# Hooks & Filters

### Action Hooks

1. **`payment_page_after_payment`**
   * **Purpose**: Triggered after a payment is successfully processed.
   * **Usage**: Allows developers to execute additional actions like logging the transaction, notifying users, or updating external systems.
   * **Example**:

     ```php
     add_action('payment_page_after_payment', 'log_payment_details', 10, 2);

     function log_payment_details($transaction_id, $amount) {
         // Log the transaction details
         error_log("Transaction processed. ID: $transaction_id, Amount: $amount");
     }
     ```
2. **`payment_page_settings_saved`**
   * **Purpose**: Called after the plugin settings are saved.
   * **Usage**: Use this hook to perform actions like clearing caches, sending notifications, or validating settings.
   * **Example**:

     ```php
     add_action('payment_page_settings_saved', 'clear_cache_after_settings_change');

     function clear_cache_after_settings_change() {
         // Clear cached data after settings are updated
         my_cache_clear_function();
     }
     ```
3. **`payment_page_gateway_initialized`**
   * **Purpose**: Invoked when a payment gateway is initialized.
   * **Usage**: Perform setup actions, such as validating configurations or preparing necessary resources.
   * **Example**:

     ```php
     add_action('payment_page_gateway_initialized', 'check_gateway_configuration');

     function check_gateway_configuration($gateway) {
         // Check if gateway configuration is correct
         if (!isset($gateway['api_key'])) {
             // Handle missing API key
             error_log("API key is missing for the gateway.");
         }
     }
     ```
4. **`payment_page_before_payment`**
   * **Purpose**: Triggered before a payment is processed.
   * **Usage**: Useful for running validation checks or modifying the payment request before it's sent to the gateway.
   * **Example**:

     ```php
     add_action('payment_page_before_payment', 'validate_payment_request', 10, 1);

     function validate_payment_request($payment_data) {
         // Perform validation on payment data
         if ($payment_data['amount'] <= 0) {
             wp_die('Invalid payment amount.');
         }
     }
     ```
5. **`payment_page_gateway_disabling`**
   * **Purpose**: Executed when a payment gateway is being disabled.
   * **Usage**: Perform cleanup actions or notify users about the change.
   * **Example**:

     ```php
     add_action('payment_page_gateway_disabling', 'notify_gateway_disabling', 10, 1);

     function notify_gateway_disabling($gateway_name) {
         // Notify users when a gateway is disabled
         wp_mail('admin@example.com', 'Gateway Disabled', "$gateway_name has been disabled.");
     }
     ```

### Filter Hooks

1. **`payment_page_gateway_options`**
   * **Purpose**: Allows modification of the list of available payment gateways.
   * **Usage**: Customize which gateways are available to the user, adding or removing options as necessary.
   * **Example**:

     ```php
     add_filter('payment_page_gateway_options', 'add_custom_gateway', 10, 1);

     function add_custom_gateway($gateways) {
         // Add a custom payment gateway
         $gateways[] = 'custom_gateway';
         return $gateways;
     }
     ```
2. **`payment_page_settings`**
   * **Purpose**: Filters the settings before they are saved.
   * **Usage**: Validate or modify settings to ensure they meet specific criteria.
   * **Example**:

     ```php
     add_filter('payment_page_settings', 'sanitize_settings_data', 10, 1);

     function sanitize_settings_data($settings) {
         // Sanitize the API key setting
         $settings['api_key'] = sanitize_text_field($settings['api_key']);
         return $settings;
     }
     ```
3. **`payment_page_transaction_response`**
   * **Purpose**: Filters the response from payment gateways before it is processed by the plugin.
   * **Usage**: Modify response data for logging, notifications, or error handling.
   * **Example**:

     ```php
     add_filter('payment_page_transaction_response', 'process_transaction_response', 10, 1);

     function process_transaction_response($response) {
         // Modify the response to include additional data
         $response['processed_time'] = current_time('mysql');
         return $response;
     }
     ```
4. **`payment_page_form_fields`**
   * **Purpose**: Allows modification of form fields rendered on the payment page.
   * **Usage**: Customize the payment form by adding or removing fields based on user needs.
   * **Example**:

     ```php
     add_filter('payment_page_form_fields', 'add_custom_form_fields', 10, 1);

     function add_custom_form_fields($fields) {
         // Add a custom input field to the payment form
         $fields['custom_field'] = '<input type="text" name="custom_field" placeholder="Enter something...">';
         return $fields;
     }
     ```
5. **`payment_page_payment_methods`**
   * **Purpose**: Filters the list of payment methods available to users during checkout.
   * **Usage**: Add, remove, or modify payment methods based on specific criteria or conditions.
   * **Example**:

     ```php
     add_filter('payment_page_payment_methods', 'modify_payment_methods', 10, 1);

     function modify_payment_methods($methods) {
         // Remove 'check' as a payment method
         if (($key = array_search('check', $methods)) !== false) {
             unset($methods[$key]);
         }
         return $methods;
     }
     ```

***

This section provides advanced developers with a detailed understanding of the available hooks and filters in the **Payment Page** plugin, including practical examples of how they can be implemented. If you need further elaboration on any specific hook or filter, or if you have additional questions, feel free to [contact support](https://paymentpageplugin.com/support/).&#x20;


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