#!/bin/bash

## This file is released under the  CC0 license
## https://creativecommons.org/publicdomain/zero/1.0/

# Check if the source image is provided
if [ -z "$1" ] || [ ! -f "$1" ]; then
	if [ -z "$1" ]; then
		echo "Usage: $0 source_image"
	else
		echo "$1 cannot be accessed."
	fi
	exit 1
fi

SOURCE_IMAGE=$1
BASENAME="$SOURCE_IMAGE"

# Function to calculate ssim
calculate_ssim() {
	local source=$1
	local target=$2
	local ssim
	ssim=$(magick compare -metric ssim "$source" "$target" null: 2>&1)
	ssim=${ssim%% *}  # Extract the first part before the space
	echo "$ssim"
}

# Function to generate images with matched ssim
generate_image() {
	local format=$1
	local ssim
	local tmpfile
	tmpfile="$(mktemp /tmp/img-XXXX.${format})"

	for ((q = 10; q <= 100; q += 5)); do
		convert "$SOURCE_IMAGE" -quality "$q" "$tmpfile"
		img_ssim=$(calculate_ssim "$SOURCE_IMAGE" "$tmpfile")
		echo "Format=${format} Q=$q SSIM=${img_ssim}"
		mv "$tmpfile" "ssim-${img_ssim}_${BASENAME}_q${q}.${format}"
	done
}
generate_image "jpg"
generate_image "webp"
generate_image "avif"