#!/bin/bash

# SHITPOST
# Takes an image and adds some shitty text to it

# someone on /r/linuxmasterrace asked what image programs were good for shitposts
# it got me thinking that there should be a cli command just for that
# days later (I'm still pretty noob)...

# Originally by Mykal Anderson
# Patched by Declan Hoare 2016-12-02:     use PNG instead of GIF for temp files to preserve quality
# Modified by coolreader18 2021-03-01:    fix some bugs and use a directory under /tmp for temporary files, add -o option
# Modified by Magnus Anderson 2021-09-21: clean up the code, make -f implied

#   DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE
#            Version 2, December 2004
# Copyright (C) 2004 Sam Hocevar <sam@hocevar.net>
# Everyone is permitted to copy and distribute verbatim or modified
# copies of this license document, and changing it is allowed as long
# as the name is changed.
# DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE
# TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND  MODIFICATION
# 0. You just DO WHAT THE FUCK YOU WANT TO.

usage() {
	printf "Usage: shitpost [-f] /path/to/file [-t top -b bottom -o outfile]\n\t-f\tPath to image file (-f is implied)\n\t-t\tTop Text\n\t-b\tBottom Text\n\t-o\tOutput file name\n"
}
# Check if imagemagick (just convert checked, but others used) is installed and exit if missing
command -v convert >/dev/null 2>&1 || { echo >&2 "I require ImageMagick but it's not installed.  Aborting."; exit 1; }

top_text=" "
bottom_text=" "
image_file=""
output_file=""

# Get CLI args
while true; do
	OPTIND=1
	while getopts "h?t:b:f:o:" opt; do
		case "$opt" in
		t)  top_text="$OPTARG"    ;;
		b)  bottom_text="$OPTARG" ;;
		f)  image_file="$OPTARG"  ;;
		o)  output_file="$OPTARG" ;;
		h|\?)
			usage
			exit 0
			;;
		esac
	done
	shift $((OPTIND-1))
	
	# If `-f` not provided, use the first non-flag argument as the image file, and continue parsing options
	[[ -z "$image_file" ]] && image_file="$1" && shift 1 && continue
	break
done

# Ensure that an image file is provided and exists. Does not check that it actually contains image data
[[ -z "$image_file" ]] && echo "You must specify an image file!" && usage && exit 1

# Let the user know any options that were invalid that were not already handled by getopts.
[[ ! -z "$@" ]] && echo "Invalid argument(s): '$@'" && echo "Ignored, continuing..."

# Set the output file to shitpost-INPUT_FILE if none was given
base=${image_file##*/}
[[ -z "$output_file" ]] && output_file="shitpost-$base"

# Create a temporary directory to hold the temporary files
tmpdir=$(mktemp -d /tmp/shitpost.XXXXXX)
trap 'rm -rf "$tmpdir"' 0 1 2 3 6

# Upscale the image if it's too shitty. This is required to make the text readable as it's generated to fit the pixels of the original
convert -resize 1024x1024\< "$image_file" "$tmpdir"/shitpost-temp-resize.png

# Get the height and width of the image to use later to size the overlays. Clipped height keeps things locked in the top and bottom fifth of the image.
image_width=$(identify -format "%[width]" "$tmpdir"/shitpost-temp-resize.png)
image_height=$(identify -format "%[height]" "$tmpdir"/shitpost-temp-resize.png)
clipped_height=$(($image_height/5))
stroke_width=$(($clipped_height/40))

convert -background none -fill white -stroke black -strokewidth "$stroke_width" -size "$image_width"x"$clipped_height" -gravity Center -font 'Impact' caption:"$top_text" "$tmpdir"/shitpost-temp-top-text.png
convert -background none -fill white -stroke black -strokewidth "$stroke_width" -size "$image_width"x"$clipped_height" -gravity Center -font 'Impact' caption:"$bottom_text" "$tmpdir"/shitpost-temp-bottom-text.png
composite -gravity north "$tmpdir"/shitpost-temp-top-text.png "$tmpdir"/shitpost-temp-resize.png "$tmpdir"/shitpost-temp-composite.png
composite -gravity south "$tmpdir"/shitpost-temp-bottom-text.png "$tmpdir"/shitpost-temp-composite.png "$output_file"

#Announce the results
echo "Created file '$output_file'"