Example - Custom Rest API End Point - FluentCRM

snippet.php

<?php
// Register the REST API route
add_action('rest_api_init', function () {
    register_rest_route('custom-fluentcrm-api/v1', '/add-note', [
        'methods'             => 'POST',
        'callback'            => 'handle_custom_fluentcrm_add_note',
        'permission_callback' => function () {
            return current_user_can('edit_users'); // Adjust capability if needed
        },
        'args' => [
            'user_input' => [
                'required' => true,
                'type'     => 'string'
            ],
            'note_content' => [
                'required' => true,
                'type'     => 'string'
            ],
            'note_type' => [
                'required' => false,
                'type'     => 'string',
                'default'  => 'custom'
            ],
            'note_title' => [
                'required' => false,
                'type'     => 'string',
                'default'  => 'Note'
            ]
        ]
    ]);
});

// Callback for the REST API
function handle_custom_fluentcrm_add_note(WP_REST_Request $request) {
    $user_input   = $request->get_param('user_input');
    $note_content = $request->get_param('note_content');
    $note_type    = $request->get_param('note_type');
    $note_title   = $request->get_param('note_title');

    $result = add_custom_note_to_fluentcrm_user($user_input, $note_content, $note_type, $note_title);

    if (is_wp_error($result)) {
        return new WP_REST_Response([
            'success' => false,
            'message' => $result->get_error_message(),
        ], 400);
    }

    return new WP_REST_Response([
        'success' => true,
        'message' => 'Note successfully added.',
    ], 200);
}

// Your provided helper function
function add_custom_note_to_fluentcrm_user($user_input, $note_content, $note_type = 'custom', $note_title = 'Note') {
    if (!class_exists('\FluentCrm\App\Models\Subscriber')) {
        return new WP_Error('fluentcrm_missing', 'FluentCRM is not active.');
    }

    $email = '';
    if (is_numeric($user_input)) {
        $user = get_user_by('ID', $user_input);
        $email = $user ? $user->user_email : '';
    } elseif (is_object($user_input) && isset($user_input->user_email)) {
        $email = $user_input->user_email;
    } elseif (is_string($user_input) && is_email($user_input)) {
        $email = $user_input;
    }

    if (!$email) {
        return new WP_Error('invalid_user', 'Invalid user input provided.');
    }

    $contact = \FluentCrm\App\Models\Subscriber::where('email', $email)->first();

    if (!$contact) {
        return new WP_Error('no_contact', "No FluentCRM contact found for email: $email");
    }

    \FluentCrm\App\Models\SubscriberNote::create([
        'subscriber_id' => $contact->id,
        'type'          => $note_type,
        'title'         => $note_title,
        'description'   => $note_content,
        'created_by'    => get_current_user_id(),
    ]);

    return true;
}