Add CL4RRedeemer (#791)

* Add CL4RRedeemer

* lint

* Clean unused vars

* Fix

* Fix the test

* More coverage

* lint

* Add description

* Fix description

Author: ben-kaufman

contracts/schemes/CL4RRedeemer.sol

@@ -0,0 +1,147 @@
+pragma solidity ^0.6.12;
+// SPDX-License-Identifier: GPL-3.0
+
+import "./ContinuousLocking4Reputation.sol";
+
+/**
+ * @title A scheme for redeeming a ContinuousLocking4Reputation contract used in a different DAO.
+ * This contract can be used to migrate from an older DAO to a new one while the older DAO 
+ * has an active ContinuousLocking4Reputation.
+ * Using it should be done by initializing this contract as a scheme in the new DAO,
+ * with the old ContinuousLocking4Reputation as an init parameter (_ct4r).
+ * Note: the old ContinuousLocking4Reputation should be unregistered as a scheme from the older DAO so
+ * that redeeming is done only through this scheme into the new DAO.
+ */
+contract CL4RRedeemer is ArcScheme {
+    using SafeMath for uint256;
+    using SafeERC20 for IERC20;
+    using RealMath for uint216;
+    using RealMath for uint256;
+    using Math for uint256;
+
+    event Redeem(uint256 indexed _lockingId, address indexed _beneficiary, uint256 _amount, uint256 _batchIndex);
+
+    struct Batch {
+        uint256 totalScore;
+        // A mapping from lockingId to its score
+        mapping(uint256=>uint) scores;
+        mapping(uint256=>uint) redeemedScores;
+    }
+
+    struct Lock {
+        uint256 amount;
+        uint256 lockingTime;
+        uint256 period;
+    }
+
+    // A mapping from batch index to batch
+    mapping(uint256 => Batch) public batches;
+
+    uint256 public reputationRewardLeft; // the amount of reputation that is still left to distribute
+    uint256 public startTime; // the time (in secs since epoch) that locking can start (is enable)
+    uint256 public redeemEnableTime;
+    uint256 public batchTime; // the length of a batch, in seconds
+    ContinuousLocking4Reputation public cl4r;
+
+    uint256 constant private REAL_FBITS = 40;
+    // What's the first non-fractional bit
+    uint256 constant private REAL_ONE = uint256(1) << REAL_FBITS;
+
+    /**
+     * @dev initialize
+     * @param _avatar the avatar to mint reputation from
+     * @param _cl4r the ContinuousLocking4Reputation address
+     */
+    function initialize(Avatar _avatar, ContinuousLocking4Reputation _cl4r) external {
+        super._initialize(_avatar);
+        require(address(_cl4r) != address(0), "ContinuousLocking4Reputation reference contract must be specified");
+        cl4r = _cl4r;
+        startTime = _cl4r.startTime();
+        reputationRewardLeft = _cl4r.reputationRewardLeft();
+        redeemEnableTime = _cl4r.redeemEnableTime();
+        batchTime = _cl4r.batchTime();
+    }
+
+    /**
+     * @dev redeem reputation function
+     * @param _beneficiary the beneficiary to redeem.
+     * @param _lockingId the lockingId to redeem from.
+     * @return reputation reputation rewarded
+     */
+    function redeem(address _beneficiary, uint256 _lockingId) public returns(uint256 reputation) {
+
+        // solhint-disable-next-line not-rely-on-time
+        require(now > redeemEnableTime, "now > redeemEnableTime");
+        Lock memory locker = Lock(0, 0, 0);
+        (locker.amount, locker.lockingTime, locker.period) = cl4r.lockers(_beneficiary, _lockingId);
+
+        require(locker.lockingTime != 0, "_lockingId does not exist");
+        uint256 batchIndexToRedeemFrom = (locker.lockingTime - startTime) / batchTime;
+        // solhint-disable-next-line not-rely-on-time
+        uint256 currentBatch = (now - startTime) / batchTime;
+        uint256 lastBatchIndexToRedeem =  currentBatch.min(batchIndexToRedeemFrom.add(locker.period));
+        for (batchIndexToRedeemFrom; batchIndexToRedeemFrom < lastBatchIndexToRedeem; batchIndexToRedeemFrom++) {
+            if (batches[batchIndexToRedeemFrom].scores[_lockingId] == 0) {
+                batches[batchIndexToRedeemFrom].totalScore = cl4r.batches(batchIndexToRedeemFrom);
+                batches[batchIndexToRedeemFrom].scores[_lockingId] = cl4r.getLockingIdScore(
+                    batchIndexToRedeemFrom, _lockingId
+                ) - batches[batchIndexToRedeemFrom].redeemedScores[_lockingId];
+                batches[
+                    batchIndexToRedeemFrom
+                ].redeemedScores[_lockingId] += batches[batchIndexToRedeemFrom].scores[_lockingId];
+            }
+            Batch storage locking = batches[batchIndexToRedeemFrom];
+            uint256 score = locking.scores[_lockingId];
+            if (score > 0) {
+                locking.scores[_lockingId] = 0;
+                uint256 batchReputationReward = cl4r.getRepRewardPerBatch(batchIndexToRedeemFrom);
+                uint256 repRelation = mul(toReal(uint216(score)), batchReputationReward);
+                uint256 redeemForBatch = div(repRelation, toReal(uint216(locking.totalScore)));
+                reputation = reputation.add(redeemForBatch);
+                emit Redeem(_lockingId, _beneficiary, uint256(fromReal(redeemForBatch)), batchIndexToRedeemFrom);
+            }
+        }
+        reputation = uint256(fromReal(reputation));
+        require(reputation > 0, "reputation to redeem is 0");
+        // check that the reputation is sum zero
+        reputationRewardLeft = reputationRewardLeft.sub(reputation);
+        require(
+        Controller(avatar.owner())
+        .mintReputation(reputation, _beneficiary), "mint reputation should succeed");
+    }
+
+    /**
+     * Multiply one real by another. Truncates overflows.
+     */
+    function mul(uint256 realA, uint256 realB) private pure returns (uint256) {
+        // When multiplying fixed point in x.y and z.w formats we get (x+z).(y+w) format.
+        // So we just have to clip off the extra REAL_FBITS fractional bits.
+        uint256 res = realA * realB;
+        require(res/realA == realB, "RealMath mul overflow");
+        return (res >> REAL_FBITS);
+    }
+
+    /**
+     * Convert an integer to a real. Preserves sign.
+     */
+    function toReal(uint216 ipart) private pure returns (uint256) {
+        return uint256(ipart) * REAL_ONE;
+    }
+
+    /**
+     * Convert a real to an integer. Preserves sign.
+     */
+    function fromReal(uint256 _realValue) private pure returns (uint216) {
+        return uint216(_realValue / REAL_ONE);
+    }
+
+    /**
+     * Divide one real by another real. Truncates overflows.
+     */
+    function div(uint256 realNumerator, uint256 realDenominator) private pure returns (uint256) {
+        // We use the reverse of the multiplication trick: convert numerator from
+        // x.y to (x+z).(y+w) fixed point, then divide by denom in z.w fixed point.
+        return uint256((uint256(realNumerator) * REAL_ONE) / uint256(realDenominator));
+    }
+
+}