#!/usr/bin/env bash
# ARG_OPTIONAL_SINGLE([start],[s],[start time HH:mm])
# ARG_OPTIONAL_SINGLE([end],[e],[end time HH:mm])\
# ARG_OPTIONAL_SINGLE([rrule],[r],[rrule can be done via https://jakubroztocil.github.io/rrule/])
# ARG_OPTIONAL_SINGLE([loop],[l],[how many dates should be generated])
# ARG_HELP([Generate events based on rrule strings])
# ARGBASH_GO()
# needed because of Argbash --> m4_ignore([
### START OF CODE GENERATED BY Argbash v2.9.0 one line above ###
# Argbash is a bash code generator used to get arguments parsing right.
# Argbash is FREE SOFTWARE, see https://argbash.io for more info
# Generated online by https://argbash.io/generate


die()
{
	local _ret="${2:-1}"
	test "${_PRINT_HELP:-no}" = yes && print_help >&2
	echo "$1" >&2
	exit "${_ret}"
}


begins_with_short_option()
{
	local first_option all_short_options='serlh'
	first_option="${1:0:1}"
	test "$all_short_options" = "${all_short_options/$first_option/}" && return 1 || return 0
}

# THE DEFAULTS INITIALIZATION - OPTIONALS
_arg_start=
_arg_end=
_arg_rrule=
_arg_loop=


print_help()
{
	printf '%s\n' "Generate events based on rrule strings"
	printf 'Usage: %s [-s|--start <arg>] [-e|--end <arg>] [-r|--rrule <arg>] [-l|--loop <arg>] [-h|--help]\n' "$0"
	printf '\t%s\n' "-s, --start: start time HH:mm (no default)"
	printf '\t%s\n' "-e, --end: end time HH:mm (no default)"
	printf '\t%s\n' "-r, --rrule: rrule can be done via https://jakubroztocil.github.io/rrule/ (no default)"
	printf '\t%s\n' "-l, --loop: how many dates should be generated (no default)"
	printf '\t%s\n' "-h, --help: Prints help"
}


parse_commandline()
{
	while test $# -gt 0
	do
		_key="$1"
		case "$_key" in
			-s|--start)
				test $# -lt 2 && die "Missing value for the optional argument '$_key'." 1
				_arg_start="$2"
				shift
				;;
			--start=*)
				_arg_start="${_key##--start=}"
				;;
			-s*)
				_arg_start="${_key##-s}"
				;;
			-e|--end)
				test $# -lt 2 && die "Missing value for the optional argument '$_key'." 1
				_arg_end="$2"
				shift
				;;
			--end=*)
				_arg_end="${_key##--end=}"
				;;
			-e*)
				_arg_end="${_key##-e}"
				;;
			-r|--rrule)
				test $# -lt 2 && die "Missing value for the optional argument '$_key'." 1
				_arg_rrule="$2"
				shift
				;;
			--rrule=*)
				_arg_rrule="${_key##--rrule=}"
				;;
			-r*)
				_arg_rrule="${_key##-r}"
				;;
			-l|--loop)
				test $# -lt 2 && die "Missing value for the optional argument '$_key'." 1
				_arg_loop="$2"
				shift
				;;
			--loop=*)
				_arg_loop="${_key##--loop=}"
				;;
			-l*)
				_arg_loop="${_key##-l}"
				;;
			-h|--help)
				print_help
				exit 0
				;;
			-h*)
				print_help
				exit 0
				;;
			*)
				_PRINT_HELP=yes die "FATAL ERROR: Got an unexpected argument '$1'" 1
				;;
		esac
		shift
	done
}

parse_commandline "$@"

# OTHER STUFF GENERATED BY Argbash

### END OF CODE GENERATED BY Argbash (sortof) ### ])
# [ <-- needed because of Argbash

IFS="
"
REPEAT=${_arg_loop:-10}
START=${_arg_start:-00:00}
END=${_arg_end:-12:00}
STARTDATE="$(date -I)T${START}"
DTSTART=$(date -u --date="${STARTDATE}" +"%Y%m%dT%H%M%SZ")
RRULE=${_arg_rrule:-FREQ=MONTHLY;BYSETPOS=1;BYDAY=TH;INTERVAL=1}
RRULE_CMD=rrule

if ! command -v ${RRULE_CMD}  &> /dev/null
then
	cat <<EOF
${RRULE_CMD} could not be found
You can install it via:
nix-shell -p cargo -p gcc
cargo install rrule --features="cli-tool"
export PATH="\$PATH:${HOME}/.cargo/bin/"
EOF
    exit
fi


for d in $(rrule "DTSTART:${DTSTART}\n${RRULE}" -l ${REPEAT});do 
	DATE=$(date -u --date="${d}" +"%Y-%m-%dT%H:%M:%SZ")
	DATEONLY=$(date -u --date="${d}" +"%Y-%m")
	cat <<EOF
  <event title="Plenum">
    <start>${DATE}</start>
    <location><link href="http://www.c3d2.de/space.html">HQ</link>, /proc, Zentralwerk, Riesaer Straße 32, 01127 Dresden</location>
    <link>https://codimd.c3d2.de/plenum-${DATEONLY}</link>
  </event>
EOF
done