#!/bin/bash

set -e

IMG=$1
NAME=$2

if [[ -z "$IMG" ]]; then
    echo "Usage: $0 <dockerimgurl> [output_file]"
	echo ""
	echo " Export docker multi-arch images specified by <dockerimageurl> to a local tar file"
	echo ""
    exit 1
fi

if [[ -z "$NAME" ]]; then
	NAME=$(echo -n $IMG |  cut -d / -f 3)
	NAME="${NAME/:/-}"
fi

echo "Export docker iamge to $NAME"

if [[ -d $NAME ]]; then
	echo "directory $NAME already exists!"
	exit 1
fi

mkdir $NAME

IMGCNT=0
for arch in $(docker manifest inspect $IMG | grep -w "\"architecture\"" | awk '{print $2}' | cut -f 2 -d \")
do
	echo "export to linux/$arch"
	docker pull --platform "linux/$arch" $IMG
	docker tag $IMG "$IMG-$arch"
	docker save "$IMG-$arch" | gzip > $NAME/img-$arch.tgz
	docker image rm $IMG "$IMG-$arch"
	IMGCNT=$((IMGCNT+1))
done

if [ "$IMGCNT" -eq "0" ]; then
	echo "This is an ordinary image"
	docker pull $IMG
	docker save $IMG | gzip > $NAME/img.tgz
	docker image rm $IMG
fi

tar cvf $NAME.tar $NAME