Voiced/src/pdf/engine/measure.test.tsx

import { createElement as h } from "react";
import { Document, Page, Text } from "@react-pdf/renderer";
import { describe, expect, it } from "vitest";
import { stack } from "../fonts/register";
import { renderPdfText } from "../testing/pdfText";
import { setupPdfTest } from "../testing/setup";
import { chunkIdentifier } from "../model/text";

const m = setupPdfTest();

const SAMPLES: string[] = [
  "Voice-over session 12 - narration for module 3",
  "Total ₹1,23,456.78",
  "AVATAR WAVE To Ty Yo",
  "anon.longsurname.voiceover@examplestudios.co.in",
  "29ABCDE1234F1Z5",
  "office fi fl ffi final",
  "BILLED TO",
  "Amount: ₹5,00,000.00 (Rupees Five Lakh Only) नमस्ते",
  "नमस्ते दुनिया, यह एक परीक्षण है",
  "ಕನ್ನಡ ಭಾಷೆಯ ಪರೀಕ್ಷೆ ಇನ್ವಾಯ್ಸ್",
  "Invoice क्रमांक INV-0042 ಇನ್ವಾಯ್ಸ್",
  "1234567890 0.00 111 000",
];

interface Case {
  text: string;
  size: number;
  weight: number;
  italic: boolean;
  spacing: number;
  caps: boolean;
}

const isIndic = (t: string) => /[\u0900-\u0DFF]/.test(t);

const cases: Case[] = [];
for (const text of SAMPLES) {
  for (const size of [7.5, 9.5, 18]) cases.push({ text, size, weight: 400, italic: false, spacing: 0, caps: false });
}
cases.push(
  { text: "Bold semibold text ₹99", size: 9.5, weight: 600, italic: false, spacing: 0, caps: false },
  { text: "Italic amount in words only", size: 9.5, weight: 400, italic: true, spacing: 0, caps: false },
  { text: "Light weight 300", size: 13, weight: 300, italic: false, spacing: 0, caps: false },
  { text: "Heavy 800 falls back to bold", size: 13, weight: 800, italic: false, spacing: 0, caps: false },
  { text: "tax invoice", size: 18, weight: 600, italic: false, spacing: 1.5, caps: true },
  { text: "description", size: 7.5, weight: 400, italic: false, spacing: 0.8, caps: true },
  { text: "billed to नमस्ते", size: 7.5, weight: 400, italic: false, spacing: 1, caps: true },
);

describe("measurer parity with react-pdf", () => {
  it("matches the width pdf.js reads from rendered text", async () => {
    const doc = h(
      Document,
      null,
      ...cases.map((c, i) =>
        h(
          Page,
          { key: i, size: { width: 900, height: 80 }, style: { padding: 20 } },
          h(
            Text,
            {
              style: {
                fontFamily: stack("IBM Plex Sans"),
                fontSize: c.size,
                fontWeight: c.weight,
                fontStyle: c.italic ? "italic" : "normal",
                letterSpacing: c.spacing,
                ...(c.caps ? { textTransform: "uppercase" } : {}),
              } as never,
            },
            // pdf.js sizes shaped Indic items from raw glyph widths (it reports 12.9 pt for a run that
            // advances 15.8 pt), so those cases end in a Latin "I" and the width is read from where
            // that glyph starts instead.
            isIndic(c.text) ? `${c.text}I` : c.text,
          ),
        ),
      ),
    );
    const pdf = await renderPdfText(doc);
    expect(pdf.pages.length).toBe(cases.length);

    let maxDev = 0;
    let worst = "";
    pdf.pages.forEach((page, i) => {
      const c = cases[i];
      const x0 = Math.min(...page.items.map((t) => t.x0));
      // pdf.js leaves the trailing letter spacing of the last glyph out of an item's width.
      let x1 = Math.max(...page.items.map((t) => t.x1)) + c.spacing;
      if (isIndic(c.text)) {
        const last = page.items[page.items.length - 1];
        expect(last.str, `${c.text}: sentinel item`).toBe("I");
        x1 = last.x0;
      }
      const measured = m.measureWidth({
        text: c.caps ? c.text.toUpperCase() : c.text,
        face: "IBM Plex Sans",
        weight: c.weight,
        italic: c.italic,
        size: c.size,
        letterSpacing: c.spacing,
      });
      const dev = Math.abs(x1 - x0 - measured);
      if (dev > maxDev) {
        maxDev = dev;
        worst = `${c.text} @${c.size} (pdf ${(x1 - x0).toFixed(3)} vs ${measured.toFixed(3)})`;
      }
      expect(dev, `${c.text} @${c.size} w${c.weight}: pdf ${(x1 - x0).toFixed(3)} measured ${measured.toFixed(3)}`).toBeLessThan(0.05);
    });
    console.log(`measurer parity: ${cases.length} cases, max deviation ${maxDev.toFixed(4)} pt (${worst})`);
  });
});

describe("measurer helpers", () => {
  it("reports uncovered code points", () => {
    expect(m.missing("Hello ₹ नमस्ते ಕನ್ನಡ")).toEqual([]);
    expect(m.missing("A 中 B")).toEqual([0x4e2d]);
  });

  it("wraps greedily at spaces and hyphens", () => {
    const input = { face: "IBM Plex Sans", weight: 400, size: 9.5 };
    const text = "one two three four five six seven eight nine ten";
    const full = m.measureWidth({ ...input, text });
    const lines = m.wrapLines(text, full * 0.6, input);
    expect(lines.length).toBe(2);
    expect(lines.join(" ")).toBe(text);
    for (const l of lines) expect(m.measureWidth({ ...input, text: l })).toBeLessThanOrEqual(full * 0.6);
    expect(m.wrapLines("abcdefghijkl", 5, input)).toEqual(["abcdefghijkl"]);
    expect(m.wrapLines("", 100, input)).toEqual([]);
  });

  it("round-trips chunkIdentifier output", () => {
    const id = "anon.longsurname.voiceover@examplestudios.co.in";
    expect(chunkIdentifier(id, 12).join("")).toBe(id);
  });
});