#!/bin/bash
function replace {
  local PATTERN=$1; shift
  local NEW_LINE=$1; shift
  local FILE=$1; shift
  [ ! "$PATTERN" ] || [ ! $FILE ] && return 1
  local BEFORE=$1
  local NEW=$(echo "${NEW_LINE}" | sed 's/\//\\\//g')
  echo  finding: $PATTERN Replace with $NEW before $BEFORE in $FILE
  touch "${FILE}" || return 1
  echo matching: $PATTERN
  match=false
  if [ "$NEW_LINE" ]; then
  sed -i '/'"${PATTERN}"'/{s/.*/'"${NEW}"'/;h};${x;/./{x;q100};{x;q20}}' "${FILE}"
   [[ $? -eq 100 ]] && match=true
   echo match $match
   if [ $match == false ]; then
    echo adding new entry $NEW_LINE
    if [ "$BEFORE" ]; then
      echo searching for $BEFORE to add line before
      # sed -i '/'"${BEFORE}"'/{i/.*/'"${NEW}"'/;h};${x;/./{x;q100};x}' "${FILE}"
      sed -i '/'"${BEFORE}"'/!{q20};/'"${BEFORE}"'/i\'"${NEW}" "${FILE}"
      echo return $?
      exit
      # ;/i '"${NEW}"'' "${FILE}"
      [[ $? -eq 100 ]] && match=true || match=false
      echo before match $match
     fi
   #  if [ $match == false ]; then
   #   echo appending to file
   #   echo "${NEW_LINE}" >> "${FILE}"
   # fi
    else echo line matched/replaced
   fi
  else
    sed '/'"${PATTERN}"'/d' "${FILE}"
   echo line removed
  fi
}