import { autorun } from "mobx";
import { createTransformer } from "mobx-utils";
import defined from "terriajs-cesium/Source/Core/defined";

interface Args {
  value: any;
  context: any;
}

export default function autoUpdate(updater: (...args: any[]) => void) {
  return function (
    target: any,
    propertyName: string,
    property: PropertyDescriptor
  ) {
    const transformer = createTransformer(
      function (args: Args) {
        return autorun(() => {
          updater.call(args.context, args.value);
        });
      },
      (disposer, value) => {
        console.log("cleanup");
        if (disposer) {
          disposer();
        }
      }
    );

    const originalGet = property.get;
    if (originalGet) {
      property.get = function () {
        const value = originalGet.call(this);
        if (defined(value)) {
          console.log("auto-updating result of " + propertyName);
          transformer({
            value: value,
            context: this
          });
        }
        return value;
      };
    }
  };
}