Add Facebook webhook integration for live video notifications

[Copilot]

Implements webhook endpoint to detect when the /tenth Facebook page starts a live video, extract the video ID and title, and pass them to a handler method.

Implementation

REST API endpoint at /wp-json/shimmer/v1/facebook-webhook:

• GET handler verifies webhook subscriptions using verify token
• POST handler processes live video events with HMAC-SHA256 signature validation
• Extracts video ID and title from payload when status === 'live' and calls FacebookWebhook::handleLiveVideo($videoId, $videoTitle)

Universal settings system at Settings → Shimmer:

• Created ShimmerSettings class for centralized settings management across all Shimmer components
• Facebook Webhook settings integrated as a section within the universal settings page
• Admin UI for configuring App Secret and Verify Token
• Falls back to wp-config.php constants for backward compatibility
• Displays webhook URL and setup instructions inline
• Fully internationalized using WordPress i18n functions

Files:

• shimmer/ShimmerSettings.php - Universal settings system (new)
• shimmer/FacebookWebhook.php - Webhook handler
• shimmer.php - Initialization for both classes

Usage

// Stub method called when live video detected
public static function handleLiveVideo(string $videoId, string $videoTitle = ''): void
{
    $logMessage = "Facebook Live Video Detected - Video ID: {$videoId}";
    if (!empty($videoTitle)) {
        $logMessage .= ", Title: {$videoTitle}";
    }
    error_log($logMessage);
    // Customize: create post, send notifications, etc.
}

Settings stored as:

• shimmer_facebook_app_secret option
• shimmer_facebook_verify_token option

Webhook subscribes to the live_videos field on Facebook page.

Internationalization

All user-facing strings use WordPress i18n functions (__(), esc_html_e(), wp_kses_post()) with text domain shimmer, making the interface ready for translation.

Original prompt

In a new branch and mostly in new files, add functionality to this plugin that can connect to Facebook and:

1. Use the webhook API to detect when the Facebook page /tenth has a new live video online,
2. Get the video ID and provide it to a stub method,
3. smoothly handle all auth.

---

✨ Let Copilot coding agent set things up for you — coding agent works faster and does higher quality work when set up for your repo.

[jkrrv]

@copilot Please also provide the stub method with the name of the video.
If you're going to add a settings interface, please move it to a different class and make it universal for all of Shimmer, not just the Facebook webhook component.
Please use i18n functions for anything that could be user-facing, including settings.

[Copilot]

@copilot Please also provide the stub method with the name of the video.
If you're going to add a settings interface, please move it to a different class and make it universal for all of Shimmer, not...

Done in commit 978b2ab:

1. Video name added to stub method: handleLiveVideo($videoId, $videoTitle) now receives both the video ID and title. The title is extracted from the webhook payload's title field (with fallback to description).

2. Settings moved to universal class: Created ShimmerSettings class that manages all Shimmer plugin settings. Settings are now located at Settings > Shimmer with a dedicated Facebook Webhook section. This class is extensible for other Shimmer components.

3. i18n functions applied: All user-facing strings now use __(), esc_html_e(), and wp_kses_post() with text domain shimmer. The settings page, field labels, descriptions, and instructions are all ready for translation.