<?php
/**
 * Asset Optimizer
 *
 * Handles asset minification and optimization.
 *
 * @package Accessibility_Audio_TTS_Player
 * @subpackage Admin\Assets
 * @since 1.0.0
 */

namespace Accessibility_Audio_TTS\Admin;

if ( ! defined( 'ABSPATH' ) ) {
	exit;
}

/**
 * Asset Optimizer class.
 *
 * @since 1.0.0
 */
class Asset_Optimizer {

	/**
	 * Minified assets cache directory
	 *
	 * @since 1.0.0
	 * @var string
	 */
	private string $cache_dir;

	/**
	 * Optimization statistics
	 *
	 * @since 1.0.0
	 * @var array
	 */
	private array $stats = array(
		'minified_files'  => 0,
		'bytes_saved'     => 0,
		'processing_time' => 0,
	);

	/**
	 * Constructor
	 *
	 * @since 1.0.0
	 */
	public function __construct() {
		$upload_dir      = wp_upload_dir();
		$this->cache_dir = $upload_dir['basedir'] . '/accessibility-audio-tts/cache/assets/';
		$this->ensure_cache_directory();
	}

	/**
	 * Get minified asset URL.
	 *
	 * @since 1.0.0
	 * @param string $src  Original asset URL.
	 * @param string $type Asset type (script/style).
	 * @return string|false Minified URL or false if not available.
	 */
	public function get_minified_url( string $src, string $type ) {
		$minified_filename = $this->get_minified_filename( $src, $type );
		$minified_path     = $this->cache_dir . $minified_filename;

		if ( file_exists( $minified_path ) ) {
			return $this->get_cache_url() . $minified_filename;
		}

		return false;
	}

	/**
	 * Create minified version of asset.
	 *
	 * @since 1.0.0
	 * @param string $src  Asset source URL.
	 * @param string $type Asset type (script/style).
	 * @return string Minified asset URL.
	 */
	public function create_minified_version( string $src, string $type ): string {
		$start_time = microtime( true );

		// Get original file content.
		$original_content = $this->get_asset_content( $src );
		if ( ! $original_content ) {
			return $src; // Return original if can't read.
		}

		// Minify content.
		$minified_content = $this->minify_content( $original_content, $type );

		// Save minified version.
		$minified_filename = $this->get_minified_filename( $src, $type );
		$minified_path     = $this->cache_dir . $minified_filename;

		// phpcs:ignore WordPress.WP.AlternativeFunctions.file_system_operations_file_put_contents -- local cache write intended.
		if ( file_put_contents( $minified_path, $minified_content ) ) {
			// Update statistics.
			++$this->stats['minified_files'];
			$this->stats['bytes_saved']     += strlen( $original_content ) - strlen( $minified_content );
			$this->stats['processing_time'] += microtime( true ) - $start_time;

			return $this->get_cache_url() . $minified_filename;
		}

		return $src; // Return original if can't save.
	}

	/**
	 * Minify asset content.
	 *
	 * @since 1.0.0
	 * @param string $content Asset content.
	 * @param string $type    Asset type (script/style).
	 * @return string Minified content.
	 */
	public function minify_asset( string $content, string $type ): string {
		return $this->minify_content( $content, $type );
	}

	/**
	 * Minify content based on type.
	 *
	 * @since 1.0.0
	 * @param string $content Content to minify.
	 * @param string $type    Content type (script/style).
	 * @return string Minified content.
	 */
	private function minify_content( string $content, string $type ): string {
		switch ( $type ) {
			case 'script':
				return $this->minify_javascript( $content );
			case 'style':
				return $this->minify_css( $content );
			default:
				return $content;
		}
	}

	/**
	 * Minify JavaScript content.
	 *
	 * @since 1.0.0
	 * @param string $js JavaScript content.
	 * @return string Minified JavaScript.
	 */
	private function minify_javascript( string $js ): string {
		// Remove comments (but preserve license comments).
		$js = preg_replace( '/\/\*(?![!*]).*?\*\//s', '', $js );
		$js = preg_replace( '/\/\/(?![!\/]).*$/m', '', $js );

		// Remove unnecessary whitespace.
		$js = preg_replace( '/\s+/', ' ', $js );

		// Remove whitespace around operators and punctuation.
		$js = preg_replace( '/\s*([{}();,:])\s*/', '$1', $js );

		// Remove trailing semicolons before }.
		$js = preg_replace( '/;+}/', '}', $js );

		return trim( $js );
	}

	/**
	 * Minify CSS content.
	 *
	 * @since 1.0.0
	 * @param string $css CSS content.
	 * @return string Minified CSS.
	 */
	private function minify_css( string $css ): string {
		// Remove comments (but preserve license comments).
		$css = preg_replace( '/\/\*(?![!*]).*?\*\//s', '', $css );

		// Remove unnecessary whitespace.
		$css = preg_replace( '/\s+/', ' ', $css );

		// Remove whitespace around CSS syntax.
		$css = preg_replace( '/\s*([{}:;,>+~])\s*/', '$1', $css );

		// Remove trailing semicolon before }.
		$css = preg_replace( '/;+}/', '}', $css );

		// Remove unnecessary quotes from URLs.
		$css = preg_replace( '/url\((["\'])([^"\']*)\1\)/', 'url($2)', $css );

		// Convert hex colors to shorter form when possible.
		$css = preg_replace( '/#([0-9a-f])\1([0-9a-f])\2([0-9a-f])\3/i', '#$1$2$3', $css );

		return trim( $css );
	}

	/**
	 * Get asset content from URL or file path.
	 *
	 * @since 1.0.0
	 * @param string $src Asset source.
	 * @return string|false Asset content or false on failure.
	 */
	private function get_asset_content( string $src ) {
		// Convert URL to file path if it's a local asset.
		if ( strpos( $src, ACCESSIBILITY_AUDIO_TTS_PLUGIN_URL ) === 0 ) {
			$file_path = str_replace( ACCESSIBILITY_AUDIO_TTS_PLUGIN_URL, ACCESSIBILITY_AUDIO_TTS_PLUGIN_DIR, $src );

			if ( file_exists( $file_path ) ) {
				// phpcs:ignore WordPress.WP.AlternativeFunctions.file_get_contents_file_get_contents -- local plugin file read.
				return file_get_contents( $file_path );
			}
		}

		// Try to fetch remote content (with timeout).
		$response = wp_remote_get(
			$src,
			array(
				'timeout'    => 10,
				'user-agent' => 'Accessibility-Audio-TTS Asset Optimizer',
			)
		);
		if ( is_wp_error( $response ) ) {
			return false;
		}
		$code = wp_remote_retrieve_response_code( $response );
		if ( 200 !== $code ) {
			return false;
		}
		return wp_remote_retrieve_body( $response );
	}

	/**
	 * Generate minified filename.
	 *
	 * @since 1.0.0
	 * @param string $src  Original asset URL.
	 * @param string $type Asset type.
	 * @return string Minified filename.
	 */
	private function get_minified_filename( string $src, string $type ): string {
		$hash      = md5( $src );
		$extension = ( 'script' === $type ) ? 'js' : 'css';

		return "accessibility-audio-tts-audio-{$hash}.min.{$extension}";
	}

	/**
	 * Get cache directory URL.
	 *
	 * @since 1.0.0
	 * @return string Cache URL.
	 */
	private function get_cache_url(): string {
		$upload_dir = wp_upload_dir();
		return $upload_dir['baseurl'] . '/accessibility-audio-tts/cache/assets/';
	}

	/**
	 * Ensure cache directory exists.
	 *
	 * @since 1.0.0
	 * @return void
	 */
	private function ensure_cache_directory(): void {
		if ( ! file_exists( $this->cache_dir ) ) {
			wp_mkdir_p( $this->cache_dir );

			// Add .htaccess for security.
			$htaccess_content  = "# AAT Asset Cache\n";
			$htaccess_content .= "<Files \"*.php\">\n";
			$htaccess_content .= "    Require all denied\n";
			$htaccess_content .= "</Files>\n";

			// phpcs:ignore WordPress.WP.AlternativeFunctions.file_system_operations_file_put_contents -- local cache write intended.
			file_put_contents( $this->cache_dir . '.htaccess', $htaccess_content );
		}
	}

	/**
	 * Clear minified assets cache.
	 *
	 * @since 1.0.0
	 * @return bool True on success.
	 */
	public function clear_minified_cache(): bool {
		if ( ! is_dir( $this->cache_dir ) ) {
			return true;
		}

		$files   = glob( $this->cache_dir . 'accessibility-audio-tts-audio-*.min.*' );
		$success = true;

		foreach ( $files as $file ) {
			if ( ! wp_delete_file( $file ) ) {
				$success = false;
			}
		}

		return $success;
	}

	/**
	 * Get optimization statistics
	 *
	 * @since 1.0.0
	 * @return array Optimization stats
	 */
	public function get_optimization_stats(): array {
		return array_merge(
			$this->stats,
			array(
				'cache_size'   => $this->get_cache_size(),
				'cached_files' => $this->get_cached_files_count(),
			)
		);
	}

	/**
	 * Get cache directory size
	 *
	 * @since 1.0.0
	 * @return int Size in bytes
	 */
	private function get_cache_size(): int {
		if ( ! is_dir( $this->cache_dir ) ) {
			return 0;
		}

		$size  = 0;
		$files = glob( $this->cache_dir . '*' );

		foreach ( $files as $file ) {
			if ( is_file( $file ) ) {
				$size += filesize( $file );
			}
		}

		return $size;
	}

	/**
	 * Get number of cached files
	 *
	 * @since 1.0.0
	 * @return int Number of cached files
	 */
	private function get_cached_files_count(): int {
		if ( ! is_dir( $this->cache_dir ) ) {
			return 0;
		}

		$files = glob( $this->cache_dir . 'accessibility-audio-tts-audio-*.min.*' );

		return count( $files );
	}

	/**
	 * Check if asset should be optimized
	 *
	 * @since 1.0.0
	 * @param string $src Asset source.
	 * @return bool True if should optimize.
	 */
	public function should_optimize_asset( string $src ): bool {
		// Don't optimize already minified files.
		if ( false !== strpos( $src, '.min.' ) ) {
			return false;
		}

		// Don't optimize external assets (unless specifically allowed).
		if ( 0 !== strpos( $src, home_url() ) && 0 !== strpos( $src, ACCESSIBILITY_AUDIO_TTS_PLUGIN_URL ) ) {
			return false;
		}

		// Check file size - don't optimize very small files.
		$content = $this->get_asset_content( $src );
		if ( $content && strlen( $content ) < 1024 ) { // Less than 1KB.
			return false;
		}

		return true;
	}
}