Added delegateAllTo function to HelioProviderV2

contracts/ceros/interfaces/IDao.sol

@@ -39,4 +39,5 @@ interface IDao {
 
     function collaterals(address token) external view returns (GemJoinLike, bytes32, uint32, address);
 
+    function locked(address token, address usr) external view returns (uint256);
 }

contracts/ceros/interfaces/IHelioProviderV2.sol

@@ -54,7 +54,7 @@ interface IHelioProviderV2 {
     // in BNB
     function provide() external payable returns (uint256);
     function provide(address _delegateTo) external payable returns (uint256);
-    function changeDelegatee(address _delegateTo) external;
+    function delegateAllTo(address _newDelegateTo) external;
 
     // in aBNBc
     // function provideInABNBc(uint256 amount) external returns (uint256);

contracts/ceros/mocks/Dao.sol

@@ -36,4 +36,8 @@ contract Dao is IDao {
 
   function collaterals(address token) external view returns (GemJoinLike gem, bytes32 ilk, uint32 live, address clip) {}
 
+  function locked(address token, address usr) public view returns (uint256) {
+    return 0;
+  }
+
 }

contracts/ceros/upgrades/HelioProviderV2.sol

@@ -121,28 +121,45 @@ ReentrancyGuardUpgradeable
     }
 
     /**
-     * CHANGE DELEGATEE
-     * @notice By burning all the collateral tokens from the
-     *         old delegatee and minting the same amount to the new delegatee,
-     *         also replace delegateTo address by the new one to perform the change.
+     * @notice Delegate all clisBNB to a new delegatee or self
+               new delegatee can be self or anyone else, but not zero address
+     * @param _newDelegateTo address of the new delegatee
      */
-    function changeDelegatee(address _newDelegateTo) external override whenNotPaused {
+    function delegateAllTo(address _newDelegateTo) external override whenNotPaused {
         require(_newDelegateTo != address(0), "delegateTo cannot be zero address");
-        require(
-            _delegation[msg.sender].amount > 0 && _delegation[msg.sender].delegateTo != _newDelegateTo,
-            "delegatee must differ from the current one"
-        );
+        // get user total deposit
+        uint256 totalLocked = _dao.locked(_ceToken, msg.sender);
+
         Delegation storage delegation = _delegation[msg.sender];
         address oldDelegateTo = delegation.delegateTo;
-        // burn old delegatee's token
-        _collateralToken.burn(oldDelegateTo, delegation.amount);
-        // mint to new delegatee
-        _collateralToken.mint(_newDelegateTo, delegation.amount);
-        // change delegation info
-        delegation.delegateTo = _newDelegateTo;
+
+        // Step 1. burn all tokens
+        if (delegation.amount > 0) {
+            // burn delegatee's token
+            _collateralToken.burn(oldDelegateTo, delegation.amount);
+            // burn self's token
+            _collateralToken.burn(msg.sender, totalLocked - delegation.amount);
+        } else {
+            _collateralToken.burn(msg.sender, totalLocked);
+        }
+
+        // Step 2. save new delegatee and mint all tokens to delegatee
+        if (_newDelegateTo == msg.sender) {
+            // mint all to self
+            _collateralToken.mint(msg.sender, totalLocked);
+            // remove delegatee
+            delete _delegation[msg.sender];
+        } else {
+            // mint all to new delegatee
+            _collateralToken.mint(_newDelegateTo, totalLocked);
+            // save delegatee's info
+            delegation.delegateTo = _newDelegateTo;
+            delegation.amount = totalLocked;
+        }
 
         emit ChangeDelegateTo(msg.sender, oldDelegateTo, _newDelegateTo);
     }
+
     /**
      * RELEASE
      */