garden2.js

const { Construct } = require("constructs");
const { writeFileSync } = require("node:fs");

class Lazy {
  constructor(producer) {
    this.producer = producer;
  }

  produce() {
    return this.producer();
  }
}

function resolveLazies(value) {
  switch (typeof value) {
    case "object":
      if (value instanceof Lazy) {
        return value.produce();
      } else if (Array.isArray(value)) {
        return value.map(resolveLazies);
      } else {
        const result = {};
        for (const [key, val] of Object.entries(value)) {
          result[key] = resolveLazies(val);
        }
        return result;
      }
    default:
      return value;
  }
}

class Flower extends Construct {
  constructor(scope, id, props) {
    super(scope, id, props);
    this.kind = props.kind;
    this.color = props.color;
    this._nativeRegions = props.nativeRegions ?? [];
  }

  get nativeRegions() {
    return new Lazy(() => [...this._nativeRegions]);
  }

  addNativeRegion(region) {
    this._nativeRegions.push(region);
  }

  toJson() {
    return {
      id: this.node.path,
      kind: this.kind,
      color: this.color,
      nativeRegions: this.nativeRegions,
    };
  }
}

class Garden extends Construct {
  constructor(scope, id, props) {
    super(scope, id, props);
  }

  synth() {
    const hasToJson = (node) => typeof node.toJson === "function";
    const objects = this.node.findAll().filter(hasToJson).map((c) => resolveLazies(c.toJson()));
    writeFileSync("garden.json", JSON.stringify(objects, null, 2));
  }
}

class Signpost extends Construct {
  constructor(scope, id, props) {
    super(scope, id);

    this._message = new Lazy(() => {
      const allRegions = new Set(props.flowers.flatMap((f) => f.nativeRegions.produce()));
  
      let message = "Welcome to Tuple Trove, home to flowers from: ";
      message += [...allRegions].join(", ");
      message += ".";
      return message;
    });
  }

  toJson() {
    return {
      id: this.node.path,
      message: this._message,
    };
  }
}

const garden = new Garden(undefined, "root");

const rose = new Flower(garden, "rose", { kind: "rose", color: "red" });
rose.addNativeRegion("Denmark");

new Signpost(garden, "signpost", { flowers: [rose] });

rose.addNativeRegion("Turkey");
rose.addNativeRegion("Greece");

garden.synth();