Loopring Pool

Loopring Pool

pragma solidity ^0.5.0;

import "github.com/openzeppelin/openzeppelin-contracts/contracts/token/ERC20/ERC20.sol";

/*
 *
 * staker1:   |===========|
 *            :           :
 * staker2:   :   |===========|
 *            :   :       :   :
 * staker3:   :   :   |===========|
 *            :   :   :   :   :   :
 *          --|---|---|---|---|---|--> (time)
 *
 * Add new stake:
 *   share = stake_duration * stake_amount;
 *   totalShares = totalShares + share;
 *
 * Remove stake:
 *   totalShares = totalShares - share;
 *
 */
contract PeriodsPool is ERC20 {
    
    struct Stake {
        uint64 at;
        uint192 amount;
    }
    
    uint256 public totalReward;
    mapping(address => Stake) public stakes;
    
    function reward(address account) public view returns(uint256) {
        return totalReward.mul(balanceOf(account)).div(totalSupply());
    }
    
    function _stake(address account, uint256 amount, uint256 duration) internal {
        require(stakes[account].at == 0, "Stake exist");
        _mint(account, amount.mul(duration));
        stakes[account] = Stake({
            at: uint64(now.add(duration)),
            amount: uint192(amount)
        });
    }
    
    function _claim(address account) internal {
        Stake memory stake = stakes[account];
        require(now >= stake.at, "Wait until staking finished");
        _burn(account, balanceOf(account));
    }

    // Make stakes non-transferable
    function _transfer(address /*sender*/, address /*recipient*/, uint256 /*amount*/) internal {
        revert();
    }
}