#!/bin/bash

IFS=$'\n'

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)

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

if [[ ! $(which 'fastmerge') ]]; then
  echo -e "$(tput setaf 1)
    This script requires 'fastmerge'.
    If you have [Homebrew](http://brew.sh), you can install it with 'brew install vitorgalvao/tiny-scripts/fastmerge'.
  $(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 delete_current_branch {
  local current_branch

  current_branch="$(git rev-parse --abbrev-ref HEAD)"
  git checkout master --quiet
  git branch -D "${current_branch}" --quiet
}

function delete_cask_repair_branches {
  [[ $(ghi list --state open --pulls --label 'outdated appcast' | tail -1) == 'None.' ]] && cask-repair --push origin --delete-branches
}

function merge_outdated_appcasts {
  local repo_name pr_number cask_name pr_url last_commit

  repo_name="${1}"

  for line in $(ghi list --state open --pulls --label 'outdated appcast' --reverse | tail +2); do
    [[ "${line}" == 'None.' ]] && break # exit early if there are no relevant issues in repo

    pr_number="$(awk '{print $1}' <<< "${line}")"
    cask_name="$(awk '{print $3}' <<< "${line}")"
    pr_url="${caskroom_online}/${repo_name}/pull/${pr_number}"

    hub checkout "${pr_url}" &>/dev/null
    last_commit="$(git log -n 1 --pretty=format:'%H')"
    delete_current_branch

    if [[ "$(hub ci-status "${last_commit}")" == 'success' ]]; then
      message "Merging pull request for ${cask_name}…"
      fastmerge --maintainer --remote origin "${pr_url}"
    else
      continue
    fi
  done
}

for repo in "${caskroom_repos[@]}"; do
  go_to_repo_and_update "${repo}"
  merge_outdated_appcasts "${repo}"
  delete_cask_repair_branches
  git gc
done