#!/bin/bash

getXML() {

	# Just read a file:

	cat "/etc/dbus-1/system.d/org.freedesktop.NetworkManager.conf"

	# Or we can wget or curl it from the network

	# or generate on-the-fly using some other command.

}

parseXML() {

	# Convert the XML tree structure into multiple relations.

	# Use XPath expressions to find record nodes

	# and to find attributes inside them.

	relpipe-in-xmltable \

		--relation 'policy' \

			--records '/busconfig/policy/allow|/busconfig/policy/deny' \

			--attribute 'policy'           string 'name()' \

			--attribute 'user'             string '../@user' \

			--attribute 'context'          string '../@context' \

			--attribute 'own'              string '@own' \

			--attribute 'send_destination' string '@send_destination' \

			--attribute 'send_interface'   string '@send_interface' \

			--attribute 'send_member'      string '@send_member' \

		--relation 'limit' \

			--records '/busconfig/limit' \

			--attribute 'name'             string '@name' \

			--attribute 'value'            integer '.'

}

filterRecords() {

	# Use native AWK command (called from relpipe-tr-awk)

	# with all its power to filter the records.

	# Work with named fields instead of numbered columns.

	relpipe-tr-awk \

		--relation "policy" \

		--where 'policy == "allow" && user != "root"'

	# Of course, we can do the same using SQL:

	# relpipe-tr-sql \

	#	--relation "policy" \

	#		"SELECT * FROM policy WHERE policy = 'allow' AND user <> 'root'"

	#	--copy 'limit'

	# Or using Scheme:

	# relpipe-tr-scheme \

	#	--relation policy \

	#	--where '(and (string= $policy "allow") (not (string= $user "root")) )'

}

formatOutput() {

	relpipe-out-tabular

	# Or generate some other format:

	# relpipe-out-ods       # spreadsheet for e.g. LibreOffice

	# relpipe-out-xml       # XML e.g. for further XSLT or XQuery processing

	# relpipe-out-recfile   # recfile for further GNU Recutils processing

	# relpipe-out-asn1      # ASN.1 BER for the telco guys

	# relpipe-out-gui       # display data in a GUI window

	# etc.

}

# put the whole pipeline together:

getXML | parseXML | filterRecords | formatOutput