import { getSingleton } from "../helpers/singletonMethod";
import { nopeObservable } from "../observables/nopeObservable";

// Symbols for the Property Registery:
const _registeredDispatcherMethods_ = Symbol('_registeredDispatcherMethods_');
const _registeredDispatcherParams_ = Symbol('_registeredDispatcherParams_');

// Interfaces for the Class
export interface IExportToDispatcherParameters {
  uri?: string,
}

export interface IExportMethodToDispatcherParameters {
  // Different uri (instead of using the name)
  uri?: string,
  // Contains Either the Property Name or the idx name.
  deletableCallbacks?: Array<number> | Array<string>
}

export interface IExportFunctionToDispatcherParameters {
  uri?: string,
  // Contains Either the Property Name or the idx name.
  deletableCallbacks?: Array<number> | Array<string>
}

export interface IExportPropertyToDispatcherParameters {
  uri?: string,
  readonly?: boolean
}

const container = getSingleton('nopeBackendDispatcher.container', () => {
  return {
    methods: new Map<string, {
      uri: string,
      callback: (...args) => Promise<any>,
      options: IExportMethodToDispatcherParameters
    }>(),
    parameters: new Map<string, {
      uri: string,
      item: nopeObservable<any>,
      options: IExportPropertyToDispatcherParameters
    }>(),
    functions: new Map<string, {
      uri: string,
      callback: (...args) => Promise<any>,
      options: IExportFunctionToDispatcherParameters
    }>()
  }
});

/**
 * Decorator used to export a Class API over openAPI
 * @param options 
 */
export function exportsElementsToDispatcher(options: IExportToDispatcherParameters) {
  return function <T extends { new(...args: any[]): {} }>(Base: T) {
    return class extends Base {
      constructor(...args: any[]) {
        super(...args);

        const _this = this as any;

        // extract the Registered Methods of the Class.
        const registeredMethods = Base.prototype[_registeredDispatcherMethods_] as Map<string, IExportMethodToDispatcherParameters>;
        const registeredParams = Base.prototype[_registeredDispatcherParams_] as Map<string, IExportPropertyToDispatcherParameters>;

        // Online if they are present, iterate over them
        if (registeredMethods) {
          registeredMethods.forEach((_options, methodName) => {
            // Register the Methods
            const uri = (options.uri || Base.prototype.name) + (_options.uri || methodName);
            container.instance.methods.set(uri, {
              callback: async (...args) => _this[methodName](...args),
              uri,
              options
            });
          });
        }

        // Online if they are present, iterate over them
        if (registeredParams) {
          registeredParams.forEach((_options, parameterName) => {
            // Register the Methods
            const uri = (options.uri || Base.prototype.name) + (_options.uri || parameterName);
            container.instance.parameters.set(uri, {
              item: _this[parameterName],
              uri,
              options
            });
          });
        }
      }
    };
  }
}

/**
 * Decorator, used to export the Method.
 * @param options 
 */
export function exportMethodToDispatcher(options: IExportMethodToDispatcherParameters) {
  return function (target: any, propertyKey: string, descriptor: PropertyDescriptor) {
    target[_registeredDispatcherMethods_] = target[_registeredDispatcherMethods_] || new Map<string, IExportMethodToDispatcherParameters>();
    // Here we just add some information that class decorator will use
    target[_registeredDispatcherMethods_].set(propertyKey, options);
  };
}

/**
 * Decorator, will create a POST and GET api for the Parameter.
 * @param options 
 */
export function exportPropertyToDispatcher(options: IExportPropertyToDispatcherParameters) {
  return function (target: any, propertyKey: string, descriptor: PropertyDescriptor) {
    target[_registeredDispatcherParams_] = target[_registeredDispatcherParams_] || new Map<string, IExportPropertyToDispatcherParameters>();
    // Here we just add some information that class decorator will use
    target[_registeredDispatcherParams_].set(propertyKey, options);
  };
}

/**
 * Defintion of a Functon.
 */
export type callable<T> = {
  (...args): T
}

/**
 * Decorator, that will export the Function to a Dispatcher
 * @param func The Function
 * @param options The Options.
 */
export function exportFunctionToDispatcher<T>(func: T, options: IExportFunctionToDispatcherParameters) {

  container.instance.functions.set(options.uri, {
    callback: async (...args) => await ((func as any)(...args)),
    options,
    uri: options.uri || (func as any).name
  });

  return func;
}