_has-ruby() {
    command -v ruby 2>&1 >/dev/null
}

_set_default_gem_home() {
    if _has-ruby && [[ -z "${GEM_HOME}" ]]; then
        RUBY_VERSION="$(ruby -e 'puts RUBY_VERSION.gsub(/\d+$/, "0")')"
        GEM_HOME="${HOME}/.gem/ruby/${RUBY_VERSION}"
        export GEM_HOME
        PATH="${GEM_HOME}/bin:${PATH}"
        export PATH
    fi
}

if ! _has-chruby && ! _has-rbenv; then
    _set_default_gem_home
fi

_auto-rubygems_gemdeps() {
    local check_dir=$PWD
    local next_check_dir=${check_dir%/*}
    while [ "$next_check_dir" != "" ]; do
        if [[ -f "$check_dir/Gemfile" ]]; then
            export RUBYGEMS_GEMDEPS="$check_dir/Gemfile"
            return
        fi
        check_dir="$next_check_dir"
        next_check_dir=${check_dir%/*}
    done
    unset RUBYGEMS_GEMDEPS
}

unpack_gem() {
    local gemname="${1:?argument missing}"
    local basename="${1%%.gem}"

    if [[ "${gemname}" == "${basename}" ]]; then
        echo "error: not a .gem: '${gemname}'"
        return 1
    fi

    if [[ ! -f "${gemname}" ]]; then
        echo "error: not a .gem: '${gemname}'"
        return 1
    fi

    mkdir -p "${basename}/data"
    tar -C "${basename}" -xvf "${gemname}"
    gunzip -f "${basename}/checksums.yaml.gz"
    gunzip -f "${basename}/metadata.gz"
    tar -C "${basename}"/data -xvzf "${basename}"/data.tar.gz && rm -f "${basename}"/data.tar.gz
}

pack_gem() {
    local dirname="${1:?argument missing}"
    local gemname="${2:-"${dirname}".gem}"
    if type shasum 2>&1 >/dev/null; then
        local sha256sum=( shasum -a 256 )
        local sha512sum=( shasum -a 512 )
    else
        local sha256sum=( sha256sum )
        local sha512sum=( sha512sum )
    fi

    if [[ ! -d "${dirname}/data" ]]; then
        echo "error: missing data: '${dirname}'"
        return 1
    fi

    if [[ ! -f "${dirname}/metadata" ]]; then
        echo "error: missing metadata: '${dirname}'"
        return 1
    fi

    tar --strip-components 2 --uid 0 --gid 0 -cvzf "${dirname}"/data.tar.gz "${dirname}"/data
    gzip < "${dirname}/metadata" > "${dirname}/metadata.gz"

    metadata_gz_sha256="$("${sha256sum[@]}" "${dirname}"/metadata.gz | sed 's/  .*//')"
    data_tar_gz_sha256="$("${sha256sum[@]}" "${dirname}"/data.tar.gz | sed 's/  .*//')"
    metadata_gz_sha512="$("${sha512sum[@]}" "${dirname}"/metadata.gz | sed 's/  .*//')"
    data_tar_gz_sha512="$("${sha512sum[@]}" "${dirname}"/data.tar.gz | sed 's/  .*//')"

    chmod u+w "${dirname}/checksums.yaml"
    cat <<CHECKSUMS > "${dirname}/checksums.yaml"
---
SHA256:
  metadata.gz: ${metadata_gz_sha256}
  data.tar.gz: ${data_tar_gz_sha256}
SHA512:
  metadata.gz: ${metadata_gz_sha512}
  data.tar.gz: ${data_tar_gz_sha512}
CHECKSUMS
    gzip < "${dirname}/checksums.yaml" > "${dirname}/checksums.yaml.gz"

    tar --strip-components 1 --uid 0 --gid 0 -cvf "${gemname}" "${dirname}"/metadata.gz "${dirname}"/data.tar.gz "${dirname}"/checksums.yaml.gz
}

# vim: ft=bash