#!/usr/bin/env bash
#
# Copyright 2018-2022 eth0 <ethernet.zero@gmail.com>
# 
# This work is free. You can redistribute it and/or modify it under the terms of
# the ISC License. See the COPYING file for more details.


# This script doesn't need any input from stdin, so just close it
exec 0<&-

# Join an array using a separator
join()
{
	local sep="$1"
	shift

	local ret
	printf -v ret "%s$sep" "$@"
	echo "${ret::-${#sep}}"
}

# Call the Matrix Booking API
api()
{
	local api='https://app.matrixbooking.com/api/v1'
	local endpoint="$1"
	shift
	# Join query parameters
	local params="$(join '&' "$@")"
	local curl_args=(-snL)

	[[ "$endpoint" != /* ]] && endpoint="/$endpoint"

	# If you send something through stdin, then it's a POST request
	if read -t0 _; then
		curl_args+=(
			-X POST
			-H 'Content-Type: application/json;charset=utf-8'
			-H "X-Time-Zone: ${TZ:-Europe/Madrid}"
			-d@-
		)
	fi

	curl "${curl_args[@]}" "$api$endpoint${params:+?}${params}" 2>/dev/null
}

# Shortcut function for jq'ing
json()
{
	local query="$1"
	shift

	jq -rc "$@" "$query" 2>/dev/null
}

# Make sure all necessary options are provided
ensure_opts()
{
	for arg; do
		if [[ -z "${!arg}" ]]; then
			err "You need to set the $arg option in $cfgfile or provide the --${arg//_/-}=<${arg^^}> option in the commandline"
			return 1
		fi
	done
}

force_opts()
{
	ensure_opts "$@" || exit 1
}

# Override variables from long options passed as arguments
# For example, --variable-name=value would set variable_name='value'
parse_args()
{
	local opt
	local val
	local arg
	for arg; do
		# Ignore any arguments that don't start with a double dash
		# So let's say there's a --variable-name='value' argument
		if [[ "$arg" == --* ]]; then
			# Remove the leading double dash
			# Result: --variable-name=value -> variable-name=value
			opt="${arg#--}"
			# Set an empty value by default just in case the argument doesn't
			# have a value, e.g. --variable-name would be the same as
			# --variable-name=''
			val=''
			# If the argument has an equals sign, take everything after it as
			# the value
			# Result: variable-name=value -> value
			[[ "$opt" == *=* ]] && val="${opt#*=}"
			# Then take everything before it as the variable name and replace
			# all dashes with underscores
			# Result: variable-name=value -> variable_name
			opt="${opt%%=*}"
			opt="${opt//-/_}"
			# Use the resulting option name as a variable nameref
			declare -n var="$opt"
			# So now, setting the nameref's value will set the variable named
			# before the option name
			var="$val"
			# Then undefine the nameref and move on
			unset -n var
		fi
	done
}

# Non-fatal error
err()
{
	echo "${0##*/}: $*" >&2
}

# Fatal error
fail()
{
	err "$*"
	exit 1
}

# Check if a command is a file on disk and not an alias or a function
is_cmd()
{
	local command="$1"
	[[ "$(type -p "$command" 2>/dev/null)" ]]
}

# Portable-ish GNU+BSD date command
_date()
{
	local datespec="$1"
	local datefmt="${2:-%F}"
	local date
	local retval

	if [[ "$OSTYPE" == *darwin* ]]; then
		# If it's a Mac and Homebrew is installed, install coreutils to get
		# GNU date as gdate
		if ! is_cmd gdate && is_cmd brew; then
			echo 'Ah, let me install GNU date for you.'
			brew install coreutils || fail "Couldn't install GNU date in your system"
		fi
		date="$(gdate -d "$datespec" "+$datefmt" 2>/dev/null)"
		retval=$?
	elif ! is_cmd date; then
		# No date command in your system? How odd!
		fail "There's no date command in your system"
	else
		# Try a GNU date calculation
		date="$(date -d "$datespec" "+$datefmt" 2>/dev/null)"
		retval=$?

		# If it doesn't generate anything, date is probably a BSD date
		# It can be a macOS without Homebrew or any other *BSD
		if [[ -z "$date" ]]; then
			# If the booking date is the default, try the BSD date equivalent
			# Unfortunately we can't translate GNU strtotime() values automatically
			# because those date specs can be complex
			[[ "$datespec" == '+2 weeks' ]] && datespec='+2w'

			# Now try a BSD date command line
			date="$(date -v"$datespec" "+$datefmt" 2>/dev/null)"
			retval=$?
		fi

		# Nothing generated with a GNU nor a BSD date command line, so whatever
		# date command is in the system, we don't know how to use it
		[[ "$date" ]] || retval=1
	fi

	echo "$date"
	return "$retval"
}

_time()
{
	local date="$1"
	local hour="$2"

	printf '%sT%02d:00:00.000' "$date" $hour
}

# Get an hour in the user's timezone from an hour in UTC
_tzhour()
{
	local hour="$1"
	local tzhour

	# First try GNU date, else BSD date
	tzhour="$(date -d "$hour:00 UTC" +%k 2>/dev/null)"
	[[ "$tzhour" ]] || tzhour="$(date -j -f '%k:%M %Z' "$hour:00 UTC" +%k 2>/dev/null)"

	echo "$tzhour"
	[[ "$tzhour" ]]
}

building_id()
{
	api /location kind=BUILDING | \
		json '.[] | select(.name == $name) | .id' \
		--arg name "$*"
}

item_id()
{
	local kind="$1"
	local location_id="$2"
	shift 2

	api /location kind="${kind^^}" l="$location_id" | \
		json '.[] | select(.name == $name) | .id' \
		--arg name "$*"
}

book_item()
{
	local item_id="$1"
	shift
	local extra_fields=()

	# Turn all remaining arguments in the form key=value into JSON key/value
	# pairs, e.g. key=value -> "key":"value"
	for arg; do
		extra_fields+=("\"${arg/=/\":\"}\"")
	done

	local extras="$(join ',' "${extra_fields[@]}")"

	api /booking notifyScope=ALL_ATTENDEES <<-JSON
	{
	  "locationId": $item_id,
	  ${extras}${extras:+,}
	  "attendees": [],
	  "extraRequests": [],
	  "bookingGroup": {},
	  "owner": $owner,
	  "ownerIsAttendee": true
	}
	JSON
}

# Print any error messages returned by the server in the JSON response
process_response()
{
	local response="$*"

	if [[ -z "$response" || "$response" == *'doctype html'* ]]; then
		return 1
	elif [[ "$(json '.messageCode' <<< "$response")" == error* ]]; then
		echo "$(json '.message' <<< "$response")"
		return 1
	fi
}

book()
{
	local area="$1"
	local area_name="$2"
	local item="$3"
	local item_name="$4"
	local date="$5"
	shift 5

	# Default values are for parking spots
	local kind=EQUIPMENT
	local startHour=${start:-$(_tzhour $default_start)}
	local endHour=${end:-$(_tzhour $default_end)}
	if [[ "${item,,}" == desk ]]; then
		kind=DESK
		# Adjust the start and end hours if different from the default
		if [[ -z "$start" ]]; then
			(( startHour-- ))
		fi
		if [[ -z "$end" ]]; then
			(( endHour-- ))
		fi
	fi

	# Get building ID
	area_id="$(building_id "$area_name")"

	if [[ -z "$area_id" ]]; then
		err "${area^} area '$area_name' not found"
		return 1
	fi

	# Get item ID
	item_id="$(item_id "$kind" "$area_id" "$item_name")"

	if [[ -z "$item_id" ]]; then
		err "${item^} '$item_name' not found"
		return 1
	fi

	echo "Booking ${item,,} '$item_name' on $date..."

	response="$(book_item "$item_id"\
		timeFrom="$(_time "$date" $startHour)" \
		timeTo="$(_time "$date" $endHour)" \
		"$@"
	)"

	if ! errormsg="$(process_response "$response")"; then
		err "${errormsg:-Error when performing the API request to book your ${item,,}}"
		return 1
	else
		echo "Your booking for ${item,,} '$item_name' on $date is $(json '.status' <<< "$response")."
	fi
}

booking_date='+2 weeks'
# Parking spots can be booked from 7am to 6pm UTC, desks from 6am to 5pm UTC
default_start=8
default_end=18

cfgfile="${XDG_CONFIG_HOME:-$HOME/.config}/matrix-booker.conf"
ignorefile="${XDG_CONFIG_HOME:-$HOME/.config}/matrix-booker-ignores.conf"

# Import all variable definitions in the config file, which means you can have
# all other sorts of comments and lines in it and they will be ignored
[[ -r "$cfgfile" ]] && source <(grep -E '^[[:alnum:]_]+=' "$cfgfile")
# Then override any variables passed as long options in the command line
(( $# )) && parse_args "$@"

# After that, make sure none of the necessary variables have been assigned an
# empty value
force_opts booking_date

# Calculate the booking date
date="$(_date "$booking_date")"
if [[ -z "$date" ]]; then
	fail "Invalid booking date '$booking_date'"
fi
# Check if the booking date is bookable: not in weekends or in a list of ignored dates
if (( $(_date "$booking_date" %u) > 5 )) || grep -qE "^${date}\$" "$ignorefile"; then
	exit 0
fi

# Get user data from Matrix Booking
userdata="$(api /user/current)"
if [[ "$userdata" == *'doctype html'* ]]; then
	fail "Login failed, please make sure to set your credentials in your ~/.netrc for app.matrixbooking.com"
fi
owner="$(json '{id: .personId, email: .email, name: .name}' <<< "$userdata")"

failed=0

if [[ "$desk_name" ]] && ensure_opts office; then
	book office "$office" desk "$desk_name" "$date"
	(( failed += $? ))
fi

if [[ "$spot_name" ]] && ensure_opts parking_area license_plate; then
	book parking "$parking_area" 'parking spot' "$spot_name" "$date" label="$license_plate"
	(( failed += $? ))
fi

(( ! failed ))