initial integration of pei, no tests

contracts/interfaces/IAaveIncentivesController.sol

@@ -0,0 +1,11 @@
+// SPDX-License-Identifier: agpl-3.0
+pragma solidity 0.6.8;
+pragma experimental ABIEncoderV2;
+
+interface IAaveIncentivesController {
+  function handleAction(
+    address user,
+    uint256 userBalance,
+    uint256 totalSupply
+  ) external;
+}

contracts/mocks/upgradeability/MockAToken.sol

@@ -9,8 +9,9 @@ contract MockAToken is AToken {
     LendingPool _pool,
     address _underlyingAssetAddress,
     string memory _tokenName,
-    string memory _tokenSymbol
-  ) public AToken(_pool, _underlyingAssetAddress, _tokenName, _tokenSymbol) {}
+    string memory _tokenSymbol,
+    address incentivesController
+  ) public AToken(_pool, _underlyingAssetAddress, _tokenName, _tokenSymbol, incentivesController) {}
 
   function getRevision() internal override pure returns (uint256) {
     return 0x2;

contracts/mocks/upgradeability/MockStableDebtToken.sol

@@ -9,8 +9,12 @@ contract MockStableDebtToken is StableDebtToken {
     address _pool,
     address _underlyingAssetAddress,
     string memory _tokenName,
-    string memory _tokenSymbol
-  ) public StableDebtToken(_pool, _underlyingAssetAddress, _tokenName, _tokenSymbol) {}
+    string memory _tokenSymbol,
+    address incentivesController
+  )
+    public
+    StableDebtToken(_pool, _underlyingAssetAddress, _tokenName, _tokenSymbol, incentivesController)
+  {}
 
   function getRevision() internal override pure returns (uint256) {
     return 0x2;

contracts/mocks/upgradeability/MockVariableDebtToken.sol

@@ -9,8 +9,18 @@ contract MockVariableDebtToken is VariableDebtToken {
     address _pool,
     address _underlyingAssetAddress,
     string memory _tokenName,
-    string memory _tokenSymbol
-  ) public VariableDebtToken(_pool, _underlyingAssetAddress, _tokenName, _tokenSymbol) {}
+    string memory _tokenSymbol,
+    address incentivesController
+  )
+    public
+    VariableDebtToken(
+      _pool,
+      _underlyingAssetAddress,
+      _tokenName,
+      _tokenSymbol,
+      incentivesController
+    )
+  {}
 
   function getRevision() internal override pure returns (uint256) {
     return 0x2;

contracts/tokenization/AToken.sol

@@ -45,8 +45,9 @@ contract AToken is VersionedInitializable, ERC20, IAToken {
     LendingPool pool,
     address underlyingAssetAddress,
     string memory tokenName,
-    string memory tokenSymbol
-  ) public ERC20(tokenName, tokenSymbol, 18) {
+    string memory tokenSymbol,
+    address incentivesController
+  ) public ERC20(tokenName, tokenSymbol, 18, incentivesController) {
     POOL = pool;
     UNDERLYING_ASSET_ADDRESS = underlyingAssetAddress;
   }
@@ -161,6 +162,21 @@ contract AToken is VersionedInitializable, ERC20, IAToken {
     return super.balanceOf(user);
   }
 
+  /**
+   * @dev returns the principal balance of the user and principal total supply.
+   * @param user the address of the user
+   * @return the principal balance of the user
+   * @return the principal total supply
+   **/
+  function getScaledUserBalanceAndSupply(address user)
+    external
+    override
+    view
+    returns (uint256, uint256)
+  {
+    return (super.balanceOf(user), super.totalSupply());
+  }
+
   /**
    * @dev calculates the total supply of the specific aToken
    * since the balance of every single user increases over time, the total supply

contracts/tokenization/ERC20.sol

@@ -5,6 +5,7 @@ import {Context} from '../misc/Context.sol';
 import {IERC20} from '../interfaces/IERC20.sol';
 import {IERC20Detailed} from '../interfaces/IERC20Detailed.sol';
 import {SafeMath} from '../libraries/math/SafeMath.sol';
+import {IAaveIncentivesController} from '../interfaces/IAaveIncentivesController.sol';
 
 /**
  * @title ERC20
@@ -14,6 +15,8 @@ import {SafeMath} from '../libraries/math/SafeMath.sol';
 contract ERC20 is Context, IERC20, IERC20Detailed {
   using SafeMath for uint256;
 
+  IAaveIncentivesController internal immutable _incentivesController;
+
   mapping(address => uint256) private _balances;
   mapping(address => mapping(address => uint256)) private _allowances;
   uint256 private _totalSupply;
@@ -24,11 +27,13 @@ contract ERC20 is Context, IERC20, IERC20Detailed {
   constructor(
     string memory name,
     string memory symbol,
-    uint8 decimals
+    uint8 decimals,
+    address incentivesController
   ) public {
     _name = name;
     _symbol = symbol;
     _decimals = decimals;
+    _incentivesController = IAaveIncentivesController(incentivesController);
   }
 
   /**
@@ -167,8 +172,16 @@ contract ERC20 is Context, IERC20, IERC20Detailed {
 
     _beforeTokenTransfer(sender, recipient, amount);
 
-    _balances[sender] = _balances[sender].sub(amount, 'ERC20: transfer amount exceeds balance');
+    uint256 oldSenderBalance = _balances[sender];
+    _balances[sender] = oldSenderBalance.sub(amount, 'ERC20: transfer amount exceeds balance');
+    uint256 oldRecipientBalance = _balances[recipient];
     _balances[recipient] = _balances[recipient].add(amount);
+
+    if (address(_incentivesController) != address(0x0)) {
+      uint256 totalSupply = _totalSupply;
+      _incentivesController.handleAction(sender, totalSupply, oldSenderBalance);
+      _incentivesController.handleAction(recipient, totalSupply, oldRecipientBalance);
+    }
     emit Transfer(sender, recipient, amount);
   }
 
@@ -177,8 +190,16 @@ contract ERC20 is Context, IERC20, IERC20Detailed {
 
     _beforeTokenTransfer(address(0), account, amount);
 
-    _totalSupply = _totalSupply.add(amount);
-    _balances[account] = _balances[account].add(amount);
+    uint256 oldTotalSupply = _totalSupply;
+    _totalSupply = oldTotalSupply.add(amount);
+
+    uint256 oldAccountBalance = _balances[account];
+    _balances[account] = oldAccountBalance.add(amount);
+
+    if (address(_incentivesController) != address(0x0)) {
+      _incentivesController.handleAction(account, oldTotalSupply, oldAccountBalance);
+    }
+
     emit Transfer(address(0), account, amount);
   }
 
@@ -187,8 +208,16 @@ contract ERC20 is Context, IERC20, IERC20Detailed {
 
     _beforeTokenTransfer(account, address(0), amount);
 
-    _balances[account] = _balances[account].sub(amount, 'ERC20: burn amount exceeds balance');
-    _totalSupply = _totalSupply.sub(amount);
+    uint256 oldTotalSupply = _totalSupply;
+    _totalSupply = oldTotalSupply.sub(amount);
+
+    uint256 oldAccountBalance = _balances[account];
+    _balances[account] = oldAccountBalance.sub(amount, 'ERC20: burn amount exceeds balance');
+
+    if (address(_incentivesController) != address(0x0)) {
+      _incentivesController.handleAction(account, oldTotalSupply, oldAccountBalance);
+    }
+
     emit Transfer(account, address(0), amount);
   }
 

contracts/tokenization/StableDebtToken.sol

@@ -26,8 +26,9 @@ contract StableDebtToken is IStableDebtToken, DebtTokenBase {
     address pool,
     address underlyingAsset,
     string memory name,
-    string memory symbol
-  ) public DebtTokenBase(pool, underlyingAsset, name, symbol) {}
+    string memory symbol,
+    address incentivesController
+  ) public DebtTokenBase(pool, underlyingAsset, name, symbol, incentivesController) {}
 
   /**
    * @dev gets the revision of the stable debt token implementation

contracts/tokenization/VariableDebtToken.sol

@@ -22,8 +22,9 @@ contract VariableDebtToken is DebtTokenBase, IVariableDebtToken {
     address pool,
     address underlyingAsset,
     string memory name,
-    string memory symbol
-  ) public DebtTokenBase(pool, underlyingAsset, name, symbol) {}
+    string memory symbol,
+    address incentivesController
+  ) public DebtTokenBase(pool, underlyingAsset, name, symbol, incentivesController) {}
 
   /**
    * @dev gets the revision of the stable debt token implementation

contracts/tokenization/base/DebtTokenBase.sol

@@ -38,8 +38,9 @@ abstract contract DebtTokenBase is ERC20, VersionedInitializable {
     address pool,
     address underlyingAssetAddress,
     string memory name,
-    string memory symbol
-  ) public ERC20(name, symbol, 18) {
+    string memory symbol,
+    address incentivesController
+  ) public ERC20(name, symbol, 18, incentivesController) {
     POOL = ILendingPool(pool);
     UNDERLYING_ASSET = underlyingAssetAddress;
   }

contracts/tokenization/interfaces/IAToken.sol

@@ -82,6 +82,14 @@ interface IAToken is IERC20 {
    **/
   function scaledBalanceOf(address user) external view returns (uint256);
 
+  /**
+   * @dev returns the principal balance of the user and principal total supply.
+   * @param user the address of the user
+   * @return the principal balance of the user
+   * @return the principal total supply
+   **/
+  function getScaledUserBalanceAndSupply(address user) external view returns (uint256, uint256);
+
   /**
    * @dev Used to validate transfers before actually executing them.
    * @param user address of the user to check