# A "zap" to deposit/withdraw Curve contract without too many transactions
# (c) Curve.Fi, 2020
from vyper.interfaces import ERC20

# External Contracts
contract yERC20:
    def totalSupply() -> uint256: constant
    def allowance(_owner: address, _spender: address) -> uint256: constant
    def transfer(_to: address, _value: uint256) -> bool: modifying
    def transferFrom(_from: address, _to: address, _value: uint256) -> bool: modifying
    def approve(_spender: address, _value: uint256) -> bool: modifying
    def name() -> string[64]: constant
    def symbol() -> string[32]: constant
    def decimals() -> uint256: constant
    def balanceOf(arg0: address) -> uint256: constant
    def deposit(depositAmount: uint256): modifying
    def withdraw(withdrawTokens: uint256): modifying
    def getPricePerFullShare() -> uint256: constant




# Tether transfer-only ABI
contract USDT:
    def transfer(_to: address, _value: uint256): modifying
    def transferFrom(_from: address, _to: address, _value: uint256): modifying


contract Curve:
    def add_liquidity(amounts: uint256[N_COINS], min_mint_amount: uint256): modifying
    def remove_liquidity(_amount: uint256, min_amounts: uint256[N_COINS]): modifying
    def remove_liquidity_imbalance(amounts: uint256[N_COINS], max_burn_amount: uint256): modifying
    def balances(i: int128) -> uint256: constant
    def A() -> uint256: constant
    def fee() -> uint256: constant
    def owner() -> address: constant


N_COINS: constant(int128) = 4
TETHERED: constant(bool[N_COINS]) = [False, False, True, False]
ZERO256: constant(uint256) = 0  # This hack is really bad XXX
ZEROS: constant(uint256[N_COINS]) = [ZERO256, ZERO256, ZERO256, ZERO256]  # <- change
LENDING_PRECISION: constant(uint256) = 10 ** 18
PRECISION: constant(uint256) = 10 ** 18
PRECISION_MUL: constant(uint256[N_COINS]) = [convert(1, uint256), convert(1000000000000, uint256), convert(1000000000000, uint256), convert(1, uint256)]
FEE_DENOMINATOR: constant(uint256) = 10 ** 10
FEE_IMPRECISION: constant(uint256) = 25 * 10 ** 8  # % of the fee

coins: public(address[N_COINS])
underlying_coins: public(address[N_COINS])
curve: public(address)
token: public(address)


@public
def __init__(_coins: address[N_COINS], _underlying_coins: address[N_COINS],
             _curve: address, _token: address):
    self.coins = _coins
    self.underlying_coins = _underlying_coins
    self.curve = _curve
    self.token = _token


@public
@nonreentrant('lock')
def add_liquidity(uamounts: uint256[N_COINS], min_mint_amount: uint256):
    tethered: bool[N_COINS] = TETHERED
    amounts: uint256[N_COINS] = ZEROS

    for i in range(N_COINS):
        uamount: uint256 = uamounts[i]

        if uamount > 0:
            # Transfer the underlying coin from owner
            if tethered[i]:
                USDT(self.underlying_coins[i]).transferFrom(
                    msg.sender, self, uamount)
            else:
                assert_modifiable(ERC20(self.underlying_coins[i])\
                    .transferFrom(msg.sender, self, uamount))

            # Mint if needed
            ERC20(self.underlying_coins[i]).approve(self.coins[i], uamount)
            yERC20(self.coins[i]).deposit(uamount)
            amounts[i] = yERC20(self.coins[i]).balanceOf(self)
            ERC20(self.coins[i]).approve(self.curve, amounts[i])

    Curve(self.curve).add_liquidity(amounts, min_mint_amount)

    tokens: uint256 = ERC20(self.token).balanceOf(self)
    assert_modifiable(ERC20(self.token).transfer(msg.sender, tokens))


@private
def _send_all(_addr: address, min_uamounts: uint256[N_COINS], one: int128):
    tethered: bool[N_COINS] = TETHERED

    for i in range(N_COINS):
        if (one < 0) or (i == one):
            _coin: address = self.coins[i]
            _balance: uint256 = yERC20(_coin).balanceOf(self)
            if _balance == 0:  # Do nothing for 0 coins
                continue
            yERC20(_coin).withdraw(_balance)

            _ucoin: address = self.underlying_coins[i]
            _uamount: uint256 = ERC20(_ucoin).balanceOf(self)
            assert _uamount >= min_uamounts[i], "Not enough coins withdrawn"

            if tethered[i]:
                USDT(_ucoin).transfer(_addr, _uamount)
            else:
                assert_modifiable(ERC20(_ucoin).transfer(_addr, _uamount))


@public
@nonreentrant('lock')
def remove_liquidity(_amount: uint256, min_uamounts: uint256[N_COINS]):
    zeros: uint256[N_COINS] = ZEROS

    assert_modifiable(ERC20(self.token).transferFrom(msg.sender, self, _amount))
    Curve(self.curve).remove_liquidity(_amount, zeros)

    self._send_all(msg.sender, min_uamounts, -1)


@public
@nonreentrant('lock')
def remove_liquidity_imbalance(uamounts: uint256[N_COINS], max_burn_amount: uint256):
    """
    Get max_burn_amount in, remove requested liquidity and transfer back what is left
    """
    tethered: bool[N_COINS] = TETHERED
    _token: address = self.token

    amounts: uint256[N_COINS] = uamounts
    for i in range(N_COINS):
        if amounts[i] > 0:
            rate: uint256 = yERC20(self.coins[i]).getPricePerFullShare()
            amounts[i] = amounts[i] * LENDING_PRECISION / rate

    # Transfrer max tokens in
    _tokens: uint256 = ERC20(_token).balanceOf(msg.sender)
    if _tokens > max_burn_amount:
        _tokens = max_burn_amount
    assert_modifiable(ERC20(_token).transferFrom(msg.sender, self, _tokens))

    Curve(self.curve).remove_liquidity_imbalance(amounts, max_burn_amount)

    # Transfer unused tokens back
    _tokens = ERC20(_token).balanceOf(self)
    assert_modifiable(ERC20(_token).transfer(msg.sender, _tokens))

    # Unwrap and transfer all the coins we've got
    self._send_all(msg.sender, ZEROS, -1)


@private
@constant
def _xp_mem(rates: uint256[N_COINS], _balances: uint256[N_COINS]) -> uint256[N_COINS]:
    result: uint256[N_COINS] = rates
    for i in range(N_COINS):
        result[i] = result[i] * _balances[i] / PRECISION
    return result


@private
@constant
def get_D(A: uint256, xp: uint256[N_COINS]) -> uint256:
    S: uint256 = 0
    for _x in xp:
        S += _x
    if S == 0:
        return 0

    Dprev: uint256 = 0
    D: uint256 = S
    Ann: uint256 = A * N_COINS
    for _i in range(255):
        D_P: uint256 = D
        for _x in xp:
            D_P = D_P * D / (_x * N_COINS + 1)  # +1 is to prevent /0
        Dprev = D
        D = (Ann * S + D_P * N_COINS) * D / ((Ann - 1) * D + (N_COINS + 1) * D_P)
        # Equality with the precision of 1
        if D > Dprev:
            if D - Dprev <= 1:
                break
        else:
            if Dprev - D <= 1:
                break
    return D


@private
@constant
def get_y(A: uint256, i: int128, _xp: uint256[N_COINS], D: uint256) -> uint256:
    """
    Calculate x[i] if one reduces D from being calculated for _xp to D

    Done by solving quadratic equation iteratively.
    x_1**2 + x1 * (sum' - (A*n**n - 1) * D / (A * n**n)) = D ** (n + 1) / (n ** (2 * n) * prod' * A)
    x_1**2 + b*x_1 = c

    x_1 = (x_1**2 + c) / (2*x_1 + b)
    """
    # x in the input is converted to the same price/precision

    assert (i >= 0) and (i < N_COINS)

    c: uint256 = D
    S_: uint256 = 0
    Ann: uint256 = A * N_COINS

    _x: uint256 = 0
    for _i in range(N_COINS):
        if _i != i:
            _x = _xp[_i]
        else:
            continue
        S_ += _x
        c = c * D / (_x * N_COINS)
    c = c * D / (Ann * N_COINS)
    b: uint256 = S_ + D / Ann
    y_prev: uint256 = 0
    y: uint256 = D
    for _i in range(255):
        y_prev = y
        y = (y*y + c) / (2 * y + b - D)
        # Equality with the precision of 1
        if y > y_prev:
            if y - y_prev <= 1:
                break
        else:
            if y_prev - y <= 1:
                break
    return y


@private
@constant
def _calc_withdraw_one_coin(_token_amount: uint256, i: int128, rates: uint256[N_COINS]) -> uint256:
    # First, need to calculate
    # * Get current D
    # * Solve Eqn against y_i for D - _token_amount
    crv: address = self.curve
    A: uint256 = Curve(crv).A()
    fee: uint256 = Curve(crv).fee() * N_COINS / (4 * (N_COINS - 1))
    fee += fee * FEE_IMPRECISION / FEE_DENOMINATOR  # Overcharge to account for imprecision
    precisions: uint256[N_COINS] = PRECISION_MUL
    total_supply: uint256 = ERC20(self.token).totalSupply()

    xp: uint256[N_COINS] = PRECISION_MUL
    S: uint256 = 0
    for j in range(N_COINS):
        xp[j] *= Curve(crv).balances(j)
        xp[j] = xp[j] * rates[j] / LENDING_PRECISION
        S += xp[j]

    D0: uint256 = self.get_D(A, xp)
    D1: uint256 = D0 - _token_amount * D0 / total_supply
    xp_reduced: uint256[N_COINS] = xp

    # xp = xp - fee * | xp * D1 / D0 - (xp - S * dD / D0 * (0, ... 1, ..0))|
    for j in range(N_COINS):
        dx_expected: uint256 = 0
        b_ideal: uint256 = xp[j] * D1 / D0
        b_expected: uint256 = xp[j]
        if j == i:
            b_expected -= S * (D0 - D1) / D0
        if b_ideal >= b_expected:
            dx_expected += (b_ideal - b_expected)
        else:
            dx_expected += (b_expected - b_ideal)
        xp_reduced[j] -= fee * dx_expected / FEE_DENOMINATOR

    dy: uint256 = xp_reduced[i] - self.get_y(A, i, xp_reduced, D1)
    dy = dy / precisions[i]

    return dy


@public
@constant
def calc_withdraw_one_coin(_token_amount: uint256, i: int128) -> uint256:
    rates: uint256[N_COINS] = ZEROS

    for j in range(N_COINS):
        rates[j] = yERC20(self.coins[j]).getPricePerFullShare()

    return self._calc_withdraw_one_coin(_token_amount, i, rates)


@public
@nonreentrant('lock')
def remove_liquidity_one_coin(_token_amount: uint256, i: int128, min_uamount: uint256, donate_dust: bool = False):
    """
    Remove _amount of liquidity all in a form of coin i
    """
    rates: uint256[N_COINS] = ZEROS
    _token: address = self.token

    for j in range(N_COINS):
        rates[j] = yERC20(self.coins[j]).getPricePerFullShare()

    dy: uint256 = self._calc_withdraw_one_coin(_token_amount, i, rates)
    assert dy >= min_uamount, "Not enough coins removed"

    assert_modifiable(
        ERC20(self.token).transferFrom(msg.sender, self, _token_amount))

    amounts: uint256[N_COINS] = ZEROS
    amounts[i] = dy * LENDING_PRECISION / rates[i]
    token_amount_before: uint256 = ERC20(_token).balanceOf(self)
    Curve(self.curve).remove_liquidity_imbalance(amounts, _token_amount)

    # Unwrap and transfer all the coins we've got
    self._send_all(msg.sender, ZEROS, i)

    if not donate_dust:
        # Transfer unused tokens back
        token_amount_after: uint256 = ERC20(_token).balanceOf(self)
        if token_amount_after > token_amount_before:
            assert_modifiable(ERC20(_token).transfer(
                msg.sender, token_amount_after - token_amount_before)
            )


@public
@nonreentrant('lock')
def withdraw_donated_dust():
    owner: address = Curve(self.curve).owner()
    assert msg.sender == owner

    _token: address = self.token
    assert_modifiable(
        ERC20(_token).transfer(owner, ERC20(_token).balanceOf(self)))

// hevm: flattened sources of /nix/store/8xb41r4qd0cjb63wcrxf1qmfg88p0961-dss-6fd7de0/src/dai.sol
pragma solidity =0.5.12;

////// /nix/store/8xb41r4qd0cjb63wcrxf1qmfg88p0961-dss-6fd7de0/src/lib.sol
// This program 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.

// This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.

/* pragma solidity 0.5.12; */

contract LibNote {
    event LogNote(
        bytes4   indexed  sig,
        address  indexed  usr,
        bytes32  indexed  arg1,
        bytes32  indexed  arg2,
        bytes             data
    ) anonymous;

    modifier note {
        _;
        assembly {
            // log an 'anonymous' event with a constant 6 words of calldata
            // and four indexed topics: selector, caller, arg1 and arg2
            let mark := msize                         // end of memory ensures zero
            mstore(0x40, add(mark, 288))              // update free memory pointer
            mstore(mark, 0x20)                        // bytes type data offset
            mstore(add(mark, 0x20), 224)              // bytes size (padded)
            calldatacopy(add(mark, 0x40), 0, 224)     // bytes payload
            log4(mark, 288,                           // calldata
                 shl(224, shr(224, calldataload(0))), // msg.sig
                 caller,                              // msg.sender
                 calldataload(4),                     // arg1
                 calldataload(36)                     // arg2
                )
        }
    }
}

////// /nix/store/8xb41r4qd0cjb63wcrxf1qmfg88p0961-dss-6fd7de0/src/dai.sol
// Copyright (C) 2017, 2018, 2019 dbrock, rain, mrchico

// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program 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 Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program.  If not, see <https://www.gnu.org/licenses/>.

/* pragma solidity 0.5.12; */

/* import "./lib.sol"; */

contract Dai is LibNote {
    // --- Auth ---
    mapping (address => uint) public wards;
    function rely(address guy) external note auth { wards[guy] = 1; }
    function deny(address guy) external note auth { wards[guy] = 0; }
    modifier auth {
        require(wards[msg.sender] == 1, "Dai/not-authorized");
        _;
    }

    // --- ERC20 Data ---
    string  public constant name     = "Dai Stablecoin";
    string  public constant symbol   = "DAI";
    string  public constant version  = "1";
    uint8   public constant decimals = 18;
    uint256 public totalSupply;

    mapping (address => uint)                      public balanceOf;
    mapping (address => mapping (address => uint)) public allowance;
    mapping (address => uint)                      public nonces;

    event Approval(address indexed src, address indexed guy, uint wad);
    event Transfer(address indexed src, address indexed dst, uint wad);

    // --- Math ---
    function add(uint x, uint y) internal pure returns (uint z) {
        require((z = x + y) >= x);
    }
    function sub(uint x, uint y) internal pure returns (uint z) {
        require((z = x - y) <= x);
    }

    // --- EIP712 niceties ---
    bytes32 public DOMAIN_SEPARATOR;
    // bytes32 public constant PERMIT_TYPEHASH = keccak256("Permit(address holder,address spender,uint256 nonce,uint256 expiry,bool allowed)");
    bytes32 public constant PERMIT_TYPEHASH = 0xea2aa0a1be11a07ed86d755c93467f4f82362b452371d1ba94d1715123511acb;

    constructor(uint256 chainId_) public {
        wards[msg.sender] = 1;
        DOMAIN_SEPARATOR = keccak256(abi.encode(
            keccak256("EIP712Domain(string name,string version,uint256 chainId,address verifyingContract)"),
            keccak256(bytes(name)),
            keccak256(bytes(version)),
            chainId_,
            address(this)
        ));
    }

    // --- Token ---
    function transfer(address dst, uint wad) external returns (bool) {
        return transferFrom(msg.sender, dst, wad);
    }
    function transferFrom(address src, address dst, uint wad)
        public returns (bool)
    {
        require(balanceOf[src] >= wad, "Dai/insufficient-balance");
        if (src != msg.sender && allowance[src][msg.sender] != uint(-1)) {
            require(allowance[src][msg.sender] >= wad, "Dai/insufficient-allowance");
            allowance[src][msg.sender] = sub(allowance[src][msg.sender], wad);
        }
        balanceOf[src] = sub(balanceOf[src], wad);
        balanceOf[dst] = add(balanceOf[dst], wad);
        emit Transfer(src, dst, wad);
        return true;
    }
    function mint(address usr, uint wad) external auth {
        balanceOf[usr] = add(balanceOf[usr], wad);
        totalSupply    = add(totalSupply, wad);
        emit Transfer(address(0), usr, wad);
    }
    function burn(address usr, uint wad) external {
        require(balanceOf[usr] >= wad, "Dai/insufficient-balance");
        if (usr != msg.sender && allowance[usr][msg.sender] != uint(-1)) {
            require(allowance[usr][msg.sender] >= wad, "Dai/insufficient-allowance");
            allowance[usr][msg.sender] = sub(allowance[usr][msg.sender], wad);
        }
        balanceOf[usr] = sub(balanceOf[usr], wad);
        totalSupply    = sub(totalSupply, wad);
        emit Transfer(usr, address(0), wad);
    }
    function approve(address usr, uint wad) external returns (bool) {
        allowance[msg.sender][usr] = wad;
        emit Approval(msg.sender, usr, wad);
        return true;
    }

    // --- Alias ---
    function push(address usr, uint wad) external {
        transferFrom(msg.sender, usr, wad);
    }
    function pull(address usr, uint wad) external {
        transferFrom(usr, msg.sender, wad);
    }
    function move(address src, address dst, uint wad) external {
        transferFrom(src, dst, wad);
    }

    // --- Approve by signature ---
    function permit(address holder, address spender, uint256 nonce, uint256 expiry,
                    bool allowed, uint8 v, bytes32 r, bytes32 s) external
    {
        bytes32 digest =
            keccak256(abi.encodePacked(
                "\x19\x01",
                DOMAIN_SEPARATOR,
                keccak256(abi.encode(PERMIT_TYPEHASH,
                                     holder,
                                     spender,
                                     nonce,
                                     expiry,
                                     allowed))
        ));

        require(holder != address(0), "Dai/invalid-address-0");
        require(holder == ecrecover(digest, v, r, s), "Dai/invalid-permit");
        require(expiry == 0 || now <= expiry, "Dai/permit-expired");
        require(nonce == nonces[holder]++, "Dai/invalid-nonce");
        uint wad = allowed ? uint(-1) : 0;
        allowance[holder][spender] = wad;
        emit Approval(holder, spender, wad);
    }
}