import { describe, expect, it } from "vitest";
import { decodeEmbedding, inspectDirectory } from "../../src/core/sfnt";

describe("SFNT directory validation", () => {
  it("inventories bounded TrueType tables", () => {
    const report = inspectDirectory(sfnt(["head", "cmap", "OS/2"]));
    expect(report.container).toBe("truetype");
    expect(report.tables.map((table) => table.tag)).toEqual([
      "head",
      "cmap",
      "OS/2",
    ]);
    expect(report.tables[2]?.description).toContain("embedding");
  });

  it("rejects unsupported and out-of-bounds containers before library parsing", () => {
    expect(() => inspectDirectory(signature("wOF2"))).toThrow(/WOFF2/u);
    const invalid = sfnt(["head"]),
      view = new DataView(invalid);
    view.setUint32(12 + 8, invalid.byteLength - 2, false);
    view.setUint32(12 + 12, 12, false);
    expect(() => inspectDirectory(invalid)).toThrow(/file boundary/u);
  });
});

describe("embedding flags", () => {
  it("decodes and enforces subsetting restrictions", () => {
    expect(decodeEmbedding(0).subsetAllowed).toBe(true);
    expect(decodeEmbedding(0x0002).level).toBe("restricted");
    expect(decodeEmbedding(0x0100)).toMatchObject({
      noSubsetting: true,
      subsetAllowed: false,
    });
    expect(decodeEmbedding(0x0208)).toMatchObject({
      level: "editable",
      bitmapOnly: true,
      subsetAllowed: false,
    });
  });
});

function signature(value: string) {
  const bytes = new Uint8Array(4);
  [...value].forEach(
    (character, index) => (bytes[index] = character.charCodeAt(0)),
  );
  return bytes.buffer;
}

function sfnt(tags: string[]) {
  const directoryBytes = 12 + tags.length * 16,
    tableBytes = 12,
    buffer = new ArrayBuffer(directoryBytes + tags.length * tableBytes),
    view = new DataView(buffer);
  view.setUint32(0, 0x0001_0000, false);
  view.setUint16(4, tags.length, false);
  tags.forEach((tag, index) => {
    const base = 12 + index * 16;
    [...tag].forEach((character, offset) =>
      view.setUint8(base + offset, character.charCodeAt(0)),
    );
    view.setUint32(base + 4, index + 1, false);
    view.setUint32(base + 8, directoryBytes + index * tableBytes, false);
    view.setUint32(base + 12, tableBytes, false);
  });
  return buffer;
}