#!/bin/bash

readonly caskroom_online='https://github.com/caskroom'
readonly caskroom_repos_dir='/tmp/caskroom_repos'
readonly caskroom_repos=(homebrew-cask homebrew-versions homebrew-fonts homebrew-eid)
readonly curl_flags=(--silent --location --header 'User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_9_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/33.0.1750.152 Safari/537.36')
inaccessible_appcasts=()

if [[ ! $(which 'ghi') ]] || ! security find-internet-password -s github.com -l 'ghi token' &> /dev/null; then
  echo -e "$(tput setaf 1)
    This script requires 'ghi' installed and configured.
    If you have [Homebrew](http://brew.sh), you can install it with 'brew install ghi'.
    To configure it, run 'ghi config --auth <username>'. Your Github password will be required, but is never stored.
  $(tput sgr0)" | sed -E 's/ {4}//' >&2
  exit 1
fi

function message {
  echo "${1}"
}

function go_to_repos_dir {
  [[ ! -d "${caskroom_repos_dir}" ]] && mkdir -p "${caskroom_repos_dir}"
  cd "${caskroom_repos_dir}" || exit 1
}

function go_to_repo_and_update {
  local repo_name repo_dir casks_dir

  repo_name="${1}"
  repo_dir="${caskroom_repos_dir}/${repo_name}"
  casks_dir="${repo_dir}/Casks"

  if [[ ! -d "${repo_dir}" ]]; then
    go_to_repos_dir

    message "Cloning ${repo_name}…"
    git clone "https://github.com/caskroom/${repo_name}.git" --quiet

    cd "${casks_dir}" || exit 1
  else
    cd "${casks_dir}" || exit 1

    message "Updating ${repo_name}…"
    git pull --rebase origin master --quiet
  fi
}

function open_issue {
  local repo_name cask_name cask_url version appcast_url issue_number

  repo_name="${1}"
  cask_name="${2}"
  cask_url="${caskroom_online}/${repo_name}/blob/master/Casks/${cask_name}.rb"
  version="${3}"
  appcast_url="${4}"

  message="$(echo "Outdated cask: ${cask_name}

    Outdated cask: [\`${cask_name}\`](${cask_url}).

    Info:
    + version: \`${version}\`.
    + appcast url: ${appcast_url}.
  " | sed -E 's/^ {4}//')"

  issue_number=$(ghi open --label 'outdated appcast' --message "${message}" | head -1 | perl -pe 's/^#(\d+): .*/\1/')
  message "Opened issue: https://github.com/caskroom/${repo_name}/issues/${issue_number}."
}

function is_appcast_available {
  local appcast_url

  appcast_url="${1}"

  http_status="$(curl "${curl_flags[@]}" --head --write-out '%{http_code}' "${appcast_url}" -o '/dev/null')"

  [[ "${http_status}" == 200 ]]
}

function report_outdated_appcasts {
  local repo_name cask_name appcast_url current_checkpoint new_checkpoint version

  repo_name="${1}"

  for cask_file in ./*; do
    appcast_url="$(brew cask _stanza appcast "${cask_file}")"
    [[ -z "${appcast_url}" ]] && continue # skip early if there is no appcast

    cask_name="$(basename "${cask_file%.*}")"

    message "Verifying appcast checkpoint for ${cask_name}…"

    if is_appcast_available "${appcast_url}"; then
      current_checkpoint="$(brew cask _stanza --yaml appcast "${cask_file}" | grep '^- :checkpoint' | awk '{print $3}')"
      new_checkpoint="$(curl "${curl_flags[@]}" --compressed "${appcast_url}" | sed 's|<pubDate>[^<]*</pubDate>||g' | shasum --algorithm 256 | awk '{ print $1 }')"
    else
      message "There was an error checking the appcast for ${cask_name}."
      inaccessible_appcasts+=("${repo_name}/${cask_name}")
      continue
    fi

    if [[ "${current_checkpoint}" != "${new_checkpoint}" ]]; then
      version="$(brew cask _stanza version "${cask_file}")"

      message "${cask_name} is outdated. Opening issue in ${repo_name}…"
      open_issue "${repo_name}" "${cask_name}" "${version}" "${appcast_url}"
    fi
  done
}

for repo in "${caskroom_repos[@]}"; do
  go_to_repo_and_update "${repo}"
  report_outdated_appcasts "${repo}"
done

if [[ ${#inaccessible_appcasts[@]} -gt 0 ]];then
  echo # empty line
  message 'Some casks have appcasts that errored out, and may need to be rechecked:'
  printf '%s\n' "${inaccessible_appcasts[@]}"
fi