#!/usr/bin/env bash
set -euo pipefail

# Show progress on pipes if `pv` is installed
# Otherwise use plain cat
if ! command -v pv &> /dev/null
then
    PV="cat"
else
    PV="pv"
fi

pack () {
    local cloudprovider=$1
    local unpacked_image=$2
    local packed_image=$3
    local unpacked_image_dir
    unpacked_image_dir=$(mktemp -d)
    local unpacked_image_filename
    unpacked_image_filename=disk.raw
    local tmp_tar_file
    tmp_tar_file=$(mktemp -t verity.XXXXXX.tar)
    cp ${unpacked_image} "${unpacked_image_dir}/${unpacked_image_filename}"

    case $cloudprovider in

    gcp)
        echo "📥 Packing GCP image..."
        tar --owner=0 --group=0 -C "${unpacked_image_dir}" -Sch --format=oldgnu -f "${tmp_tar_file}" "${unpacked_image_filename}"
        "${PV}" "${tmp_tar_file}" | pigz -9c  > "${packed_image}"
        rm "${tmp_tar_file}"
        echo "  Repacked image stored in ${packed_image}"
        ;;

    azure)
        echo "📥 Packing Azure image..."
        truncate -s %1MiB "${unpacked_image_dir}/${unpacked_image_filename}"
        qemu-img convert -p -f raw -O vpc -o force_size,subformat=fixed "${unpacked_image_dir}/${unpacked_image_filename}" "$packed_image"
        echo "  Repacked image stored in ${packed_image}"
        ;;

    *)
        echo  "unknown cloud provider"
        exit 1
        ;;
    esac

    rm -r ${unpacked_image_dir}

}

if [ $# -ne 3 ]; then
    echo "Usage: $0 <cloudprovider> <unpacked_image> <packed_image>"
    exit 1
fi

pack "${1}" "${2}" "${3}"