import { cloneElement, createElement as h, type ReactElement, type ReactNode } from "react";
import { Document, Page, renderToBuffer } from "@react-pdf/renderer";
import { computeFrame, PAGE_SIZES, type PageFrame } from "../engine/geometry";
import { walk, type LayoutNode, type LayoutPage } from "../engine/layoutTree";
import { stack } from "../fonts/register";

/** Small fixtures for tests that need a tiny react-pdf document. */
export const FAMILY = stack("IBM Plex Sans");
export const PAGE_W = 400;
export const PAD = 20;

export const txt = (extra: Record<string, unknown> = {}) => ({ fontFamily: FAMILY, fontSize: 10, lineHeight: "12pt", ...extra });

export function doc(children: ReactNode, o: { height?: number; width?: number; pad?: number | Record<string, number> } = {}): ReactElement {
  const pad = o.pad ?? PAD;
  return h(
    Document,
    null,
    h(
      Page,
      { size: { width: o.width ?? PAGE_W, height: o.height ?? 300 }, style: typeof pad === "number" ? { padding: pad } : pad },
      children,
    ),
  );
}

/** A frame matching `doc()`: uniform padding `PAD`, optional footer reserve inside the bottom padding. */
export function frameFor(o: { height?: number; width?: number; footerReserve?: number; continuationReserve?: number } = {}): PageFrame {
  return computeFrame({
    page: { ...PAGE_SIZES.A4, width: o.width ?? PAGE_W, height: o.height ?? 300 },
    margins: { top: PAD, right: PAD, bottom: PAD, left: PAD },
    footerReserve: o.footerReserve ?? 0,
    continuationReserve: o.continuationReserve ?? 0,
    letterMode: false,
  });
}

export function find(page: LayoutPage, pred: (n: LayoutNode) => boolean): LayoutNode[] {
  const out: LayoutNode[] = [];
  walk(page.nodes, (n) => {
    if (pred(n)) out.push(n);
  });
  return out;
}

export const byId = (page: LayoutPage, id: string) => find(page, (n) => n.id === id);

/** react-pdf's own layout tree, for facts the normalised tree hides (style values, raw props). */
export async function rawLayout(el: ReactElement): Promise<{ type: string; children: any[] }> {
  let raw: any;
  const withHook = cloneElement(el as ReactElement<any>, { onRender: (p: any) => (raw = p._INTERNAL__LAYOUT__DATA_) });
  await renderToBuffer(withHook as never);
  return raw;
}