Added initial support for processing custom components in templates

We will very probably need support for rendering our own custom Vue
components in our server-side rendering. Add an initial sketch of
what that might look like.

Bug: T395802

Author: codders

src/HtmlParser.php

@@ -6,6 +6,7 @@
 
 use DOMDocument;
 use DOMElement;
+use DOMXPath;
 use Exception;
 use LibXMLError;
 
@@ -14,6 +15,12 @@
  */
 class HtmlParser {
 
+	private array $components;
+
+	public function __construct( array $components = [] ) {
+		$this->components = $components;
+	}
+
 	/**
 	 * Parse the given HTML string into a DOM document.
 	 */
@@ -46,9 +53,24 @@ public function parseHtml( string $html ): DOMDocument {
 			//TODO Throw an exception
 		}
 
+		$this->substituteComponents( $document );
+
 		return $document;
 	}
 
+	private function substituteComponents( DOMDocument $document ) {
+		$xpath = new DOMXPath( $document );
+		foreach ( $this->components as $componentName => $template ) {
+			$entries = $xpath->query( '//' . $componentName );
+			foreach ( $entries as $entry ) {
+				$templateRoot = $this->getBodyElement( $this->parseHtml( $template ) )->firstChild;
+				$templateNode = $document->importNode( $templateRoot, true );
+				$entry->parentNode->append( $templateNode );
+				$entry->remove();
+			}
+		}
+	}
+
 	/**
 	 * Get the root node of the template represented by the given document.
 	 */

src/Templating.php

@@ -4,6 +4,12 @@
 
 class Templating {
 
+	private array $components;
+
+	public function __construct( array $componentTemplates = [] ) {
+		$this->components = $componentTemplates;
+	}
+
 	/**
 	 * @param string $template
 	 * @param array $data
@@ -12,7 +18,7 @@ class Templating {
 	 * @return string
 	 */
 	public function render( $template, array $data, array $methods = [] ) {
-		$htmlParser = new HtmlParser();
+		$htmlParser = new HtmlParser( $this->components );
 		$document = $htmlParser->parseHtml( $template );
 		$rootNode = $htmlParser->getRootNode( $document );
 		$component = new Component( $rootNode, $methods );

tests/integration/FixtureTest.php

@@ -18,7 +18,8 @@ class FixtureTest extends TestCase {
 	 * @dataProvider provideFixtures
 	 */
 	public function testPhpRenderingEqualsVueJsRendering( $template, array $data, $expectedResult ) {
-		$templating = new Templating();
+		$components = $this->loadFixtureComponents();
+		$templating = new Templating( $components );
 		$methods = [
 			'message' => 'strval',
 			'directionality' => function () {
@@ -31,14 +32,39 @@ public function testPhpRenderingEqualsVueJsRendering( $template, array $data, $e
 		$this->assertEqualHtml( $expectedResult, $result );
 	}
 
+	public function loadFixtureComponents() {
+		$componentDir = __DIR__ . '/fixture/components';
+
+		$components = [];
+		/** @var DirectoryIterator $fileInfo */
+		foreach ( new DirectoryIterator( $componentDir ) as $fileInfo ) {
+			if ( $fileInfo->isDot() || $fileInfo->isDir() ) {
+				continue;
+			}
+
+			$document = new DOMDocument();
+			// Ignore all warnings issued by DOMDocument when parsing
+			// as soon as VueJs template is not actually a "valid" HTML
+			/** @noinspection UsageOfSilenceOperatorInspection */
+			// @codingStandardsIgnoreLine
+			@$document->loadHTMLFile( $fileInfo->getPathname() );
+
+			$componentName = $this->getAttribute( $document, 'template', 'component-name' );
+			$template = $this->getContents( $document, 'template' );
+
+			$components[$componentName] = $template;
+		}
+		return $components;
+	}
+
 	public function provideFixtures() {
 		$fixtureDir = __DIR__ . '/fixture';
 
 		$cases = [];
 
 		/** @var DirectoryIterator $fileInfo */
 		foreach ( new DirectoryIterator( $fixtureDir ) as $fileInfo ) {
-			if ( $fileInfo->isDot() ) {
+			if ( $fileInfo->isDot() || $fileInfo->isDir() ) {
 				continue;
 			}
 
@@ -67,6 +93,10 @@ public function provideFixtures() {
 		return $cases;
 	}
 
+	private function getAttribute( DOMDocument $document, $elementId, $attributeId ) {
+		return $document->getElementById( $elementId )->getAttribute( $attributeId );
+	}
+
 	/**
 	 * @param DOMDocument $document
 	 * @param string $elementId

tests/integration/fixture/components/subcomponent.vue

@@ -0,0 +1,15 @@
+<template id="template" component-name="subcomponent">
+<div><p>Subcomponent!</p></div>
+</template>
+
+<script>
+const { defineComponent } = require( 'vue' );
+
+// @vue/component
+module.exports = exports = defineComponent( {
+	name: 'SubComponent',
+	setup() {
+		return { };
+	}
+} );
+</script>

tests/integration/fixture/spc_test.html

@@ -0,0 +1,14 @@
+<template id="template">
+ <div>
+	<p>Surrounding HTML</p>
+	<subcomponent>
+</subcomponent></div>
+</template>
+
+<script id="data" type="application/json">
+    {"condition":true , "link":"<a href=\"URL\">link</a>"}
+</script>
+<div id="result">
+	<!-- generated by `npm run-script populate-fixtures` -->
+	<div><p>Surrounding HTML</p><div><p>Subcomponent!</p></div></div>
+</div>

tests/integration/populate_fixtures_with_expected_results.js

@@ -4,6 +4,7 @@ const { renderToString } = require( 'vue/server-renderer' );
 const fs = require( 'fs' );
 
 const fixtureDir = __dirname + '/fixture';
+const componentDir = fixtureDir + '/components';
 const generatedComment = '<!-- generated by `npm run-script populate-fixtures` -->';
 
 const defaultMethods = {
@@ -13,6 +14,20 @@ const defaultMethods = {
 	}
 };
 
+const components = {};
+
+readComponentDir().then( function ( files ) {
+	files.forEach( function ( fileName ) {
+		var filePath = componentDir + '/' + fileName;
+		readFile( filePath )
+			.then( extractComponentTemplate )
+			.then( function ( componentData ) {
+				console.log( 'loaded component ' + fileName + ' : ' + componentData.componentName );
+				components[componentData.componentName] = componentData.template;
+			} )
+	} );
+} );
+
 readFixtureDir().then( function ( files ) {
 	files.forEach( function ( fileName ) {
 		var filePath = fixtureDir + '/' + fileName;
@@ -27,10 +42,24 @@ readFixtureDir().then( function ( files ) {
 	} );
 } );
 
+function getTemplateHtml( templateElement ) {
+	return cheerio.load( templateElement.html() ).html( { decodeEntities: false } ).trim();
+}
+
+function extractComponentTemplate( html ) {
+	const $ = cheerio.load( html );
+	const templateRoot = $( '#template' );
+
+	const componentName = templateRoot.attr( 'component-name' );
+	console.log("Found component with name " + componentName);
+	const template = getTemplateHtml( templateRoot );
+	return { componentName: componentName, template };
+}
+
 function extractDataFromFixture( html ) {
 	const $ = cheerio.load( html );
 
-	const template = cheerio.load( $( '#template' ).html() ).html( { decodeEntities: false } ).trim();
+	const template = getTemplateHtml( $( '#template' ) );
 	const data = JSON.parse( $( '#data' ).html() );
 
 	return { template: template, data: data };
@@ -42,6 +71,9 @@ function renderTemplate( fixtureData ) {
 		data: () => fixtureData.data,
 		methods: defaultMethods
 	} );
+	for ( [ componentName, template ] of Object.entries(components) ) {
+		app.component( componentName, { template } );
+	};
 
 	return renderToString( app );
 }
@@ -80,18 +112,26 @@ function saveFile( filePath, contents ) {
 	} );
 }
 
-function readFixtureDir() {
+function readDirFiles( dirPath ) {
 	return new Promise( function ( resolve, reject ) {
-		fs.readdir( fixtureDir, function ( err, items ) {
+		fs.readdir( dirPath, { withFileTypes: true }, function ( err, items ) {
 			if ( err ) {
 				reject( err )
 			} else {
-				resolve( items );
+				resolve( items.filter((item) => item.isFile()).map((item) => item.name) );
 			}
 		} );
 	} );
 }
 
+function readComponentDir() {
+	return readDirFiles( componentDir );
+}
+
+function readFixtureDir() {
+	return readDirFiles( fixtureDir );
+}
+
 function saveResultToFile(filePath, renderResult) {
 	readFile( filePath ).then( function ( html ) {
 		const $ = cheerio.load( html );