#!/bin/bash

## Create the response FIFO
rm -f response
mkfifo response

function handle_GET_home() {
  RESPONSE=$(cat home.html | \
    sed "s/{{$COOKIE_NAME}}/$COOKIE_VALUE/")
}

function handle_GET_login() {
  RESPONSE=$(cat login.html)
}

function handle_POST_login() {
  RESPONSE=$(cat post-login.http | \
    sed "s/{{cookie_name}}/$INPUT_NAME/" | \
    sed "s/{{cookie_value}}/$INPUT_VALUE/")
}

function handle_POST_logout() {
  RESPONSE=$(cat post-logout.http | \
    sed "s/{{cookie_name}}/$COOKIE_NAME/" | \
    sed "s/{{cookie_value}}/$COOKIE_VALUE/")
}

function handle_not_found() {
  RESPONSE=$(cat 404.html)
}

function handleRequest() {
  ## Read request
  while read line; do
    echo $line
    trline=$(echo $line | tr -d '[\r\n]')

    [ -z "$trline" ] && break

    HEADLINE_REGEX='(.*?)\s(.*?)\sHTTP.*?'
    [[ "$trline" =~ $HEADLINE_REGEX ]] &&
      REQUEST=$(echo $trline | sed -E "s/$HEADLINE_REGEX/\1 \2/")

    CONTENT_LENGTH_REGEX='Content-Length:\s(.*?)'
    [[ "$trline" =~ $CONTENT_LENGTH_REGEX ]] &&
      CONTENT_LENGTH=$(echo $trline | sed -E "s/$CONTENT_LENGTH_REGEX/\1/")

    COOKIE_REGEX='Cookie:\s(.*?)\=(.*?).*?'
    [[ "$trline" =~ $COOKIE_REGEX ]] &&
      read COOKIE_NAME COOKIE_VALUE <<< $(echo $trline | sed -E "s/$COOKIE_REGEX/\1 \2/")
  done

  ## Read body
  if [ ! -z "$CONTENT_LENGTH" ]; then
    BODY_REGEX='(.*?)=(.*?)'

    while read -n$CONTENT_LENGTH -t1 line; do
      echo $line
      trline=`echo $line | tr -d '[\r\n]'`

      [ -z "$trline" ] && break

      read INPUT_NAME INPUT_VALUE <<< $(echo $trline | sed -E "s/$BODY_REGEX/\1 \2/")
    done
  fi

  ## Route to the response handlers
  case "$REQUEST" in
    "GET /login")   handle_GET_login ;;
    "GET /")        handle_GET_home ;;
    "POST /login")  handle_POST_login ;;
    "POST /logout") handle_POST_logout ;;
    *)              handle_not_found ;;
  esac

  echo -e "$RESPONSE" > response
}

echo 'Listening on 3000...'

## Keep server running forever
while true; do
  ## 1. wait for FIFO
  ## 2. creates a socket and listens to the port 3000
  ## 3. as soon as a request message arrives to the socket, pipes it to the handleRequest function
  ## 4. the handleRequest function processes the request message and routes it to the response handler, which writes to the FIFO
  ## 5. as soon as the FIFO receives a message, it's sent to the socket
  ## 6. closes the connection (`-N`), closes the socket and repeat the loop
  cat response | nc -lN 3000 | handleRequest
done