icsutils/gcgetics.sh

#!/usr/bin/env bash

#  Author: Martin Winkler
# License: Please refer to the repository
#  Origin: https://winklerfamilie.eu/git/SmallThings/icsutils.git

# Exit on error. Append "|| true" if you expect an error.
set -o errexit
# Exit on error inside any functions or subshells.
set -o errtrace
# Do not allow use of undefined vars. Use ${VAR:-} to use an undefined VAR
set -o nounset
# Catch the error in case mysqldump fails (but gzip succeeds) in `mysqldump |gzip`
set -o pipefail

# gc = google calendar
gc::getIcsUsage() {
  cat <<USAGE_END
Usage: ${0##*/} [OPTIONS] [URL/FILE]

 Parses a google calendar embbeded URL content for any number
 of containted google calendar id (cid). 

 [OPTIONS]
   --file,  -f  : Input is a file containing a previous curl
                  of a google calendar embbeded link.
   --help,  -h  : Show this help.
   --           : End of Options.

 [URL/FILE]
   Such a URL usually starts with:
     "https://calendar.google.com/calendar/../embed?"
   Where ".." may be empty or a more specific reference.

   If [URL/FILE] is empty or "-", standard input is used.

USAGE_END
}

gc::makeIcsUrl() {
  # Exclude public holiday calendar
  local rexHoliday='group\.v\.calendar'
  [[ "${1:?}" =~ $rexHoliday ]] && return 1
  echo "https://calendar.google.com/calendar/ical/${1}/public/basic.ics"
}

gc::findcid() {
  local arg=""
  local content=""
  local file=0
  local cids=()
  local title=()

  local color_green= ; [ -t 1 ] && color_green='\033[1;32m'
  local color_blue= ; [ -t 1 ] && color_blue='\033[1;34m'
  local color_red= ; [ -t 1 ] && color_red='\033[2;31m'
  local color_less= ; [ -t 1 ] && color_less='\033[0m'

  for arg in "${@}" ; do
    case "$1" in
      --file|-f)
        file=1
        shift 1 ;;
      --)
        shift && break ;;
    esac
  done

  if [[ "${1}" = "-" ]] || [ -z "${1}" ] ; then 
    file=1
    shift
  fi
  if (( file )) ; then
    content=$(<"${1:-"/dev/stdin"}")
  else
    # could grep for "cids", but unsure if result is always on one line
    content="$(curl --silent -L "${1:-}")"
  fi

  while IFS= read -r line || [[ "${line}" ]] ; do
    cids+=("${line}")
  done < <(grep -oP '(?<=")[^"]*@(group|group\.v)\.calendar\.google\.com(?=")' <<<"${content}")

  while IFS= read -r line || [[ "${line}" ]] ; do
    title+=("${line}")
  done < <(grep -oP '(?<="title":")[^"]*(?=")' <<<"${content}")

  for i in "${!cids[@]}" ; do
    printf '%12s: %b%s%b\n' "Title" "${color_green}" "${title[$i]}" "${color_less}"
    printf '%12s: %s\n' "Calendar ID" "${cids[$i]}"
    printf '%12s: %b' "ICS Url" "${color_blue}"
    gc::makeIcsUrl "${cids[$i]}" || printf '%b\n' "${color_red}No ics file for this calendar${color_less}"
    printf '%b' "${color_less}"
    echo
  done
}

gc::getIcs() {
  local arg=
  local element=
  local opt=""

  readonly shortMax=80
  local shortEnd=0

  local color_yellow= ; [ -t 1 ] && color_yellow='\033[1;33m'
  local color_less= ; [ -t 1 ] && color_less='\033[0m'

  # shellcheck disable=SC2034 # arg not used
  for arg in "${@}" ; do
    case "$1" in
      --help|-h)
        gc::getIcsUsage
        return 0 ;;
      --file|-f)
        opt="-f"
        shift ;;
      --)
        shift && break ;;
    esac
  done

  local args=("${@}")
  
  # Use standard input if no files are present
  [ $# -eq 0 ] && args[0]="-"

  for element in "${args[@]}" ; do
    if [[ $# -gt 1 ]] ; then
      printf "%b## CID information from: " "${color_yellow}"
      # Shorten the URL of PATH if it is greater than $shortMax
      if [[ ${#element} -gt ${shortMax} ]] ; then
        shortEnd=$((${#element} - shortMax/2))
        printf '%s[...]%s' \
          "${element:0:$((shortMax/2))}" \
          "${element:${shortEnd}:${#element}}"
      else
        printf '%s' "${element}"
      fi
      printf '%b\n\n' "${color_less}"
    fi
    gc::findcid ${opt} "${element}"
  done
}

### Check if script is _sourced
### https://stackoverflow.com/a/28776166
_sourced=0
if [ -n "${ZSH_EVAL_CONTEXT:-}" ]; then
  case ${ZSH_EVAL_CONTEXT:-} in *:file) _sourced=1;; esac
elif [ -n "${KSH_VERSION:-}" ]; then
  [ "$(cd "$(dirname -- "$0")" && pwd -P)/$(basename -- "$0")" \
    != "$(cd "$(dirname -- "${.sh.file}")" && pwd -P)/$(basename -- "${.sh.file}")" ] && _sourced=1
elif [ -n "${BASH_VERSION:-}" ]; then
  (return 0 2>/dev/null) && _sourced=1
else # All other shells: examine $0 for known shell binary filenames
  # Detects `sh` and `dash`; add additional shell filenames as needed.
  case ${0##*/} in sh|dash) _sourced=1;; esac
fi
###

if (( ! _sourced )); then
  gc::getIcs "${@}"
fi