Build/PHPCS: set up the PHPCS ruleset properly

* Add XSD schema.
* Set the command line arguments.
* Remove `exclude-pattern`s which are already set via YoastCS.
* Add configuration for the `WordPress.WP.I18n` sniff.
* Add configuration for the `Yoast.Files.Filename` sniff and remove the exclusion.
* Add configuration for the `WordPress.NamingConventions.PrefixAllGlobals` sniff.

.phpcs.xml.dist

@@ -1,18 +1,88 @@
 <?xml version="1.0"?>
-<ruleset name="Yoast Comment Hacks">
+<ruleset xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+	name="Yoast Comment Hacks"
+	xsi:noNamespaceSchemaLocation="./vendor/squizlabs/php_codesniffer/phpcs.xsd">
+
 	<description>Yoast Comment Hacks rules for PHP_CodeSniffer</description>
 
-    <file>.</file>
+	<!--
+	#############################################################################
+	COMMAND LINE ARGUMENTS
+	https://github.com/squizlabs/PHP_CodeSniffer/wiki/Annotated-ruleset.xml
+	#############################################################################
+	-->
+
+	<file>.</file>
+
+	<!-- Only check PHP files. -->
+	<arg name="extensions" value="php"/>
+
+	<!-- Show progress, show the error codes for each message (source). -->
+	<arg value="ps"/>
+
+	<!-- Strip the filepaths down to the relevant bit. -->
+	<arg name="basepath" value="./"/>
+
+	<!-- Check up to 8 files simultaneously. -->
+	<arg name="parallel" value="8"/>
+
+
+	<!--
+	#############################################################################
+	USE THE YoastCS RULESET
+	#############################################################################
+	-->
+
+	<rule ref="Yoast"/>
+
+
+	<!--
+	#############################################################################
+	SNIFF SPECIFIC CONFIGURATION
+	#############################################################################
+	-->
+
+	<!-- Verify that all gettext calls use the correct text domain. -->
+	<rule ref="WordPress.WP.I18n">
+		<properties>
+			<property name="text_domain" type="array">
+				<element value="yoast-comment-hacks"/>
+			</property>
+		</properties>
+	</rule>
+
+	<rule ref="Yoast.Files.FileName">
+		<properties>
+			<!-- Don't trigger on the main file as renaming it would deactivate the plugin. -->
+			<property name="exclude" type="array">
+				<element value="yoast-comment-hacks.php"/>
+			</property>
+
+			<!-- Remove the following prefixes from the names of object structures. -->
+			<property name="prefixes" type="array">
+				<element value="yoast_comment"/>
+			</property>
+		</properties>
+
+		<exclude-pattern>*/deprecated/deprecated-classes\.php$</exclude-pattern>
+	</rule>
 
-	<exclude-pattern>tests/*</exclude-pattern>
-	<exclude-pattern>vendor/*</exclude-pattern>
-	<exclude-pattern>node_modules/*</exclude-pattern>
+	<!-- Verify that everything in the global namespace is prefixed with a plugin specific prefix. -->
+	<rule ref="WordPress.NamingConventions.PrefixAllGlobals">
+		<properties>
+			<!-- Provide the prefixes to look for. -->
+			<property name="prefixes" type="array">
+				<!-- Temporarily allowed until the prefixes are fixed. -->
+				<element value="yoast_ch"/>
+				<element value="yst_comment"/>
 
-    <arg name="extensions" value="php" />
-    <arg value="nsp" />
+				<!-- These are the new prefixes which all code should comply with in the future. -->
+				<element value="yoast_comment"/>
+				<element value="Yoast\WP\Comment"/>
+			</property>
+		</properties>
 
-    <rule ref="Yoast">
-        <exclude name="Yoast.Files.FileName.InvalidClassFileName"/>
-    </rule>
+		<exclude-pattern>*/deprecated/*\.php$</exclude-pattern>
+	</rule>
 
 </ruleset>