fulcrm_webhook/fulcrm_webhook.module

<?php

function fulcrm_webhook_permission() {
  return array( 'administer fulcrm webhooks' => array( 'title' => t('Administer fulcrm webhooks'),
                                                       'description' => t('Perform main installation/administration tasks for fulcrm webhooks.'),
                                                       ),                          
                );
}

function fulcrm_webhook_menu() {
    /*
    $items[ 'admin/config/services/fulcrm' ] = array( 'page callback' => 'system_admin_menu_block_page',
                                                      'file' => 'system.admin.inc',
                                                      'file path' => drupal_get_path('module', 'system'),
                                                      'title' => 'fulcrm',
                                                      'description' => 'Configuration integration with fulcrm.org.',
                                                      'position' => 'right',
                                                      'access callback' => 'user_access',
                                                      'access arguments' => array('access administration pages'),
                                                      );
   */
    $items[ 'admin/config/services/fulcrm/webhook' ] = array( 'page callback' => 'fulcrm_webhook_admin',
                                                              'file' => 'fulcrm_webhook.admin.inc',
                                                              'title' => 'fulcrm webhooks',
                                                              'description' => 'Configure webhooks for fulcrm.org.',
                                                              'access callback' => 'user_access',
                                                              'access arguments' => array('administer fulcrm webhooks'),
                                                              );
    $items[ 'services/fulcrm/webhook/%' ] = array( 'page callback' => 'fulcrm_webhook_webhook',
                                                   'page arguments' => array(3),
                                                   'type' => MENU_CALLBACK,
                                                   'access callback' => 'user_access',
                                                   'access arguments' => array('access content'),
                                                   );

    return $items;
}

function fulcrm_webhook_get_pk_for_entity_type( $entity_type, $entity_id, $fulcrm_type ) {
    $query = db_select( 'fulcrm_webhook_entity_mapping', 'fwem' )
        ->fields( 'fwem', array( 'fulcrm_pk' ) )
        ->condition( 'entity_type', $entity_type )
        ->condition( 'entity_id', $entity_id )
        ->condition( 'fulcrm_type', $fulcrm_type );
    $result = $query->execute();
    return $result->fetchField();
}

function fulcrm_webhook_set_entity_mapping( $entity_type, $bundle, $entity_id, $fulcrm_type, $fulcrm_pk ) {
    db_merge( 'fulcrm_webhook_entity_mapping' )
        ->key( array( 'entity_type' => $entity_type,
                      'bundle' => $bundle,
                      'entity_id' => $entity_id,
                      ) )
        ->insertFields( array( 'fulcrm_type' => $fulcrm_type,
                               'fulcrm_pk' => $fulcrm_pk,
                               'entity_type' => $entity_type,
                               'bundle' => $bundle,
                               'entity_id' => $entity_id,
                               ) )
        ->updateFields( array( 'fulcrm_type' => $fulcrm_type,
                               'fulcrm_pk' => $fulcrm_pk,
                               ) )
        ->execute();
}

function fulcrm_webhook_load_entity_for_url( $url ) {
    $fulcrm_type = fulcrm_apiv2_url_to_type( $url );
    $fulcrm_pk = fulcrm_apiv2_url_to_pk( $url );

    $query = db_select( 'fulcrm_webhook_entity_mapping', 'fwem' )
        ->fields( 'fwem', array( 'entity_type', 'entity_id' ) )
        ->condition( 'fulcrm_type', $fulcrm_type )
        ->condition( 'fulcrm_pk', $fulcrm_pk );

    $result = $query->execute();
    foreach ( $result as $row )
        return entity_load( $row->entity_type, array( $row->entity_id ) )[ $row->entity_id ];
}

function fulcrm_webhook_createupdate_entity( $data ) {
    $return = array( 'data' => $data );

    if ( array_key_exists( 'url', $data ) ) {
        $url = $data[ 'url' ];
        $fulcrm_type = fulcrm_apiv2_url_to_type( $url );
        $fulcrm_pk = fulcrm_apiv2_url_to_pk( $url );

        $query = db_select( 'fulcrm_webhook_entity_mapping', 'fwem' )
            ->fields( 'fwem', array( 'entity_type', 'entity_id' ) )
            ->condition( 'fulcrm_type', $fulcrm_type )
            ->condition( 'fulcrm_pk', $fulcrm_pk );

        $found = false;
        $result = $query->execute();
        foreach ( $result as $row ) {
            $found = true;
            $return = array( 'data' => $data, 'entity' => entity_load( $row->entity_type, array( $row->entity_id ) ) );

            foreach ( module_implements( 'update_entity_for_fulcrm_' . $fulcrm_type ) as $module ) {
                $function = $module . '_update_entity_for_fulcrm_' . $fulcrm_type;
                if ( function_exists( $function ) ) {
                    $function( $return );
                }
            }
        }
        if ( $found ) {
            foreach ( module_implements( 'update_for_fulcrm_' . $fulcrm_type ) as $module ) {
                $function = $module . '_update_for_fulcrm_' . $fulcrm_type;
                if ( function_exists( $function ) ) {
                    $function( $return );
                }
            }
            return $return;
        }

        foreach ( module_implements( 'create_for_fulcrm_' . $fulcrm_type ) as $module ) {
            $function = $module . '_create_for_fulcrm_' . $fulcrm_type;
            if ( function_exists( $function ) ) {
                $function( $return );
            }
        }

        foreach ( module_implements( 'create_entity_for_fulcrm_' . $fulcrm_type ) as $module ) {
            $function = $module . '_create_entity_for_fulcrm_' . $fulcrm_type;
            if ( function_exists( $function ) ) {
                $function( $return );

                if ( array_key_exists( 'entity', $return ) ) {
                    fulcrm_webhook_set_entity_mapping( $entity_type = $return[ 'entity_type' ],
                                                       $bundle = array_key_exists( 'bundle', $return ) ? $return[ 'bundle' ] : $return[ 'entity_type' ],
                                                       $entity_id = $return[ 'entity_id' ],
                                                       $fulcrm_type = $fulcrm_type,
                                                       $fulcrm_pk = $fulcrm_pk );
                }
            }
        }
    }

    return $return;
}

function fulcrm_webhook_delete_entity( $data ) {
    $return = array( 'data' => $data );

    if ( array_key_exists( 'url', $data ) ) {
        $url = $data[ 'url' ];
        $fulcrm_type = fulcrm_apiv2_url_to_type( $url );
        $fulcrm_pk = fulcrm_apiv2_url_to_pk( $url );
        $return[ 'fulcrm_type' ] = $fulcrm_type;
        $return[ 'fulcrm_pk' ] = $fulcrm_pk;

        $query = db_select( 'fulcrm_webhook_entity_mapping', 'fwem' )
            ->fields( 'fwem', array( 'entity_type', 'entity_id' ) )
            ->condition( 'fulcrm_type', $fulcrm_type )
            ->condition( 'fulcrm_pk', $fulcrm_pk );

        $result = $query->execute();
        foreach ( $result as $row ) {
            $return[ 'entity' ] = entity_load( $row->entity_type, array( $row->entity_id ) );

            foreach ( module_implements( 'delete_entity_for_fulcrm_' . $fulcrm_type ) as $module ) {
                $function = $module . '_delete_entity_for_fulcrm_' . $fulcrm_type;
                if ( function_exists( $function ) ) {
                    $function( $return );
                }
            }
        }

        foreach ( module_implements( 'delete_for_fulcrm_' . $fulcrm_type ) as $module ) {
            $function = $module . '_delete_for_fulcrm_' . $fulcrm_type;
            if ( function_exists( $function ) ) {
                $function( $return );
            }
        }

        db_delete( 'fulcrm_webhook_entity_mapping', 'fwem' )
            ->condition( 'fulcrm_type', $fulcrm_type )
            ->condition( 'fulcrm_pk', $fulcrm_pk )
            ->execute();
    }

    return $return;
}

function fulcrm_webhook_webhook( $uuid ) {
    if ( $uuid === variable_get( 'fulcrm_webhook_url' ) ) {
        $headers = getallheaders();
        $payload = null;
        $payload_error = null;
        $method = $_SERVER[ 'REQUEST_METHOD' ];

        if ( array_key_exists( 'Content-Type', $headers ) && ( $headers[ 'Content-Type' ] === 'application/json' ) ) {
            $payload = json_decode( file_get_contents( "php://input" ), $assoc = TRUE );
            $payload_error = json_last_error();
            if ( function_exists( 'json_last_error_msg' ) )
                $payload_error_msg = json_last_error_msg();
            else
                $payload_error_msg = 'JSON error unavailable';
        } else {
            $payload_error_msg = 'no payload';
        }

        $client_id = fulcrm_apiv2_client_id();

        if ( fulcrm_apiv2_prevent_loop( $headers ) ) {
            $op = null;

            if ( $method === 'GET' ) {
                drupal_json_output( array( "status" => "error", "info" => "GET requests do nothing; webhooks must POST, PATCH, PUT, or DELETE" ) );
                return;                
            }

            if ( $payload === null ) {
                drupal_json_output( array( 'status' => 'error', 'info' => $payload_error_msg ) );
                return;
            }

            $return = null;

            switch ( $method ) {
            case 'DELETE':
                $return = fulcrm_webhook_delete_entity( $payload );
                break;
            case 'POST':
            case 'PATCH':
            case 'PUT':
                $return = fulcrm_webhook_createupdate_entity( $payload );
                break;
            default:
                drupal_json_output( array( 'status' => 'error', 'info' => 'unsupported method' ) );
                break;
            }

            if ( is_array( $return ) ) {
                if ( array_key_exists( 'response', $return ) )
                    drupal_json_output( array( 'status' => 'ok', 'response' => $return[ 'response' ] ) );
                else
                    drupal_json_output( array( 'status' => 'ok' ) );
            } else {
                drupal_json_output( array( 'status' => 'error', 'info' => 'no return from internal methods' ) );
            }
        } else {
            drupal_json_output( array( 'status' => 'ok', 'info' => 'loop prevention' ) );
        }
    } else {
        drupal_access_denied();
    }
}