use libsignal_protocol::*;
use rand::SeedableRng;

/// Test PQXDH key component generation
///
/// PQXDH extends X3DH with post-quantum cryptography:
/// - Classical components: Identity keys (IK), Signed prekeys (SPK), One-time prekeys (OPK)
/// - Post-quantum components: KEM identity keys (IK_KEM), KEM prekeys (SPK_KEM), KEM one-time prekeys (OPK_KEM)
/// - Hybrid approach combines classical ECDH with post-quantum KEM for quantum resistance
///
/// Note: This is a placeholder implementation. Full PQXDH requires:
/// - Kyber KEM (NIST ML-KEM) or similar post-quantum KEM
/// - Hybrid key derivation combining classical and PQ secrets
#[test]
fn test_pqxdh_key_generation() -> Result<(), SignalProtocolError> {
    println!("🔐⚛️ Testing PQXDH Key Generation Components");
    println!("🔑 Note: Using classical keys as placeholder for post-quantum components");

    let mut rng = rand_chacha::ChaCha20Rng::from_seed([1u8; 32]);

    // === Classical cryptographic components (same as X3DH) ===

    // Generate identity key pairs (long-term keys)
    let _alice_identity = IdentityKeyPair::generate(&mut rng);
    let bob_identity = IdentityKeyPair::generate(&mut rng);
    println!("✅ Classical identity keys (IK_A, IK_B) generated");

    // Generate signed prekey pair
    let bob_signed_prekey_pair = KeyPair::generate(&mut rng);
    let bob_signed_prekey_signature = bob_identity
        .private_key()
        .calculate_signature(&bob_signed_prekey_pair.public_key.serialize(), &mut rng)?;

    assert_eq!(bob_signed_prekey_signature.len(), 64);
    println!(" Classical signed prekey (SPK_B) with signature generated");

    // Generate one-time prekey
    let _bob_one_time_prekey = KeyPair::generate(&mut rng);
    println!(" Classical one-time prekey (OPK_B) generated");

    // === Post-quantum KEM components (placeholder) ===

    // TODO: Replace with actual Kyber/ML-KEM implementation
    // For now, using classical keys as placeholders to demonstrate structure

    // KEM identity keys
    let _alice_kem_identity = KeyPair::generate(&mut rng);
    let _bob_kem_identity = KeyPair::generate(&mut rng);
    println!("Post-quantum KEM identity keys (IK_KEM_A, IK_KEM_B) generated [PLACEHOLDER]");

    // KEM signed prekey
    let _bob_kem_signed_prekey = KeyPair::generate(&mut rng);
    println!("Post-quantum KEM signed prekey (SPK_KEM_B) generated [PLACEHOLDER]");

    // KEM one-time prekey
    let _bob_kem_one_time_prekey = KeyPair::generate(&mut rng);
    println!("Post-quantum KEM one-time prekey (OPK_KEM_B) generated [PLACEHOLDER]");

    println!("All PQXDH cryptographic components created successfully!");
    println!("   Classical components: IK, SPK, OPK (ECDH-based)");
    println!("   PQ components: IK_KEM, SPK_KEM, OPK_KEM (KEM-based, placeholder)");

    Ok(())
}

/// Test PQXDH key agreement protocol
///
/// PQXDH performs both classical and post-quantum key agreements:
///
/// Classical DH operations (same as X3DH):
/// - DH1 = DH(IK_A, SPK_B)
/// - DH2 = DH(EK_A, IK_B)
/// - DH3 = DH(EK_A, SPK_B)
/// - DH4 = DH(EK_A, OPK_B) [if one-time prekey available]
///
/// Post-quantum KEM operations:
/// - KEM1 = Encap(IK_KEM_B) -> (ciphertext1, shared_secret1)
/// - KEM2 = Encap(SPK_KEM_B) -> (ciphertext2, shared_secret2)
/// - KEM3 = Encap(OPK_KEM_B) -> (ciphertext3, shared_secret3) [if available]
///
/// Final shared secret:
/// - SK = KDF(DH1 || DH2 || DH3 || DH4 || KEM1 || KEM2 || KEM3)
///
/// This provides security even if quantum computers break ECDH in the future
#[test]
fn test_pqxdh_key_agreement() -> Result<(), SignalProtocolError> {
    println!("= Testing PQXDH Key Agreement Protocol");
    println!("�  Note: Using classical DH as placeholder for post-quantum KEM");

    let mut rng = rand_chacha::ChaCha20Rng::from_seed([1u8; 32]);

    // === Generate Alice's keys ===
    let alice_identity = IdentityKeyPair::generate(&mut rng);
    let alice_ephemeral = KeyPair::generate(&mut rng);
    let alice_kem_identity = KeyPair::generate(&mut rng); // Placeholder for KEM
    println!(" Alice's keys generated (IK_A, EK_A, IK_KEM_A)");

    // === Generate Bob's keys ===
    let bob_identity = IdentityKeyPair::generate(&mut rng);
    let bob_signed_prekey = KeyPair::generate(&mut rng);
    let bob_one_time_prekey = KeyPair::generate(&mut rng);
    let bob_kem_identity = KeyPair::generate(&mut rng); // Placeholder
    let bob_kem_signed_prekey = KeyPair::generate(&mut rng); // Placeholder
    let bob_kem_one_time_prekey = KeyPair::generate(&mut rng); // Placeholder
    println!(" Bob's keys generated (IK_B, SPK_B, OPK_B, IK_KEM_B, SPK_KEM_B, OPK_KEM_B)");

    // === Classical DH operations (Alice's side) ===

    println!("\n=� Classical DH operations:");

    // DH1 = DH(IK_A, SPK_B)
    let dh1_alice = alice_identity
        .private_key()
        .calculate_agreement(&bob_signed_prekey.public_key)?;

    // DH2 = DH(EK_A, IK_B)
    let dh2_alice = alice_ephemeral
        .private_key
        .calculate_agreement(bob_identity.public_key())?;

    // DH3 = DH(EK_A, SPK_B)
    let dh3_alice = alice_ephemeral
        .private_key
        .calculate_agreement(&bob_signed_prekey.public_key)?;

    // DH4 = DH(EK_A, OPK_B)
    let dh4_alice = alice_ephemeral
        .private_key
        .calculate_agreement(&bob_one_time_prekey.public_key)?;

    println!("   Alice completed 4 classical DH operations");

    // === Classical DH operations (Bob's side) ===

    let dh1_bob = bob_signed_prekey
        .private_key
        .calculate_agreement(alice_identity.public_key())?;

    let dh2_bob = bob_identity
        .private_key()
        .calculate_agreement(&alice_ephemeral.public_key)?;

    let dh3_bob = bob_signed_prekey
        .private_key
        .calculate_agreement(&alice_ephemeral.public_key)?;

    let dh4_bob = bob_one_time_prekey
        .private_key
        .calculate_agreement(&alice_ephemeral.public_key)?;

    println!("   Bob completed 4 classical DH operations");

    // Verify DH outputs match
    assert_eq!(dh1_alice, dh1_bob, "DH1 outputs must match");
    assert_eq!(dh2_alice, dh2_bob, "DH2 outputs must match");
    assert_eq!(dh3_alice, dh3_bob, "DH3 outputs must match");
    assert_eq!(dh4_alice, dh4_bob, "DH4 outputs must match");
    println!("   All classical DH outputs verified");

    // === Post-quantum KEM operations (placeholder using DH) ===

    println!("\n=� Post-quantum KEM operations (placeholder):");

    // TODO: Replace with actual KEM operations
    // Real KEM: (ciphertext, shared_secret) = Encapsulate(public_key)
    //           shared_secret = Decapsulate(ciphertext, private_key)

    // KEM1: Alice encapsulates to Bob's KEM identity key
    let kem1_alice = alice_kem_identity
        .private_key
        .calculate_agreement(&bob_kem_identity.public_key)?;
    let kem1_bob = bob_kem_identity
        .private_key
        .calculate_agreement(&alice_kem_identity.public_key)?;

    // KEM2: Alice encapsulates to Bob's KEM signed prekey
    let kem2_alice = alice_kem_identity
        .private_key
        .calculate_agreement(&bob_kem_signed_prekey.public_key)?;
    let kem2_bob = bob_kem_signed_prekey
        .private_key
        .calculate_agreement(&alice_kem_identity.public_key)?;

    // KEM3: Alice encapsulates to Bob's KEM one-time prekey
    let kem3_alice = alice_kem_identity
        .private_key
        .calculate_agreement(&bob_kem_one_time_prekey.public_key)?;
    let kem3_bob = bob_kem_one_time_prekey
        .private_key
        .calculate_agreement(&alice_kem_identity.public_key)?;

    assert_eq!(kem1_alice, kem1_bob, "KEM1 shared secrets must match");
    assert_eq!(kem2_alice, kem2_bob, "KEM2 shared secrets must match");
    assert_eq!(kem3_alice, kem3_bob, "KEM3 shared secrets must match");
    println!("   All PQ-KEM shared secrets verified (placeholder)");

    // === Hybrid key derivation ===

    println!("\n=� Hybrid key derivation:");

    // Concatenate all key material: DH1 || DH2 || DH3 || DH4 || KEM1 || KEM2 || KEM3
    let mut hybrid_key_material_alice = Vec::new();
    hybrid_key_material_alice.extend_from_slice(&dh1_alice);
    hybrid_key_material_alice.extend_from_slice(&dh2_alice);
    hybrid_key_material_alice.extend_from_slice(&dh3_alice);
    hybrid_key_material_alice.extend_from_slice(&dh4_alice);
    hybrid_key_material_alice.extend_from_slice(&kem1_alice);
    hybrid_key_material_alice.extend_from_slice(&kem2_alice);
    hybrid_key_material_alice.extend_from_slice(&kem3_alice);

    let mut hybrid_key_material_bob = Vec::new();
    hybrid_key_material_bob.extend_from_slice(&dh1_bob);
    hybrid_key_material_bob.extend_from_slice(&dh2_bob);
    hybrid_key_material_bob.extend_from_slice(&dh3_bob);
    hybrid_key_material_bob.extend_from_slice(&dh4_bob);
    hybrid_key_material_bob.extend_from_slice(&kem1_bob);
    hybrid_key_material_bob.extend_from_slice(&kem2_bob);
    hybrid_key_material_bob.extend_from_slice(&kem3_bob);

    assert_eq!(
        hybrid_key_material_alice, hybrid_key_material_bob,
        "Hybrid key material must match"
    );
    println!(
        "   Hybrid key material: {} bytes (4 DH + 3 KEM)",
        hybrid_key_material_alice.len()
    );

    // Apply HKDF to derive final shared secret
    use hkdf::Hkdf;
    use sha2::Sha256;

    let salt = [0xFFu8; 32];
    let info = b"PQXDH-SyftBox-v1";

    let hk = Hkdf::<Sha256>::new(Some(&salt), &hybrid_key_material_alice);
    let mut shared_secret_alice = [0u8; 32];
    hk.expand(info, &mut shared_secret_alice)
        .map_err(|_| SignalProtocolError::InvalidState("HKDF expand failed", "".to_string()))?;

    let hk = Hkdf::<Sha256>::new(Some(&salt), &hybrid_key_material_bob);
    let mut shared_secret_bob = [0u8; 32];
    hk.expand(info, &mut shared_secret_bob)
        .map_err(|_| SignalProtocolError::InvalidState("HKDF expand failed", "".to_string()))?;

    // Verify final shared secrets match
    assert_eq!(
        shared_secret_alice, shared_secret_bob,
        "Final shared secrets must match"
    );

    println!(
        "   Final shared secret (SK) derived: {} bytes",
        shared_secret_alice.len()
    );
    println!("  =� SK (hex): {}", hex::encode(&shared_secret_alice[..8]));

    println!("\n<� PQXDH Key Agreement completed successfully!");
    println!("   Hybrid security: Protected against both classical and quantum attacks");
    println!("   Classical: 4 ECDH operations (immediate security)");
    println!("   Post-quantum: 3 KEM operations (future quantum resistance) [PLACEHOLDER]");

    Ok(())
}

/// Test post-quantum KEM simulation
///
/// This test demonstrates how a real KEM (Key Encapsulation Mechanism) would work.
/// In a real implementation with Kyber/ML-KEM:
/// - Encapsulate(pk) -> (ciphertext, shared_secret)
/// - Decapsulate(sk, ciphertext) -> shared_secret
///
/// Properties:
/// - Only holder of private key can decapsulate
/// - Ciphertext can be public
/// - Provides IND-CCA2 security (quantum-resistant)
#[test]
fn test_kem_simulation() -> Result<(), SignalProtocolError> {
    println!("= Testing KEM Simulation (Placeholder)");
    println!("�  Real implementation would use Kyber/ML-KEM");

    let mut rng = rand_chacha::ChaCha20Rng::from_seed([1u8; 32]);

    // Generate KEM key pair (receiver)
    let receiver_kem_keypair = KeyPair::generate(&mut rng);
    println!(" Receiver KEM key pair generated");

    // === Sender: Encapsulate ===
    println!("\n=� Sender encapsulates:");

    // Real KEM: (ciphertext, shared_secret) = KEM.Encapsulate(receiver_pk)
    // Placeholder: Generate ephemeral key and perform DH
    let sender_ephemeral = KeyPair::generate(&mut rng);
    let shared_secret_sender = sender_ephemeral
        .private_key
        .calculate_agreement(&receiver_kem_keypair.public_key)?;

    // Ciphertext would be the encapsulated key; here it's the ephemeral public key
    let ciphertext = sender_ephemeral.public_key.serialize();

    println!(
        "   Shared secret generated: {} bytes",
        shared_secret_sender.len()
    );
    println!("   Ciphertext created: {} bytes", ciphertext.len());
    println!("  =� Ciphertext (hex): {}", hex::encode(&ciphertext[..8]));

    // === Receiver: Decapsulate ===
    println!("\n=� Receiver decapsulates:");

    // Real KEM: shared_secret = KEM.Decapsulate(receiver_sk, ciphertext)
    // Placeholder: Deserialize ephemeral public key and perform DH
    let sender_ephemeral_pk = PublicKey::deserialize(&ciphertext)?;
    let shared_secret_receiver = receiver_kem_keypair
        .private_key
        .calculate_agreement(&sender_ephemeral_pk)?;

    println!(
        "   Shared secret recovered: {} bytes",
        shared_secret_receiver.len()
    );

    // === Verify ===
    assert_eq!(
        shared_secret_sender, shared_secret_receiver,
        "Encapsulated and decapsulated secrets must match"
    );

    println!("   Shared secrets match!");
    println!(
        "  =� Shared secret (hex): {}",
        hex::encode(&shared_secret_sender[..8])
    );

    println!("\n<� KEM simulation completed successfully!");
    println!("   Real Kyber-768 would provide:");
    println!("   - Public key: 1184 bytes");
    println!("   - Ciphertext: 1088 bytes");
    println!("   - Shared secret: 32 bytes");
    println!("   - Security level: NIST Level 3 (quantum-resistant)");

    Ok(())
}
