AssetsManager.php

<?php


/*

    USAGES

    require __DIR__ . '/AssetsManager.php';
    $assets = new AssetsManager( 'assets/', 'cache/');

    <link rel="stylesheet" href="<?php echo $assets->getAssetUrl('css/style.min.css'); ?>">
    <script src="<?php echo $assets->getAssetUrl('js/vendors.min.js', false); ?>" defer></script>
    <script src="<?php echo $assets->getAssetUrl('js/app.min.js'); ?>" defer></script>

    use at your own risk
    
*/

class AssetsManager {

    private $assetPath;
    private $cachePath;

    /**
     * AssetsManager constructor.
     *
     * @param string $assetPath The path to the asset files.
     * @param string $cachePath The path to the cache folder.
     */
    public function __construct( $assetPath, $cachePath ) {
        $this->assetPath = $assetPath;
        $this->cachePath = $cachePath;
    }

    /**
     * Minify CSS content.
     *
     * @param string $content The CSS content to be minified.
     * @return string The minified CSS content.
     */
    private function minifyCSS( $content ) {
        // Remove CSS comments (/* ... */)
        $content = preg_replace('!/\*[^*]*\*+([^/][^*]*\*+)*/!', '', $content);

        // Remove leading and trailing whitespace
        $content = trim($content);

        // Remove whitespace around selectors, properties, and values
        $content = preg_replace('/\s*([{}|:;,])\s*/', '$1', $content);

        // Remove semicolons before closing braces
        $content = preg_replace('/;\s*}/', '}', $content);

        // Remove empty rules
        $content = preg_replace('/[^{}]+{}/', '', $content);

        // Remove trailing semicolons from rules
        $content = preg_replace('/;\s*}/', '}', $content);

        // Remove leading zeros from decimal values
        $content = preg_replace('/(\s|:|,)0+\.(\d+)/', '$1.$2', $content);

        // Remove units from zero values
        $content = preg_replace('/(\s|:)0+([a-zA-Z]+)/', '$1$2', $content);

        return $content;
    }

    /**
     * Minify JS content.
     *
     * @param string $content The JS content to be minified.
     * @return string The minified JS content.
     */
    private function minifyJS( $content ) {
        // Remove JS comments (// ... and /* ... */)
        $content = preg_replace('!/\*[^*]*\*+([^/][^*]*\*+)*/!', '', $content);
        $content = preg_replace('/\/\/(.+)$/', '', $content);

        // Remove leading and trailing whitespace
        $content = trim($content);

        // Remove line breaks and multiple whitespace
        $content = preg_replace('/\s+/', ' ', $content);

        // Remove unnecessary whitespace around operators and brackets
        $content = preg_replace('/\s*([=!<>+\-*\/%&|^~?:]=|\+\+|--|\+=|-=|\*=|\/=|%=|&&|\|\||<<|>>|>>>)\s*/', '$1', $content);
        $content = preg_replace('/\s*([{}()[\],;])\s*/', '$1', $content);

        return $content;
    }

    /**
     * Get the URL for the asset file, either from the cache or generate a new minified version.
     *
     * @param string $filePath The path to the asset file.
     * @return string The URL of the asset file.
     * @throws Exception If the file extension is invalid.
     */
    public function getAssetUrl( $filePath, $minifyAndCache = true ) {
        if ( $minifyAndCache === false ) {
            return $this->assetPath . $filePath;
        }

        $extension = pathinfo( $filePath, PATHINFO_EXTENSION );

        // Check if the file extension is valid (CSS or JS)
        if ( $extension !== 'css' && $extension !== 'js' ) {
            // Invalid file extension, throw an exception
            throw new Exception( 'Invalid file extension. Only CSS and JS files are supported.' );
        }

        $cachedFile = $this->getCachedFilePath( $filePath );

        // Check if the cached file exists and if the original file has been modified
        if ( file_exists( $cachedFile ) && !$this->isFileModified( $filePath, $cachedFile ) ) {
            // Retrieve the URL from the cache folder
            return $this->getCacheUrl( $cachedFile );
        }

        // Generate the minified version
        $minifiedFile = $this->generateMinifiedFile( $filePath, $extension );

        // Move the minified file to the cache folder
        $this->moveToCache( $minifiedFile, $cachedFile );

        // Retrieve the URL from the cache folder

        return $this->getCacheUrl( $cachedFile );
    }

    /**
     * Generate a minified version of the asset file.
     *
     * @param string $filePath The path to the asset file.
     * @param string $extension The file extension.
     * @return string The path to the minified file.
     */
    private function generateMinifiedFile( $filePath, $extension ) {
        $fileContent = file_get_contents( $this->assetPath . $filePath );

        $minifiedContent = '';

        if ( $extension === 'css' ) {
            // Minify CSS
            $minifiedContent = $this->minifyCSS( $fileContent, 'css' );
        } elseif ( $extension === 'js' ) {
            // Minify JS
            $minifiedContent = $this->minifyJS( $fileContent, 'js' );
        }

        // Get the original file name without the extension
        $originalFileName = pathinfo( $filePath, PATHINFO_FILENAME );

        // Generate the minified file name with the original file name and version
        $minifiedFileName = $originalFileName . '.' . filemtime( $this->assetPath . $filePath ) . '.min.' . $extension;

        // Get the directory path of the cache file
        $cacheDirectory = dirname( $this->cachePath . $minifiedFileName );

        // Create the directory if it doesn't exist
        if ( !file_exists( $cacheDirectory ) ) {
            mkdir( $cacheDirectory, 0777, true );
        }

        // Write the minified content to a new file
        $minifiedFilePath = $this->cachePath . $minifiedFileName;

        file_put_contents( $minifiedFilePath, $minifiedContent );

        return $minifiedFilePath;
    }

    /**
     * Check if the original asset file has been modified.
     *
     * @param string $filePath The path to the asset file.
     * @param string $cachedFile The path to the cached file.
     * @return bool Whether the original file has been modified or not.
     */
    private function isFileModified( $filePath, $cachedFile ) {
        $originalTimestamp = filemtime( $this->assetPath . $filePath );
        $cachedTimestamp = filemtime( $cachedFile );

        return $originalTimestamp > $cachedTimestamp;
    }

    /**
     * Get the path to the cached file.
     *
     * @param string $filePath The path to the asset file.
     * @return string The path to the cached file.
     */
    private function getCachedFilePath( $filePath ) {
        // Get the directory name of the asset file
        $directoryName = pathinfo( $filePath, PATHINFO_DIRNAME );

        // Get the original file name without the extension
        $originalFileName = pathinfo( $filePath, PATHINFO_FILENAME );

        // Generate a unique file name for the cached version with the original file name, directory, and version
        $cachedFileName = $directoryName . '/' . $originalFileName . '.' . filemtime( $this->assetPath . $filePath ) . '.' . pathinfo( $filePath, PATHINFO_EXTENSION );

        return $this->cachePath . $cachedFileName;
    }

    /**
     * Move a file to the cache folder.
     *
     * @param string $sourceFile The path to the source file.
     * @param string $destinationFile The path to the destination file.
     * @return void
     */
    private function moveToCache( $sourceFile, $destinationFile ) {
        // Create the parent directory if it doesn't exist
        $parentDirectory = pathinfo( $destinationFile, PATHINFO_DIRNAME );
        if ( !file_exists( $parentDirectory ) ) {
            mkdir( $parentDirectory, 0777, true );
        }

        // Move the file to the cache folder
        rename( $sourceFile, $destinationFile );
    }

    /**
     * Get the URL of the cached file.
     *
     * @param string $cachedFile The path to the cached file.
     * @return string The URL of the cached file.
     */
    private function getCacheUrl( $cachedFile ) {
        // Get the relative path to the cached file
        $relativePath = str_replace( $this->cachePath, '', $cachedFile );

        // Combine the cache folder path with the relative path
        $cacheUrl = rtrim( $this->cachePath, '/' ) . '/' . ltrim( $relativePath, '/' );

        return $cacheUrl;
    }

    /**
     * Delete all cache files.
     *
     * @return void
     */
    public function deleteCacheFiles() {
        foreach (glob($dir) as $file) {
            if (is_dir($file)) { 
                rmrf("$file/*");
                rmdir($file);
            } else {
                unlink($file);
            }
        }
    }
    
}