#!/bin/ksh -e

# https://romanzolotarev.com/ssg/txt2img.sh
# copyright 2025-2026 romanzolotarev.com
#
# permission to use, copy, modify, and/or distribute this software for any
# purpose with or without fee is hereby granted, provided that the above
# copyright notice and this permission notice appear in all copies.
#
# the software is provided "as is" and the author disclaims all warranties with
# regard to this software including all implied warranties of merchantability
# and fitness. in no event shall the author be liable for any special, direct,
# indirect, or consequential damages or any damages whatsoever resulting from
# loss of use, data or profits, whether in an action of contract, negligence or
# other tortious action, arising out of or in connection with the use or
# performance of this software.

info() { echo "$@" >&2; }
fail() { info "$@" && exit 1; }
usage() { fail 'usage: '"${0##*/}"' [-scale percent] [-background color] [-extent wxh] -o output < [input]'; }

scale="100"
background="transparent"
extent=""
out=""

while
	test $# -gt 0
do
	case "$1" in
	-scale) shift && scale="$1" ;;
	-background) shift && background="$1" ;;
	-extent) shift && extent="$1" ;;
	-o) shift && out="$1" ;;
	-*) info "unknown option: $1" && usage ;;
	*) usage ;;
	esac
	shift
done

if test -z "$out"; then info 'missing option: -o' && usage; fi
if test -f "$out"; then fail "$out already exists"; fi

lines=$(cat)
width=$(echo "$lines" | awk '
{
	for (i=length; i>0; i--) {
		c = substr($0,i,1);
		if (c=="*" || c=="." || c==" ") {
			if (i > max) max = i;
			break;
		}
	}
}
END { print max }')
test -n "$width" || fail "no '*' or '.' in input"
height=$(echo "$lines" | wc -l | tr -d ' ')

m() {
	set -- convert - -strip -scale "${scale}%" -background "$background"
	if test -n "$extent"; then set -- "$@" -gravity center -extent "$extent"; fi
	"$@" "$out" 2>/dev/null
}

{
	echo 'P7
	WIDTH '"$width"'
	HEIGHT '"$height"'
	DEPTH 4
	MAXVAL 255
	TUPLTYPE RGB_ALPHA
	ENDHDR'
	echo "$lines" | awk -v width="$width" '
function emit(r, g, b, a) {
  printf("%c%c%c%c", r, g, b, a);
}
{
  l = sprintf("%-*s", width, $0);
  for (i = 1; i <= width; i++) {
    c = substr(l, i, 1);
    if (c == "*") emit(0, 0, 0, 255);
    else if (c == ".") emit(255, 255, 255, 255);
    else emit(0, 0, 0, 0);
  }
}'
} | m