mtgwallpaper

#!/bin/bash

readonly program="$(basename "${0}")"
readonly config_file="${HOME}/.config/mtgwallpaper"
readonly valid_dimensions=('2560x1600' '1920x1080' '1280x960' 'iPhone' 'Tablet' 'Facebook')

function error_message {
  echo -e "$(tput setaf 1)${1}$(tput sgr0)" >&2
  exit 1
}

function wrong_setting {
  error_message "${1}\nRun \`${program} --init\` to create/overwrite the settings file with sensible defaults."
}

function syntax_error {
  error_message "${program}: ${1}\nTry \`${program} --help\` for more information."
  exit 1
}

function string_in_array? {
  local string="${1}"

  for value in "${@:2}"; do
    [[ "${string}" == "${value}" ]] && return 0
  done
  return 1
}

function create_default_config {
  echo "Creating a configuration with sensible defaults on ${config_file}" >&2

  echo "wallpaper_directory=\"\${HOME}/Pictures/MTG_wallpapers\"
    maximum_wallpaper_count=\"10\"
    wallpaper_dimensions=\"2560x1600\" # Valid options (capitalisation matters): ${valid_dimensions[*]}
    last_walpaper_url=\"\" # Do not touch, as it will be automatically updated" | sed -E 's/^ {4}//' > "${config_file}"
}

function usage {
  echo "
    Usage:
      ${program} [options]

    Options:
      -i, --init       Create a settings file with sensible defaults (overwrites any existing one) and exit.
      -e, --edit       Open the configuration file in a text editor and exit.
      -d, --download   Run the script to get new wallpapers.
      -h, --help       Show this help.
  " | sed -E 's/^ {4}//'
}

# Available flags
while [[ "${1}" ]]; do
  case "${1}" in
    -h | --help)
      usage
      exit 0
      ;;
    -i | --init)
      create_default_config
      exit 0
      ;;
    -e | --edit)
      open -t "${config_file}"
      exit 0
      ;;
    -d | --download)
      start_download='true'
      ;;
    -*)
      syntax_error "unrecognized option: ${1}"
      ;;
    *)
      break
      ;;
  esac
  shift
done

trap 'exit 1' SIGINT

[[ -n "${start_download}" ]] || error_message 'You need to give the `--download` flag to download wallpapers.'

# Make sure all settings are valid
[[ -f "${config_file}" ]] && source "${config_file}" || wrong_setting 'There is no settings file.'
[[ -n "${wallpaper_directory}" ]] || wrong_setting "wallpaper_directory in ${config_file} is missing."
[[ "${maximum_wallpaper_count}" =~ ^[0-9]+$ ]] || failure "maximum_wallpaper_count if ${config_file} needs to be a whole number."
string_in_array? "${wallpaper_dimensions}" "${valid_dimensions[@]}" || failure "wallpaper_dimensions in ${config_file} needs to be one of ${valid_dimensions[*]}."

if [[ ! -d "${wallpaper_directory}" ]]; then
  if ! mkdir -p "${wallpaper_directory}"; then
    error_message "You don’t have permissions to create ${wallpaper_directory}."
  fi
fi

# Main section
cd "${wallpaper_directory}" || exit 1

recent_wallpaper_urls="$(curl --silent 'http://magic.wizards.com/en/articles/media/wallpapers' | grep "download.*${wallpaper_dimensions}" | sed -E 's/.*href="([^"]*).*/\1/')"

# Update latest wallpaper url
most_recent_wallpaper_url="$(head -1 <<< "${recent_wallpaper_urls}")"
sed -i '' '/last_walpaper_url/d' "${config_file}"
echo "last_walpaper_url=\"${most_recent_wallpaper_url}\" # Do not touch, as it will be automatically updated" >> "${config_file}"

# Download new wallpapers
for wallpaper_url in ${recent_wallpaper_urls}; do
  [[ "${wallpaper_url}" == "${most_recent_wallpaper_url}" ]] && break
  curl --silent --remote-name "${wallpaper_url}"
done

# Delete old wallpapers
while [[ "$(ls -1 | wc -l)" -gt "${maximum_wallpaper_count}" ]]; do
  rm "$(ls -1t | tail -1)"
done