dagger-contracts/contracts/Collateral.sol

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withdrawn += amount;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withdrawn 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withdrawn);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withdrawn + funds.slashed);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