use bitcoin::{bech32, SigHashType};
use bitcoin::hashes::hash160::Hash as BitcoinHash160;
use bitcoin::hashes::sha256::Hash as BitcoinSha256;
use bitcoin::hashes::{Hash, HashEngine, HmacEngine, Hmac};
use bitcoin::secp256k1;
use bitcoin::secp256k1::{PublicKey, Secp256k1, SecretKey, SignOnly, Signature};
use bitcoin::util::address::Payload;
use bitcoin::util::bip32::{ChildNumber, ExtendedPrivKey, ExtendedPubKey};
use bitcoin::Network;

fn hkdf_extract_expand(salt: &[u8], secret: &[u8], info: &[u8], output: &mut [u8]) {
    let mut hmac = HmacEngine::<BitcoinSha256>::new(salt);
    hmac.input(secret);
    let prk = Hmac::from_engine(hmac).into_inner();

    let mut t = [0; 32];
    let mut n: u8 = 0;

    for chunk in output.chunks_mut(32) {
        let mut hmac = HmacEngine::<BitcoinSha256>::new(&prk[..]);
        n = n.checked_add(1).expect("HKDF size limit exceeded.");
        if n != 1 {
            hmac.input(&t);
        }
        hmac.input(&info);
        hmac.input(&[n]);
        t = Hmac::from_engine(hmac).into_inner();
        chunk.copy_from_slice(&t);
    }
}

pub fn hkdf_sha256(secret: &[u8], info: &[u8], salt: &[u8]) -> [u8; 32] {
    let mut result = [0u8; 32];
    hkdf_extract_expand(salt, secret, info, &mut result);
    result
}

pub fn hkdf_sha256_keys(secret: &[u8], info: &[u8], salt: &[u8]) -> [u8; 32 * 6] {
    let mut result = [0u8; 32 * 6];
    hkdf_extract_expand(salt, secret, info, &mut result);
    result
}

pub fn channels_seed(node_seed: &[u8]) -> [u8; 32] {
    hkdf_sha256(node_seed, "peer seed".as_bytes(), &[])
}

// This function will panic if the SecretKey::from_slice fails.  Only
// use where failure is an option (ie, startup).
pub fn node_keys_native(
    secp_ctx: &Secp256k1<SignOnly>,
    node_seed: &[u8],
) -> (PublicKey, SecretKey) {
    let node_private_bytes = hkdf_sha256(node_seed, "nodeid".as_bytes(), &[]);
    let node_secret_key = SecretKey::from_slice(&node_private_bytes).unwrap();
    let node_id = PublicKey::from_secret_key(&secp_ctx, &node_secret_key);
    (node_id, node_secret_key)
}

pub fn node_keys_lnd(
    secp_ctx: &Secp256k1<SignOnly>,
    network: Network,
    master: ExtendedPrivKey,
) -> (PublicKey, SecretKey) {
    let key_family_node_key = 6;
    let index = 0;
    derive_key_lnd(secp_ctx, network, master, key_family_node_key, index)
}

pub fn derive_key_lnd(
    secp_ctx: &Secp256k1<SignOnly>,
    network: Network,
    master: ExtendedPrivKey,
    key_family: u32,
    index: u32,
) -> (PublicKey, SecretKey) {
    let bip43purpose = 1017;
    #[rustfmt::skip]
    let coin_type = match network { // NOT TESTED
        bitcoin::Network::Bitcoin => 0,
        bitcoin::Network::Testnet => 1,
        bitcoin::Network::Regtest => 1, // NOT TESTED
        bitcoin::Network::Signet => 1, // NOT TESTED
    };
    let branch = 0;
    let node_ext_prv = master
        .ckd_priv(
            &secp_ctx,
            ChildNumber::from_hardened_idx(bip43purpose).unwrap(),
        )
        .unwrap()
        .ckd_priv(
            &secp_ctx,
            ChildNumber::from_hardened_idx(coin_type).unwrap(),
        )
        .unwrap()
        .ckd_priv(
            &secp_ctx,
            ChildNumber::from_hardened_idx(key_family).unwrap(),
        )
        .unwrap()
        .ckd_priv(&secp_ctx, ChildNumber::from_normal_idx(branch).unwrap())
        .unwrap()
        .ckd_priv(&secp_ctx, ChildNumber::from_normal_idx(index).unwrap())
        .unwrap();
    let node_ext_pub = &ExtendedPubKey::from_private(&secp_ctx, &node_ext_prv);
    (node_ext_pub.public_key.key, node_ext_prv.private_key.key)
}

// This function will panic if the ExtendedPrivKey::new_master fails.
// Only use where failure is an option (ie, startup).
pub fn get_account_extended_key_native(
    secp_ctx: &Secp256k1<SignOnly>,
    network: Network,
    node_seed: &[u8],
) -> ExtendedPrivKey {
    let bip32_seed = hkdf_sha256(node_seed, "bip32 seed".as_bytes(), &[]);
    let master = ExtendedPrivKey::new_master(network.clone(), &bip32_seed).unwrap();
    master
        .ckd_priv(&secp_ctx, ChildNumber::from_normal_idx(0).unwrap())
        .unwrap()
        .ckd_priv(&secp_ctx, ChildNumber::from_normal_idx(0).unwrap())
        .unwrap()
}

// This function will panic if the ExtendedPrivKey::new_master fails.
// Only use where failure is an option (ie, startup).
pub fn get_account_extended_key_lnd(
    secp_ctx: &Secp256k1<SignOnly>,
    network: Network,
    node_seed: &[u8],
) -> ExtendedPrivKey {
    // Must match btcsuite/btcwallet/waddrmgr/scoped_manager.go
    let master = ExtendedPrivKey::new_master(network.clone(), node_seed).unwrap();
    let purpose = 84;
    let cointype = 0;
    let account = 0;
    master
        .ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(purpose).unwrap())
        .unwrap()
        .ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(cointype).unwrap())
        .unwrap()
        .ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(account).unwrap())
        .unwrap()
}

pub fn derive_public_key<T: secp256k1::Signing>(
    secp_ctx: &Secp256k1<T>,
    per_commitment_point: &PublicKey,
    base_point: &PublicKey,
) -> Result<PublicKey, secp256k1::Error> {
    let mut sha = BitcoinSha256::engine();
    sha.input(&per_commitment_point.serialize());
    sha.input(&base_point.serialize());
    let res = BitcoinSha256::from_engine(sha).into_inner();

    let hashkey = PublicKey::from_secret_key(&secp_ctx, &SecretKey::from_slice(&res)?);
    base_point.combine(&hashkey)
}

// FIXME - copied from chan_utils.derive_public_revocation_key, lobby to increase visibility.
pub fn derive_revocation_pubkey<T: secp256k1::Verification>(
    secp_ctx: &Secp256k1<T>,
    per_commitment_point: &PublicKey,
    revocation_base_point: &PublicKey,
) -> Result<PublicKey, secp256k1::Error> {
    let rev_append_commit_hash_key = {
        let mut sha = BitcoinSha256::engine();
        sha.input(&revocation_base_point.serialize());
        sha.input(&per_commitment_point.serialize());

        BitcoinSha256::from_engine(sha).into_inner()
    };
    let commit_append_rev_hash_key = {
        let mut sha = BitcoinSha256::engine();
        sha.input(&per_commitment_point.serialize());
        sha.input(&revocation_base_point.serialize());

        BitcoinSha256::from_engine(sha).into_inner()
    };

    let mut part_a = revocation_base_point.clone();
    part_a.mul_assign(&secp_ctx, &rev_append_commit_hash_key)?;
    let mut part_b = per_commitment_point.clone();
    part_b.mul_assign(&secp_ctx, &commit_append_rev_hash_key)?;
    part_a.combine(&part_b)
}

// FIXME - copied from chan_utils, lobby to increase visibility.
pub fn derive_private_revocation_key<T: secp256k1::Signing>(
    secp_ctx: &Secp256k1<T>,
    per_commitment_secret: &SecretKey,
    revocation_base_secret: &SecretKey,
) -> Result<SecretKey, secp256k1::Error> {
    let revocation_base_point = PublicKey::from_secret_key(&secp_ctx, &revocation_base_secret);
    let per_commitment_point = PublicKey::from_secret_key(&secp_ctx, &per_commitment_secret);

    let rev_append_commit_hash_key = {
        let mut sha = BitcoinSha256::engine();
        sha.input(&revocation_base_point.serialize());
        sha.input(&per_commitment_point.serialize());

        BitcoinSha256::from_engine(sha).into_inner()
    };
    let commit_append_rev_hash_key = {
        let mut sha = BitcoinSha256::engine();
        sha.input(&per_commitment_point.serialize());
        sha.input(&revocation_base_point.serialize());

        BitcoinSha256::from_engine(sha).into_inner()
    };

    let mut part_a = revocation_base_secret.clone();
    part_a.mul_assign(&rev_append_commit_hash_key)?;
    let mut part_b = per_commitment_secret.clone();
    part_b.mul_assign(&commit_append_rev_hash_key)?;
    part_a.add_assign(&part_b[..])?;
    Ok(part_a)
}

pub fn payload_for_p2wpkh(key: &PublicKey) -> Payload {
    let mut hash_engine = BitcoinHash160::engine();
    hash_engine.input(&key.serialize());
    Payload::WitnessProgram {
        version: bech32::u5::try_from_u8(0).expect("0<32"),
        program: BitcoinHash160::from_engine(hash_engine)[..].to_vec(),
    }
}

pub fn signature_to_bitcoin_vec(sig: Signature) -> Vec<u8> {
    let mut sigvec = sig.serialize_der().to_vec();
    sigvec.push(SigHashType::All as u8);
    sigvec
}

#[cfg(test)]
mod tests {
    use super::*;
    use bitcoin::Network::Testnet;

    #[test]
    fn node_keys_native_test() -> Result<(), ()> {
        let secp_ctx = Secp256k1::signing_only();
        let (node_id, _) = node_keys_native(&secp_ctx, &[0u8; 32]);
        let node_id_bytes = node_id.serialize().to_vec();
        assert!(
            hex::encode(&node_id_bytes)
                == "02058e8b6c2ad363ec59aa136429256d745164c2bdc87f98f0a68690ec2c5c9b0b"
        );
        Ok(())
    }

    #[test]
    fn node_keys_lnd_test() -> Result<(), ()> {
        let secp_ctx = Secp256k1::signing_only();
        let network = Testnet;
        let master = ExtendedPrivKey::new_master(network.clone(), &[0u8; 32]).unwrap();
        let (node_id, _) = node_keys_lnd(&secp_ctx, network, master);
        let node_id_bytes = node_id.serialize().to_vec();
        assert_eq!(
            hex::encode(&node_id_bytes),
            "0287a5eab0a005ea7f08a876257b98868b1e5b5a9167385904396743faa61a4745"
        );
        Ok(())
    }

    #[test]
    fn channels_seed_test() -> Result<(), ()> {
        let seed = channels_seed(&[0u8; 32]);
        assert_eq!(
            hex::encode(&seed),
            "ab7f29780659755f14afb82342dc19db7d817ace8c312e759a244648dfc25e53"
        );
        Ok(())
    }

    #[test]
    fn get_account_extended_key_test() -> Result<(), ()> {
        let secp_ctx = Secp256k1::signing_only();
        let key = get_account_extended_key_native(&secp_ctx, Network::Testnet, &[0u8; 32]);
        assert_eq!(format!("{}", key), "tprv8ejySXSgpWvEBguEGNFYNcHz29W7QxEodgnwbfLzBCccBnxGAq4vBkgqUYPGR5EnCbLvJE7YQsod6qpid85JhvAfizVpqPg3WsWB6UG3fEL");
        Ok(())
    }

    #[test]
    fn test_hkdf() {
        let secret = [1u8];
        let info = [2u8];
        let salt = [3u8];
        let mut output = [0u8; 32*6];
        hkdf_extract_expand(&salt, &secret, &info, &mut output);
        assert_eq!(hex::encode(output.to_vec()), "13a04658302cc5173a8077f2f296662a7a3ddb2359be92770b13e0b9e63a23d0efbbb13e74af4687137801e1628d1d1876d251b31d1321383568a9387da7c0baa7dee83ba374bba3774ef01140e4c4293791a512e536764bf4405aea511be32d5fd71a0b7a7ef3638312e476eb323fbac5f3d549ccf0fe0eabb38fe7bc16ad01db2288e57de45eabecd561ede4dc89164099ed7f0b0db5250e2b377e2aa84f520838612dccbde870f7b06a1e03f3cd79d30da717c55e15442a0b4dd02aafcd86");
        let mut output = [0u8; 32];
        hkdf_extract_expand(&salt, &secret, &info, &mut output);
        assert_eq!(hex::encode(output.to_vec()), "13a04658302cc5173a8077f2f296662a7a3ddb2359be92770b13e0b9e63a23d0");
    }
}