// Shared by the template scripts (thumbnails, compare): bundles the TypeScript renderer for node and
// rasterises PDFs with pdf.js + @napi-rs/canvas.
import { build } from "esbuild";
import { mkdirSync } from "node:fs";
import path from "node:path";
import { pathToFileURL } from "node:url";
import { ROOT } from "../logo/lib.mjs";

export { ROOT };
export const CANVA_DIR = path.join(ROOT, "templates", "reference");

/**
 * Bundles scripts/templates/entry.ts into node_modules/.cache (so bare imports such as react resolve from
 * node_modules) and imports it. Node packages stay external; only the app's own sources are bundled.
 */
export async function loadRenderer() {
  const dir = path.join(ROOT, "node_modules", ".cache", "voiced-templates");
  mkdirSync(dir, { recursive: true });
  const outfile = path.join(dir, `bundle-${Date.now()}.mjs`);
  await build({
    entryPoints: [path.join(ROOT, "scripts/templates/entry.ts")],
    outfile,
    bundle: true,
    packages: "external",
    platform: "node",
    format: "esm",
    jsx: "automatic",
    logLevel: "error",
  });
  return import(pathToFileURL(outfile).href);
}

export async function loadCanvas() {
  try {
    return await import("@napi-rs/canvas");
  } catch {
    console.error("@napi-rs/canvas is not installed (it is an optional dev dependency); run npm install");
    process.exit(1);
  }
}

/** Rasterises page `pageNo` of PDF bytes at `scale` on a white background; returns the canvas. */
export async function rasterize(bytes, pageNo = 1, scale = 1.6) {
  const { createCanvas } = await loadCanvas();
  const pdfjs = await import("pdfjs-dist/legacy/build/pdf.mjs");
  const task = pdfjs.getDocument({ data: new Uint8Array(bytes), useSystemFonts: false, disableFontFace: true, isEvalSupported: false, verbosity: 0 });
  const doc = await task.promise;
  try {
    const page = await doc.getPage(pageNo);
    const vp = page.getViewport({ scale });
    const canvas = createCanvas(Math.ceil(vp.width), Math.ceil(vp.height));
    const ctx = canvas.getContext("2d");
    ctx.fillStyle = "#ffffff";
    ctx.fillRect(0, 0, canvas.width, canvas.height);
    await page.render({ canvasContext: ctx, canvas, viewport: vp }).promise;
    return canvas;
  } finally {
    await task.destroy();
  }
}

/** Text items of page 1 with baselines measured from the page top, for numeric comparison. */
export async function textItems(bytes, pageNo = 1) {
  const pdfjs = await import("pdfjs-dist/legacy/build/pdf.mjs");
  const task = pdfjs.getDocument({ data: new Uint8Array(bytes), useSystemFonts: false, disableFontFace: true, isEvalSupported: false, verbosity: 0 });
  const doc = await task.promise;
  try {
    const page = await doc.getPage(pageNo);
    const vp = page.getViewport({ scale: 1 });
    const content = await page.getTextContent();
    return content.items
      .filter((it) => "str" in it && it.str.trim() !== "")
      .map((it) => {
        const m = vp.transform;
        const [px, py] = [it.transform[4], it.transform[5]];
        const [x, y] = [m[0] * px + m[2] * py + m[4], m[1] * px + m[3] * py + m[5]];
        return { str: it.str, x: Math.round(x * 10) / 10, baseline: Math.round(y * 10) / 10, w: Math.round(it.width * 10) / 10, size: Math.round(Math.hypot(it.transform[0], it.transform[1]) * 10) / 10 };
      });
  } finally {
    await task.destroy();
  }
}