#!/bin/sh

# USAGE

# ./extractIco <input ico> <outp ico>
# Make sure the output extension is '.ico'!

# Example
# ./extractIco.sh ~/SOME_MULTIPLE_ICO.png ~/Desktop/SINGLE.ico

# Exec Paths
IMAGEMAGICK_CONVERT=$(which convert)
IMAGEMAGICK_IDENTIFY=$(which identify)

if [ ! -x "${IMAGEMAGICK_CONVERT}" ]; then
	echo "Cannot find required ImageMagick Convert executable" >&2
	exit 1;
fi
if [ ! -x "${IMAGEMAGICK_IDENTIFY}" ]; then
	echo "Cannot find required ImageMagick Identify executable" >&2
	exit 1;
fi

# Parameters
SOURCE=$1
DEST=$2

# Check source and destination arguments
if [ -z "${SOURCE}" ]; then
	echo "No source image specified" >&2
	exit 1
fi

if [ -z "${DEST}" ]; then
	echo "No destination specified" >&2
	exit 1
fi

# check if source exists
if [ ! -f "${SOURCE}" ]; then
    echo "Source file not found" >&2
    exit 1
fi

# File Infrastructure
NAME=$(basename "${SOURCE}")
EXT="${NAME##*.}"
BASE="${NAME%.*}"
TEMP_DIR="${BASE}.iconset"

if [ "${EXT}" != "ico" ]; then
  echo "Source file is not a .ico" >&2
  exit 1
fi

# check if .ico is a sequence
IS_ICO_SET="$(identify ${SOURCE} | grep -e "\w\.ico\[0")"

if [ "${IS_ICO_SET}" ]; then
    mkdir "${TEMP_DIR}"

	# extract the largest(?) image from the set
	convert "${SOURCE}" "${TEMP_DIR}/${BASE}.png"
	convert "${TEMP_DIR}/${BASE}-0.png" "${DEST}"

    # Clean up the temp dir
    rm -rf "${TEMP_DIR}"
else
    cp "${SOURCE}" "${DEST}"
fi