typeset_gemini() {
	local pre=false

	while read -r line; do
		case "$line" in
		'```')
			flip pre
			continue
			;;
		=\>*) gemini_link "$line" $pre ;;
		\#*) gemini_header "$line" $pre ;;
		\**) gemini_list "$line" $pre ;;
		*) gemini_text "$line" $pre ;;
		esac
	done
}

gemini_link() {
	local re="^(=>)[[:blank:]]*([^[:blank:]]+)[[:blank:]]*(.*)"
	local s t a # sigil, text, annotation(url)
	if ! ${2-false} && [[ "$1" =~ $re ]]; then
		s="${BASH_REMATCH[1]}"
		t="${BASH_REMATCH[3]}"
		a="${BASH_REMATCH[2]}"

		printf "$C_SIGIL%-${MARGIN}s" "$s"
		fold_line "$WIDTH" "$(printf "$C_LINK_TITLE%s $C_LINK_URL%s$C_RESET\n" \
			"$t" "$a")"
	else
		gemini_pre "$1"
	fi
}

gemini_header() {
	local re="^(#+)[[:blank:]]*(.*)"
	local s t a # sigil, text, annotation(lvl)
	if ! ${2-false} && [[ "$1" =~ $re ]]; then
		s="${BASH_REMATCH[1]}"
		a="${#BASH_REMATCH[1]}"
		t="${BASH_REMATCH[2]}"

		local hdrfmt
		hdrfmt="$(eval echo "\$C_HEADER$a")"
		printf "$C_SIGIL%-${MARGIN}s$hdrfmt%s$C_RESET\n" \
			"$s" "$(fold_line "$WIDTH" "$t")"
	else
		gemini_pre "$1"
	fi
}

gemini_list() {
	local re="^(\*)[[:blank:]]*(.*)"
	local s t a # sigil, text, annotation(n/a)
	if ! ${2-false} && [[ "$1" =~ $re ]]; then
		s="${BASH_REMATCH[1]}"
		t="${BASH_REMATCH[2]}"

		printf "$C_SIGIL%-${MARGIN}s$C_LIST%s$C_RESET\n" \
			"$s" "$(fold_line "$WIDTH" "$t")"
	else
		gemini_pre "$1"
	fi
}

gemini_text() {
	printf "%${MARGIN}s" ' '
	if ! ${2-false}; then
		fold_line "$WIDTH" "$1"
	else
		gemini_pre "$1"
	fi
}

gemini_pre() {
	printf "%${MARGIN}s%s" ' ' "$1"
}

flip() { # flip NAME
	[[ "${!1}" == true || "${!1}" == false ]] || return 1

	if "${!1}"; then
		eval "$1=false"
	else
		eval "$1=true"
	fi
}

fold_line() { # fold_line WIDTH TEXT
	local width="$1"
	local ll=0 wl plain
	# shellcheck disable=2086
	# TODO: determine if this is the best way to do it
	set -- $2

	for word; do
		plain="${word//$'\x1b'\[*([0-9;])m/}"
		wl=$((${#plain} + 1))
		if (((ll + wl) >= width)); then
			printf "\n%${MARGIN}s" ' '
			ll=$wl
		else
			ll=$((ll + wl))
		fi
		printf '%s ' "$word"
	done
	printf '\n'
}

# just here for reference
strip() { # strip control sequences
	# https://stackoverflow.com/a/55872518
	shopt -s extglob
	while IFS='' read -r x; do
		# remove colors
		echo "${x//$'\x1b'\[*([0-9;])m/}"
	done
}

test() {
	MARGIN=4
	WIDTH=60
	#shopt -s checkwinsize; (:;:)
	#WIDTH="$((COLUMNS - (MARGIN*2)))"
	C_LINK_TITLE=$'\e[34m'
	C_LINK_URL=$'\e[31m'
	C_RESET=$'\e[0m'
	typeset_gemini <<-'EOF'
		# Project Gemini
		
		## Overview
		
		Gemini is a new internet protocol which:
		
		* Is heavier than gopher
		* Is lighter than the web
		* Will not replace either
		* Strives for maximum power to weight ratio
		* Takes user privacy very seriously
		
		## Resources
		
		=> docs/	Gemini documentation
		=> software/	Gemini software
		=> servers/	Known Gemini servers
		=> https://lists.orbitalfox.eu/listinfo/gemini	Gemini mailing list
		=> gemini://gemini.conman.org/test/torture/	Gemini client torture test
		
		## Web proxies
		
		=> https://portal.mozz.us/?url=gemini%3A%2F%2Fgemini.circumlunar.space%2F&fmt=fixed	Gemini-to-web proxy service
		=> https://proxy.vulpes.one/gemini/gemini.circumlunar.space	Another Gemini-to-web proxy service
		
		## Search engines
		
		=> gemini://gus.guru/	Gemini Universal Search engine
		=> gemini://houston.coder.town	Houston search engine
		
		## Geminispace aggregators (experimental!)
		
		=> capcom/	CAPCOM
		=> gemini://rawtext.club:1965/~sloum/spacewalk.gmi	Spacewalk
		
		## Free Gemini hosting
		
		=> users/	Users with Gemini content on this server
	EOF
}
test