import { describe, expect, it } from "vitest";
import { manifestCsv, manifestJson } from "../../src/file/manifest";
import {
  detectKnownSignature,
  extensionMismatch,
} from "../../src/file/signatures";
import {
  extractStrings,
  looksLikeText,
  shannonEntropy,
} from "../../src/file/text";

describe("file signatures", () => {
  it("detects PNG without claiming parser validation", () =>
    expect(
      detectKnownSignature(
        Uint8Array.of(0x89, 0x50, 0x4e, 0x47, 0x0d, 0x0a, 0x1a, 0x0a),
      ),
    ).toMatchObject({ extension: "png", mime: "image/png" }));
  it("accounts for container extension aliases", () => {
    expect(extensionMismatch("book.epub", "zip")).toBeUndefined();
    expect(extensionMismatch("image.txt", "png")).toMatch(/does not match/u);
  });
});

describe("bounded text helpers", () => {
  it("extracts ASCII and UTF-16LE strings", () =>
    expect(
      extractStrings(
        Uint8Array.from([65, 66, 67, 68, 0, 90, 0, 89, 0, 88, 0, 87, 0]),
      ),
    ).toEqual(expect.arrayContaining(["ABCD", "ZYXW"])));
  it("distinguishes NUL-containing binary data", () =>
    expect(looksLikeText(Uint8Array.of(65, 0, 66))).toBe(false));
  it("measures a uniform byte distribution", () =>
    expect(
      shannonEntropy(Uint8Array.from({ length: 256 }, (_, index) => index)),
    ).toBeCloseTo(8));
});

describe("manifests", () => {
  const records = [
    {
      name: "=formula",
      path: "=formula",
      size: 1,
      type: "text/plain",
      lastModified: 0,
    },
  ];
  it("is deterministic", () =>
    expect(manifestJson(records)).toBe(manifestJson(records)));
  it("neutralises spreadsheet-leading formulas", () =>
    expect(manifestCsv(records)).toContain("'=formula"));
});