#!/bin/bash

readonly ARGS="$@"

function usage {
  cat <<- EOF
  ./scrape.sh [options]

  Scrape facebook event pages.

  This script will always return an JSON array.

  OPTIONS:
    -e --event                        Facebook event id. Scrape a single Facebook
                                      event.
    -p --page                         Facebook page id. Scrape all events of a
                                      specific facebook page.
    -a --pages                        Array of Facebook page ids. This is a space
                                      seperated list of page ids.
    -h --help -?                      print usage

  EXAMPLES:
  Scrape events of a facebook page with id 133713371337
  ./scrape.sh --page 133713371337
  ./scrape.sh -p 133713371337

  Scrape a facebook event with id 420420420420
  ./scrape.sh --event 420420420420
  ./scrape.sh -e 420420420420

  Scrape a facebook event with id 123 and all events from page 1323
  ./scrape.sh --event 123 --page 1323
EOF
}

function parse_args {
  if [ "$1" = "" ]; then
    echo ""
  fi

  while [[ $# -gt 0 ]]; do
    key="$1"
    case $key in
      -e|--event)
        shift
        local event_id;
        event_id=$1
        ;;
      -p|--page)
        ;;
      -a|--pages)
        ;;
      *)
        usage
        exit 1
        ;;
    esac
    shift
  done
}

function install_node_dependencies {
  if ! [ -d node_modules ]; then
    yarn
  fi
}

function check_dependencies {
  local missing;
  missing=false;

  if [ ! $(command -v node) ]; then
    echo "Dependency missing. Please install node.js and make it available to the path as 'node'."
    missing=true
  fi

  if [ ! $(command -v yarn) ]; then
    echo "Dependency missing. Please install yarn and make it available to the path as 'yarn'."
    missing=true
  fi

  install_node_dependencies

  if [ "${missing}" != "false" ]; then
    exit 1;
  fi

  return 0;
}

check_dependencies \
  && parse_args "${ARGS}" \
  && scrape