import { Class, Instance, isInstanceOf } from 'immutable-class';
import { Timezone } from 'chronoshift';
import { $, Expression } from 'plywood';
import { Essence, DataSource, Filter, Splits, Customization} from '../../../common/models/index';

export interface LinkGenerator {
  (dataSource: DataSource, timezone: Timezone, filter: Filter, splits: Splits): string;
}

export interface ExternalViewValue {
  title: string;
  linkGenerator: string;
  linkGeneratorFn?: LinkGenerator;
  sameWindow?: boolean;
}

var check: Class<ExternalViewValue, ExternalViewValue>;
export class ExternalView implements Instance<ExternalViewValue, ExternalViewValue> {

  static isExternalView(candidate: any): candidate is ExternalView {
    return isInstanceOf(candidate, ExternalView);
  }

  static fromJS(parameters: ExternalViewValue): ExternalView {
    var value = parameters;
    return new ExternalView({
      title: value.title,
      linkGenerator: value.linkGenerator,
      linkGeneratorFn: value.linkGeneratorFn,
      sameWindow: value.sameWindow
    });
  }

  public title: string;
  public linkGenerator: string;
  public sameWindow: boolean;
  public linkGeneratorFn: LinkGenerator;

  constructor(parameters: ExternalViewValue) {
    const { title, linkGenerator } = parameters;
    if (!title) throw new Error("External view must have title");
    if (typeof linkGenerator !== 'string') throw new Error("Must provide link generator function");
    this.title = title;
    this.linkGenerator = linkGenerator;
    var linkGeneratorFnRaw: LinkGenerator = null;
    try {
      linkGeneratorFnRaw = new Function('dataSource', 'timezone', 'filter', 'splits', linkGenerator) as LinkGenerator;
    } catch (e) {
      throw new Error(`Error constructing link generator function: ${e.message}`);
    }
    this.linkGeneratorFn = (dataSource: DataSource, timezone: Timezone, filter: Filter, splits: Splits) => {
      try {
        return linkGeneratorFnRaw(dataSource, timezone, filter, splits);
      } catch (e) {
        console.warn(`Error with custom link generating function '${title}': ${e.message} [${linkGenerator}]`);
        return null;
      }
    };
    this.sameWindow = Boolean(parameters.sameWindow);
  }

  public toJS(): ExternalViewValue {
    var js: ExternalViewValue = {
      title: this.title,
      linkGenerator: this.linkGenerator
    };
    if (this.sameWindow === true) js.sameWindow = true;
    return js;
  }

  public valueOf(): ExternalViewValue {
    var value: ExternalViewValue = {
      title: this.title,
      linkGenerator: this.linkGenerator
    };
    if (this.sameWindow === true) value.sameWindow = true;
    return value;
  }

  public toJSON(): ExternalViewValue {
    return this.toJS();
  }

  public equals(other: ExternalView): boolean {
    return ExternalView.isExternalView(other) &&
      this.title === other.title &&
      this.linkGenerator === other.linkGenerator &&
      this.sameWindow === other.sameWindow;
  }

  public toString(): string {
    return `${this.title}: ${this.linkGenerator}`;
  }
}
check = ExternalView;