package com.peachpasswords

import com.peachpasswords.sync.SASDerivation
import com.peachpasswords.sync.computeVaultId
import com.peachpasswords.sync.noiseNKHkdf2ForTest
import com.peachpasswords.sync.noiseNKInitHashForTest
import com.peachpasswords.vault.VaultCrypto
import org.junit.Assert.assertArrayEquals
import org.junit.Assert.assertEquals
import org.junit.Assert.assertFalse
import org.junit.Assert.assertNotEquals
import org.junit.Test
import java.text.Normalizer

/**
 * MN-4: cross-platform known-answer tests. These pin the byte-level output of the
 * primitives Android shares with the browser, so a regression on either side
 * (encoding, params, algorithm) is caught immediately. The Android implementations
 * are exact ports of the browser source, so these golden vectors hold on both.
 *
 * Inputs are fixed and printable; expected outputs are frozen below.
 */
class CrossPlatformKATTest {

    private fun hex(b: ByteArray) = b.joinToString("") { "%02x".format(it) }

    // Argon2id over the non-BMP password "test🔑" (U+1F511, UTF-8) and a fixed salt.
    private val argonSalt = ByteArray(VaultCrypto.SALT_SIZE) { it.toByte() }

    @Test fun argon2id_non_bmp_password_vector() {
        // password "test🔑" (UTF-8) + salt bytes 0x00..0x0f, Argon2id m=64MiB t=3 p=4.
        // Generated from peach-browser argon2.ts deriveKey after the LV-1 NFC fix —
        // the emoji is NFC-stable, so this vector holds across the normalization fix.
        val key = VaultCrypto.deriveKey("test🔑", argonSalt)
        assertEquals("a519dd4e695d25c6cd69a2f89d51ddcabd952c979f5714ab29fb77f6d1ad3728", hex(key))
    }

    @Test fun nfc_normalization_makes_composed_and_decomposed_match() {
        // MF-4 / LV-1: "café" decomposed (e + U+0301) and composed (U+00E9) must
        // derive the same key, matching the browser's password.normalize("NFC").
        val nfd = Normalizer.normalize("café", Normalizer.Form.NFD)
        val nfc = Normalizer.normalize("café", Normalizer.Form.NFC)
        assertNotEquals(nfd, nfc)
        assertArrayEquals(VaultCrypto.deriveKey(nfd, argonSalt), VaultCrypto.deriveKey(nfc, argonSalt))
    }

    @Test fun deriveKeyRaw_does_not_normalize() {
        val nfd = Normalizer.normalize("café", Normalizer.Form.NFD)
        val nfc = Normalizer.normalize("café", Normalizer.Form.NFC)
        assertFalse(
            VaultCrypto.deriveKeyRaw(nfd, argonSalt).contentEquals(VaultCrypto.deriveKeyRaw(nfc, argonSalt)),
        )
    }

    @Test fun compute_vault_id_vector() {
        // Blake3-256( masterKey(0x00..0x1f) || "peach-vault-id" ), hex.
        val masterKey = ByteArray(32) { it.toByte() }
        assertEquals("ae0ec54041c9ba3e20c0c2d33bdeb2552f3b9a3fb4be3286ec0ef0a61be2fc9c", computeVaultId(masterKey))
    }

    @Test fun sas_derivation_vector() {
        // First 4 bytes 0x12345678 = 305419896; 305419896 mod 1_000_000 = 419896.
        val handshakeHash = byteArrayOf(0x12, 0x34, 0x56, 0x78) + ByteArray(28)
        assertEquals("419896", SASDerivation.derive(handshakeHash))
    }

    // PCH-01-002: the Noise protocol-name init hash and the MixKey/Split HKDF now
    // derive over BLAKE2s to match the declared pattern name. These vectors are
    // pinned IDENTICALLY in peach-browser's noise-blake2s-kat.test.ts — a mismatch
    // here means the two repos' Noise wire derivations have diverged (which would
    // break cross-device pairing/sync). A SHA-256 revert on either side also fails.
    @Test fun noise_nk_init_hash_is_blake2s_vector() {
        assertEquals(
            "e01688d376ef280a27a8af5c559024a02017585b3763763e4f3c7118a979b09e",
            hex(noiseNKInitHashForTest()),
        )
    }

    @Test fun noise_hkdf2_blake2s_vector() {
        // ck = 0x00..0x1f, ikm = 0x20..0x3f.
        val ck = ByteArray(32) { it.toByte() }
        val ikm = ByteArray(32) { (it + 32).toByte() }
        val (nk1, nk2) = noiseNKHkdf2ForTest(ck, ikm)
        assertEquals("6a96444e20e8d4c1cee974416acae1c10b3c92886010e54ed94dafb2c3b80ea0", hex(nk1))
        assertEquals("57af120b0de7acbe7907ec149c5ae870a2dbb74232b65777ba4123f1f7f888f5", hex(nk2))
    }
}