#!/usr/bin/env bash
#
# Summary: Save an installed Python version as a relocatable archive
#
# Usage: pyenv binary save <version> [<output-dir>] [--name <name>]
#
#   Packs an installed version into a relocatable .tar.gz (relative paths) and
#   writes a metadata file listing the build platform and the system libraries
#   it links against, so an installer can check compatibility before unpacking.
#
#   <version>      An installed version, as listed by `pyenv versions --bare'.
#   <output-dir>   Where to write the archive and metadata (default: `.').
#   --name <name>  Use <name> as the archive and metadata base name instead of
#                  <version>-<platform>.
#
set -e
[ -n "$PYENV_DEBUG" ] && set -x

# Provide pyenv completions
if [ "$1" = "--complete" ]; then
  echo --name
  exec pyenv-versions --bare
fi

version=""
output_dir=""
package_name=""

while [ $# -gt 0 ]; do
  case "$1" in
  --name )
    [ $# -ge 2 ] && [ -n "$2" ] || { echo "pyenv-binary: --name needs a value" >&2; exit 1; }
    package_name="$2"; shift 2 ;;
  -* )
    echo "pyenv-binary: unknown option \`$1'" >&2; exit 1 ;;
  * )
    if [ -z "$version" ]; then
      version="$1"
    elif [ -z "$output_dir" ]; then
      output_dir="$1"
    else
      echo "pyenv-binary: unexpected argument \`$1'" >&2
      exit 1
    fi
    shift ;;
  esac
done

output_dir="${output_dir:-$PWD}"

if [ -z "$version" ]; then
  echo "Usage: pyenv binary save <version> [<output-dir>] [--name <name>]" >&2
  exit 1
fi

# A version is a single directory name under versions/. With no slash allowed,
# the only remaining names that could point elsewhere are `.' and `..'.
case "$version" in
*/* | .. | . )
  echo "pyenv-binary: invalid version name \`${version}'" >&2
  exit 1
  ;;
esac

case "$package_name" in
*/* | .. | . | *[[:cntrl:]]* )
  echo "pyenv-binary: invalid package name \`${package_name}'" >&2
  exit 1
  ;;
esac

prefix="${PYENV_ROOT}/versions/${version}"
if [ ! -d "${prefix}/bin" ]; then
  echo "pyenv-binary: version \`${version}' is not installed" >&2
  exit 1
fi

os="$(uname -s)"
arch="$(uname -m)"
platform="$(printf '%s' "$os" | tr '[:upper:]' '[:lower:]')-${arch}"

# Record the distro and libc version. Platform and arch alone are too coarse to
# judge compatibility: a build is only portable to a matching libc (e.g. a
# glibc 2.36 build will not load on an older glibc, nor on musl at all).
distro=""
libc=""
if [ -r /etc/os-release ]; then
  distro="$( . /etc/os-release && printf '%s %s' "${ID:-}" "${VERSION_ID:-}" )"
elif [ "$os" = "Darwin" ]; then
  distro="macos $(sw_vers -productVersion 2>/dev/null)"
fi
if [ "$os" = "Linux" ]; then
  libc="$(getconf GNU_LIBC_VERSION 2>/dev/null || true)"
fi

# List the external shared libraries the install links against: those that
# resolve outside its own prefix, so they must already exist on the target.
# The interpreter plus every bundled shared object are inspected.
system_deps() {
  local f
  {
    for f in "${prefix}"/bin/python*; do
      [ -e "$f" ] && printf '%s\n' "$f"
    done
    # CPython ships its extension modules as *.so (and *.dylib on macOS). A
    # bare *.so.* is unusual for CPython itself, but the odd build carries a
    # versioned copy alongside, so match it too rather than miss a dependency.
    find "${prefix}" -type f \( -name '*.so' -o -name '*.so.*' -o -name '*.dylib' \)
  } | sort -u | while IFS= read -r f; do
    if [ "$os" = "Darwin" ]; then
      otool -L "$f" 2>/dev/null | tail -n +2 | awk -v pfx="${prefix}/" \
        '$1 !~ /^@/ && substr($1, 1, length(pfx)) != pfx { print $1 }'
    else
      ldd "$f" 2>/dev/null | awk -v pfx="${prefix}/" \
        '$2 == "=>" && $3 ~ /^\// && substr($3, 1, length(pfx)) != pfx { print $1 }'
    fi
  done | sort -u
}

mkdir -p "$output_dir"
package_name="${package_name:-${version}-${platform}}"
archive="${package_name}.tar.gz"
metadata="${package_name}.meta"

tar -C "$(dirname "$prefix")" -czf "${output_dir}/${archive}" "$(basename "$prefix")"

{
  echo "# pyenv-binary metadata"
  echo "version=${version}"
  echo "os=${os}"
  echo "arch=${arch}"
  echo "platform=${platform}"
  [ -n "$distro" ] && echo "distro=${distro}"
  [ -n "$libc" ] && echo "libc=${libc}"
  echo "archive=${archive}"
  system_deps | while IFS= read -r dep; do
    [ -n "$dep" ] && echo "dep=${dep}"
  done
} > "${output_dir}/${metadata}"

echo "Saved ${archive} and ${metadata} to ${output_dir}"