'use strict';
const { test } = require('node:test');
const assert = require('node:assert');
const crypto = require('node:crypto');
const Sha256 = require('./sha256');

const ref = (buf) => crypto.createHash('sha256').update(buf).digest('hex');

test('known vectors', () => {
  assert.strictEqual(Sha256.hex(new Uint8Array(0)), 'e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855');
  assert.strictEqual(Sha256.hex(new TextEncoder().encode('abc')), 'ba7816bf8f01cfea414140de5dae2223b00361a396177a9cb410ff61f20015ad');
  assert.strictEqual(
    Sha256.hex(new TextEncoder().encode('abcdbcdecdefdefgefghfghighijhijkijkljklmklmnlmnomnopnopq')),
    '248d6a61d20638b8e5c026930c3e6039a33ce45964ff2167f6ecedd419db06c1');
});

test('every length around block boundaries matches node:crypto', () => {
  for (let n = 0; n <= 200; n++) {
    const buf = crypto.randomBytes(n);
    assert.strictEqual(Sha256.hex(new Uint8Array(buf)), ref(buf), 'length ' + n);
  }
});

test('random chunk boundaries give the same digest as one shot', () => {
  const buf = crypto.randomBytes(3 * 1024 * 1024 + 17);
  for (let round = 0; round < 5; round++) {
    const h = Sha256.create();
    let pos = 0;
    while (pos < buf.length) {
      const n = Math.min(buf.length - pos, 1 + Math.floor(Math.random() * 200000));
      h.update(new Uint8Array(buf.buffer, buf.byteOffset + pos, n));
      pos += n;
    }
    assert.strictEqual(h.hex(), ref(buf));
    assert.strictEqual(h.bytes, buf.length);
  }
});

test('update after digest throws; isHex', () => {
  const h = Sha256.create();
  h.hex();
  assert.throws(() => h.update(new Uint8Array(1)));
  assert.ok(Sha256.isHex(ref(Buffer.from('x'))));
  assert.ok(!Sha256.isHex('ABC'));
});

// ---- WebAssembly engine ----
test('wasm engine is available in Node and matches the JS engine and node:crypto', () => {
  const crypto = require('node:crypto');
  assert.equal(Sha256.engine(), 'wasm');
  const sizes = [0, 1, 55, 56, 63, 64, 65, 1000, (1 << 20) - 1, 1 << 20, (1 << 20) + 1, 3_000_001];
  for (const n of sizes) {
    const buf = Buffer.alloc(n).map((_, i) => (i * 7 + n) & 255);
    const want = crypto.createHash('sha256').update(buf).digest('hex');
    assert.equal(Sha256.create().update(buf).hex(), want, `wasm ${n}`);
    assert.equal(Sha256.create({ js: true }).update(buf).hex(), want, `js ${n}`);
  }
});

test('wasm engine hashes streamed odd-sized chunks like one-shot', () => {
  const crypto = require('node:crypto');
  const buf = Buffer.alloc(2_500_003).map((_, i) => (i * 13) & 255);
  const h = Sha256.create();
  for (let o = 0; o < buf.length; o += 77_777) h.update(buf.subarray(o, o + 77_777));
  assert.equal(h.hex(), crypto.createHash('sha256').update(buf).digest('hex'));
});

test('falls back to the JS engine when WebAssembly is unavailable', () => {
  const { execFileSync } = require('node:child_process');
  const out = execFileSync(process.execPath, ['-e',
    "delete globalThis.WebAssembly; const S=require('./frontend/sha256.js');" +
    "console.log(S.engine(), S.hex(new TextEncoder().encode('abc')))"], { cwd: require('node:path').join(__dirname, '..') }).toString().trim();
  assert.equal(out, 'js ba7816bf8f01cfea414140de5dae2223b00361a396177a9cb410ff61f20015ad');
});