import { Id } from '../types';
import { BaseModel } from './base';
import { Keys } from './entities';

/**
 * @param {BaseModel} parent The parent BaseModel
 * @param {string} relationKey The name of the property on the parent to refer the relation to (e.g. users.forms where forms is the relationKey)
 * @param {string} foreignKey The foreignKey on the relation refering to the parent. (e.g userId on a form)
 * @param {Keys} storeKey The store key of the relation items.
 */

export class BelongsTo<DataType> {
  protected _parent: BaseModel<any>;
  public _foreignKey: string;
  public _relationKey: string;
  public _storeKey: Keys;

  constructor(
    parent: BaseModel<any>,
    relationKey: string,
    foreignKey: string,
    storeKey: Keys,
  ) {
    this._parent = parent;
    this._foreignKey = foreignKey;
    this._relationKey = relationKey;
    this._storeKey = storeKey;
  }

  async getLocal(parentId: Id): Promise<DataType | undefined> {
    const actualId = await this._parent.getId(parentId);
    const parentItem = this._parent._store.get(
      this._parent._storeKey,
      actualId,
    );
    if (parentItem && parentItem[this._foreignKey]) {
      return this._parent._store.get(
        this._storeKey,
        parentItem[this._foreignKey],
      );
    }
    return;
  }

  async get(parentId: Id) {
    const actualId = await this._parent.getId(parentId);
    const cached = this.getLocal(actualId);
    if (cached) {
      return cached;
    }
    const data = await this._parent._requestModel[this._relationKey].get(
      actualId,
    );
    this._parent._store.set(this._storeKey, data, { deep: false });
    return data;
  }
}

export function belongsTo<DataType>({
  relationKey,
  foreignKey,
  storeKey,
}: {
  relationKey: string;
  foreignKey: string;
  storeKey: Keys;
}) {
  return function _DecoratorName<C extends { new (...args: any[]): {} }>(
    ctor: C,
  ) {
    return class extends ctor {
      constructor(...args: any[]) {
        super(...args);
        this[relationKey] = new BelongsTo<DataType>(
          <BaseModel<any>>(<unknown>this),
          relationKey,
          foreignKey,
          storeKey,
        );
      }
    };
  };
}