VAL-102 Return additional pool statistics to help with yield calculations

contracts/Pool.sol

@@ -190,7 +190,12 @@ contract Pool is IPool, ERC20 {
     /**
      * @dev The pool accounting variables;
      */
-    function accountings() external view returns (IPoolAccountings memory) {
+    function accountings()
+        external
+        view
+        override
+        returns (IPoolAccountings memory)
+    {
         return _accountings;
     }
 
@@ -275,17 +280,30 @@ contract Pool is IPool, ERC20 {
         require(_fundedLoans[msg.sender], "Pool: not funded loan");
 
         ILoanLifeCycleState loanState = ILoan(msg.sender).state();
-        if (loanState == ILoanLifeCycleState.Matured) {
-            _activeLoans.remove(msg.sender);
+        if (
+            loanState == ILoanLifeCycleState.Matured ||
+            loanState == ILoanLifeCycleState.Defaulted
+        ) {
+            require(_activeLoans.remove(msg.sender), "Pool: not active loan");
         } else if (loanState == ILoanLifeCycleState.Active) {
             _activeLoans.add(msg.sender);
-        } else if (loanState == ILoanLifeCycleState.Defaulted) {
-            _activeLoans.remove(msg.sender);
-            _accountings.outstandingLoanPrincipals -= ILoan(msg.sender)
-                .outstandingPrincipal();
         }
     }
 
+    /**
+     * @inheritdoc IPool
+     */
+    function onLoanDefaulted(address loan, uint256 firstLossApplied)
+        external
+        override
+        onlyPoolController
+    {
+        uint256 outstandingPrincipal = ILoan(loan).outstandingPrincipal();
+        _accountings.outstandingLoanPrincipals -= outstandingPrincipal;
+        _accountings.totalDefaults += outstandingPrincipal;
+        _accountings.totalFirstLossApplied += firstLossApplied;
+    }
+
     /**
      * @inheritdoc IPool
      */
@@ -313,6 +331,18 @@ contract Pool is IPool, ERC20 {
         );
     }
 
+    /**
+     * @inheritdoc IPool
+     */
+    function currentExpectedInterest()
+        external
+        view
+        override
+        returns (uint256)
+    {
+        return PoolLib.calculateExpectedInterest(_activeLoans);
+    }
+
     /**
      * @inheritdoc IPool
      */
@@ -668,7 +698,8 @@ contract Pool is IPool, ERC20 {
             assets,
             previewDeposit(assets),
             maxDeposit(receiver),
-            _mint
+            _mint,
+            _accountings
         );
     }
 
@@ -727,7 +758,8 @@ contract Pool is IPool, ERC20 {
             assets,
             previewDeposit(assets),
             maxDeposit(receiver),
-            _mint
+            _mint,
+            _accountings
         );
     }
 
@@ -853,6 +885,9 @@ contract Pool is IPool, ERC20 {
         // Burn the shares
         _burn(owner, shares);
 
+        // Updating accountings
+        _accountings.totalAssetsWithdrawn += assets;
+
         emit Withdraw(owner, owner, owner, assets, shares);
     }
 

contracts/interfaces/IPool.sol

@@ -10,9 +10,12 @@ import {EnumerableSet} from "@openzeppelin/contracts/utils/structs/EnumerableSet
  * @title Data type storing collected accounting statistics
  */
 struct IPoolAccountings {
-    uint256 defaultsTotal;
     uint256 outstandingLoanPrincipals;
     uint256 fixedFeeDueDate;
+    uint256 totalAssetsDeposited;
+    uint256 totalAssetsWithdrawn;
+    uint256 totalDefaults;
+    uint256 totalFirstLossApplied;
 }
 
 /**
@@ -172,6 +175,11 @@ interface IPool is IERC4626 {
      */
     function onLoanStateTransitioned() external;
 
+    /**
+     * @dev Called by the PoolController, notifies the Pool that a loan has been defaulted.
+     */
+    function onLoanDefaulted(address loan, uint256 firstLossApplied) external;
+
     /**
      * @dev Called by the Pool Controller, it transfers the fixed fee
      */
@@ -191,4 +199,9 @@ interface IPool is IERC4626 {
      * @dev The total available supply that is not marked for withdrawal
      */
     function totalAvailableSupply() external view returns (uint256);
+
+    /**
+     * @dev The accrued interest at the current block.
+     */
+    function currentExpectedInterest() external view returns (uint256 interest);
 }

contracts/libraries/PoolLib.sol

@@ -323,7 +323,8 @@ library PoolLib {
         uint256 assets,
         uint256 shares,
         uint256 maxDeposit,
-        function(address, uint256) mint
+        function(address, uint256) mint,
+        IPoolAccountings storage accountings
     ) internal returns (uint256) {
         require(shares > 0, "Pool: 0 deposit not allowed");
         require(assets <= maxDeposit, "Pool: Exceeds max deposit");
@@ -332,6 +333,7 @@ library PoolLib {
         mint(sharesReceiver, shares);
 
         emit Deposit(msg.sender, sharesReceiver, assets, shares);
+        accountings.totalAssetsDeposited += assets;
         return shares;
     }
 
@@ -360,6 +362,7 @@ library PoolLib {
             : firstLossBalance;
 
         FirstLossVault(firstLossVault).withdraw(firstLossRequired, pool);
+        IPool(pool).onLoanDefaulted(loan, firstLossRequired);
 
         emit LoanDefaulted(loan);
         emit FirstLossApplied(loan, firstLossRequired);

contracts/mocks/PoolLibTestWrapper.sol

@@ -14,6 +14,7 @@ contract PoolLibTestWrapper is ERC20("PoolLibTest", "PLT") {
     using EnumerableSet for EnumerableSet.AddressSet;
 
     EnumerableSet.AddressSet private _activeLoans;
+    IPoolAccountings private _accountings;
 
     event LifeCycleStateTransition(IPoolLifeCycleState state);
     event FirstLossDeposited(
@@ -157,7 +158,8 @@ contract PoolLibTestWrapper is ERC20("PoolLibTest", "PLT") {
                 assets,
                 shares,
                 maxDeposit,
-                _mint
+                _mint,
+                _accountings
             );
     }