#!/usr/bin/env bash

set -eu

usage() {
  echo "Usage: ./configure [OPTION]"
  echo
  echo "Configuration:"
  echo "  -h, --help              display this help and exit"
  echo
  echo "Installation directories:"
  echo "  --destination=[local|global] install Python package locally or globally"
}


# -allow a command to fail with !’s side effect on errexit
# -use return value from ${PIPESTATUS[0]}, because ! hosed $?
! getopt --test > /dev/null
if [[ ${PIPESTATUS[0]} -ne 4 ]]; then
    echo 'getopt not available'
    exit 1
fi

LONGOPTS=destination:,help
OPTIONS=h

! PARSED=$(getopt --options=$OPTIONS --longoptions=$LONGOPTS --name "$0" -- "$@")
if [[ ${PIPESTATUS[0]} -ne 0 ]]; then
    # e.g. return value is 1
    #  then getopt has complained about wrong arguments to stdout
    exit 2
fi

# read getopt’s output this way to handle the quoting right:
eval set -- "$PARSED"

destination="local"

while true; do
    case "$1" in
      --destination)
        destination="$2"
        shift 2
        ;;
      -h|--help)
        usage
        exit 1
        ;;
      --)
        shift
        break
        ;;
      *)
        echo "Programming error"
        exit 3
        ;;
    esac
done

case "$destination" in
  local)
    install_global=false
    ;;
  global)
    install_global=true
    ;;
  *)
    echo "Destination (--destination) must be 'local' or 'global', paths are not allowed."
    exit 3
    ;;
esac

cat << EOF > config.mk
# this file is autogenerated by ./configure
install_global=$install_global
EOF


if ! python3 --version &>/dev/null; then
  echo 'Error: python3 missing'
  exit 1
fi

if ! pip3 --version &>/dev/null; then
  echo 'Error: pip3 missing'
  exit 1
fi