LeverageZapOdos

event Deposit:
    user: indexed(address)
    user_collateral: uint256
    user_borrowed: uint256
    user_collateral_from_borrowed: uint256
    debt: uint256
    leverage_collateral: uint256

@external
@nonreentrant('lock')
def callback_deposit(user: address, stablecoins: uint256, user_collateral: uint256, d_debt: uint256,
                    callback_args: DynArray[uint256, 10], callback_bytes: Bytes[10**4] = b"") -> uint256[2]:
    """
    @notice Callback method which should be called by controller to create leveraged position
    @param user Address of the user
    @param stablecoins Always 0
    @param user_collateral The amount of collateral token provided by user
    @param d_debt The amount to be borrowed (in addition to what has already been borrowed)
    @param callback_args [factory_id, controller_id, user_borrowed]
                        0-1. factory_id, controller_id are needed to check that msg.sender is the one of our controllers
                        2. user_borrowed - the amount of borrowed token provided by user (needs to be exchanged for collateral)
    return [0, user_collateral_from_borrowed + leverage_collateral]
    """
    controller: address = Factory(self.FACTORIES[callback_args[0]]).controllers(callback_args[1])
    assert msg.sender == controller, "wrong controller"
    amm: LLAMMA = LLAMMA(Controller(controller).amm())
    borrowed_token: address = amm.coins(0)
    collateral_token: address = amm.coins(1)

    self._approve(borrowed_token, ROUTER)
    self._approve(collateral_token, controller)

    user_borrowed: uint256 = callback_args[2]
    self._transferFrom(borrowed_token, user, self, user_borrowed)
    raw_call(ROUTER, callback_bytes)  # buys leverage_collateral for user_borrowed + dDebt
    additional_collateral: uint256 = ERC20(collateral_token).balanceOf(self)
    leverage_collateral: uint256 = d_debt * 10**18 / (d_debt + user_borrowed) * additional_collateral / 10**18
    user_collateral_from_borrowed: uint256 = additional_collateral - leverage_collateral

    log Deposit(user, user_collateral, user_borrowed, user_collateral_from_borrowed, d_debt, leverage_collateral)

    return [0, additional_collateral]

@internal
def _transferFrom(token: address, _from: address, _to: address, amount: uint256):
    if amount > 0:
        assert ERC20(token).transferFrom(_from, _to, amount, default_return_value=True)


@internal
def _approve(coin: address, spender: address):
    if ERC20(coin).allowance(self, spender) == 0:
        assert ERC20(coin).approve(spender, max_value(uint256), default_return_value=True)

@external
@nonreentrant('lock')
def create_loan_extended(collateral: uint256, debt: uint256, N: uint256, callbacker: address, callback_args: DynArray[uint256,5], callback_bytes: Bytes[10**4] = b""):
    """
    @notice Create loan but pass stablecoin to a callback first so that it can build leverage
    @param collateral Amount of collateral to use
    @param debt Stablecoin debt to take
    @param N Number of bands to deposit into (to do autoliquidation-deliquidation),
        can be from MIN_TICKS to MAX_TICKS
    @param callbacker Address of the callback contract
    @param callback_args Extra arguments for the callback (up to 5) such as min_amount etc
    """
    # Before callback
    self.transfer(BORROWED_TOKEN, callbacker, debt)

    # For compatibility
    callback_sig: bytes4 = CALLBACK_DEPOSIT_WITH_BYTES
    if callback_bytes == b"":
        callback_sig = CALLBACK_DEPOSIT
    # Callback
    # If there is any unused debt, callbacker can send it to the user
    more_collateral: uint256 = self.execute_callback(
        callbacker, callback_sig, msg.sender, 0, collateral, debt, callback_args, callback_bytes).collateral

    # After callback
    self._create_loan(collateral + more_collateral, debt, N, False)
    self.transferFrom(COLLATERAL_TOKEN, msg.sender, AMM.address, collateral)
    self.transferFrom(COLLATERAL_TOKEN, callbacker, AMM.address, more_collateral)

@internal
def execute_callback(callbacker: address, callback_sig: bytes4,
                    user: address, stablecoins: uint256, collateral: uint256, debt: uint256,
                    callback_args: DynArray[uint256, 5], callback_bytes: Bytes[10**4]) -> CallbackData:
    assert callbacker != COLLATERAL_TOKEN.address

    data: CallbackData = empty(CallbackData)
    data.active_band = AMM.active_band()
    band_x: uint256 = AMM.bands_x(data.active_band)
    band_y: uint256 = AMM.bands_y(data.active_band)

    # Callback
    response: Bytes[64] = raw_call(
        callbacker,
        concat(callback_sig, _abi_encode(user, stablecoins, collateral, debt, callback_args, callback_bytes)),
        max_outsize=64
    )
    data.stablecoins = convert(slice(response, 0, 32), uint256)
    data.collateral = convert(slice(response, 32, 32), uint256)

    # Checks after callback
    assert data.active_band == AMM.active_band()
    assert band_x == AMM.bands_x(data.active_band)
    assert band_y == AMM.bands_y(data.active_band)

    return data

DEAD_SHARES: constant(uint256) = 1000
MAX_TICKS_UINT: constant(uint256) = 50
MAX_P_BASE_BANDS: constant(int256) = 5
MAX_SKIP_TICKS: constant(uint256) = 1024

@external
@view
def max_borrowable(controller: address, _user_collateral: uint256, _leverage_collateral: uint256, N: uint256, p_avg: uint256) -> uint256:
    """
    @notice Calculation of maximum which can be borrowed with leverage
    """
    # max_borrowable = collateral / (1 / (k_effective * max_p_base) - 1 / p_avg)
    AMM: LLAMMA = LLAMMA(Controller(controller).amm())
    BORROWED_TOKEN: address = AMM.coins(0)
    COLLATERAL_TOKEN: address = AMM.coins(1)
    COLLATERAL_PRECISION: uint256 = pow_mod256(10, 18 - ERC20(COLLATERAL_TOKEN).decimals())

    user_collateral: uint256 = _user_collateral * COLLATERAL_PRECISION
    leverage_collateral: uint256 = _leverage_collateral * COLLATERAL_PRECISION
    k_effective: uint256 = self._get_k_effective(controller, user_collateral + leverage_collateral, N)
    max_p_base: uint256 = self._max_p_base(controller)
    max_borrowable: uint256 = user_collateral * 10**18 / (10**36 / k_effective * 10**18 / max_p_base - 10**36 / p_avg)

    return min(max_borrowable * 999 / 1000, ERC20(BORROWED_TOKEN).balanceOf(controller)) # Cannot borrow beyond the amount of coins Controller has

@internal
@view
def _get_k_effective(controller: address, collateral: uint256, N: uint256) -> uint256:
    """
    @notice Intermediary method which calculates k_effective defined as x_effective / p_base / y,
            however discounted by loan_discount.
            x_effective is an amount which can be obtained from collateral when liquidating
    @param N Number of bands the deposit is made into
    @return k_effective
    """
    # x_effective = sum_{i=0..N-1}(y / N * p(n_{n1+i})) =
    # = y / N * p_oracle_up(n1) * sqrt((A - 1) / A) * sum_{0..N-1}(((A-1) / A)**k)
    # === d_y_effective * p_oracle_up(n1) * sum(...) === y * k_effective * p_oracle_up(n1)
    # d_k_effective = 1 / N / sqrt(A / (A - 1))
    # d_k_effective: uint256 = 10**18 * unsafe_sub(10**18, discount) / (SQRT_BAND_RATIO * N)
    # Make some extra discount to always deposit lower when we have DEAD_SHARES rounding
    CONTROLLER: Controller = Controller(controller)
    A: uint256 = LLAMMA(CONTROLLER.amm()).A()
    SQRT_BAND_RATIO: uint256 = isqrt(unsafe_div(10 ** 36 * A, unsafe_sub(A, 1)))

    discount: uint256 = CONTROLLER.loan_discount()
    d_k_effective: uint256 = 10**18 * unsafe_sub(
        10**18, min(discount + (DEAD_SHARES * 10**18) / max(collateral / N, DEAD_SHARES), 10**18)
    ) / (SQRT_BAND_RATIO * N)
    k_effective: uint256 = d_k_effective
    for i in range(1, MAX_TICKS_UINT):
        if i == N:
            break
        d_k_effective = unsafe_div(d_k_effective * (A - 1), A)
        k_effective = unsafe_add(k_effective, d_k_effective)
    return k_effective

@internal
@view
def _max_p_base(controller: address) -> uint256:
    """
    @notice Calculate max base price including skipping bands
    """
    AMM: LLAMMA = LLAMMA(Controller(controller).amm())
    A: uint256 = AMM.A()
    LOGN_A_RATIO: int256 = self.wad_ln(A * 10**18 / (A - 1))

    p_oracle: uint256 = AMM.price_oracle()
    # Should be correct unless price changes suddenly by MAX_P_BASE_BANDS+ bands
    n1: int256 = self.wad_ln(AMM.get_base_price() * 10**18 / p_oracle)
    if n1 < 0:
        n1 -= LOGN_A_RATIO - 1  # This is to deal with vyper's rounding of negative numbers
    n1 = unsafe_div(n1, LOGN_A_RATIO) + MAX_P_BASE_BANDS
    n_min: int256 = AMM.active_band_with_skip()
    n1 = max(n1, n_min + 1)
    p_base: uint256 = AMM.p_oracle_up(n1)

    for i in range(MAX_SKIP_TICKS + 1):
        n1 -= 1
        if n1 <= n_min:
            break
        p_base_prev: uint256 = p_base
        p_base = unsafe_div(p_base * A, A - 1)
        if p_base > p_oracle:
            return p_base_prev

    return p_base

event Repay:
    user: indexed(address)
    state_collateral_used: uint256
    borrowed_from_state_collateral: uint256
    user_collateral: uint256
    user_collateral_used: uint256
    borrowed_from_user_collateral: uint256
    user_borrowed: uint256

@external
@nonreentrant('lock')
def callback_repay(user: address, stablecoins: uint256, collateral: uint256, debt: uint256,
                callback_args: DynArray[uint256,10], callback_bytes: Bytes[10 ** 4] = b"") -> uint256[2]:
    """
    @notice Callback method which should be called by controller to create leveraged position
    @param user Address of the user
    @param stablecoins The value from user_state
    @param collateral The value from user_state
    @param debt The value from user_state
    @param callback_args [factory_id, controller_id, user_collateral, user_borrowed]
                        0-1. factory_id, controller_id are needed to check that msg.sender is the one of our controllers
                        2. user_collateral - the amount of collateral token provided by user (needs to be exchanged for borrowed)
                        3. user_borrowed - the amount of borrowed token to repay from user's wallet
    return [user_borrowed + borrowed_from_collateral, remaining_collateral]
    """
    controller: address = Factory(self.FACTORIES[callback_args[0]]).controllers(callback_args[1])
    assert msg.sender == controller, "wrong controller"
    amm: LLAMMA = LLAMMA(Controller(controller).amm())
    borrowed_token: address = amm.coins(0)
    collateral_token: address = amm.coins(1)

    self._approve(collateral_token, ROUTER)
    self._approve(borrowed_token, controller)
    self._approve(collateral_token, controller)

    initial_collateral: uint256 = ERC20(collateral_token).balanceOf(self)
    user_collateral: uint256 = callback_args[2]
    if callback_bytes != b"":
        self._transferFrom(collateral_token, user, self, user_collateral)
        # Buys borrowed token for collateral from user's position + from user's wallet.
        # The amount to be spent is specified inside callback_bytes.
        raw_call(ROUTER, callback_bytes)
    else:
        assert user_collateral == 0
    remaining_collateral: uint256 = ERC20(collateral_token).balanceOf(self)
    state_collateral_used: uint256 = 0
    borrowed_from_state_collateral: uint256 = 0
    user_collateral_used: uint256 = user_collateral
    borrowed_from_user_collateral: uint256 = ERC20(borrowed_token).balanceOf(self)  # here it's total borrowed_from_collateral
    if remaining_collateral < initial_collateral:
        state_collateral_used = initial_collateral - remaining_collateral
        borrowed_from_state_collateral = state_collateral_used * 10**18 / (state_collateral_used + user_collateral_used) * borrowed_from_user_collateral / 10**18
        borrowed_from_user_collateral = borrowed_from_user_collateral - borrowed_from_state_collateral
    else:
        user_collateral_used = user_collateral - (remaining_collateral - initial_collateral)

    user_borrowed: uint256 = callback_args[3]
    self._transferFrom(borrowed_token, user, self, user_borrowed)

    log Repay(user, state_collateral_used, borrowed_from_state_collateral, user_collateral, user_collateral_used, borrowed_from_user_collateral, user_borrowed)

    return [borrowed_from_state_collateral + borrowed_from_user_collateral + user_borrowed, remaining_collateral]

@internal
def _transferFrom(token: address, _from: address, _to: address, amount: uint256):
    if amount > 0:
        assert ERC20(token).transferFrom(_from, _to, amount, default_return_value=True)


@internal
def _approve(coin: address, spender: address):
    if ERC20(coin).allowance(self, spender) == 0:
        assert ERC20(coin).approve(spender, max_value(uint256), default_return_value=True)

ROUTER: public(immutable(address))

@external
def __init__(_router: address, _factories: DynArray[address, 2]):
    ROUTER = _router
    self.FACTORIES = _factories

FACTORIES: public(DynArray[address, 2])

@external
def __init__(_router: address, _factories: DynArray[address, 2]):
    ROUTER = _router
    self.FACTORIES = _factories