\"last-modified\" content=\";&${MDATE};1" -i'' "$OUT"
printf "[ok] \tdate: %s (%s)\n" "$DATE" "$MDATE"

LEADING=$(grep -e '^leading: ' -m 1 "$IN" | cut -f 2- -d ' ' | sedesc)
sed "s;<div class=\"leading\">;&${LEADING};1" -i'' "$OUT"
printf "[ok] \tleading: %s\n" "$(echo "$LEADING" | unesc)"

METADESC="\&laquo\;${BOMBER}\&raquo\; \&mdash\; ${LEADING}"
sed "s;<meta name=\"description\" content=\";&${METADESC};1" -i'' "$OUT"
printf "[ok] \tmeta description\n"

if [ -f "$(echo $IN | cut -f 1 -d /)/nav.html" ] ; then
NAVLINE=$(grep -n '<nav>' "$OUT" | cut -f 1 -d :) ;
sed "${NAVLINE}r $(echo "$OUT" | cut -f 1 -d /)/nav.html" -i'' "$OUT" ;
sed '/^<!--title:/d' -i'' "$OUT" ;
printf "[ok] \tsitemap\n" ;
fi

grep -q '<p><img' "$OUT" && {	# skip if no figures found
# escaping backslashes with '@', to be unescaped later:
grep -n '<p><img' "$OUT" | sed 's/\\/@/g' | \
while IFS='' read -r data ; do
	LINE=$(echo "$data" | cut -f 1 -d :) ;	# extract line number
	FILE=$(echo "$data" | cut -f 2 -d \") ;	# extract file path
	CAPT=$(echo "$data" | cut -f 4 -d \") ;	# extract image caption

	if [ "$FILE" = "%tex" ] ; then 		# for tex figures (to be caught and rendered later)
		sed "${LINE}s;.*;<figure><%tex \"${CAPT}\" /></figure>;" -i'' "$OUT" ;
	else
		sed "${LINE}s;.*;<figure><a href=\"${FILE}\"><img src=\"${FILE}\" alt=\"\"></a><figcaption><p>${CAPT}</p></figcaption></figure>;" -i'' "$OUT" ;
		printf "[ok] \timage at line %s\n" "$LINE" ;
	fi
done
}


toc() {

tmp=$(mktemp -p /tmp) 

# format headers from source as md list
grep -e '^#' "$IN" | sed -e 's; ;- ;' -e 's;^#;;' -e 's;#;	;g' > "$tmp"

# convert to html, write to tempfile (reset)
buffer=$(cat "$tmp") ; echo "$buffer" | lowdown -Thtml > "$tmp"

# prepend starting tag, remove empty lines
sed -e '1i <nav class="toc">' -e '/^$/d' -i'' "$tmp" 

# get queue of headers from output
HEADERS=$(grep -e "^<h[[:digit:]] id=" "$OUT")

# for each toc list item:
grep -e "^<li>" "$tmp" | while IFS='' read -r data ; do
	# get next header in queue, extract id
	HEADER=$(echo "$HEADERS" | head -n 1) ;
	ID=$(echo "$HEADER" | cut -f 2 -d \" | sedesc) ;

	# rewrite toc item as link with id
	ITEM=$(echo "$data" | sed "s;^<li>\([^</>]*\)\(</li>\)*$;\1;" | sedesc) ;
	sed -e "s;^<li>\(${ITEM}\);<li><a href=\"#${ID}\">\1;" -e "s;\([[:alnum:]]\)</li>$;\1</a></li>;" -i'' "$tmp" ;

	# remove processed header from queue
	HEADERS=$(echo "$HEADERS" | sed '1d') ;

	printf "\tassembled header: %s\n" "$(echo $ITEM | unesc)" ;
done

# close link tags on open lines, append closing tag
sed "s;[[:alnum:]]$;&</a>;" -i'' "$tmp"
echo '</nav>' >> "$tmp"

# get toc line number in output, insert data from tempfile
TOCLINE=$(wc -l md-header | cut -f 1 -d ' ')
sed "${TOCLINE}r $tmp" -i'' "$OUT"

rm "$tmp"

printf "[ok] \ttable of contents\n"

}


math() {

# [ $(npx katex -V 2>&1 | grep '404 Not Found') ] && { printf "[warn] \tkatex not found, skipping math rendering\n" ; return ; }

sed '/main.css/a <link rel="stylesheet" href="/css/katex.css">' -i'' "$OUT"

# display / "block" style:
grep -n '<figure><%tex' "$OUT" | \
while IFS='' read -r data ; do
	LINE=$(echo "$data" | cut -f 1 -d :) ;
	EQNBODY=$(echo "$data" | cut -f 2 -d \" ) ;
	printf "\trendering tex figure at line %s ... " "$LINE" ;
	
	tmp=$(mktemp -p /tmp) ;
	echo "<figure>" > "$tmp" ;
	echo "$EQNBODY" | sed 's/@/\\/g' | npx katex -d >> "$tmp" 2>&1 ;
	echo "</figure>" >> "$tmp" ;
	sed ':a;N;$!ba;s/\n//g' -i'' "$tmp" ;

	if grep -q "KaTeX parse error" "$tmp" ; then
		printf "\n[warn] \ttex expression at line %s contained errors, skipping\n" "$LINE" ;
	else
		sed "${LINE}d" -i'' "$OUT" ;
		sed "$(expr $LINE - 1)r $tmp" -i'' "$OUT" ;
		printf "complete\n" ;
	fi ;

	rm "$tmp" ;
done

# inline / "span" style:
sed 's;<img src="%itex" alt=".*" />;\n&\n;g' -i'' "$OUT"
grep -n '<img src="%itex"' "$OUT" | sed 's/\\/@/g' | \
while IFS='' read -r data ; do
	LINE=$(echo "$data" | cut -f 1 -d :) ;
	EQNBODY=$(echo "$data" | cut -f 4 -d \" ) ;
	printf "\trendering inline tex figure at line %s ... " "$LINE" ;
	
	tmp=$(mktemp -p /tmp) ;
	echo "$EQNBODY" | sed 's/@/\\/g' | npx katex > "$tmp" 2>&1 ;
	sed ':a;N;$!ba;s/\n//g' -i'' "$tmp" ;

	if grep -q "KaTeX parse error" "$tmp" ; then
		printf "\n[warn] \tinline tex expression at line %s contained errors, skipping\n" "$LINE" ;
	else
		sed "${LINE}d" -i'' "$OUT" ;
		sed "$(expr $LINE - 1)r $tmp" -i'' "$OUT" ;
		printf "complete\n" ;
	fi ;

	rm "$tmp" ;
done

printf "[ok] \tmath typesetting\n"

}


opts=$(grep -e '^opts: ' -m 1 $IN | cut -f 2- -d ' ')
while [ "$opts" ] ; do
case "$opts" in
	(*[Cc]*)
		toc
		opts=$(echo $opts | sed 's/[Cc]//g') ;;
	(*[Ff]*)
		sed "/^<footer>/,/^<\/footer>/d" -i'' "$OUT"
		printf "[ok] \tfooterless\n"
		opts=$(echo "$opts" | sed 's/[Ff]//g') ;;
	(*[Hh]*)
		sed -e "/^<header>/,/^<\/header>/d" -e '/^<meta name="description"/d' -i'' "$OUT"
		sed "/bg.js/d" -i'' "$OUT"
		printf "[ok] \theaderless\n"
		opts=$(echo "$opts" | sed 's/[Hh]//g') ;;
	(*[Mm]*)
		math
		opts=$(echo "$opts" | sed 's/[Mm]//g') ;;
	(*)
		printf "[warn] \tmetadata: unrecognized option(s) \"%s\"\n" "${opts}" ;;
esac
done


printf "%s \tbuild complete: %s\n" "[->]" "$OUT"