listmgr

#!/bin/dash
#
# listmgr - HTML list manager.
# Utility to elegantly print UL and LI tags while creating an HTML list.
# POSIX compliant. Compatible with 'sbase' (suckless.org).
# © Andrea Calligaris; released under the MIT License.
# See "license-listmgr.txt" file for copyright and license details.
# Usage: include the file in your main script to be able to use the functions.

# get_ul_and_li_tags()
# get_final_ul_and_li_tags()

# Block of spaces for each depth level. Purely visual, for the HTML source.
SPACES_BLOCK='   '

# Get the required UL and LI tags to be inserted before the current entry of
# the HTML list. This includes all the necessary closing of previous entries.
get_ul_and_li_tags()
{
	just_started=$1
	curr_depth_lvl="$2"
	previous_depth_lvl="$3"
	is_the_whole_list_closing=${4:-false}

	tags="</li>
" # Literal new line; ugly, but '\n' doesn't work because it's discarded when
  # at the end.

	spaces=$( yes "$SPACES_BLOCK" | head -n "$curr_depth_lvl" | tr -d '\n' )

	if [ "$just_started" = true ]; then
		tags="" # No previous entry to close.
		just_started=false
	fi

	if [ "$curr_depth_lvl" -gt "$previous_depth_lvl" ]; then
		tags=$( printf "\n%s<ul>\n%s" "$spaces" "$spaces" )
	elif [ "$curr_depth_lvl" -lt "$previous_depth_lvl" ]; then
		tags=$( printf "</li>" )
		depth_diff=$(( previous_depth_lvl - curr_depth_lvl ))
		for i in $(seq $depth_diff); do
			subdcount=$(( previous_depth_lvl - i ))
			spaces=$( yes "$SPACES_BLOCK" | head -n "$subdcount" \
				| tr -d '\n' )
			tags=$( printf "%s\n%s%s</ul>\n%s</li>" \
				"$tags" "$spaces" "$SPACES_BLOCK" "$spaces" )
		done
		spaces=$( yes "$SPACES_BLOCK" | head -n "$curr_depth_lvl" \
			| tr -d '\n' )
		if [ "$is_the_whole_list_closing" = false ]; then
			tags=$( printf "%s\n%s" "$tags" "$spaces" )
		else
			tags=$( printf "%s\n" "$tags" )
		fi
	else
		# Add the required spaces for the next entry.
		if [ "$is_the_whole_list_closing" = false ]; then
			tags="${tags}${spaces}"
		fi
	fi

	# Append the LI tag for the next entry.
	if [ "$is_the_whole_list_closing" = false ]; then
		tags="${tags}<li>"
	fi

	echo "$tags"
}

# Once done with the list, all remaining UL and LI tags need to be closed,
# taking into account the reached depth level.
get_final_ul_and_li_tags()
{
	previous_depth_lvl="$1"

	curr_depth_lvl=1 # Move to the first depth level.
	ul_and_li_tags=$( get_ul_and_li_tags \
		false "$curr_depth_lvl" "$previous_depth_lvl" true )

	echo "$ul_and_li_tags"
}