google_oauth2

#!/bin/bash
# Google Oauth 2 for bash
# Copyright (C) 2018 Samuel Rodriguez Sevilla <laparca@laparca.es>
# Copyright (C) 2018 Distribuidira Internacional de Alimentacion S.A.
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU Affero General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU Affero General Public License for more details.
#
# You should have received a copy of the GNU Affero General Public License
# along with this program.  If not, see <https://www.gnu.org/licenses/>.

# This should be eliminated from here

[ -n "$DEBUG" ] && set -x

function show_text_or_default() {
	if [ -z "$2" ]; then
		echo "$1 no esta definido." 1>&2
	else
		echo "$2"
	fi
}

function configure_option() {
	local value
	echo "$1 no esta definido. Por favor, indique que valor debe tener:"
	read value

	eval "$1=$value"
}

function configure_proxy() {
	local result
	local proxy_url

	if [ -n "${https_proxy}" ]; then
		PROXY="-x $https_proxy"
	elif [ -z "${PROXY}" ]; then
		echo "¿Desea configurar un proxy (s/N)? "
		read result
		if [ "$result" == "s" ] || [ "$result" == "S" ]; then
			echo "Introduzca la URL del proxy: "
			read proxy_url
			if [ -n "$proxy_url" ]; then
				PROXY="-x $proxy_url"
			fi
		fi
	fi
}

SOME_OPTION_WAS_MODIFIED=false
function check_option_or_action() {
	local var="$1"
	if [ -z "${!var}" ]; then
		"$2" "$1"
		SOME_OPTION_WAS_MODIFIED=true
	fi
}

# Checks if a environment variable is seted. In other case it shows an error an
# exit.
function check_option_or_error() {
	local var="$1"
	if [ -z "${!var}" ]; then
		show_text_or_default "$1" "$2"
		exit 1
	fi
}

function check_option_or_default() {
	local var="$1"
	if [ -z "${!var}" ]; then
		eval "$1='$2'"
	fi
}

function check_file_or_action() {
	[ ! -f "$1" ] && "$2"
}

function save_options_in() {
	local dest="$1"
	shift
	
	mkdir -p "$(dirname "$dest")" 2> /dev/null

	[ -f "${dest}" ] && cp "${dest}" "${dest}.$(date +%Y%m%d%H%M%S)"

	for option in $@; do
		echo "$option=${!option}" >> "$dest"
	done
}

GOOGLE_CLIENT_PATH="~/.config/bash_google_oauth2_client"
# Initial checks
check_option_or_default "GOOGLE_CLIENT_CONFIGURATION_FILE" "${GOOGLE_CLIENT_PATH}/client"
if [ -f "$GOOGLE_CLIENT_CONFIGURATION_FILE" ]; then
	. "$GOOGLE_CLIENT_CONFIGURATION_FILE"
fi

check_option_or_action  "CLIENT_ID"     configure_option
check_option_or_action  "CLIENT_SECRET" configure_option
check_option_or_default "TOKEN_FILE"    "${GOOGLE_CLIENT_PATH}/token"
check_option_or_default "API_SCOPE"     "https://www.googleapis.com/auth/spreadsheets"
check_file_or_action "${GOOGLE_CLIENT_CONFIGURATION_FILE}" configure_proxy

if $SOME_OPTION_WAS_MODIFIED; then
	save_options_in "$GOOGLE_CLIENT_CONFIGURATION_FILE" "CLIENT_ID" "CLIENT_SECRET" "PROXY"
fi

# Callback need for command line programas
CALLBACK_URI="urn:ietf:wg:oauth:2.0:oob"

function setup() {
	echo "Es necesario abrir la siguiente URL:"
	echo "https://accounts.google.com/o/oauth2/auth?client_id=${CLIENT_ID}&redirect_uri=${CALLBACK_URI}&scope=${API_SCOPE}&response_type=code&request=offline"
	echo "Cuando lo haya hecho introduzca a continuacion el codigo devuelto:"
	read code

	curl ${PROXY} -d "code=${code}" -d client_id="${CLIENT_ID}" -d client_secret="${CLIENT_SECRET}" -d redirect_uri="${CALLBACK_URI}" -d 'grant_type=authorization_code' -d 'request=offline' 'https://www.googleapis.com/oauth2/v4/token' | sed '/{/d;/}/d;s/,\s*$//g;s/\s*"\([a-zA-Z_0-9]\+\)":\s*\(.*\)$/\1=\2/' > "${TOKEN_FILE}"
	echo "code=\"$code\"" >> "${TOKEN_FILE}"
}

function renewToken() {
	. "${TOKEN_FILE}"
	modifDate="$(stat -L -c %Y "${TOKEN_FILE}")"
	if [ -z "$expires_in" ]; then
	   expires_in=0
	fi
	fechExp="$(($modifDate + $expires_in))"
	fechNow="$(date +%s)"
	if [ ${fechNow} -gt ${fechExp} ]; then
		curl ${PROXY} -d refresh_token="${refresh_token}" -d client_id="${CLIENT_ID}" -d client_secret="${CLIENT_SECRET}" -d 'grant_type=refresh_token' 'https://www.googleapis.com/oauth2/v4/token' | sed '/{/d;/}/d;s/,\s*$//g;s/\s*"\([a-zA-Z_0-9]\+\)":\s*\(.*\)$/\1=\2/' > "${TOKEN_FILE}"
		echo "refresh_token=\"${refresh_token}\"" >> "${TOKEN_FILE}"
		echo "code=\"$code\"" >> "${TOKEN_FILE}"
	fi
}

# If the token was never negotiated then do the setup
if [ ! -f "${TOKEN_FILE}" ]; then
	setup
fi

# Try renew the auth token if necesary
renewToken

# Import the data for do connections to the API
. "${TOKEN_FILE}"