go_commands=(go)

_go-installed() {
  which go > /dev/null 2>&1
}

_within-go-project() {
  local check_dir=$PWD
  while [ "$(dirname $check_dir)" != "/" ]; do
    if [ -f "$check_dir/.gopath" ]; then
        echo "$check_dir"
        return
    fi
    check_dir="$(dirname $check_dir)"
  done
  false
}

_run-with-gopath() {
  local go_path
  if _go-installed && go_path=$(_within-go-project); then
    GOPATH="$go_path" $@
  else
    $@
  fi
}

for cmd in $go_commands; do
  eval "function gopath_$cmd () { _run-with-gopath $cmd \$@}"
  alias $cmd=gopath_$cmd

  if which _$cmd > /dev/null 2>&1; then
        compdef _$cmd gopath_$cmd=$cmd
  fi
done