<?php
/**
 * JavaScript Optimizer class.
 *
 * @package SpeedNest
 */

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

/**
 * Class WPSCO_JS_Optimizer
 *
 * Handles JS minification, defer, async, delay, and safe optimizations.
 * Never breaks jQuery, WooCommerce, Elementor, or payment gateways.
 */
class WPSCO_JS_Optimizer {

    /**
     * Scripts to always exclude from optimization.
     *
     * @var array
     */
    private $protected_scripts = array();

    /**
     * Constructor.
     */
    public function __construct() {
        if ( wpsco_get_setting( 'emergency_disable', false ) ) {
            return;
        }

        $this->protected_scripts = $this->get_protected_scripts();

        if ( wpsco_get_setting( 'js_minify', false ) ) {
            add_action( 'wp_enqueue_scripts', array( $this, 'process_scripts' ), 999999 );
        }

        if ( wpsco_get_setting( 'js_defer', false ) ) {
            add_filter( 'script_loader_tag', array( $this, 'add_defer' ), 10, 3 );
        }

        if ( wpsco_get_setting( 'js_delay', false ) ) {
            add_action( 'wp_enqueue_scripts', array( $this, 'enqueue_delay_script' ) );
            add_filter( 'script_loader_tag', array( $this, 'maybe_delay_script' ), 20, 3 );
        }
    }

    /**
     * Get list of protected script handles that must never be optimized.
     *
     * @return array
     */
    private function get_protected_scripts() {
        $protected = array(
            // jQuery.
            'jquery',
            'jquery-core',
            'jquery-migrate',
            // WordPress Core utilities.
            'underscore',
            'wp-util',
            'wp-hooks',
            'wp-i18n',
            'wp-api-fetch',
            'wp-polyfill',
            'regenerator-runtime',
            // Sliders & carousels (crucial for hero banners).
            'slick',
            'slick-theme',
            'swiper',
            'owl-carousel',
            'flexslider',
            'imagesloaded',
            'masonry',
            // WooCommerce critical.
            'wc-checkout',
            'wc-cart',
            'wc-add-to-cart',
            'wc-add-to-cart-variation',
            'wc-single-product',
            'wc-cart-fragments',
            'woocommerce',
            'wc-gateway-stripe',
            // Payment gateways.
            'stripe',
            'stripe_v3',
            'razorpay',
            'razorpay_checkout',
            'paypal',
            'ppcp-smart-button',
            'ppcp-gateway',
            // reCAPTCHA.
            'recaptcha',
            'google-recaptcha',
            'wpcf7-recaptcha',
            // Elementor.
            'elementor',
            'elementor-pro',
            'elementor-frontend',
            'elementor-pro-frontend',
            'elementor-frontend-modules',
            'elementor-webpack-runtime',
            'elementor-waypoints',
            // WordPress admin.
            'admin-bar',
            'wp-auth-check',
            'heartbeat',
        );

        // Merge with user auto-exclusions.
        $auto_exclusions = wpsco_get_setting( 'js_auto_exclusions', array() );
        $user_exclusions = wpsco_get_setting( 'js_exclusions', array() );

        return array_unique( array_merge( $protected, $auto_exclusions, $user_exclusions ) );
    }

    /**
     * Check if a script handle is protected.
     *
     * @param string $handle Script handle.
     * @return bool
     */
    private function is_protected( $handle ) {
        // Direct match.
        if ( in_array( $handle, $this->protected_scripts, true ) ) {
            return true;
        }

        // Partial match for common patterns.
        $partial_patterns = array(
            'wc-', 'woocommerce', 'stripe', 'razorpay', 'paypal',
            'recaptcha', 'captcha', 'elementor', 'admin',
            'slick', 'swiper', 'slider', 'carousel', 'underscore', 'wp-util', 'wp-hooks',
        );

        foreach ( $partial_patterns as $pattern ) {
            if ( stripos( $handle, $pattern ) !== false ) {
                return true;
            }
        }

        return false;
    }

    /**
     * Process enqueued scripts for minification.
     */
    /**
     * Process enqueued scripts for in-memory inline minification.
     *
     * Safely minifies inline script blocks and localization payloads without
     * writing any dynamic executable JavaScript files to disk (strictly adhering
     * to WordPress Plugin Security Guidelines).
     */
    public function process_scripts() {
        if ( is_admin() ) {
            return;
        }

        global $wp_scripts;
        if ( ! $wp_scripts instanceof WP_Scripts ) {
            return;
        }

        foreach ( $wp_scripts->queue as $handle ) {
            if ( ! isset( $wp_scripts->registered[ $handle ] ) ) {
                continue;
            }

            if ( $this->is_protected( $handle ) ) {
                continue;
            }

            $script = $wp_scripts->registered[ $handle ];

            // Safely minify registered inline script data in memory without generating dynamic JS files on disk.
            if ( ! empty( $script->extra['data'] ) && is_string( $script->extra['data'] ) ) {
                $minified = $this->minify_js( $script->extra['data'] );
                if ( false !== $minified && ! empty( $minified ) ) {
                    $wp_scripts->registered[ $handle ]->extra['data'] = $minified;
                }
            }

            if ( ! empty( $script->extra['after'] ) && is_array( $script->extra['after'] ) ) {
                foreach ( $script->extra['after'] as $idx => $inline ) {
                    if ( is_string( $inline ) ) {
                        $minified = $this->minify_js( $inline );
                        if ( false !== $minified && ! empty( $minified ) ) {
                            $wp_scripts->registered[ $handle ]->extra['after'][ $idx ] = $minified;
                        }
                    }
                }
            }

            if ( ! empty( $script->extra['before'] ) && is_array( $script->extra['before'] ) ) {
                foreach ( $script->extra['before'] as $idx => $inline ) {
                    if ( is_string( $inline ) ) {
                        $minified = $this->minify_js( $inline );
                        if ( false !== $minified && ! empty( $minified ) ) {
                            $wp_scripts->registered[ $handle ]->extra['before'][ $idx ] = $minified;
                        }
                    }
                }
            }
        }
    }

    /**
     * Minify JavaScript content.
     *
     * Safe minification: removes comments and excess whitespace.
     * Does NOT alter logic, variable names, or structure.
     *
     * @param string $js JavaScript content.
     * @return string|false Minified JS or false on failure.
     */
    public function minify_js( $js ) {
        if ( empty( $js ) ) {
            return '';
        }

        try {
            // Preserve strings and regex literals.
            $preserved = array();
            $index     = 0;

            // Preserve template literals.
            $js = preg_replace_callback(
                '/`(?:[^`\\\\]|\\\\.)*`/s',
                function ( $matches ) use ( &$preserved, &$index ) {
                    $placeholder = '"___WPSCO_TMPL_' . $index . '___"';
                    $preserved[ $placeholder ] = $matches[0];
                    $index++;
                    return $placeholder;
                },
                $js
            );

            // Preserve double-quoted strings.
            $js = preg_replace_callback(
                '/"(?:[^"\\\\]|\\\\.)*"/s',
                function ( $matches ) use ( &$preserved, &$index ) {
                    $placeholder = '"___WPSCO_DQ_' . $index . '___"';
                    $preserved[ $placeholder ] = $matches[0];
                    $index++;
                    return $placeholder;
                },
                $js
            );

            // Preserve single-quoted strings.
            $js = preg_replace_callback(
                "/\x27(?:[^\x27\\\\]|\\\\.)*\x27/s",
                function ( $matches ) use ( &$preserved, &$index ) {
                    $placeholder = "'___WPSCO_SQ_" . $index . "___'";
                    $preserved[ $placeholder ] = $matches[0];
                    $index++;
                    return $placeholder;
                },
                $js
            );

            // Safe comment stripping: remove block comments (preserving conditional /*! comments).
            $js = preg_replace( '/\/\*(?!\!)[^*]*\*+(?:[^/*][^*]*\*+)*\//', '', $js );

            // Strip trailing whitespace from ends of lines without removing line breaks.
            // Preserving line breaks guarantees Automatic Semicolon Insertion (ASI) never breaks.
            $js = preg_replace( '/[ \t]+$/m', '', $js );

            // Collapse excessive blank lines.
            $js = preg_replace( '/\n{3,}/', "\n\n", $js );

            // Restore preserved content.
            foreach ( $preserved as $placeholder => $original ) {
                $js = str_replace( $placeholder, $original, $js );
            }

            return trim( $js );
        } catch ( \Exception $e ) {
            wpsco_log( 'JS minification error: ' . $e->getMessage(), 'error' );
            return false;
        }
    }

    /**
     * Add defer attribute to script tags.
     *
     * @param string $tag    Script tag.
     * @param string $handle Script handle.
     * @param string $src    Script source.
     * @return string
     */
    public function add_defer( $tag, $handle, $src ) {
        if ( is_admin() ) {
            return $tag;
        }

        if ( $this->is_protected( $handle ) ) {
            return $tag;
        }

        // Never defer theme scripts to ensure UI elements (sliders, menus, customizers) run immediately.
        if ( strpos( $src, '/wp-content/themes/' ) !== false || strpos( $src, '/themes/' ) !== false ) {
            return $tag;
        }

        // Don't double-add.
        if ( strpos( $tag, 'defer' ) !== false || strpos( $tag, 'async' ) !== false ) {
            return $tag;
        }

        return str_replace( ' src=', ' defer src=', $tag );
    }

    /**
     * Maybe delay a script tag.
     *
     * Only delays heavy external tracking, analytics, and marketing scripts
     * (GA4, GTM, FB Pixel, Clarity, TikTok, Hotjar, Chat widgets).
     * Never delays WordPress core, theme, Elementor, WooCommerce, or slider scripts.
     *
     * @param string $tag    Script tag.
     * @param string $handle Script handle.
     * @param string $src    Script source.
     * @return string
     */
    public function maybe_delay_script( $tag, $handle, $src ) {
        if ( is_admin() ) {
            return $tag;
        }

        if ( $this->is_protected( $handle ) ) {
            return $tag;
        }

        // Never delay internal theme scripts or WordPress core scripts.
        if ( strpos( $src, '/wp-content/themes/' ) !== false || strpos( $src, '/wp-includes/' ) !== false ) {
            return $tag;
        }

        // Check if handle or src matches user explicit delay list.
        $user_delays  = wpsco_get_setting( 'js_delay_list', array() );
        $should_delay = false;

        if ( ! empty( $user_delays ) && is_array( $user_delays ) ) {
            foreach ( $user_delays as $delay_item ) {
                if ( ! empty( $delay_item ) && ( stripos( $handle, $delay_item ) !== false || stripos( $src, $delay_item ) !== false ) ) {
                    $should_delay = true;
                    break;
                }
            }
        }

        // Default heavy marketing/analytics trackers to delay (matches enqueued scripts; does not connect externally).
        // Fully disclosed in readme.txt under External Services.
        if ( ! $should_delay ) {
            $trackers = array(
                'googletagmanager.com',
                'google-analytics.com',
                'gtm.js',
                'analytics.js',
                'connect.facebook.net',
                'fbevents.js',
                'clarity.ms',
                'static.hotjar.com',
                'analytics.tiktok.com',
                'pintrk',
                'tawk.to',
                'crisp.chat',
            );

            foreach ( $trackers as $tracker ) {
                if ( stripos( $src, $tracker ) !== false || stripos( $handle, $tracker ) !== false ) {
                    $should_delay = true;
                    break;
                }
            }
        }

        if ( ! $should_delay ) {
            return $tag; // Keep internal and library scripts loading normally.
        }

        // Change type to prevent execution until interaction or timeout.
        $tag = str_replace( "type='text/javascript'", "type='wpsco/delayed'", $tag );
        $tag = str_replace( 'type="text/javascript"', 'type="wpsco/delayed"', $tag );

        if ( strpos( $tag, 'type=' ) === false ) {
            $tag = str_replace( '<script ', '<script type="wpsco/delayed" ', $tag );
        }

        return $tag;
    }

    /**
     * Enqueue the delay loader script using WordPress core script registration.
     */
    public function enqueue_delay_script() {
        if ( is_admin() ) {
            return;
        }

        $timeout = (int) wpsco_get_setting( 'js_delay_timeout', 3 );
        $timeout = max( 1, min( 10, $timeout ) ) * 1000;
        $trigger = wpsco_get_setting( 'js_delay_trigger', 'interaction' );

        $js = '(function(){var loaded=false;function loadDelayed(){if(loaded)return;loaded=true;var scripts=document.querySelectorAll(\'script[type="wpsco/delayed"]\');var i=0;function loadNext(){if(i>=scripts.length){try{window.dispatchEvent(new CustomEvent(\'wpsco_delayed_scripts_loaded\'));}catch(e){}return;}var old=scripts[i];i++;var s=document.createElement(\'script\');if(old.id)s.id=old.id;s.type=\'text/javascript\';if(old.src){s.src=old.src;s.onload=s.onerror=function(){loadNext();};old.parentNode.replaceChild(s,old);}else{s.textContent=old.textContent;old.parentNode.replaceChild(s,old);setTimeout(loadNext,1);}}loadNext();}';
        if ( 'interaction' === $trigger || 'all' === $trigger ) {
            $js .= 'var events=[\'scroll\',\'click\',\'touchstart\',\'mousemove\',\'keydown\'];events.forEach(function(e){window.addEventListener(e,loadDelayed,{once:true,passive:true});});';
        }
        $js .= 'setTimeout(loadDelayed,' . intval( $timeout ) . ');})();';

        wp_register_script( 'speednest-delay-loader', false, array(), WPSCO_VERSION, true );
        wp_enqueue_script( 'speednest-delay-loader' );
        wp_add_inline_script( 'speednest-delay-loader', $js );
    }

    /**
     * Backward-compatible output delay script method.
     */
    public function output_delay_script() {
        $this->enqueue_delay_script();
    }

    /**
     * Convert URL to file path.
     *
     * @param string $url URL.
     * @return string|false
     */
    private function url_to_path( $url ) {
        return wpsco_url_to_path( $url );
    }
}