#!/usr/bin/env bash

install_python() {
  local version=$1
  local install_path=$2

  if [ "$TMPDIR" = "" ]; then
    local tmp_download_dir=$(mktemp -d)
  else
    local tmp_download_dir=$TMPDIR
  fi

  # path to the tar file
  local source_path="${tmp_download_dir}/Python-${version}.tgz"

  download_source $version $source_path

  # running this in a subshell
  # because we don't want to disturb current working dir
  (
    cd $(dirname $source_path)
    tar zxf $source_path || exit 1

    cd "Python-${version}"

    local configure_options="$(construct_configure_options $install_path)"

    if [ "$ASDF_PKG_MISSING" != "" ]; then
        echo "WARNING: Might use OS-provided pkgs for the following: $ASDF_PKG_MISSING"
    fi

    # set in os_based_configure_options
    # we unset it here because echo-ing changes the return value of the function
    unset ASDF_PKG_MISSING

    echo "Building with options: $configure_options"

    ./configure $configure_options || exit 1
    make || exit 1
    make install || exit 1
  )
}

construct_configure_options() {
  local install_path=$1

  if [ "$PYTHON_CONFIGURE_OPTIONS" = "" ]; then
    local configure_options="$(os_based_configure_options) --prefix=$install_path"

    if [ "$PYTHON_EXTRA_CONFIGURE_OPTIONS" != "" ]; then
      configure_options="$configure_options $PYTHON_EXTRA_CONFIGURE_OPTIONS"
    fi
  else
    local configure_options="$PYTHON_CONFIGURE_OPTIONS --prefix=$install_path"
  fi

  echo "$configure_options"
}


homebrew_package_path() {
  local package_name=$1

  if [ "$(brew ls --versions $package_name)" = "" ]; then
    echo ""
  else
    echo "$(brew --prefix $package_name)"
  fi
}


exit_if_homebrew_not_installed() {
  if [ "$(brew --version 2>/dev/null)" = "" ]; then
    echo "ERROR: Please install homebrew for OSX"
    exit 1
  fi
}


os_based_configure_options() {
  local operating_system=$(uname -a)
  local configure_options=""

  if [[ "$operating_system" =~ "Darwin" ]]; then

    exit_if_homebrew_not_installed

    local openssl_path=$(homebrew_package_path openssl)
    local readline_path=$(homebrew_package_path readline)
  else
    local openssl_path=/usr
  fi

  if [ "$openssl_path" = "" ]; then
    export ASDF_PKG_MISSING="openssl"
  else
    configure_options="--with-openssl-dir=$openssl_path"
  fi

  if [ "$readline_path" != "" ]; then
    configure_options="$configure_options --with-readline-dir=$readline_path"
  fi

  configure_options="$configure_options --enable-shared --disable-install-doc"
  echo $configure_options
}


download_source() {
  local version=$1
  local download_path=$2
  local download_url="https://www.python.org/ftp/python/$version/Python-$version.tgz"


  if [ -f $download_path ]; then
    rm $download_path
  fi

  echo "Downloading from $download_url"
  curl -#Lo $download_path $download_url
}

install_python $ASDF_INSTALL_VERSION $ASDF_INSTALL_PATH