# void escape_regex_string_param(char* param)
#
# Escape special regex characters
function escape_regex_string_param() {
	local escaped_result=$@
	escaped_result=${escaped_result//\\/\\\\}
	escaped_result=${escaped_result//./\\.}
	escaped_result=${escaped_result//+/\\+}
	escaped_result=${escaped_result//(/\\(}
	escaped_result=${escaped_result//)/\\)}
	escaped_result=${escaped_result//[/\\[}
	escaped_result=${escaped_result//]/\\]}
	escaped_result=${escaped_result//\{/\\\{}
	escaped_result=${escaped_result//\}/\\\}}
	escaped_result=${escaped_result//\?/\\\?}
	escaped_result=${escaped_result//\*/\\\*}
	escaped_result=${escaped_result//\//\\/} 
	escaped_result=${escaped_result//|/\\|} 
	escaped_result=${escaped_result//&/\\&} 
	escaped_result=${escaped_result//~/\\~} 
	escaped_result=${escaped_result//^/\\^} 
	escaped_result=${escaped_result//$/\\$} 
	echo $escaped_result
}

# 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}
	if [[ ! -f ${filepath} ]]; then
		touch ${filepath} && \
			chmod 0600 ${filepath} || \
			return 1
	fi
	
	#escape username and remotename, used in following sed calls
	local regex_username=$(escape_regex_string_param ${username})
	local regex_remotename=$(escape_regex_string_param ${remotename})
	local regex_password
	local regex_filter="[ \t]*\"?${regex_username}\"?[ \t]*\"?${regex_remotename}\"?[ \t]*"
	
	#read old password, including " chars 
	#for being able to distinct when we need to add or update auth info
	local old_password=$(
		sed -r -e "/^${regex_filter}\".*\"[ \t]*\$/\
			{s/^${regex_filter}(\".*\")[ \t]*\$/\1/;q;};\
			d;" \
				${filepath}
		)

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