import { describe, expect, it } from 'vitest';
import {
  avcConfigSps,
  avcConfigWithColour,
  spsColour,
  spsWithColour,
} from '../../src/core/recording/avcColour';
import type { MatroskaColour } from '../../src/core/recording/matroska';

const hex = (text: string) => Uint8Array.from(text.match(/../g)!.map((pair) => parseInt(pair, 16)));
const toHex = (bytes: Uint8Array) => [...bytes].map((value) => value.toString(16).padStart(2, '0')).join('');

/** Chrome 136 on Windows, a game view recording (RGBX frames): a VUI, but no `video_signal_type`. */
const GAME_VIEW = hex(
  '0164002affe100196764002aac2b403c0113f2e022000007d00003a9801e38554001000468ee3cb0fdf8f800',
);
/** The same file after the rewrite, as ffmpeg's `trace_headers` read it: full range, BT.709, sRGB. */
const GAME_VIEW_FIXED = hex(
  '0164002affe1001c6764002aac2b403c0113f2e02dc043405000003e80001d4c00f1c2aa01000468ee3cb0fdf8f800',
);
/** Chrome 136 on Windows, a recording of the editor (canvas frames): the colour already in the SPS. */
const EDITOR = hex('01640c33ffe1001367640c33ac18d0050016b4d40434041e1108d401000468ce3c80fdf8f800');
/** A baseline SPS without a VUI: 320×240, written by hand. */
const BASELINE = hex('6742c01eda0507e4');

const FULL_SRGB: MatroskaColour = { matrix: 1, transfer: 13, primaries: 1, fullRange: true };
const TV_SRGB: MatroskaColour = { matrix: 1, transfer: 13, primaries: 1, fullRange: false };

describe('avcConfigWithColour', () => {
  it('writes the colour into an SPS that lacks it, as ffmpeg reads it back', () => {
    expect(spsColour(avcConfigSps(GAME_VIEW)[0]!)).toBeNull();
    const fixed = avcConfigWithColour(GAME_VIEW, FULL_SRGB);
    expect(toHex(fixed)).toBe(toHex(GAME_VIEW_FIXED));
    expect(spsColour(avcConfigSps(fixed)[0]!)).toEqual(FULL_SRGB);
  });

  it('keeps everything around the SPS byte for byte', () => {
    const fixed = avcConfigWithColour(GAME_VIEW, FULL_SRGB);
    expect(toHex(fixed.subarray(0, 6))).toBe(toHex(GAME_VIEW.subarray(0, 6)));
    const pps = (config: Uint8Array) => config.subarray(6 + 2 + avcConfigSps(config)[0]!.length);
    expect(toHex(pps(fixed))).toBe(toHex(pps(GAME_VIEW)));
  });

  it('changes nothing where the SPS already says the same colour', () => {
    expect(spsColour(avcConfigSps(EDITOR)[0]!)).toEqual(TV_SRGB);
    expect(toHex(avcConfigWithColour(EDITOR, TV_SRGB))).toBe(toHex(EDITOR));
  });

  it('replaces a colour the SPS says with the one asked for', () => {
    const changed = avcConfigWithColour(EDITOR, FULL_SRGB);
    expect(spsColour(avcConfigSps(changed)[0]!)).toEqual(FULL_SRGB);
    expect(toHex(avcConfigWithColour(changed, TV_SRGB))).toBe(toHex(EDITOR));
  });

  it('is the same once written twice', () => {
    const once = avcConfigWithColour(GAME_VIEW, FULL_SRGB);
    expect(toHex(avcConfigWithColour(once, FULL_SRGB))).toBe(toHex(once));
  });

  it('refuses what is no avcC', () => {
    expect(() => avcConfigWithColour(hex('00000001'), FULL_SRGB)).toThrow();
  });
});

describe('spsWithColour', () => {
  it('gives an SPS without a VUI one that says the colour', () => {
    expect(spsColour(BASELINE)).toBeNull();
    const fixed = spsWithColour(BASELINE, FULL_SRGB);
    // As ffmpeg's `trace_headers` reads it: 320×240 still, then the VUI with the colour alone.
    expect(toHex(fixed)).toBe('6742c01eda0507e9b808680810');
    expect(spsColour(fixed)).toEqual(FULL_SRGB);
  });

  it('escapes what would read as a start code, and reads it back', () => {
    // Zeros in all three numbers put 00 00 00 into this SPS, which has to go out as 00 00 03 00.
    const zero: MatroskaColour = { matrix: 0, transfer: 0, primaries: 0, fullRange: false };
    const escaped = avcConfigWithColour(EDITOR, zero);
    expect(toHex(avcConfigSps(escaped)[0]!)).toBe('67640c33ac18d0050016b4d4000003001e1108d4');
    expect(spsColour(avcConfigSps(escaped)[0]!)).toEqual(zero);
    expect(toHex(avcConfigWithColour(escaped, TV_SRGB))).toBe(toHex(EDITOR));
  });

  it('refuses a NAL unit that is no SPS', () => {
    expect(() => spsWithColour(hex('68ee3cb0'), FULL_SRGB)).toThrow();
  });
});