/**
 * OpusFormatDecoder / OpusSidecar tests.
 *
 * There is no TS test runner configured in this repo (no package.json, no jest/vitest, no other
 * *.test.ts). Rather than introduce a heavy harness, this file is a self-contained, zero-dependency
 * test: a ~15-line inline assert/test harness, no `node:` imports, no DOM. It exercises the pure
 * parser / resolver / alignment logic (none of which touches the DOM or Web Audio).
 *
 * It is EXCLUDED from the production tsc build (tsconfig `exclude: Interop/**\/*.test.ts`) so it
 * never ships in wwwroot/js. To run it (Node 22+ strips TS types natively — no tsc, no deps), the
 * test's `.js` import specifiers must resolve to the COMPILED decoder modules, so run a copy from
 * the compiled output directory:
 *
 *   # 1. produce the compiled decoder modules (the normal build already does this):
 *   dotnet build DeepDrftPublic/DeepDrftPublic.csproj
 *   # 2. run this test next to the compiled .js siblings (Node strips the types at load):
 *   cp DeepDrftPublic/Interop/audio/OpusFormatDecoder.test.ts DeepDrftPublic/wwwroot/js/audio/
 *   node DeepDrftPublic/wwwroot/js/audio/OpusFormatDecoder.test.ts
 *
 * A thrown error / non-zero exit signals failure; "ALL <n> TESTS PASSED" signals success. (The
 * copied file lives only in the gitignored wwwroot/js output; the source under Interop is the
 * committed artifact.)
 *
 * The sidecar bytes built in `makeSidecar` reproduce the C# wire format byte-for-byte
 * (DeepDrftContent.Processors.Opus.OpusSidecar.ToBytes / OggOpusSeekIndex.ToBytes):
 *   [uint32 setupHeaderLength][setup bytes]
 *   [uint64 totalByteLength][double totalDuration][uint32 count][uint16 preSkip][uint16 reserved]
 *   count x [uint64 granulePosition][uint64 byteOffset]    — all little-endian.
 * The C# serializer is the source of truth; this verifies the TS parser is its exact counterpart.
 */

import { parseSidecar, presentationTimeSeconds, OPUS_SAMPLE_RATE } from './OpusSidecar.js';
import type { OpusSeekData } from './OpusSidecar.js';
import { OpusFormatDecoder } from './OpusFormatDecoder.js';
import type { FormatInfo } from './IFormatDecoder.js';

// --- tiny inline harness (no dependencies) ---------------------------------------------------
let passed = 0;
const failures: string[] = [];
function test(name: string, fn: () => void): void {
    try {
        fn();
        passed++;
    } catch (e) {
        failures.push(`FAIL: ${name}\n    ${(e as Error).message}`);
    }
}
function assertEqual(actual: unknown, expected: unknown, msg?: string): void {
    if (actual !== expected) {
        throw new Error(`${msg ?? 'assertEqual'}: expected ${String(expected)}, got ${String(actual)}`);
    }
}
function assertArray(actual: ArrayLike<number>, expected: number[], msg?: string): void {
    const a = Array.from(actual);
    if (a.length !== expected.length || a.some((v, i) => v !== expected[i])) {
        throw new Error(`${msg ?? 'assertArray'}: expected [${expected}], got [${a}]`);
    }
}
function assertNull(actual: unknown, msg?: string): void {
    if (actual !== null) throw new Error(`${msg ?? 'assertNull'}: expected null, got ${String(actual)}`);
}
function assertNotNull<T>(actual: T | null, msg?: string): T {
    if (actual === null) throw new Error(`${msg ?? 'assertNotNull'}: got null`);
    return actual;
}

interface SidecarSpec {
    setupHeader: number[];
    totalByteLength: number;
    totalDuration: number;
    preSkip: number;
    points: Array<{ granule: number; byteOffset: number }>;
}

/** Serialize a sidecar blob exactly as the C# OpusSidecar/OggOpusSeekIndex writers do. */
function makeSidecar(spec: SidecarSpec): Uint8Array {
    const SEEK_INDEX_HEADER_SIZE = 24;
    const SEEK_POINT_SIZE = 16;
    const setupLen = spec.setupHeader.length;
    const total = 4 + setupLen + SEEK_INDEX_HEADER_SIZE + spec.points.length * SEEK_POINT_SIZE;

    const bytes = new Uint8Array(total);
    const view = new DataView(bytes.buffer);

    view.setUint32(0, setupLen, true);
    bytes.set(spec.setupHeader, 4);

    let p = 4 + setupLen;
    writeUint64(view, p, spec.totalByteLength);
    view.setFloat64(p + 8, spec.totalDuration, true);
    view.setUint32(p + 16, spec.points.length, true);
    view.setUint16(p + 20, spec.preSkip, true);
    // bytes 22-23 reserved (zero)

    p += SEEK_INDEX_HEADER_SIZE;
    for (const pt of spec.points) {
        writeUint64(view, p, pt.granule);
        writeUint64(view, p + 8, pt.byteOffset);
        p += SEEK_POINT_SIZE;
    }
    return bytes;
}

function writeUint64(view: DataView, offset: number, value: number): void {
    view.setUint32(offset, value >>> 0, true);
    view.setUint32(offset + 4, Math.floor(value / 0x100000000), true);
}

function formatInfoFor(sidecar: Uint8Array): FormatInfo {
    const decoder = new OpusFormatDecoder();
    const parsed = assertNotNull(parseSidecar(sidecar), 'sidecar should parse');
    decoder.setSidecar(parsed);
    return assertNotNull(decoder.tryParseHeader([], 0), 'tryParseHeader should build FormatInfo');
}

// --- parseSidecar: byte-for-byte round-trip against the C# layout -----------------------------

test('parseSidecar round-trips the C# binary layout exactly', () => {
    const setup = [0x4f, 0x70, 0x75, 0x73, 0x48, 0x65, 0x61, 0x64]; // "OpusHead" stand-in
    const spec: SidecarSpec = {
        setupHeader: setup,
        totalByteLength: 1_234_567,
        totalDuration: 212.5,
        preSkip: 312,
        points: [
            { granule: 312, byteOffset: 4096 },          // first point: granule == preSkip -> t=0
            { granule: 312 + 24000, byteOffset: 9000 },  // +0.5 s
            { granule: 312 + 48000, byteOffset: 14000 }, // +1.0 s
        ],
    };

    const parsed: OpusSeekData = assertNotNull(parseSidecar(makeSidecar(spec)));
    assertEqual(parsed.kind, 'opus-sidecar', 'kind');
    assertArray(parsed.setupHeaderBytes, setup, 'setup header bytes');
    assertEqual(parsed.totalByteLength, spec.totalByteLength, 'totalByteLength');
    assertEqual(parsed.totalDurationSeconds, spec.totalDuration, 'totalDuration');
    assertEqual(parsed.preSkip, spec.preSkip, 'preSkip');
    assertEqual(parsed.points.length, 3, 'point count');
    assertEqual(parsed.points[1].granulePosition, 312 + 24000, 'point[1].granule');
    assertEqual(parsed.points[1].byteOffset, 9000, 'point[1].byteOffset');
});

test('parseSidecar honours a borrowed view byteOffset (sidecar not at buffer start)', () => {
    const blob = makeSidecar({
        setupHeader: [1, 2, 3, 4],
        totalByteLength: 100,
        totalDuration: 1.0,
        preSkip: 0,
        points: [{ granule: 0, byteOffset: 8 }],
    });
    const padded = new Uint8Array(blob.length + 7);
    padded.set(blob, 7);
    const parsed = assertNotNull(parseSidecar(padded.subarray(7)));
    assertArray(parsed.setupHeaderBytes, [1, 2, 3, 4], 'borrowed setup bytes');
    assertEqual(parsed.points[0].byteOffset, 8, 'borrowed point offset');
});

test('parseSidecar returns null on a truncated blob', () => {
    const blob = makeSidecar({
        setupHeader: [0],
        totalByteLength: 1,
        totalDuration: 0,
        preSkip: 0,
        points: [{ granule: 0, byteOffset: 0 }],
    });
    assertNull(parseSidecar(blob.subarray(0, 3)), 'short of length prefix');
    assertNull(parseSidecar(blob.subarray(0, blob.length - 4)), 'declared count overruns');
});

test('presentationTimeSeconds applies preSkip and clamps at zero (RFC 7845)', () => {
    assertEqual(presentationTimeSeconds(312, 312), 0, 'granule == preSkip');
    assertEqual(presentationTimeSeconds(0, 312), 0, 'below preSkip clamps');
    assertEqual(presentationTimeSeconds(312 + OPUS_SAMPLE_RATE, 312), 1.0, '+48000 -> 1 s');
});

// --- calculateByteOffset: binary search over the precomputed index (exact, not interpolation) -

test('calculateByteOffset returns the page-start of the largest entry with time <= t', () => {
    const points = [0, 1, 2, 3].map(i => ({
        granule: 1000 + i * (OPUS_SAMPLE_RATE / 2),
        byteOffset: 4096 + i * 5000,
    }));
    const info = formatInfoFor(makeSidecar({
        setupHeader: [9, 9, 9, 9], totalByteLength: 999_999, totalDuration: 1.5, preSkip: 1000, points,
    }));
    const d = new OpusFormatDecoder();
    assertEqual(d.calculateByteOffset(info, 0.0), 4096, 't=0 -> first point');
    assertEqual(d.calculateByteOffset(info, 0.4), 4096, 'just before bucket 1');
    assertEqual(d.calculateByteOffset(info, 0.5), 9096, 'exactly bucket 1');
    assertEqual(d.calculateByteOffset(info, 0.9), 9096, 'within bucket 1');
    assertEqual(d.calculateByteOffset(info, 1.0), 14096, 'exactly bucket 2');
    assertEqual(d.calculateByteOffset(info, 99), 19096, 'past end -> last point');
});

test('calculateByteOffset never interpolates between points', () => {
    const info = formatInfoFor(makeSidecar({
        setupHeader: [0], totalByteLength: 10_000, totalDuration: 1.0, preSkip: 0,
        points: [{ granule: 0, byteOffset: 100 }, { granule: OPUS_SAMPLE_RATE, byteOffset: 9000 }],
    }));
    const d = new OpusFormatDecoder();
    assertEqual(d.calculateByteOffset(info, 0.5), 100, 'midpoint snaps to lower page start');
});

test('calculateByteOffset degrades to audioDataOffset with an empty index', () => {
    const info = formatInfoFor(makeSidecar({
        setupHeader: [1, 2, 3, 4, 5], totalByteLength: 0, totalDuration: 0, preSkip: 0, points: [],
    }));
    const d = new OpusFormatDecoder();
    assertEqual(info.audioDataOffset, 5, 'audioDataOffset == setup header length');
    assertEqual(d.calculateByteOffset(info, 10), info.audioDataOffset, 'empty index degrades');
});

// --- getAlignedSegmentSize: Ogg "OggS" page-boundary alignment --------------------------------

function withOggS(len: number, ...pageStarts: number[]): Uint8Array {
    const out = new Uint8Array(len).fill(0xaa);
    for (const s of pageStarts) { out[s] = 0x4f; out[s + 1] = 0x67; out[s + 2] = 0x67; out[s + 3] = 0x53; }
    return out;
}
const stubInfo = { audioDataOffset: 0 } as FormatInfo;

test('getAlignedSegmentSize cuts at the last OggS page start within the window', () => {
    const raw = withOggS(64, 4, 40);
    assertEqual(new OpusFormatDecoder().getAlignedSegmentSize(stubInfo, 64, 64, false, raw), 40, 'last page start');
});

test('getAlignedSegmentSize waits (returns 0) when no page boundary is found mid-stream', () => {
    const raw = withOggS(64);
    assertEqual(new OpusFormatDecoder().getAlignedSegmentSize(stubInfo, 64, 64, false, raw), 0, 'no boundary');
});

test('getAlignedSegmentSize flushes the whole candidate on stream completion without a boundary', () => {
    const raw = withOggS(64);
    assertEqual(new OpusFormatDecoder().getAlignedSegmentSize(stubInfo, 64, 64, true, raw), 64, 'flush on complete');
});

test('getAlignedSegmentSize ignores a page start at offset 0 (needs a real cut point)', () => {
    const raw = withOggS(64, 0);
    assertEqual(new OpusFormatDecoder().getAlignedSegmentSize(stubInfo, 64, 64, false, raw), 0, 'offset 0 skipped');
});

// --- wrapSegment: OpusHead/OpusTags setup-header carry ----------------------------------------

test('wrapSegment prepends the cached setup bytes to a page run', () => {
    const setup = [0x4f, 0x70, 0x75, 0x73, 0x48, 0x65, 0x61, 0x64]; // "OpusHead"
    const info = formatInfoFor(makeSidecar({
        setupHeader: setup, totalByteLength: 100, totalDuration: 1, preSkip: 0,
        points: [{ granule: 0, byteOffset: setup.length }],
    }));
    const pageRun = new Uint8Array([0x4f, 0x67, 0x67, 0x53, 0x11, 0x22]); // "OggS" + payload
    const wrapped = new OpusFormatDecoder().wrapSegment(info, pageRun);
    assertArray(wrapped.subarray(0, setup.length), setup, 'setup header first');
    assertArray(wrapped.subarray(setup.length), [0x4f, 0x67, 0x67, 0x53, 0x11, 0x22], 'page run follows');
});

// --- report ----------------------------------------------------------------------------------
if (failures.length > 0) {
    console.error(failures.join('\n'));
    throw new Error(`${failures.length} test(s) failed, ${passed} passed`);
}
console.log(`ALL ${passed} TESTS PASSED`);