#!/bin/sh
usage () {
  echo "usage: $0 [-w] [-h]"
  echo "   -w   use the WSL ssh-agent instead of OpenSSH for Windows"
  echo "   -h   show help and exit"
}

# Use OpenSSH for Windows by default.
WSL_SSH_AGENT=false

while getopts ":wh" arg; do
  case "$arg" in
    w)
      WSL_SSH_AGENT=true
      ;;

    h)
      >&2 usage
      exit 0
      ;;

    ?)
      >&2 echo "ERROR: unknown option -$OPTARG"
      >&2 usage
      exit 1
      ;;
  esac
  shift
done

if [ "$WSL_SSH_AGENT" = true ]; then
  if [ "$#" -gt 0 ]; then
    SHLVL=0 exec ssh-agent "$SHELL" -c "$@"
  else
    SHLVL=0 exec ssh-agent "$SHELL"
  fi
fi

require() {
  if ! command -v "$@" >/dev/null 2>&1; then
    >&2 echo "ERROR: required command not found: $1"
    exit 1
  fi
}

require socat
require npiperelay

# Forward SSH Agent requests from withitn WSL to OpenSSH for Windows, based on:
# https://stuartleeks.com/posts/wsl-ssh-key-forward-to-windows/
export SSH_AUTH_SOCK=$HOME/.ssh/agent.sock
[ -S "$SSH_AUTH_SOCK" ] && rm "$SSH_AUTH_SOCK"
socat UNIX-LISTEN:$SSH_AUTH_SOCK,fork EXEC:"npiperelay -ei -s //./pipe/openssh-ssh-agent",nofork &
if [ "$#" -gt 0 ]; then
  SHLVL=0 exec "$SHELL" -c "$@"
else
  SHLVL=0 exec "$SHELL"
fi