// 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/>.
//

//! # Wallet
//!
//! Everything to do with the wallet
//!

use std::collections::HashMap;
use std::default::Default;
use serde::{Serialize, Deserialize, Serializer, Deserializer};

use secp256k1::key::PublicKey;

use byteorder::{ByteOrder, LittleEndian};
use blockdata::utxoset::UtxoSet;
use network::constants::Network;
use wallet::bip32::{self, ChildNumber, ExtendedPrivKey, ExtendedPubKey};
use wallet::bip32::ChildNumber::{Normal, Hardened};
use wallet::address::Address;
use wallet::address_index::AddressIndex;

/// A Wallet error
#[derive(Clone, PartialEq, Eq, Debug)]
pub enum Error {
    /// Tried to lookup an account by name, but none was found
    AccountNotFound,
    /// Tried to add an account when one already exists with that name
    DuplicateAccount,
    /// An error occured in a BIP32 derivation
    Bip32Error(bip32::Error),
    /// Tried to use a wallet without an address index
    NoAddressIndex
}

/// Each account has two chains, as specified in BIP32
pub enum AccountChain {
    /// Internal addresses are used within the wallet for change, etc,
    /// and in principle every generated one will be used.
    Internal,
    /// External addresses are shared, and might not be used after generatation,
    /// complicating recreating the whole wallet from seed.
    External
}

/// An account
#[derive(Clone, PartialEq, Eq, Serialize, Deserialize, Debug)]
pub struct Account {
    internal_path: Vec<ChildNumber>,
    internal_used: Vec<ChildNumber>,
    internal_next: u32,
    external_path: Vec<ChildNumber>,
    external_used: Vec<ChildNumber>,
    external_next: u32
}

impl Default for Account {
    fn default() -> Account {
        Account {
            internal_path: vec![Hardened(0), Normal(1)],
            internal_used: vec![],
            internal_next: 0,
            external_path: vec![Hardened(0), Normal(0)],
            external_used: vec![],
            external_next: 0
        }
    }
}

/// A wallet
#[derive(Clone, PartialEq, Eq, Debug)]
pub struct Wallet {
    master: ExtendedPrivKey,
    accounts: HashMap<String, Account>,
    index: Option<AddressIndex>
}

impl Serialize for Wallet {
    fn serialize<S>(&self, s: &mut S) -> Result<(), S::Error>
            where S: Serializer {
        let len = self.accounts.len();
        try!(self.master.serialize(s));
        self.accounts.serialize(s)
    }
}

impl Deserialize for Wallet {
    fn deserialize<D>(d: &mut D) -> Result<Wallet, D::Error>
            where D: Deserializer {
        Ok(Wallet {
            master: try!(Deserialize::deserialize(d)),
            accounts: try!(Deserialize::deserialize(d)),
            index: None
        })
    }
}

impl Wallet {
    /// Creates a new wallet from a BIP32 seed
    #[inline]
    pub fn from_seed(network: Network, seed: &[u8]) -> Result<Wallet, bip32::Error> {
        let mut accounts = HashMap::new();
        accounts.insert(String::new(), Default::default());

        Ok(Wallet {
            master: try!(ExtendedPrivKey::new_master(network, seed)),
            accounts: accounts,
            index: None
        })
    }

    /// Creates the address index
    #[inline]
    pub fn build_index(&mut self, utxo_set: &UtxoSet) {
        let new = AddressIndex::new(utxo_set, self);
        self.index = Some(new);
    }

    /// Accessor for the wallet's address index
    #[inline]
    pub fn index<'a>(&'a self) -> Option<&'a AddressIndex> {
        self.index.as_ref()
    }

    /// Mutable accessor for the wallet's address index
    #[inline]
    pub fn index_mut<'a>(&'a mut self) -> Option<&'a mut AddressIndex> {
        self.index.as_mut()
    }

    /// Adds an account to a wallet
    pub fn account_insert(&mut self, name: String)
                         -> Result<(), Error> {
        if self.accounts.contains_key(&name) {
            return Err(Error::DuplicateAccount);
        }

        let idx = self.accounts.len() as u32;
        self.accounts.insert(name, Account {
            internal_path: vec![Hardened(idx), Normal(1)],
            internal_used: vec![],
            internal_next: 0,
            external_path: vec![Hardened(idx), Normal(0)],
            external_used: vec![],
            external_next: 0
        });
        Ok(())
    }

    /// Locates an account in a wallet
    #[inline]
    pub fn account_get<'a>(&'a self, name: &str) -> Option<&'a Account> {
        self.accounts.get(name)
    }

    /// Create a new address
    pub fn new_address(&mut self,
                       account: &str,
                       chain: AccountChain)
                      -> Result<Address, Error> {
        let account = self.accounts.get_mut(account);
        let account = match account { Some(a) => a, None => return Err(Error::AccountNotFound) };
        let index = match self.index { Some(ref i) => i, None => return Err(Error::NoAddressIndex) };

        let (mut i, master) = match chain {
            AccountChain::Internal => (account.internal_next,
                                       try!(ExtendedPrivKey::from_path(
                                                &self.master,
                                                account.internal_path.as_slice()).map_err(Error::Bip32Error))),
            AccountChain::External => (account.external_next,
                                       try!(ExtendedPrivKey::from_path(
                                                &self.master,
                                                account.external_path.as_slice()).map_err(Error::Bip32Error))),
        };

        // Scan for next admissible address
        let mut sk = try!(master.ckd_priv(Normal(i)).map_err(Error::Bip32Error));
        let mut address = Address::from_key(
                              master.network,
                              &PublicKey::from_secret_key(&sk.secret_key, true));
        while !index.admissible_address(&address) {
            i += 1;
            sk = try!(master.ckd_priv(Normal(i)).map_err(Error::Bip32Error));
            address = Address::from_key(
                                    master.network,
                                    &PublicKey::from_secret_key(&sk.secret_key, true));
        }

        match chain {
            AccountChain::Internal => {
                account.internal_used.push(Normal(i));
                account.internal_next = i + 1;
            }
            AccountChain::External => {
                account.external_used.push(Normal(i));
                account.external_next = i + 1;
            }
        }

        Ok(address)
    }

    /// Returns the network of the wallet
    #[inline]
    pub fn network(&self) -> Network {
        self.master.network
    }

    /// Returns a key suitable for keying hash functions for DoS protection
    #[inline]
    pub fn siphash_key(&self) -> (u64, u64) {
        (LittleEndian::read_u64(&self.master.chain_code[0..8]),
         LittleEndian::read_u64(&self.master.chain_code[8..16]))
    }

    /// Total balance
    pub fn total_balance(&self) -> Result<u64, Error> {
        let mut ret = 0;
        for (_, account) in self.accounts.iter() {
            ret += try!(self.account_balance(account));
        }
        Ok(ret)
    }

    /// Account balance
    pub fn balance(&self, account: &str) -> Result<u64, Error> {
        let account = self.accounts.get(account);
        let account = match account { Some(a) => a, None => return Err(Error::AccountNotFound) };
        self.account_balance(account)
    }

    fn account_balance(&self, account: &Account) -> Result<u64, Error> {
        let index = match self.index { Some(ref i) => i, None => return Err(Error::NoAddressIndex) };

        let mut ret = 0;

        // Sum internal balance
        let master = try!(ExtendedPrivKey::from_path(
                              &self.master,
                              account.internal_path.as_slice()).map_err(Error::Bip32Error));
        for &cnum in account.internal_used.iter() {
            let sk = try!(master.ckd_priv(cnum).map_err(Error::Bip32Error));
            let pk = ExtendedPubKey::from_private(&sk);
            let addr = Address::from_key(pk.network, &pk.public_key);
            for out in index.find_by_script(&addr.script_pubkey()).iter() {
                ret += out.txo.value;
            }
        }
        // Sum external balance
        let master = try!(ExtendedPrivKey::from_path(
                              &self.master,
                              account.external_path.as_slice()).map_err(Error::Bip32Error));
        for &cnum in account.external_used.iter() {
            let sk = try!(master.ckd_priv(cnum).map_err(Error::Bip32Error));
            let pk = ExtendedPubKey::from_private(&sk);
            let addr = Address::from_key(pk.network, &pk.public_key);
            for out in index.find_by_script(&addr.script_pubkey()).iter() {
                ret += out.txo.value;
            }
        }

        Ok(ret)
    }
}