export class DeepArray<T> extends Array<T> {
	public constructor(array: T[]|Array<T>|DeepArray<T>) {
		// console.log("Constructing DeepArray<T> with array =", array);
    	super();
    	this.push(...array);
  	}
	public mapRecursive<FromT, ToT>(this: FromT[], callbackfn: (value: FromT, index: number, array: DeepArray<FromT>) => ToT, childrenPropertyName: string): DeepArray<ToT> | undefined {
		if(!childrenPropertyName){
			throw "mapRecursive requires parameter `childrenPropertyName`";
		}
		const result: DeepArray<ToT> = new DeepArray([]);
		this.forEach((element: any) => {
			if (Array.isArray(element[childrenPropertyName])) {
				result.push(...(new DeepArray<FromT>(element[childrenPropertyName])).mapRecursive<FromT,ToT>(callbackfn, childrenPropertyName) as ToT[]);
			} else {
				result.push(callbackfn(element, 0, new DeepArray<FromT>(this)));
			}
		});
	    return result;
	}
	public findRecursive<T>(this: DeepArray<T>, predicate: (value: T) => boolean, childrenPropertyName: string): T | undefined {
		if(!childrenPropertyName){
			throw "findRecursive requires parameter `childrenPropertyName`";
		}
		let initialFind = this.find(predicate);
		if (initialFind) {
			return initialFind;
		}
		let elementsWithChildren = this.asArray().filter((x: any, index: number, array: T[]) => { return x[childrenPropertyName] });
		if (elementsWithChildren.length) {
			let childElements: T[] = [];
			elementsWithChildren.forEach((x: any) => {
				if (x[childrenPropertyName])
					childElements.push(...x[childrenPropertyName]);
			});
			return new DeepArray<T>(childElements).findRecursive(predicate, childrenPropertyName);
		}
		return undefined;
	}
	public asArray<T>(this: T[]): T[] {
		let a: T[] = [];
		a.push(...this);
		return a;
	}
}

/**
 * @example
 * // How to use this module:
 * // Example usage:
 * type Simple = string;
 * interface Complex {
 *   interestingProperty: Simple;
 *   recursiveChildren?: Complex[];
 * }
 * let deepArray = new DeepArray<Complex>([ { interestingProperty: 'a', recursiveChildren: [ { interestingProperty: 'b' } ] }]);
 * // Example 1: Map from Complex to Simple.
 * deepArray.mapRecursive<Complex, Simple>((complex) => complex.interestingProperty, 'recursiveChildren');
 * // Example 2: Find an element deeply in the tree.
 * let result = deepArray.findRecursive<Complex>((complex) => complex.interestingProperty === 'b', 'recursiveChildren');
 */

// How to use this module:
// Example usage:
type Simple = string;
interface Complex {
  interestingProperty: Simple;
  recursiveChildren?: Complex[];
}
let deepArray = new DeepArray<Complex>([ { interestingProperty: 'a', recursiveChildren: [ { interestingProperty: 'b' } ] }]);
// Example 1: Map from Complex to Simple.
deepArray.mapRecursive<Complex, Simple>((complex) => complex.interestingProperty, 'recursiveChildren');
// Example 2: Find an element deeply in the tree.
console.log("Checkpoint 3");
let result = deepArray.findRecursive<Complex>((complex) => complex.interestingProperty === 'b', 'recursiveChildren');