<?php

/**
 * Load custom field data from storage.
 *
 * This query loads the data directly into the field objects and does not
 * return it to the caller. It can bulk load data for any list of fields,
 * even if they have different objects or object types.
 */
final class PhabricatorCustomFieldStorageQuery extends Phobject {

  private $fieldMap = array();
  private $storageSources = array();

  /**
   * @param array<PhabricatorCustomField> $fields
   */
  public function addFields(array $fields) {
    assert_instances_of($fields, PhabricatorCustomField::class);

    foreach ($fields as $field) {
      $this->addField($field);
    }

    return $this;
  }

  public function addField(PhabricatorCustomField $field) {
    $role_storage = PhabricatorCustomField::ROLE_STORAGE;

    if (!$field->shouldEnableForRole($role_storage)) {
      return $this;
    }

    $storage = $field->newStorageObject();
    $source_key = $storage->getStorageSourceKey();

    $this->fieldMap[$source_key][] = $field;

    if (empty($this->storageSources[$source_key])) {
      $this->storageSources[$source_key] = $storage;
    }

    return $this;
  }

  public function execute() {
    foreach ($this->storageSources as $source_key => $storage) {
      $fields = idx($this->fieldMap, $source_key, array());
      $this->loadFieldsFromStorage($storage, $fields);
    }
  }

  private function loadFieldsFromStorage($storage, array $fields) {
    // Only try to load fields which have a persisted object.
    $loadable = array();
    foreach ($fields as $key => $field) {
      $object = $field->getObject();
      $phid = $object->getPHID();
      if (!$phid) {
        continue;
      }

      $loadable[$key] = $field;
    }

    if ($loadable) {
      $data = $storage->loadStorageSourceData($loadable);
    } else {
      $data = array();
    }

    foreach ($fields as $key => $field) {
      if (array_key_exists($key, $data)) {
        $value = $data[$key];
        $field->setValueFromStorage($value);
        $field->didSetValueFromStorage();
      } else if (isset($loadable[$key])) {
        // NOTE: We set this only if the object exists. Otherwise, we allow
        // the field to retain any default value it may have.
        $field->setValueFromStorage(null);
        $field->didSetValueFromStorage();
      }
    }
  }

}