// Rust Bitcoin Library
// Written in 2014 by
//     Andrew Poelstra <apoelstra@wpsoftware.net>
// To the extent possible under law, the author(s) have dedicated all
// copyright and related and neighboring rights to this software to
// the public domain worldwide. This software is distributed without
// any warranty.
//
// You should have received a copy of the CC0 Public Domain Dedication
// along with this software.
// If not, see <http://creativecommons.org/publicdomain/zero/1.0/>.
//

//! Private key
//!
//! A private key represents the secret data associated with its proposed use
//!

use std::fmt::{self, Write};
use std::str::FromStr;
use secp256k1::{self, Secp256k1};
use secp256k1::key::{PublicKey, SecretKey};
use consensus::encode;
use network::constants::Network;
use util::base58;

#[derive(Clone, PartialEq, Eq)]
/// A Bitcoin ECDSA private key
pub struct PrivateKey {
    /// Whether this private key represents a compressed address
    pub compressed: bool,
    /// The network on which this key should be used
    pub network: Network,
    /// The actual ECDSA key
    pub key: SecretKey
}

impl PrivateKey {
    /// Computes the public key as supposed to be used with this secret
    pub fn public_key<C: secp256k1::Signing>(&self, secp: &Secp256k1<C>) -> PublicKey {
        PublicKey::from_secret_key(secp, &self.key)
    }

    /// Format the private key to WIF format.
    pub fn fmt_wif(&self, fmt: &mut fmt::Write) -> fmt::Result {
        let mut ret = [0; 34];
        ret[0] = match self.network {
            Network::Bitcoin => 128,
            Network::Testnet | Network::Regtest => 239,
        };
        ret[1..33].copy_from_slice(&self.key[..]);
        let privkey = if self.compressed {
            ret[33] = 1;
            base58::check_encode_slice(&ret[..])
        } else {
            base58::check_encode_slice(&ret[..33])
        };
        fmt.write_str(&privkey)
    }

    /// Get WIF encoding of this private key.
    pub fn to_wif(&self) -> String {
        let mut buf = String::new();
        buf.write_fmt(format_args!("{}", self)).unwrap();
        buf.shrink_to_fit();
        buf
    }

    /// Parse WIF encoded private key.
    pub fn from_wif(wif: &str) -> Result<PrivateKey, encode::Error> {
        let data = base58::from_check(wif)?;

        let compressed = match data.len() {
            33 => false,
            34 => true,
            _ => { return Err(encode::Error::Base58(base58::Error::InvalidLength(data.len()))); }
        };

        let network = match data[0] {
            128 => Network::Bitcoin,
            239 => Network::Testnet,
            x   => { return Err(encode::Error::Base58(base58::Error::InvalidVersion(vec![x]))); }
        };

        let key = SecretKey::from_slice(&data[1..33])
            .map_err(|_| base58::Error::Other("Secret key out of range".to_owned()))?;

        Ok(PrivateKey {
            compressed: compressed,
            network: network,
            key: key
        })
    }
}

impl fmt::Display for PrivateKey {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        self.fmt_wif(f)
    }
}

impl fmt::Debug for PrivateKey {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        write!(f, "[private key data]")
    }
}

impl FromStr for PrivateKey {
    type Err = encode::Error;
    fn from_str(s: &str) -> Result<PrivateKey, encode::Error> {
        PrivateKey::from_wif(s)
    }
}

#[cfg(test)]
mod tests {
    use super::PrivateKey;
    use secp256k1::Secp256k1;
    use std::str::FromStr;
    use network::constants::Network::Testnet;
    use network::constants::Network::Bitcoin;
    use util::address::Address;

    #[test]
    fn test_key_derivation() {
        // testnet compressed
        let sk = PrivateKey::from_wif("cVt4o7BGAig1UXywgGSmARhxMdzP5qvQsxKkSsc1XEkw3tDTQFpy").unwrap();
        assert_eq!(sk.network, Testnet);
        assert_eq!(sk.compressed, true);
        assert_eq!(&sk.to_wif(), "cVt4o7BGAig1UXywgGSmARhxMdzP5qvQsxKkSsc1XEkw3tDTQFpy");

        let secp = Secp256k1::new();
        let pk = Address::p2pkh(&sk.public_key(&secp), sk.network);
        assert_eq!(&pk.to_string(), "mqwpxxvfv3QbM8PU8uBx2jaNt9btQqvQNx");

        // test string conversion
        assert_eq!(&sk.to_string(), "cVt4o7BGAig1UXywgGSmARhxMdzP5qvQsxKkSsc1XEkw3tDTQFpy");
        let sk_str =
            PrivateKey::from_str("cVt4o7BGAig1UXywgGSmARhxMdzP5qvQsxKkSsc1XEkw3tDTQFpy").unwrap();
        assert_eq!(&sk.to_wif(), &sk_str.to_wif());

        // mainnet uncompressed
        let sk = PrivateKey::from_wif("5JYkZjmN7PVMjJUfJWfRFwtuXTGB439XV6faajeHPAM9Z2PT2R3").unwrap();
        assert_eq!(sk.network, Bitcoin);
        assert_eq!(sk.compressed, false);
        assert_eq!(&sk.to_wif(), "5JYkZjmN7PVMjJUfJWfRFwtuXTGB439XV6faajeHPAM9Z2PT2R3");

        let secp = Secp256k1::new();
        let pk = Address::p2upkh(&sk.public_key(&secp), sk.network);
        assert_eq!(&pk.to_string(), "1GhQvF6dL8xa6wBxLnWmHcQsurx9RxiMc8");
    }
}