#!/bin/bash

# Copyright 2016 The Kubernetes Authors All rights reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

set -eux -o pipefail

if (($# < 2)); then
  echo "ERROR: given ! ($#) number of parameters but expect 2."
  echo "USAGE: ./check_install_golang.sh VERSION_TO_INSTALL INSTALL_PATH"
  exit 1
fi

VERSION_TO_INSTALL=${1}
INSTALL_PATH=${2}

# installs or updates golang if right version doesn't exists
function check_and_install_golang() {
  if ! go version &>/dev/null; then
    echo "WARNING: No golang installation found in your environment."
    install_golang "$VERSION_TO_INSTALL" "$INSTALL_PATH"
    return
  fi

  # golang has been installed and check its version
  if [[ $(go version) =~ (([0-9]+)\.([0-9]+).([0-9]+).([\.0-9]*)) ]]; then
    HOST_VERSION=${BASH_REMATCH[1]}
    if [ $HOST_VERSION = $VERSION_TO_INSTALL ]; then
      echo "go version on the host looks good : $HOST_VERSION"
    else
      echo "WARNING: expected go version to be $VERSION_TO_INSTALL but got $HOST_VERSION"
      install_golang "$VERSION_TO_INSTALL" "$INSTALL_PATH"
    fi
  else
    echo "ERROR: Failed to parse golang version: $(go version)"
    return
  fi
}

# install_golang takes two parameters version and path to install.
function install_golang() {
  echo "Installing golang version: $1 on $2"
  pushd /tmp >/dev/null

  INSTALLOS=linux
  if [[ "$OSTYPE" == "darwin"* ]]; then
    INSTALLOS=darwin
  fi
  # using sudo because previously installed versions might have been installed by a different user.
  # as it was the case on jenkins VM.
  sudo curl -qL -O "https://storage.googleapis.com/golang/go${1}.${INSTALLOS}-amd64.tar.gz" &&
    sudo tar -xf go${1}.${INSTALLOS}-amd64.tar.gz &&
    sudo rm -rf "${2}/go" &&
    sudo mv go "${2}/" && sudo chown -R $(whoami): ${2}/go
  popd >/dev/null
}

check_and_install_golang