export interface MagicController {
  get(key: string): Promise<any>;
  set(key: string, val: any): Promise<any>;
}

export interface MagicConfig {
  modules: {
    [key: string]: {
      data: { [key: string]: any };
      controller: MagicController;
    };
  };
  spinnerTimeout?: number;
  pendingOnPush?: boolean;
}

export class MagicValue {
  public pending: boolean;
  public spinning: boolean;
  public error: any;
  private runningTimeout: number;

  constructor(
    private config: MagicConfig,
    private controller: MagicController,
    private keyName: string,
    public val?: any
  ) {}

  startTask() {
    this.pending = true;
    this.runningTimeout = setTimeout(
      () => (this.spinning = true),
      this.config.spinnerTimeout || 2000
    );
  }

  finishTask() {
    if (this.runningTimeout) clearTimeout(this.runningTimeout);
    this.pending = false;
    this.spinning = false;
  }

  pull() {
    this.startTask();

    return this.controller
      .get(this.keyName)
      .then(fetchedVal => {
        this.val = fetchedVal;
        this.finishTask();
        return fetchedVal;
      })
      .catch(err => {
        console.error(err);
        this.error = err;
        this.finishTask();
      });
  }

  push() {
    if (this.config.pendingOnPush !== false) this.startTask();
    return this.controller
      .set(this.keyName, this.val)
      .then(() => this.finishTask())
      .catch(err => {
        console.error(err);
        this.error = err;
        this.finishTask;
      });
  }
}

export interface MagicModule {
  [dataItemName: string]: MagicValue;
}

export class Magic {
  [moduleName: string]: MagicModule;

  constructor(config: MagicConfig) {
    let modulesConfig = config.modules || {};

    for (let moduleName of Object.keys(modulesConfig)) {
      let module = modulesConfig[moduleName];

      if (!module.data) {
        throw new Error(`Module "${moduleName}" has no configured data`);
      }

      if (!module.controller) {
        throw new Error(`Module "${moduleName}" has no configurred controller`);
      }

      this[moduleName] = {};
      for (let key of Object.keys(module.data)) {
        this[moduleName][key] = new MagicValue(
          config,
          module.controller,
          key,
          module.data[key]
        );
        this[moduleName][key].pull();
      }
    }
  }
}