use anyhow::Result;
use rand::{thread_rng, RngCore};
use sp_client::bitcoin::key::Secp256k1;
use sp_client::bitcoin::secp256k1::schnorr::Signature;
use sp_client::bitcoin::secp256k1::{Keypair, Message, SecretKey, XOnlyPublicKey};
use sp_client::bitcoin::hashes::{sha256t_hash_newtype, Hash, HashEngine};

sha256t_hash_newtype! {
    pub struct AnkMessageTag = hash_str("4nk/Message");

    #[hash_newtype(forward)]
    pub struct AnkMessageHash(_);
}

impl AnkMessageHash {
    pub fn from_message(message: &[u8]) -> Self {
        let mut eng = AnkMessageHash::engine();
        eng.input(&message);
        AnkMessageHash::from_engine(eng)
    }
}

pub fn sign_message(message: &[u8], signing_key: SecretKey) -> Result<Signature> {
    let message_hash = AnkMessageHash::from_message(message);

    let secp = Secp256k1::signing_only();

    let keypair = Keypair::from_secret_key(&secp, &signing_key);

    let mut aux_rand = [0u8; 32];

    thread_rng().fill_bytes(&mut aux_rand);

    let sig = secp.sign_schnorr_with_aux_rand(&Message::from_digest(message_hash.to_byte_array()), &keypair, &aux_rand);

    Ok(sig)
}

pub fn verify(sig: Signature, message: &[u8], x_only_key: XOnlyPublicKey) -> Result<()> {
    let secp = Secp256k1::verification_only();
    let message_hash = AnkMessageHash::from_message(message);
    secp.verify_schnorr(&sig, &Message::from_digest(message_hash.to_byte_array()), &x_only_key)?;

    Ok(())
}