<?php
/*
When an Activity is received (i.e. POSTed) to an Actor's outbox, the server must:

  0. Make sure the request is authenticated
  1. Add the Activity to the Actor's outbox collection in the DB
  2. Deliver the Activity to the appropriate inboxes based on the received Activity
       This involves discovering all the inboxes, including nested ones if the target
       is a collection, deduplicating inboxes, and the POSTing the Activity to each
       target inbox.
  3. Perform side effects as necessary
*/
namespace outbox;

function create_outbox_table() {
    global $wpdb;
    $wpdb->query(
        "
        CREATE TABLE IF NOT EXISTS activitypub_outbox (
            id INT UNSIGNED AUTO_INCREMENT PRIMARY KEY,
            actor VARCHAR(128) NOT NULL,
            activity TEXT NOT NULL
        );
        "
    );
}

function persist_activity( $actor, $activity ) {
    // TODO validate activity and actor; handle errors
    global $wpdb;
    $activity_json = wp_json_encode($activity);
    $wpdb->insert( 'activitypub_outbox',
                   array(
                       "actor" => $actor,
                       "activity" => $activity_json,
                   ) );
    $persisted = json_decode( $wpdb->get_var( sprintf(
        "SELECT activity FROM activitypub_outbox WHERE id = %d", $wpdb->insert_id
    ) ) );
    $response = new WP_REST_Response( $persisted );
    $response->set_status( 201 );
    // TODO set location header of response to created object URL
    return $response;
}

function handle_activity( $actor, $activity ) {
    if ( !array_key_exists( "type", $activity ) ) {
        return new WP_Error(
            'invalid_activity',
            __( 'Invalid activity', 'activitypub' ),
            array( 'status' => 400 )
        );
    }
    switch ( $activity["type"] ) {
    case "Create":
        break;
    case "Update":
        break;
    case "Delete":
        break;
    case "Follow":
        break;
    case "Add":
        break;
    case "Remove":
        break;
    case "Like":
        break;
    case "Block":
        break;
    case "Undo":
        break;
    default:
        // handle wrapping object in Create activity
        break;
    }
}
?>