<?php

namespace MediaWiki\Skins\Vector\Tests\Structure;

use DerivativeContext;
use ExtensionRegistry;
use HashBagOStuff;
use MediaWiki\Output\OutputPage;
use MediaWiki\Request\FauxRequest;
use MediaWiki\ResourceLoader\Context;
use MediaWiki\ResourceLoader\Module;
use MediaWikiIntegrationTestCase;
use RequestContext;
use Wikimedia\DependencyStore\KeyValueDependencyStore;

/**
 * @group Database
 */
class PerformanceBudgetTest extends MediaWikiIntegrationTestCase {

	/**
	 * Get the maximum size of modules in bytes as defined in bundlesize.config.json
	 *
	 * @param string $skinName
	 *
	 * @return array
	 */
	protected function getMaxSize( $skinName ) {
		$configFile = dirname( __DIR__, 3 ) . '/bundlesize.config.json';
		$bundleSizeConfig = json_decode( file_get_contents( $configFile ), true );
		return $bundleSizeConfig[ 'total' ][ $skinName ] ?? [];
	}

	/**
	 * Calculates the size of a module
	 *
	 * @param string $moduleName
	 * @param string $skinName
	 *
	 * @return float|int
	 * @throws \Wikimedia\RequestTimeout\TimeoutException
	 * @throws MediaWiki\Config\ConfigException
	 */
	protected function getContentTransferSize( $moduleName, $skinName ) {
		// Calculate Size
		$resourceLoader = $this->getServiceContainer()->getResourceLoader();
		$resourceLoader->setDependencyStore( new KeyValueDependencyStore( new HashBagOStuff() ) );
		$request = new FauxRequest(
			[
				'lang' => 'en',
				'modules' => $moduleName,
				'skin' => $skinName,
			]
		);

		$context = new Context( $resourceLoader, $request );
		$module = $resourceLoader->getModule( $moduleName );
		$contentContext = new \MediaWiki\ResourceLoader\DerivativeContext( $context );
		$contentContext->setOnly(
			$module->getType() === Module::LOAD_STYLES
				? Module::TYPE_STYLES
				: Module::TYPE_COMBINED
		);
		// Create a module response for the given module and calculate the size
		$content = $resourceLoader->makeModuleResponse( $contentContext, [ $moduleName => $module ] );
		$contentTransferSize = strlen( gzencode( $content, 9 ) );
		// Adjustments for core modules [T343407]
		$contentTransferSize -= 17;
		return $contentTransferSize;
	}

	/**
	 * Prepares a skin for testing, assigning context and output page
	 *
	 * @param string $skinName
	 *
	 * @return \Skin
	 * @throws \SkinException
	 */
	protected function prepareSkin( string $skinName ): \Skin {
		$skinFactory = $this->getServiceContainer()->getSkinFactory();
		$skin = $skinFactory->makeSkin( $skinName );
		$title = $this->getExistingTestPage()->getTitle();
		$context = new DerivativeContext( RequestContext::getMain() );
		$context->setTitle( $title );
		$context->setSkin( $skin );
		$outputPage = new OutputPage( $context );
		$context->setOutput( $outputPage );
		$skin->setContext( $context );
		$outputPage->setTitle( $title );
		$outputPage->output( true );
		return $skin;
	}

	/**
	 * Converts a string to bytes
	 *
	 * @param string|int|float $size
	 *
	 * @return float|int
	 */
	private function getSizeInBytes( $size ) {
		if ( is_string( $size ) ) {
			if ( strpos( $size, 'KB' ) !== false || strpos( $size, 'kB' ) !== false ) {
				$size = (float)str_replace( [ 'KB', 'kB', ' KB', ' kB' ], '', $size );
				$size = $size * 1024;
			} elseif ( strpos( $size, 'B' ) !== false ) {
				$size = (float)str_replace( [ ' B', 'B' ], '', $size );
			}
		}
		return $size;
	}

	/**
	 * Get the list of skins and their maximum size
	 *
	 * @return array
	 */
	public function provideSkinsForModulesSize() {
		$allowedSkins = [ 'vector-2022', 'vector' ];
		$skins = [];
		foreach ( $allowedSkins as $skinName ) {
			$maxSizes = $this->getMaxSize( $skinName );
			if ( empty( $maxSizes ) ) {
				continue;
			}
			$skins[ $skinName ] = [ $skinName, $maxSizes ];
		}
		return $skins;
	}

	/**
	 * @param string $key either styles or scripts.
	 * @return bool
	 */
	private function getAdditionalBudgetForInstalledExtensions( $key = 'styles' ) {
		/**
		 * @todo: In future this should be defined in the extensions themselves via bundlesize.config.json
		 */
		$additional = [
			'scripts' => [
				// ext.echo.centralauth
				'Echo' => 2000,
				// ext.checkUser.clientHints
				'CheckUser' => 1000,
				// ext.popups
				'Popups' => 2000,
				// ext.flaggedRevs.advanced
				'FlaggedRevs' => 2000,
				// ext.growthExperiments.SuggestedEditSession
				// Note this seems pretty high compared to other numbers,
				// so we may want to work with Growth team to optimize this down.
				'GrowthExperiments' => 5000,
				// ext.wikimediaEvents
				// Note this seems pretty high compared to other numbers,
				// so we may want to optimize this in future when we attempt to add new schemas.
				'WikimediaEvents' => 11000,
				// wikibase.vector.searchClient and ext.wikimediaevents.wikibase and wikibase.client.data-bridge.init
				'Wikibase' => 2000,
				// ext.visualEditor.desktopArticleTarget.init and ext.visualEditor.targetLoader
				// Note this seems pretty high compared to other numbers,
				// so we may want to work with VisualEditor to optimize this down.
				'VisualEditor' => 14000,
				// ext.eventLogging
				'EventLogging' => 1000,
				// ext.uls.interface
				'UniversalLanguageSelector' => 4000,
				// ext.wikilambda.languageselector
				'WikiLambda' => 2000,
			],
			'styles' => [
				'FlaggedRevs' => 1000,
			],
		];
		$total = 0;
		// The flagged revisions extension is only loaded in certain environments.
		// Since the environment is based on FlaggedRevs not being installed, extra budget is allocated.
		// More context: https://phabricator.wikimedia.org/T360102#9632324
		foreach ( $additional[ $key ] ?? [] as $extension => $budget ) {
			if ( ExtensionRegistry::getInstance()->isLoaded( $extension ) ) {
				$total += $budget;
			}
		}
		return $total;
	}

	/**
	 * Tests the size of modules in allowed skins
	 *
	 * @param string $skinName
	 * @param array $maxSizes
	 *
	 * @dataProvider provideSkinsForModulesSize
	 * @coversNothing
	 *
	 * @return void
	 * @throws \Wikimedia\RequestTimeout\TimeoutException
	 * @throws MediaWiki\Config\ConfigException
	 */
	public function testTotalModulesSize( $skinName, $maxSizes ) {
		$skin = $this->prepareSkin( $skinName );
		$moduleStyles = $skin->getOutput()->getModuleStyles();
		$size = 0;
		foreach ( $moduleStyles as $moduleName ) {
			$size += $this->getContentTransferSize( $moduleName, $skinName );
		}
		$stylesMaxSize = $this->getSizeInBytes( $maxSizes[ 'styles' ] ) +
			$this->getAdditionalBudgetForInstalledExtensions( 'styles' );

		$message = $this->createMessage( $skinName, $size, $stylesMaxSize, $moduleStyles );
		$this->assertLessThanOrEqual( $stylesMaxSize, $size, $message );
		$modulesScripts = $skin->getOutput()->getModules();
		$size = 0;
		foreach ( $modulesScripts as $moduleName ) {
			$size += $this->getContentTransferSize( $moduleName, $skinName );
		}
		$scriptsMaxSize = $this->getSizeInBytes( $maxSizes[ 'scripts' ] ) +
			$this->getAdditionalBudgetForInstalledExtensions( 'scripts' );
		$message = $this->createMessage( $skinName, $size, $scriptsMaxSize, $modulesScripts, true );
		$this->assertLessThanOrEqual( $scriptsMaxSize, $size, $message );
	}

	/**
	 * Creates a message for the assertion
	 *
	 * @param string $skinName
	 * @param int|float $size
	 * @param int|float $maxSize
	 * @param array $modules
	 * @param bool $scripts
	 *
	 * @return string
	 */
	private function createMessage( $skinName, $size, $maxSize, $modules, $scripts = false ) {
		$debugInformation = "[PLEASE DO NOT SKIP THIS TEST. If this is blocking a deploy this might " .
			"signal a potential performance regression with the desktop site." .
			"Instead of skipping the test you can increase the value in bundlesize.config.json " .
			"and create a ticket to investigate this error. If the error is > 1kb please tag " .
			"this as a train blocker." .
			"Please tag the ticket #Web-Team-Backlog.\n\n" .
			"The following modules are enabled on page load:\n" .
			implode( "\n", $modules );
		$moduleType = $scripts ? 'scripts' : 'styles';
		return "T346813: Performance budget for $moduleType in skin" .
			" $skinName on main article namespace has been exceeded." .
			" Total size of $moduleType modules is " . $this->bytesToKbsRoundup( $size ) . " Kbs is greater" .
			" than the current budget size of " . $this->bytesToKbsRoundup( $maxSize ) . " Kbs" .
			" (see Vector/bundlesize.config.json).\n" .
			"If you are adding code on page load, please reduce $moduleType that you are loading on page load" .
			" or talk to the web team about increasing the budget.\n" .
			"If you are not adding code, and this seems to be an error, " .
			"it is possible that something running without CI has bypassed this check and we " .
			"can address this separately." .
			"Please reach out to the web team to discuss this via Phabricator or #talk-to-web." .
			"$debugInformation";
	}

	/**
	 * Converts bytes to Kbs and rounds up to the nearest 0.1
	 *
	 * @param int|float $sizeInBytes
	 *
	 * @return float
	 */
	private function bytesToKbsRoundup( $sizeInBytes ) {
		return ceil( ( $sizeInBytes * 10 ) / 1024 ) / 10;
	}
}