<?php
/*
Plugin Name: Newsletter Signup
Description: A simple plugin that provides a shortcode for a newsletter signup form with admin management and unsubscribe functionality.
Version: 2.0.3
Author: Mike Vahldieck
Plugin URI: http://it-breeze.info
Author URI: http://it-breeze.info
License: GPL2
*/

<?php
/*
Plugin Name: Newsletter Signup
Description: A simple plugin that provides a shortcode for a newsletter signup form with admin management and unsubscribe functionality.
Version: 2.0.3
Author: Mike Vahldieck
Plugin URI: http://it-breeze.info
Author URI: http://it-breeze.info
License: GPL2
*/

// Exit if accessed directly.
if ( ! defined( 'ABSPATH' ) ) {
    exit;
}

/**
 * 1. Create the database table upon activation
 */
register_activation_hook( __FILE__, 'my_newsletter_plugin_activate' );
function my_newsletter_plugin_activate() {
    global $wpdb;
    $table_name = $wpdb->prefix . 'newsletter_signups';
    $charset_collate = $wpdb->get_charset_collate();

    // SQL to create the table if not exists
    $sql = "CREATE TABLE IF NOT EXISTS $table_name (
        id mediumint(9) NOT NULL AUTO_INCREMENT,
        email VARCHAR(200) NOT NULL,
        status VARCHAR(20) DEFAULT 'active' NOT NULL,
        created_at DATETIME DEFAULT CURRENT_TIMESTAMP NOT NULL,
        unsubscribed_at DATETIME NULL,
        PRIMARY KEY (id),
        UNIQUE KEY email (email)
    ) $charset_collate;";

    require_once( ABSPATH . 'wp-admin/includes/upgrade.php' );
    dbDelta( $sql );
}

/**
 * 2. Add admin menu
 */
add_action( 'admin_menu', 'my_newsletter_admin_menu' );
function my_newsletter_admin_menu() {
    add_menu_page(
        'Newsletter Subscribers',
        'Newsletter',
        'manage_options',
        'newsletter-subscribers',
        'my_newsletter_admin_page',
        'dashicons-email-alt',
        30
    );
}

/**
 * 3. Admin page content
 */
function my_newsletter_admin_page() {
    global $wpdb;
    $table_name = $wpdb->prefix . 'newsletter_signups';
    
    // Handle bulk actions
    if ( isset( $_POST['action'] ) && $_POST['action'] === 'delete_selected' && isset( $_POST['subscriber_ids'] ) ) {
        if ( wp_verify_nonce( $_POST['_wpnonce'], 'bulk_delete_subscribers' ) ) {
            $ids = array_map( 'intval', $_POST['subscriber_ids'] );
            $placeholders = implode( ',', array_fill( 0, count( $ids ), '%d' ) );
            $wpdb->query( $wpdb->prepare( "DELETE FROM $table_name WHERE id IN ($placeholders)", $ids ) );
            echo '<div class="notice notice-success"><p>Selected subscribers deleted successfully.</p></div>';
        }
    }
    
    // Handle individual delete
    if ( isset( $_GET['action'] ) && $_GET['action'] === 'delete' && isset( $_GET['id'] ) ) {
        if ( wp_verify_nonce( $_GET['_wpnonce'], 'delete_subscriber_' . $_GET['id'] ) ) {
            $wpdb->delete( $table_name, array( 'id' => intval( $_GET['id'] ) ), array( '%d' ) );
            echo '<div class="notice notice-success"><p>Subscriber deleted successfully.</p></div>';
        }
    }
    
    // Get all subscribers
    $subscribers = $wpdb->get_results( "SELECT * FROM $table_name ORDER BY created_at DESC" );
    $total_subscribers = count( $subscribers );
    $active_subscribers = count( array_filter( $subscribers, function( $s ) { return $s->status === 'active'; } ) );
    $unsubscribed_subscribers = $total_subscribers - $active_subscribers;
    
    ?>
    <div class="wrap">
        <h1>Newsletter Subscribers</h1>
        
        <div class="newsletter-stats" style="margin: 20px 0;">
            <div style="display: flex; gap: 20px;">
                <div class="stats-box" style="background: #fff; padding: 15px; border-left: 4px solid #00a32a; box-shadow: 0 1px 3px rgba(0,0,0,0.1);">
                    <h3 style="margin: 0; color: #00a32a;">Active Subscribers</h3>
                    <p style="font-size: 24px; margin: 5px 0 0 0; font-weight: bold;"><?php echo $active_subscribers; ?></p>
                </div>
                <div class="stats-box" style="background: #fff; padding: 15px; border-left: 4px solid #dba617; box-shadow: 0 1px 3px rgba(0,0,0,0.1);">
                    <h3 style="margin: 0; color: #dba617;">Unsubscribed</h3>
                    <p style="font-size: 24px; margin: 5px 0 0 0; font-weight: bold;"><?php echo $unsubscribed_subscribers; ?></p>
                </div>
                <div class="stats-box" style="background: #fff; padding: 15px; border-left: 4px solid #0073aa; box-shadow: 0 1px 3px rgba(0,0,0,0.1);">
                    <h3 style="margin: 0; color: #0073aa;">Total</h3>
                    <p style="font-size: 24px; margin: 5px 0 0 0; font-weight: bold;"><?php echo $total_subscribers; ?></p>
                </div>
            </div>
        </div>
        
        <?php if ( empty( $subscribers ) ) : ?>
            <p>No subscribers found.</p>
        <?php else : ?>
            <form method="post">
                <?php wp_nonce_field( 'bulk_delete_subscribers' ); ?>
                <div class="tablenav top">
                    <div class="alignleft actions bulkactions">
                        <select name="action">
                            <option value="-1">Bulk Actions</option>
                            <option value="delete_selected">Delete</option>
                        </select>
                        <input type="submit" class="button action" value="Apply" onclick="return confirm('Are you sure you want to delete the selected subscribers?');">
                    </div>
                </div>
                
                <table class="wp-list-table widefat fixed striped">
                    <thead>
                        <tr>
                            <td class="manage-column column-cb check-column">
                                <input type="checkbox" id="cb-select-all-1">
                            </td>
                            <th class="manage-column">Email</th>
                            <th class="manage-column">Status</th>
                            <th class="manage-column">Subscribed Date</th>
                            <th class="manage-column">Unsubscribed Date</th>
                            <th class="manage-column">Actions</th>
                        </tr>
                    </thead>
                    <tbody>
                        <?php foreach ( $subscribers as $subscriber ) : ?>
                            <tr>
                                <th class="check-column">
                                    <input type="checkbox" name="subscriber_ids[]" value="<?php echo esc_attr( $subscriber->id ); ?>">
                                </th>
                                <td><strong><?php echo esc_html( $subscriber->email ); ?></strong></td>
                                <td>
                                    <span class="status-<?php echo esc_attr( $subscriber->status ); ?>" style="padding: 4px 8px; border-radius: 3px; font-size: 12px; font-weight: bold; color: white; background-color: <?php echo $subscriber->status === 'active' ? '#00a32a' : '#dba617'; ?>">
                                        <?php echo esc_html( ucfirst( $subscriber->status ) ); ?>
                                    </span>
                                </td>
                                <td><?php echo esc_html( date( 'Y-m-d H:i:s', strtotime( $subscriber->created_at ) ) ); ?></td>
                                <td><?php echo $subscriber->unsubscribed_at ? esc_html( date( 'Y-m-d H:i:s', strtotime( $subscriber->unsubscribed_at ) ) ) : '—'; ?></td>
                                <td>
                                    <a href="<?php echo wp_nonce_url( admin_url( 'admin.php?page=newsletter-subscribers&action=delete&id=' . $subscriber->id ), 'delete_subscriber_' . $subscriber->id ); ?>" 
                                       class="button button-small" 
                                       onclick="return confirm('Are you sure you want to delete this subscriber?');">
                                        Delete
                                    </a>
                                </td>
                            </tr>
                        <?php endforeach; ?>
                    </tbody>
                </table>
            </form>
        <?php endif; ?>
    </div>
    
    <script>
    document.getElementById('cb-select-all-1').addEventListener('change', function() {
        var checkboxes = document.querySelectorAll('input[name="subscriber_ids[]"]');
        for (var checkbox of checkboxes) {
            checkbox.checked = this.checked;
        }
    });
    </script>
    <?php
}

/**
 * 4. Register the [newsletter_signup_form] shortcode
 */
add_shortcode( 'newsletter', 'my_newsletter_form_shortcode' );
function my_newsletter_form_shortcode() {
    // If the form has been submitted, process the submission
    if ( isset( $_POST['my_newsletter_email'] ) ) {
        return handle_my_newsletter_form_submission();
    }

    // Generate a simple math captcha
    $num1 = rand( 1, 10 );
    $num2 = rand( 1, 10 );
    $captcha_answer = $num1 + $num2;

    // Otherwise, display the form
    ob_start();
    ?>
    <form method="POST" action="">
        <?php wp_nonce_field( 'my_newsletter_action', 'my_newsletter_nonce' ); ?>
        <p>
            <label for="my_newsletter_email">E-Mail Adresse:</label><br>
            <input type="email" name="my_newsletter_email" id="my_newsletter_email" required style="width: 100%; max-width: 300px; padding: 8px; margin-top: 5px;">
        </p>
        <p>
           
            What is <?php echo $num1; ?> + <?php echo $num2; ?>? 
            <input type="number" name="captcha_answer" id="captcha_answer" required style="width: 60px; padding: 8px; margin-left: 10px;" min="1" max="20">
            <input type="hidden" name="captcha_expected" value="<?php echo esc_attr( $captcha_answer ); ?>">
        </p>
        <p style="text-align: center;">
            <button type="submit" style="border-radius: 16px;">Anmelden</button>
        </p>
    </form>
    <?php
    return ob_get_clean();
}

/**
 * 5. Handle the form submission
 */
function handle_my_newsletter_form_submission() {
    if ( ! isset( $_POST['my_newsletter_nonce'] ) ||
         ! wp_verify_nonce( $_POST['my_newsletter_nonce'], 'my_newsletter_action' ) ) {
        return '<p style="color: red;">Error: Security check failed. Please try again.</p>';
    }

    // Validate captcha first
    $captcha_answer = intval( $_POST['captcha_answer'] ?? 0 );
    $captcha_expected = intval( $_POST['captcha_expected'] ?? 0 );
    
    if ( $captcha_answer !== $captcha_expected ) {
        return '<p style="color: red;">Incorrect answer to the math question. Please try again.</p>' . my_newsletter_form_shortcode();
    }

    $email = sanitize_email( $_POST['my_newsletter_email'] );

    // Basic validation
    if ( empty( $email ) || ! is_email( $email ) ) {
        return '<p style="color: red;">Please enter a valid email address.</p>' . my_newsletter_form_shortcode();
    }

    global $wpdb;
    $table_name = $wpdb->prefix . 'newsletter_signups';

    // Check if email already exists
    $existing_subscriber = $wpdb->get_row( $wpdb->prepare(
        "SELECT * FROM $table_name WHERE email = %s LIMIT 1",
        $email
    ) );

    if ( $existing_subscriber ) {
        if ( $existing_subscriber->status === 'unsubscribed' ) {
            // Reactivate unsubscribed user
            $wpdb->update(
                $table_name,
                array( 
                    'status' => 'active',
                    'unsubscribed_at' => null 
                ),
                array( 'email' => $email ),
                array( '%s', '%s' ),
                array( '%s' )
            );
            return '<p style="color: green;">Welcome back! You have been resubscribed to our newsletter.</p>';
        } else {
            return '<p style="color: orange;">This email is already signed up for our newsletter.</p>';
        }
    }

    // Insert into the database
    $result = $wpdb->insert(
        $table_name,
        array( 
            'email' => $email,
            'status' => 'active'
        ),
        array( '%s', '%s' )
    );

    if ( $result === false ) {
        return '<p style="color: red;">Sorry, there was an error signing you up. Please try again.</p>';
    }

    // Return a success message
    return '<p style="color: green;">Thank you for signing up for our newsletter!</p>';
}

/**
 * 6. Register the [newsletter_unsubscribe] shortcode
 */
add_shortcode( 'newsletter_unsubscribe', 'my_newsletter_unsubscribe_shortcode' );
function my_newsletter_unsubscribe_shortcode( $atts ) {
    $atts = shortcode_atts( array(
        'success_message' => 'You have been successfully unsubscribed from our newsletter.',
        'error_message' => 'Sorry, we could not find your email address in our system.',
        'form_title' => 'Unsubscribe from Newsletter'
    ), $atts );

    // Handle unsubscribe from URL parameter (for email links)
    if ( isset( $_GET['unsubscribe_email'] ) && isset( $_GET['unsubscribe_token'] ) ) {
        return handle_unsubscribe_from_url();
    }

    // If the form has been submitted, process the unsubscription
    if ( isset( $_POST['unsubscribe_email'] ) ) {
        return handle_my_newsletter_unsubscribe( $atts );
    }

    // Otherwise, display the unsubscribe form
    ob_start();
    ?>
    <div class="newsletter-unsubscribe-form">
        <h3><?php echo esc_html( $atts['form_title'] ); ?></h3>
        <form method="POST" action="">
            <?php wp_nonce_field( 'my_newsletter_unsubscribe_action', 'my_newsletter_unsubscribe_nonce' ); ?>
            <p>
                <label for="unsubscribe_email">Enter your email address to unsubscribe:</label><br>
                <input type="email" name="unsubscribe_email" id="unsubscribe_email" required style="width: 100%; max-width: 300px; padding: 8px; margin-top: 5px;">
            </p>
            <p>
                <button type="submit" style="background-color: #dc3545; color: white; padding: 10px 20px; border: none; border-radius: 4px; cursor: pointer;">
                    Unsubscribe
                </button>
            </p>
        </form>
    </div>
    <?php
    return ob_get_clean();
}

/**
 * 7. Handle the unsubscribe form submission
 */
function handle_my_newsletter_unsubscribe( $atts ) {
    if ( ! isset( $_POST['my_newsletter_unsubscribe_nonce'] ) ||
         ! wp_verify_nonce( $_POST['my_newsletter_unsubscribe_nonce'], 'my_newsletter_unsubscribe_action' ) ) {
        return '<p style="color: red;">Error: Security check failed. Please try again.</p>';
    }

    $email = sanitize_email( $_POST['unsubscribe_email'] );

    // Basic validation
    if ( empty( $email ) || ! is_email( $email ) ) {
        return '<p style="color: red;">Please enter a valid email address.</p>';
    }

    global $wpdb;
    $table_name = $wpdb->prefix . 'newsletter_signups';

    // Check if email exists and is active
    $subscriber = $wpdb->get_row( $wpdb->prepare(
        "SELECT * FROM $table_name WHERE email = %s LIMIT 1",
        $email
    ) );

    if ( ! $subscriber ) {
        return '<p style="color: red;">' . esc_html( $atts['error_message'] ) . '</p>';
    }

    if ( $subscriber->status === 'unsubscribed' ) {
        return '<p>You have already been unsubscribed from our newsletter.</p>';
    }

    // Update the subscriber status to unsubscribed
    $result = $wpdb->update(
        $table_name,
        array( 
            'status' => 'unsubscribed',
            'unsubscribed_at' => current_time( 'mysql' )
        ),
        array( 'email' => $email ),
        array( '%s', '%s' ),
        array( '%s' )
    );

    if ( $result === false ) {
        return '<p style="color: red;">Sorry, there was an error processing your unsubscribe request. Please try again.</p>';
    }

    return '<p style="color: green;">' . esc_html( $atts['success_message'] ) . '</p>';
}

/**
 * 8. Handle unsubscribe from URL (for email links)
 */
function handle_unsubscribe_from_url() {
    $email = sanitize_email( $_GET['unsubscribe_email'] );
    $token = sanitize_text_field( $_GET['unsubscribe_token'] );

    // Verify token (simple hash-based verification)
    $expected_token = hash( 'sha256', $email . 'unsubscribe_salt_' . wp_salt() );
    
    if ( ! hash_equals( $expected_token, $token ) ) {
        return '<p style="color: red;">Invalid unsubscribe link. Please try again.</p>';
    }

    global $wpdb;
    $table_name = $wpdb->prefix . 'newsletter_signups';

    // Check if email exists
    $subscriber = $wpdb->get_row( $wpdb->prepare(
        "SELECT * FROM $table_name WHERE email = %s LIMIT 1",
        $email
    ) );

    if ( ! $subscriber ) {
        return '<p style="color: red;">Email address not found in our system.</p>';
    }

    if ( $subscriber->status === 'unsubscribed' ) {
        return '<p>You have already been unsubscribed from our newsletter.</p>';
    }

    // Update the subscriber status to unsubscribed
    $wpdb->update(
        $table_name,
        array( 
            'status' => 'unsubscribed',
            'unsubscribed_at' => current_time( 'mysql' )
        ),
        array( 'email' => $email ),
        array( '%s', '%s' ),
        array( '%s' )
    );

    return '<p style="color: green;">You have been successfully unsubscribed from our newsletter.</p>';
}

/**
 * 9. Helper function to generate unsubscribe URLs for emails
 */
function get_newsletter_unsubscribe_url( $email, $page_id = null ) {
    if ( ! $page_id ) {
        // Try to find a page with the unsubscribe shortcode
        global $wpdb;
        $page = $wpdb->get_row( $wpdb->prepare(
            "SELECT ID FROM {$wpdb->posts} WHERE post_content LIKE %s AND post_status = 'publish' AND post_type = 'page' LIMIT 1",
            '%[newsletter_unsubscribe%'
        ) );
        
        if ( $page ) {
            $page_id = $page->ID;
        } else {
            return home_url(); // Fallback to home page
        }
    }

    $token = hash( 'sha256', $email . 'unsubscribe_salt_' . wp_salt() );
    
    return add_query_arg( array(
        'unsubscribe_email' => urlencode( $email ),
        'unsubscribe_token' => $token
    ), get_permalink( $page_id ) );
}

/**
 * 10. Add export functionality (bonus feature)
 */
add_action( 'wp_ajax_export_newsletter_subscribers', 'export_newsletter_subscribers' );
function export_newsletter_subscribers() {
    if ( ! current_user_can( 'manage_options' ) ) {
        wp_die( 'Unauthorized' );
    }

    global $wpdb;
    $table_name = $wpdb->prefix . 'newsletter_signups';
    $subscribers = $wpdb->get_results( "SELECT email, status, created_at, unsubscribed_at FROM $table_name ORDER BY created_at DESC" );

    header( 'Content-Type: text/csv' );
    header( 'Content-Disposition: attachment; filename="newsletter_subscribers_' . date( 'Y-m-d' ) . '.csv"' );
    
    $output = fopen( 'php://output', 'w' );
    fputcsv( $output, array( 'Email', 'Status', 'Subscribed Date', 'Unsubscribed Date' ) );
    
    foreach ( $subscribers as $subscriber ) {
        fputcsv( $output, array(
            $subscriber->email,
            $subscriber->status,
            $subscriber->created_at,
            $subscriber->unsubscribed_at
        ) );
    }
    
    fclose( $output );
    exit;
}
?>