import assert from 'node:assert/strict';
import test from 'node:test';

import {
  buildDiagnosticLoader,
  inspectFrankenElf,
  sha256,
} from '../../scripts/autonomous/build-kstuff-diagnostic-loader.mjs';

const MARKER = Buffer.from([0xeb, 0x0b, 0x50, 0x4c, 0x44, 0x00]);

function frankenElf(size) {
  const buffer = Buffer.alloc(size, 0x41);
  MARKER.copy(buffer);
  buffer.writeBigUInt64LE(64n, 32);
  buffer.writeUInt16LE(1, 56);
  buffer.writeUInt32LE(1, 64);
  buffer.writeUInt32LE(5, 68);
  buffer.writeBigUInt64LE(0n, 72);
  buffer.writeBigUInt64LE(BigInt(size), 96);
  buffer.writeBigUInt64LE(BigInt(size), 104);
  return buffer;
}

test('in-place diagnostic build preserves bytes after the exact embedded image span', () => {
  const prefix = Buffer.alloc(96, 0x23);
  const officialPayload = frankenElf(192);
  const suffix = Buffer.alloc(80, 0x7d);
  const officialLoader = Buffer.concat([prefix, officialPayload, suffix]);
  const diagnosticPayload = frankenElf(160);
  const manifest = { officialLoader: {
    size: officialLoader.length,
    sha256: sha256(officialLoader),
    embeddedPayloadOffset: prefix.length,
    embeddedPayloadSize: officialPayload.length,
  } };

  const result = buildDiagnosticLoader({ officialLoader, diagnosticPayload, manifest });
  assert.deepEqual(result.output.subarray(prefix.length + officialPayload.length), suffix);
  assert.equal(result.evidence.zeroPaddingBytes, 32);
  assert.equal(inspectFrankenElf(diagnosticPayload).imageSpan, diagnosticPayload.length);
});

test('in-place diagnostic build rejects a payload larger than the official image span', () => {
  const prefix = Buffer.alloc(96, 0x23);
  const officialPayload = frankenElf(192);
  const suffix = Buffer.alloc(80, 0x7d);
  const officialLoader = Buffer.concat([prefix, officialPayload, suffix]);
  const diagnosticPayload = frankenElf(208);
  const manifest = { officialLoader: {
    size: officialLoader.length,
    sha256: sha256(officialLoader),
    embeddedPayloadOffset: prefix.length,
    embeddedPayloadSize: officialPayload.length,
  } };

  assert.throws(
    () => buildDiagnosticLoader({ officialLoader, diagnosticPayload, manifest }),
    /rebuild the loader from pinned source/,
  );
});