76 lines
2.0 KiB
Solidity
76 lines
2.0 KiB
Solidity
// SPDX-License-Identifier: MIT
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pragma solidity ^0.8.0;
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import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
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abstract contract Collateral {
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IERC20 public immutable token;
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CollateralFunds private funds;
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mapping(address => uint256) private balances;
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constructor(IERC20 _token) collateralInvariant {
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token = _token;
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}
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function balanceOf(address account) public view returns (uint256) {
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return balances[account];
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}
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function add(address account, uint256 amount) private {
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balances[account] += amount;
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funds.balance += amount;
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}
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function subtract(address account, uint256 amount) private {
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balances[account] -= amount;
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funds.balance -= amount;
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}
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function transferFrom(address sender, uint256 amount) internal {
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address receiver = address(this);
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require(token.transferFrom(sender, receiver, amount), "Transfer failed");
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}
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function deposit(uint256 amount) public collateralInvariant {
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transferFrom(msg.sender, amount);
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funds.deposited += amount;
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add(msg.sender, amount);
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}
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function isWithdrawAllowed() internal virtual returns (bool);
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function withdraw() public collateralInvariant {
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require(isWithdrawAllowed(), "Account locked");
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uint256 amount = balanceOf(msg.sender);
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funds.withdrawn += amount;
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subtract(msg.sender, amount);
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assert(token.transfer(msg.sender, amount));
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}
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function _slash(address account, uint256 percentage)
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internal
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collateralInvariant
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{
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uint256 amount = (balanceOf(account) * percentage) / 100;
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funds.slashed += amount;
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subtract(account, amount);
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}
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modifier collateralInvariant() {
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CollateralFunds memory oldFunds = funds;
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_;
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assert(funds.deposited >= oldFunds.deposited);
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assert(funds.withdrawn >= oldFunds.withdrawn);
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assert(funds.slashed >= oldFunds.slashed);
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assert(funds.deposited == funds.balance + funds.withdrawn + funds.slashed);
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}
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struct CollateralFunds {
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uint256 balance;
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uint256 deposited;
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uint256 withdrawn;
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uint256 slashed;
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}
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}
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