#!/bin/sh

ERROR=0

# shellcheck disable=2154 # 2154 irrelevant because the ENV variable should come from container invokation
if [ "${SSH_USER}" = "" ] ; then
  echo You must set the SSH_USER environment variable
  ERROR=1
fi

# shellcheck disable=2154 # 2154 irrelevant because the ENV variable should come from container invokation
# shellcheck disable=2153 # 2153 irrelevant because SSH_HOST is the correct ENV variable
if [ "${SSH_HOST}" = "" ] ; then
  echo You must set the SSH_HOST environment variable
  ERROR=1
fi

# shellcheck disable=2154 # 2154 irrelevant because the ENV variable should come from container invokation
if [ "${REMOTE_HOST}" = "" ] ; then
  echo You must set the REMOTE_HOST environment variable
  ERROR=1
fi

# shellcheck disable=2154 # 2154 irrelevant because the ENV variable should come from container invokation
if [ "${REMOTE_PORT}" = "" ] ; then
  echo You must set the REMOTE_PORT environment variable
  ERROR=1
fi

# shellcheck disable=2154 # 2154 irrelevant because the ENV variable should come from container invokation
if [ "${LOCAL_PORT}" = "" ] ; then
  echo You must set the LOCAL_PORT environment variable
  ERROR=1
fi

SSH_PORT=${SSH_PORT:-22}
SSH_IDENTITY_PATH=${SSH_IDENTITY_PATH:-/id_rsa}

if [ ! -r "${SSH_IDENTITY_PATH}" ] ; then
  echo "The specified identity file (${SSH_IDENTITY_PATH}) is not readable"
  ERROR=1
fi

if [ "${ERROR}" = "1" ] ; then
  echo "Quitting"
  exit 1
fi

while true ; do
  ssh \
    -p "${SSH_PORT}" -i "${SSH_IDENTITY_PATH}" \
    -o StrictHostKeyChecking=no -N \
    -L "0.0.0.0:${LOCAL_PORT}:${REMOTE_HOST}:${REMOTE_PORT}" \
    "${SSH_USER}@${SSH_HOST}" 
  echo "Connection closed. Waiting 5 seconds before retry."
  sleep 5s
done