import { isPlainObject, DojoNodePosition, Rendition, isDocumentFragmentNode, placeAt, collectNodes, isMounted, startupWidgets } from "./traits";

export abstract class RenditionBase<TNode extends Node> implements Rendition<TNode> {
    private _attrs = {};

    private _children: unknown[] = [];

    private _created = false;

    visitNext(v: unknown) {
        if (this._created)
            throw new Error("The Element is already created");

        if (v === null || v === undefined || typeof v === "boolean")
            // skip null, undefined, booleans ( this will work:  {value && <span>{value}</span>} )
            return;

        if (isPlainObject(v)) {
            this._attrs = {... this._attrs, ...v};
        } else if (v instanceof Array) {
            v.forEach(x => this.visitNext(x));
        } else {
            this._children.push(v);
        }
    }

    ensureCreated() {
        if (!this._created) {
            this._create(this._attrs, this._children);
            this._children = [];
            this._attrs = {};
            this._created = true;
        }
    }

    /** Is rendition was instantiated to the DOM node */
    isCreated() {
        return this._created;
    }

    /** Creates DOM node if not created. No additional actions are taken. */
    getDomNode() {
        this.ensureCreated();
        return this._getDomNode();
    }

    /** Creates DOM node if not created, places it to the specified position
     * and calls startup() method for all widgets contained by this node.
     *
     * @param {string | Node} refNode The reference node where the created
     *   DOM should be placed.
     * @param {DojoNodePosition} position Optional parameter, specifies the
     *   position relative to refNode. Default is "last" (i.e. last child).
     */
    placeAt(refNode: string | Node, position: DojoNodePosition = "last") {
        const domNode = this.getDomNode();

        const startupPending = isDocumentFragmentNode(domNode) ? collectNodes(domNode.childNodes) : [domNode];

        placeAt(domNode, refNode, position);

        if (isMounted(startupPending[0]))
            startupPending.forEach(n => startupWidgets(n));

    }

    protected abstract _create(attrs: object, children: unknown[]): void;

    protected abstract _getDomNode(): TNode;
}