// Copyright 2015-2020 Parity Technologies (UK) Ltd.
// This file is part of OpenEthereum.

// OpenEthereum is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// OpenEthereum is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with OpenEthereum.  If not, see <http://www.gnu.org/licenses/>.

use super::{Address, Error, Public, Secret, SECP256K1};
use keccak::Keccak256;
use rustc_hex::ToHex;
use secp256k1::key;
use std::fmt;

pub fn public_to_address(public: &Public) -> Address {
    let hash = public.keccak256();
    let mut result = Address::default();
    result.copy_from_slice(&hash[12..]);
    result
}

#[derive(Debug, Clone, PartialEq)]
/// secp256k1 key pair
pub struct KeyPair {
    secret: Secret,
    public: Public,
}

impl fmt::Display for KeyPair {
    fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
        writeln!(f, "secret:  {}", self.secret.to_hex())?;
        writeln!(f, "public:  {}", self.public.to_hex())?;
        write!(f, "address: {}", self.address().to_hex())
    }
}

impl KeyPair {
    /// Create a pair from secret key
    pub fn from_secret(secret: Secret) -> Result<KeyPair, Error> {
        let context = &SECP256K1;
        let s: key::SecretKey = key::SecretKey::from_slice(context, &secret[..])?;
        let pub_key = key::PublicKey::from_secret_key(context, &s)?;
        let serialized = pub_key.serialize_vec(context, false);

        let mut public = Public::default();
        public.copy_from_slice(&serialized[1..65]);

        let keypair = KeyPair {
            secret: secret,
            public: public,
        };

        Ok(keypair)
    }

    pub fn from_secret_slice(slice: &[u8]) -> Result<KeyPair, Error> {
        Self::from_secret(Secret::from_unsafe_slice(slice)?)
    }

    pub fn from_keypair(sec: key::SecretKey, publ: key::PublicKey) -> Self {
        let context = &SECP256K1;
        let serialized = publ.serialize_vec(context, false);
        let secret = Secret::from(sec);
        let mut public = Public::default();
        public.copy_from_slice(&serialized[1..65]);

        KeyPair {
            secret: secret,
            public: public,
        }
    }

    pub fn secret(&self) -> &Secret {
        &self.secret
    }

    pub fn public(&self) -> &Public {
        &self.public
    }

    pub fn address(&self) -> Address {
        public_to_address(&self.public)
    }
}

#[cfg(test)]
mod tests {
    use std::str::FromStr;
    use KeyPair;
    use Secret;

    #[test]
    fn from_secret() {
        let secret =
            Secret::from_str("a100df7a048e50ed308ea696dc600215098141cb391e9527329df289f9383f65")
                .unwrap();
        let _ = KeyPair::from_secret(secret).unwrap();
    }

    #[test]
    fn keypair_display() {
        let expected =
"secret:  a100df7a048e50ed308ea696dc600215098141cb391e9527329df289f9383f65
public:  8ce0db0b0359ffc5866ba61903cc2518c3675ef2cf380a7e54bde7ea20e6fa1ab45b7617346cd11b7610001ee6ae5b0155c41cad9527cbcdff44ec67848943a4
address: 5b073e9233944b5e729e46d618f0d8edf3d9c34a".to_owned();
        let secret =
            Secret::from_str("a100df7a048e50ed308ea696dc600215098141cb391e9527329df289f9383f65")
                .unwrap();
        let kp = KeyPair::from_secret(secret).unwrap();
        assert_eq!(format!("{}", kp), expected);
    }
}