Add Transition Scheme (#769)

* Add Transition Scheme

* solhint

* Add asset transferred event

* Fix

* Add large test

* Cap assets

* uint -> uint256

contracts/schemes/TransitionScheme.sol

@@ -0,0 +1,100 @@
+pragma solidity 0.5.17;
+
+import "../controller/Controller.sol";
+
+/**
+ * @title A scheme for transitioning the DAO's assets to a new one.
+ */
+
+contract TransitionScheme {
+
+    uint256 public constant ASSETS_CAP = 100;
+
+    event OwnershipTransferred(Avatar indexed _avatar, address indexed _newAvatar, address indexed _asset);
+
+    Avatar public avatar;
+    address payable public newAvatar;
+    address[] public externalTokens;
+    address[] public assetAddresses;
+    bytes4[] public selectors;
+
+    /**
+     * @dev initialize
+     * @param _avatar the avatar to migrate from
+     * @param _newAvatar the avatar to migrate to
+     * @param _externalTokens external tokens to allow transfer to the new avatar
+     * @param _assetAddresses the assets to transfer
+     * @param _selectors the functions to call to to transfer the assets
+     */
+    function initialize(
+        Avatar _avatar,
+        address payable _newAvatar,
+        address[] calldata _externalTokens,
+        address[] calldata _assetAddresses,
+        bytes4[] calldata _selectors
+    ) external {
+        require(_assetAddresses.length <= ASSETS_CAP, "cannot transfer more than 100 assets");
+        require(_assetAddresses.length == _selectors.length, "Arrays length mismatch");
+        require(avatar == Avatar(0), "can be called only one time");
+        require(_avatar != Avatar(0), "avatar cannot be zero");
+        avatar = _avatar;
+        newAvatar = _newAvatar;
+        externalTokens = _externalTokens;
+        assetAddresses = _assetAddresses;
+        selectors = _selectors;
+    }
+
+    /**
+     * @dev transferAssets function
+     * transfer the DAO assets to a new DAO
+     */
+    function transferAssets() external {
+        for (uint256 i=0; i < assetAddresses.length; i++) {
+            bytes memory genericCallReturnValue;
+            bool success;
+            Controller controller = Controller(avatar.owner());
+            (success, genericCallReturnValue) =
+            controller.genericCall(
+                assetAddresses[i],
+                abi.encodeWithSelector(selectors[i], newAvatar),
+                avatar,
+                0
+            );
+            if (success) {
+                emit OwnershipTransferred(avatar, newAvatar, assetAddresses[i]);
+            }
+        }
+    }
+
+    /**
+     * @dev sendEther function
+     * @param _amount the amount of ether to send to the new avatar
+     */
+    function sendEther(uint256 _amount) external {
+        require(
+            Controller(avatar.owner()).sendEther(_amount, newAvatar, avatar),
+            "Sending ether should succeed"
+        );
+    }
+
+    /**
+     * @dev sendExternalToken function
+     * @param _amounts the amounts of tokens to send to the new avatar
+     */
+    function sendExternalToken(uint256[] calldata _amounts) external {
+        require(externalTokens.length == _amounts.length, "Arrays length mismatch");
+        for (uint256 i=0; i < externalTokens.length; i++) {
+            if (_amounts[i] > 0) {
+                require(
+                    Controller(avatar.owner()).externalTokenTransfer(
+                        IERC20(externalTokens[i]),
+                        newAvatar,
+                        _amounts[i],
+                        avatar
+                    ),
+                    "Sending external token should succeed"
+                );
+            }
+        }
+    }
+}

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@daostack/arc",
-  "version": "0.0.1-rc.41",
+  "version": "0.0.1-rc.42",
   "description": "A platform for building DAOs",
   "files": [
     "contracts/",