updateFlutterVersion

# updateFlutterVersion 1.23456
function updateFlutterVersion {
  cd $HOME/installs/flutter

  CURRENTVERSION=$(git describe --tags)

  if [ "${CURRENTVERSION}" == "$1" ]; then
    echo "it looks like you're already on that branch"
    echo "not changing version"
    say 'failed'
  else 
    if [ -d $HOME/installs/flutter_$1 ]; then
      echo
      echo "found version '$1' locally, no need to download"
      echo "Would you like to change Flutter version from '${CURRENTVERSION}' to '$1'?"
      if ! asksure; then
        return
      fi

      cd ..
      mv $HOME/installs/flutter $HOME/installs/flutter_${CURRENTVERSION}
      mv $HOME/installs/flutter_$1 $HOME/installs/flutter
      echo
      say 'success'
      echo 'flutter updated'
    else
      CURRENTVERSION=$(git describe --tags)
      echo "version not found locally"
      if [ ! $(git tag -l "$1") ]; then
        echo "Flutter version '$1' not found in git, would you like to pull the latest from git?"
        if ! asksure; then
          return
        fi
        git pull
      fi

      if [ $(git tag -l "$1") ]; then
        echo "Flutter version '$1' found in git"
        echo "Would you like to change Flutter version from '${CURRENTVERSION}' to '$1'?"
        if ! asksure; then
          return
        fi

        echo "Would you like to save a copy of Flutter version from '${CURRENTVERSION}'?  It may use up 20gb of data and take a few minutes to copy the data"
        if asksure; then
          cp -R $HOME/installs/flutter $HOME/installs/flutter_${CURRENTVERSION}
        fi

        git checkout $1
        flutter doctor
        flutter precache
        echo
        echo
        df -k .
        echo
        say 'success'
        echo 'flutter updated'
      else 
        say 'failed'
        echo "couldn't find Flutter version '$1' in git"
      fi
    fi
  fi
  echo
  echo
  echo
  flutter --version
}