// Crypto round-trip + verifier derivation tests.
//
// These lock down the invariants the CODE_AUDIT flagged as highest-risk for
// silent regression: the AES key must ALWAYS be raw PBKDF2 bytes (so entries
// stay decryptable across auth-scheme changes), and the transmitted verifier
// must be decoupled from that key under the v2 scheme.

const test = require('node:test');
const assert = require('node:assert/strict');
const { pbkdf2Sync, createHash } = require('node:crypto');
const { loadApp } = require('./harness.js');

const ctx = loadApp();
const T = ctx.__test;

// Reference PBKDF2 computed independently via Node (NOT via app.js) so the
// vectors actually cross-check rather than being self-referential. app.js
// feeds the salt STRING's UTF-8 bytes to PBKDF2 (salt = enc.encode(saltHex)),
// so the Node reference must do the same.
function refKeyHex(pwd, saltHex, iters) {
    return pbkdf2Sync(pwd, Buffer.from(saltHex, 'utf8'), iters, 32, 'sha256').toString('hex');
}
function refSha256Hex(str) {
    return createHash('sha256').update(str, 'utf8').digest('hex');
}

test('bytesToHex: lowercase, zero-padded, round-trips known bytes', () => {
    assert.equal(T.bytesToHex(new Uint8Array([0, 1, 15, 16, 255])), '00010f10ff');
    assert.equal(T.bytesToHex(new Uint8Array([])), '');
});

test('deriveKeyAndVerifier: AES key is raw PBKDF2 output (matches Node reference)', async () => {
    const pwd = 'correct horse battery staple';
    const saltHex = 'a1b2c3d4e5f6';
    const iters = 600000;
    const expectKeyHex = refKeyHex(pwd, saltHex, iters);

    const { cryptoKey } = await T.deriveKeyAndVerifier(pwd, saltHex, iters, T.HASH_ALGO_V2);
    const raw = await ctx.crypto.subtle.exportKey('raw', cryptoKey);
    assert.equal(T.bytesToHex(new Uint8Array(raw)), expectKeyHex,
        'AES key must equal hex(PBKDF2) regardless of hash_algo');
});

test('deriveKeyAndVerifier: legacy algo verifier IS the key hex', async () => {
    const pwd = 'hunter2';
    const saltHex = 'deadbeef';
    const iters = 100000;
    const expectKeyHex = refKeyHex(pwd, saltHex, iters);

    // Any non-v2 label → verifier verbatim = key hex (pre-decoupling accounts).
    const { verifier } = await T.deriveKeyAndVerifier(pwd, saltHex, iters, 'pbkdf2-sha256');
    assert.equal(verifier, expectKeyHex);

    // Unknown/empty algo must also fall through to key hex (safe rollout path).
    const empty = await T.deriveKeyAndVerifier(pwd, saltHex, iters, '');
    assert.equal(empty.verifier, expectKeyHex);
});

test('deriveKeyAndVerifier: v2 verifier is decoupled SHA-256(keyHex + domain)', async () => {
    const pwd = 'hunter2';
    const saltHex = 'deadbeef';
    const iters = 100000;
    const keyHex = refKeyHex(pwd, saltHex, iters);
    const expectVerifier = refSha256Hex(keyHex + T.AUTH_VERIFIER_DOMAIN);

    const { verifier } = await T.deriveKeyAndVerifier(pwd, saltHex, iters, T.HASH_ALGO_V2);
    assert.equal(verifier, expectVerifier);
    // The whole point of v2: the transmitted verifier must NOT be the key.
    assert.notEqual(verifier, keyHex, 'v2 verifier must not leak the AES key');
});

// ---- Argon2id KDF (js/argon2.js — vendored @noble/hashes) -------------------

test('vendored argon2id matches the RFC 9106 §5.3 test vector', () => {
    // Independent cross-check that the bundled library is correct (not just
    // self-consistent). Same vector used to validate the vendored bundle.
    const out = T.NobleArgon2.argon2id(
        new Uint8Array(32).fill(1), new Uint8Array(16).fill(2),
        { t: 3, m: 32, p: 4, dkLen: 32,
          key: new Uint8Array(8).fill(3),
          personalization: new Uint8Array(12).fill(4), version: 0x13 });
    assert.equal(T.bytesToHex(out),
        '0d640df58d78766c08c037a34a8b53c9d01ef0452d75b65eb52520e96b01e659');
});

test('argon2idAsync matches argon2id (deriveKeyBytes uses the async variant)', async () => {
    // deriveKeyBytes now calls argon2idAsync (yields to the event loop so the
    // unlock spinner animates). It must produce the exact same key as the sync
    // path — assert parity on the RFC vector.
    const args = [new Uint8Array(32).fill(1), new Uint8Array(16).fill(2),
        { t: 3, m: 32, p: 4, dkLen: 32, key: new Uint8Array(8).fill(3),
          personalization: new Uint8Array(12).fill(4), version: 0x13 }];
    const sync  = T.NobleArgon2.argon2id(...args);
    const async_ = await T.NobleArgon2.argon2idAsync(...args);
    assert.equal(T.bytesToHex(async_), T.bytesToHex(sync));
    assert.equal(T.bytesToHex(async_),
        '0d640df58d78766c08c037a34a8b53c9d01ef0452d75b65eb52520e96b01e659');
});

test('isDecoupledVerifierAlgo: all -v2 markers decouple, legacy does not', () => {
    assert.equal(T.isDecoupledVerifierAlgo(T.HASH_ALGO_V2), true);
    assert.equal(T.isDecoupledVerifierAlgo(T.HASH_ALGO_ARGON2), true);
    assert.equal(T.isDecoupledVerifierAlgo('pbkdf2-sha256'), false);
    assert.equal(T.isDecoupledVerifierAlgo('pbkdf2'), false);
    assert.equal(T.isDecoupledVerifierAlgo(''), false);
});

test('deriveKeyAndVerifier: argon2id branch derives an Argon2 key, NOT PBKDF2', async () => {
    const pwd = 'correct horse battery staple';
    const saltHex = 'a1b2c3d4e5f6a1b2';

    // The raw key bytes must equal argon2id(pwd, saltHex-utf8, params) — cross
    // checked against the vendored lib directly (small params for test speed).
    const params = { m: 256, t: 1, p: 1 };
    const expectKey = T.bytesToHex(T.NobleArgon2.argon2id(
        new TextEncoder().encode(pwd), new TextEncoder().encode(saltHex),
        { t: params.t, m: params.m, p: params.p, dkLen: 32, version: 0x13 }));

    const { cryptoKey, verifier } = await T.deriveKeyAndVerifier(
        pwd, saltHex, 0, T.HASH_ALGO_ARGON2, params);
    const raw = await ctx.crypto.subtle.exportKey('raw', cryptoKey);
    assert.equal(T.bytesToHex(new Uint8Array(raw)), expectKey, 'AES key must be the Argon2id output');

    // Differs from what PBKDF2 would give for the same pw/salt (different KDF).
    assert.notEqual(T.bytesToHex(new Uint8Array(raw)), refKeyHex(pwd, saltHex, 100000));

    // argon2id-v2 is a '-v2' scheme → verifier is decoupled SHA-256, not the key.
    assert.equal(verifier, refSha256Hex(expectKey + T.AUTH_VERIFIER_DOMAIN));
    assert.notEqual(verifier, expectKey, 'argon2id-v2 verifier must not leak the key');
});

test('deriveKeyAndVerifier: argon2id uses ARGON2_DEFAULT_PARAMS when none passed', async () => {
    // OWASP baseline is the default (m=19456, t=2, p=1). Just assert the
    // default object is what we expect; deriving at 19 MiB is left to one
    // explicit round-trip below to keep the suite fast.
    assert.deepEqual({ ...T.ARGON2_DEFAULT_PARAMS }, { m: 19456, t: 2, p: 1 });
});

test('argon2 param contract: identical params → identical key+verifier (register↔login)', async () => {
    // Register derives with params P; login re-derives with the params the
    // challenge echoes back. If those match, the key + verifier must match
    // exactly — otherwise the user could register but never log in.
    const pwd = 'pw', salt = 'saltsaltsalt', params = { m: 512, t: 2, p: 1 };
    const a = await T.deriveKeyAndVerifier(pwd, salt, 0, T.HASH_ALGO_ARGON2, params);
    const b = await T.deriveKeyAndVerifier(pwd, salt, 0, T.HASH_ALGO_ARGON2, { ...params });
    const ra = new Uint8Array(await ctx.crypto.subtle.exportKey('raw', a.cryptoKey));
    const rb = new Uint8Array(await ctx.crypto.subtle.exportKey('raw', b.cryptoKey));
    assert.equal(T.bytesToHex(ra), T.bytesToHex(rb));
    assert.equal(a.verifier, b.verifier);
});

test('argon2 param sensitivity: differing params → different key (transmission matters)', async () => {
    // If the server drops/garbles the echoed params, the client derives a
    // different key → login fails closed rather than silently mis-deriving.
    const pwd = 'pw', salt = 'saltsaltsalt';
    const a = await T.deriveKeyAndVerifier(pwd, salt, 0, T.HASH_ALGO_ARGON2, { m: 512, t: 2, p: 1 });
    const b = await T.deriveKeyAndVerifier(pwd, salt, 0, T.HASH_ALGO_ARGON2, { m: 512, t: 3, p: 1 });
    assert.notEqual(a.verifier, b.verifier);
});

test('encrypt/decrypt round-trips under an Argon2id-derived key', async () => {
    const { cryptoKey } = await T.deriveKeyAndVerifier(
        'master', 'saltsaltsalt', 0, T.HASH_ALGO_ARGON2, { m: 512, t: 1, p: 1 });
    T.state.cryptoKey = cryptoKey;
    const { encrypted, iv } = await T.encryptPwd('argon-secret 🔐');
    assert.equal(await T.decryptPwd(encrypted, iv), 'argon-secret 🔐');
});

test('verifierFromKeyHex: pure mapping matches deriveKeyAndVerifier', async () => {
    const keyHex = 'ab'.repeat(32);
    assert.equal(await T.verifierFromKeyHex(keyHex, 'anything-legacy'), keyHex);
    assert.equal(await T.verifierFromKeyHex(keyHex, T.HASH_ALGO_V2),
        refSha256Hex(keyHex + T.AUTH_VERIFIER_DOMAIN));
});

test('deriveKeyAndVerifier: default iterations = 100000 when falsy', async () => {
    const pwd = 'x';
    const saltHex = 'salt';
    const withDefault = await T.deriveKeyAndVerifier(pwd, saltHex, 0, 'pbkdf2-sha256');
    assert.equal(withDefault.verifier, refKeyHex(pwd, saltHex, 100000));
});

test('encryptPwd/decryptPwd: round-trips arbitrary strings under the vault key', async () => {
    // encryptPwd/decryptPwd read state.cryptoKey — set it to a derived key.
    const { cryptoKey } = await T.deriveKeyAndVerifier('master', 'saltsalt', 100000, T.HASH_ALGO_V2);
    T.state.cryptoKey = cryptoKey;

    for (const plain of ['', 'a', 'password123!', 'emoji 🔐 unicode ✓', 'x'.repeat(5000)]) {
        const { encrypted, iv } = await T.encryptPwd(plain);
        assert.equal(await T.decryptPwd(encrypted, iv), plain, `round-trip failed for len ${plain.length}`);
    }
});

test('encryptPwd: fresh random IV per call (no IV reuse)', async () => {
    const { cryptoKey } = await T.deriveKeyAndVerifier('m', 's', 100000, T.HASH_ALGO_V2);
    T.state.cryptoKey = cryptoKey;
    const a = await T.encryptPwd('same-plaintext');
    const b = await T.encryptPwd('same-plaintext');
    assert.notEqual(a.iv, b.iv, 'IVs must differ');
    assert.notEqual(a.encrypted, b.encrypted, 'ciphertext must differ for reused plaintext');
});

test('decryptPwd: tampered ciphertext returns "[ERROR]" (AEAD integrity)', async () => {
    const { cryptoKey } = await T.deriveKeyAndVerifier('m', 's', 100000, T.HASH_ALGO_V2);
    T.state.cryptoKey = cryptoKey;
    const { encrypted, iv } = await T.encryptPwd('secret');

    // Flip a byte in the ciphertext.
    const bytes = Uint8Array.from(atob(encrypted), c => c.charCodeAt(0));
    bytes[0] ^= 0xff;
    const tampered = btoa(String.fromCharCode(...bytes));
    assert.equal(await T.decryptPwd(tampered, iv), '[ERROR]');

    // Wrong IV also fails closed.
    assert.equal(await T.decryptPwd(encrypted, btoa('bad-iv-1234')), '[ERROR]');
});

test('decryptPwd: wrong key returns "[ERROR]" (not garbage plaintext)', async () => {
    const k1 = await T.deriveKeyAndVerifier('pw-one', 'salt', 100000, T.HASH_ALGO_V2);
    T.state.cryptoKey = k1.cryptoKey;
    const { encrypted, iv } = await T.encryptPwd('top secret');

    const k2 = await T.deriveKeyAndVerifier('pw-two', 'salt', 100000, T.HASH_ALGO_V2);
    T.state.cryptoKey = k2.cryptoKey;
    assert.equal(await T.decryptPwd(encrypted, iv), '[ERROR]');
});