import type { l } from "@atproto/lex";

export const BRAND = Symbol.for("$");

export type Element = {
  type: l.NsidString;
  key?: string;
  props?: l.LexMap;
};

export type LexiconComponent = {
  readonly $nsid: l.NsidString;
};

export function createElement(
  type: l.NsidString,
  key?: string,
  props?: Record<string, unknown> | null
): Element {
  const el: Record<string, unknown> = { $: BRAND, type };
  if (key != null) el.key = key;
  if (props != null) el.props = props;
  return el as Element;
}

export function isValidElement(value: unknown): value is Element {
  return (
    typeof value === "object" &&
    value !== null &&
    (value as { $?: unknown }).$ === BRAND
  );
}

export function keyStaticChildren<T>(children: T): T {
  if (Array.isArray(children)) {
    return children.map((child, i) =>
      isValidElement(child) && child.key == null
        ? { ...child, key: String(i) }
        : child
    ) as T;
  }
  if (isValidElement(children) && children.key == null) {
    return { ...children, key: "0" } as T;
  }
  return children;
}