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// SPDX-License-Identifier: AGPL-3.0-or-later
/// flop.sol -- Debt auction
// Copyright (C) 2018 Rain <rainbreak@riseup.net>
//
// 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;
// FIXME: This contract was altered compared to the production version.
// It doesn't use LibNote anymore.
// New deployments of this contract will need to include custom events (TO DO).
interface VatLike {
function move(address,address,uint) external;
function suck(address,address,uint) external;
}
interface GemLike {
function mint(address,uint) external;
}
interface VowLike {
function Ash() external returns (uint);
function kiss(uint) external;
}
/*
This thing creates gems on demand in return for dai.
- `lot` gems in return for bid
- `bid` dai paid
- `gal` receives dai income
- `ttl` single bid lifetime
- `beg` minimum bid increase
- `end` max auction duration
*/
contract Flopper {
// --- Auth ---
mapping (address => uint) public wards;
function rely(address usr) external auth { wards[usr] = 1; }
function deny(address usr) external auth { wards[usr] = 0; }
modifier auth {
require(wards[msg.sender] == 1, "Flopper/not-authorized");
_;
}
// --- Data ---
struct Bid {
uint256 bid; // dai paid [rad]
uint256 lot; // gems in return for bid [wad]
address guy; // high bidder
uint48 tic; // bid expiry time [unix epoch time]
uint48 end; // auction expiry time [unix epoch time]
}
mapping (uint => Bid) public bids;
VatLike public vat; // CDP Engine
GemLike public gem;
uint256 constant ONE = 1.00E18;
uint256 public beg = 1.05E18; // 5% minimum bid increase
uint256 public pad = 1.50E18; // 50% lot increase for tick
uint48 public ttl = 3 hours; // 3 hours bid lifetime [seconds]
uint48 public tau = 2 days; // 2 days total auction length [seconds]
uint256 public kicks = 0;
uint256 public live; // Active Flag
address public vow; // not used until shutdown
// --- Events ---
event Kick(
uint256 id,
uint256 lot,
uint256 bid,
address indexed gal
);
// --- Init ---
constructor(address vat_, address gem_) public {
wards[msg.sender] = 1;
vat = VatLike(vat_);
gem = GemLike(gem_);
live = 1;
}
// --- Math ---
function add(uint48 x, uint48 y) internal pure returns (uint48 z) {
require((z = x + y) >= x);
}
function mul(uint x, uint y) internal pure returns (uint z) {
require(y == 0 || (z = x * y) / y == x);
}
function min(uint x, uint y) internal pure returns (uint z) {
if (x > y) { z = y; } else { z = x; }
}
// --- Admin ---
function file(bytes32 what, uint data) external auth {
if (what == "beg") beg = data;
else if (what == "pad") pad = data;
else if (what == "ttl") ttl = uint48(data);
else if (what == "tau") tau = uint48(data);
else revert("Flopper/file-unrecognized-param");
}
// --- Auction ---
function kick(address gal, uint lot, uint bid) external auth returns (uint id) {
require(live == 1, "Flopper/not-live");
require(kicks < uint(-1), "Flopper/overflow");
id = ++kicks;
bids[id].bid = bid;
bids[id].lot = lot;
bids[id].guy = gal;
bids[id].end = add(uint48(now), tau);
emit Kick(id, lot, bid, gal);
}
function tick(uint id) external {
require(bids[id].end < now, "Flopper/not-finished");
require(bids[id].tic == 0, "Flopper/bid-already-placed");
bids[id].lot = mul(pad, bids[id].lot) / ONE;
bids[id].end = add(uint48(now), tau);
}
function dent(uint id, uint lot, uint bid) external {
require(live == 1, "Flopper/not-live");
require(bids[id].guy != address(0), "Flopper/guy-not-set");
require(bids[id].tic > now || bids[id].tic == 0, "Flopper/already-finished-tic");
require(bids[id].end > now, "Flopper/already-finished-end");
require(bid == bids[id].bid, "Flopper/not-matching-bid");
require(lot < bids[id].lot, "Flopper/lot-not-lower");
require(mul(beg, lot) <= mul(bids[id].lot, ONE), "Flopper/insufficient-decrease");
if (msg.sender != bids[id].guy) {
vat.move(msg.sender, bids[id].guy, bid);
// on first dent, clear as much Ash as possible
if (bids[id].tic == 0) {
uint Ash = VowLike(bids[id].guy).Ash();
VowLike(bids[id].guy).kiss(min(bid, Ash));
}
bids[id].guy = msg.sender;
}
bids[id].lot = lot;
bids[id].tic = add(uint48(now), ttl);
}
function deal(uint id) external {
require(live == 1, "Flopper/not-live");
require(bids[id].tic != 0 && (bids[id].tic < now || bids[id].end < now), "Flopper/not-finished");
gem.mint(bids[id].guy, bids[id].lot);
delete bids[id];
}
// --- Shutdown ---
function cage() external auth {
live = 0;
vow = msg.sender;
}
function yank(uint id) external {
require(live == 0, "Flopper/still-live");
require(bids[id].guy != address(0), "Flopper/guy-not-set");
vat.suck(vow, bids[id].guy, bids[id].bid);
delete bids[id];
}
}