# void escape_regex_string_param(char* param)
#
# Escape special regex characters
function escape_regex_string_param() {
	echo $@ | sed 's/\([/.*]\)/[\1]/g;s/\(\\\)/\\\\/g;'
}

# void double_backslashes(char* param)
#
# Escape special regex characters
function double_backslashes() {
	echo $@ | sed 's/\(\\\)/\\\\/g;'
}

# bool update_secrets_file(char* filepath, char* username, char* remotename, char* password)
#
# Add/update PAP/CHAP authentication information 
function update_secrets_file() {
	local filepath=${1} username=${2} remotename=${3} password=${4}
	[[ ! -f ${filepath} ]] && {
		touch ${filepath} && \
			chmod 0600 ${filepath} || \
			return 1
	}
	
	#escape username and remotename, used in following sed calls
	local regex_username=$(escape_regex_string_param ${username})
	local regex_remotename=$(escape_regex_string_param ${remotename})
	local regex_password=$(double_backslashes ${password})

	#read old password, including " chars 
	#for being able to distinct when we need to add or update auth info
	local old_password=$(
		sed -e "/^[ \t]*\"\?${regex_username}\"\?[ \t]*${regex_remotename}[ \t]*\".*\"[ \t]*\$/\
			{s/^[ \t]*\"\?${regex_username}\"\?[ \t]*${regex_remotename}[ \t]*\(\".*\"\)[ \t]*\$/\1/;q;};\
			d;" \
				${filepath}
		)

	if [ -z "${old_password}" ]; then
		regex_username=$(double_backslashes ${username})
		regex_remotename=$(double_backslashes ${remotename})
		sed -i -e "\$a\"${regex_username}\" ${regex_remotename} \"${regex_password}\"" ${filepath}
		ewarn "Authentication info has been added to ${filepath}"
	elif [ "\"${password}\"" != "${old_password}" ]; then
		sed -i -e "/^[ \t]*\"\?${regex_username}\"\?[ \t]*${regex_remotename}[ \t]*\".*\"[ \t]*\$/\
			{s/^\([ \t]*\"\?${regex_username}\"\?[ \t]*${regex_remotename}[ \t]*\"\).*\(\"[ \t]*\)\$/\1${regex_password}\2/;q;};" \
			${filepath}
		ewarn "Authentication info has been updated in ${filepath}"
	fi
	return 0
}