#!/bin/sh
# override it with -df=*|--dest-filename=*)
dest_filename="env.js"
dest="."
# override it with -jo=*|--js-object=*)
js_object='window.process=(window.process||{});window.process.env'
run_as="job"
final_src_env_file=/tmp/.env
tmp_env_file=/tmp/env-$(date +%s)

# $1: dest
# $2: run_as
# $3: refresh_period
validation() {
  dest=$1
  run_as=$2
  refresh_period=$3
  if [ -f ${dest} ]; then
    echo "-d | --dest value must be directory not file."
    exit 1;
  fi

  if [ ! -z "${refresh_period}" ] && [ "${run_as}" = "job" ]; then
    echo "WARN: -rp=*|--refresh-period does not have effect"
    echo "   as it is not running as daemon"
  fi
}

# $1: src
# $2: envvars yes or no
prepare_src_files() {
  env_vars=$2
  if [ $# -eq 0 ]; then
    env_vars=yes
  fi
  ### prepare source ###
  if [ -f "${1}" ]; then
    cat ${1} > ${final_src_env_file}
  fi
  if [ "${env_vars}" = "yes" ]; then
    (echo;printenv) >> ${final_src_env_file}
  fi
  # remove duplicated lines
  awk '!a[$0]++' ${final_src_env_file} > ${tmp_env_file}
  cat ${tmp_env_file} > ${final_src_env_file}
  # example: filter env vars contains only REACT_APP
  if [ ! -z "${ENV_VARS_FILTER}" ]; then
    grep "${ENV_VARS_FILTER}" ${tmp_env_file} > ${final_src_env_file} 
  fi
}

# $1: dest

prepare_dest_files() {
  ### prepare destination ###
  dest=$1
  mkdir -p ${dest}
  rm -rf ${dest}/${dest_filename}
  touch ${dest}/${dest_filename}

}
# $1: js_object
# $2: dest
build_js_object() {
  js_object=$1
  dest=$2
  echo "${js_object} = {" > ${dest}/${dest_filename}
  # Read each line in .env file
  # Each line represents key=value pairs
  while read -r line || [[ -n "$line" ]];
  do
    if [ ! -z "$line" ]; then
      # Split env variables by character `=`
      if printf '%s\n' "$line" | grep -q -e '='; then
        varname=$(printf '%s\n' "$line" | sed -e 's/=.*//')
        varvalue=$(printf '%s\n' "$line" | sed -e 's/^[^=]*=//')
      fi

      # Read value of current variable if exists as Environment variable
      # value=$(printf '%s\n' "${!varname}")
      # Otherwise use value from .env file
      [[ -z $value ]] && value=${varvalue}

      # Append configuration property to JS file
      echo "  $varname: \"$value\"," >> ${dest}/${dest_filename}
    fi
  done < ${final_src_env_file}

  echo "}" >> ${dest}/${dest_filename}
}

# $1: js_object
# $2: dest
# $3: src
# $4: envvars yes or no
build_js_object_periodically() {
  prepare_src_files $3 $4
  build_js_object $1 $2
}

# $1: refresh period in seconds
# $2: body to be running each period $1
daemonize() {
  refresh_period=$1
  shift
  while :
  do
    $@
    sleep  ${refresh_period}
  done
}

cleanup() {
  rm -rf ${tmp_env_file}
}

for i in "$@"
do
case $i in
    -s=*|--src=*)
    src="${i#*=}"
    shift # past argument=value
    ;;
    -d=*|--dest=*)
    dest="${i#*=}"
    shift # past argument=value
    ;;
    -df=*|--dest-filename=*)
    dest_filename="${i#*=}"
    shift # past argument=value
    ;;
    -jo=*|--js-object=*)
    js_object="${i#*=}"
    shift # past argument=value
    ;;
    -a=*|--run-as=*)
    run_as="${i#*=}" # job or daemon
    shift # past argument=value
    ;;
    -rp=*|--refresh-period=*)
    refresh_period="${i#*=}" # in second
    shift # past argument=value
    ;;
    -ef=*|--env-vars-filter=*)
    export ENV_VARS_FILTER="${i#*=}" # in second
    shift # past argument=value
    ;;
    # include container env vars from printenv
    --env-vars)
    env_vars=yes
    shift # past argument with no value
    ;;
    *)
          # unknown option
    ;;
esac
done

validation ${dest} ${run_as} ${refresh_period}
prepare_src_files ${src} ${env_vars}
prepare_dest_files ${dest}

build_js_object "${js_object}" ${dest}

if [ "${run_as}" = "daemon" ]; then
  refresh_period=${refresh_period:-"5"}
  daemonize ${refresh_period} build_js_object_periodically "${js_object}" ${dest} ${src} ${env_vars}
fi

cleanup

# if still there is arguments not processed,
#  then consider them as CMD
if [ $# -ge 1 ]; then
  echo "running $@"
  exec $@
fi