import { Handler } from '../handler';
import { BaseHookSystem } from '../hooksystems';
import { IFilterModel, IHandlerRegistration } from './filtermodel';

/**
 * A simple in memory model for filters.
 */
export class InMemoryFilterModel implements IFilterModel {
  private handlers: {
    [k: string]: Array<Handler<any, any>>
  } = {};
  private data: {
    [filterKey: string]: {
      [handlerKey: string]: {
        priority: number,
        handler: Handler<any, any>;
      }
    }
  } = { _handlers_: {} };

  public async queryHandlers<T>(filter: BaseHookSystem<T>): Promise<Array<Handler<T, any>>> {
    const handlers = this.handlers[filter.baseKey] || [];
    return handlers
      .map((w) => new Handler(w.key, (obj: T, ...rest: any[]) => {
          if (typeof(this.data[filter.baseKey][w.key]) === 'undefined') {
            // if i was unregistered then do not run myself
            return Promise.resolve(obj);
          }
          try {
            return w.handle(obj, ...rest);
          } catch (e) {
            return Promise.reject(e);
          }
        }
      ));
  }

  // tslint:disable-next-line
  public async registerHandler<T>(obj: { hookSystem: BaseHookSystem<T>; handler: Handler<T, any>; priority?: number }): Promise<IHandlerRegistration> {
    const {hookSystem, handler} = obj;
    if (typeof(this.data[hookSystem.baseKey]) === 'undefined') {
      this.data[hookSystem.baseKey] = {};
    }
    this.data[hookSystem.baseKey][handler.key] = {
      handler,
      priority: obj.priority || 10,
    };
    const handlers = Object.keys(this.data[hookSystem.baseKey])
      .map((handlerKey) => this.data[hookSystem.baseKey][handlerKey]);
    handlers.sort((a, b) => a.priority - b.priority);

    this.handlers[hookSystem.baseKey] = handlers.map((h) => h.handler);
    return {
      id        : handler.key,
      unregister: async () => {
        delete this.data[hookSystem.baseKey][handler.key];
        const index = this.handlers[hookSystem.baseKey].findIndex((a) => a.key === handler.key);
        if (index === -1) {
          console.warn(`Unregistering same handler twice ${handler.key}`);
        }
        this.handlers[hookSystem.baseKey].splice(index, 1);
        return true;
      },
    };
  }
}