vault share pricing and unmatured position valuation

contracts/interfaces/IEverlong.sol

@@ -1,31 +1,46 @@
 // SPDX-License-Identifier: Apache-2.0
 pragma solidity ^0.8.20;
 
-import { IERC4626 } from "openzeppelin/interfaces/IERC4626.sol";
+import { ERC4626 } from "solady/tokens/ERC4626.sol";
 import { IEverlongAdmin } from "./IEverlongAdmin.sol";
 import { IEverlongEvents } from "./IEverlongEvents.sol";
-import { IEverlongPositions } from "./IEverlongPositions.sol";
+import { IEverlongPortfolio } from "./IEverlongPortfolio.sol";
 
-interface IEverlong is
+abstract contract IEverlong is
+    ERC4626,
     IEverlongAdmin,
-    IERC4626,
     IEverlongEvents,
-    IEverlongPositions
+    IEverlongPortfolio
 {
+    // ╭─────────────────────────────────────────────────────────╮
+    // │ Structs                                                 │
+    // ╰─────────────────────────────────────────────────────────╯
+
+    /// @notice Tracks the total amount of bonds managed by Everlong
+    ///         with the same maturity.
+    struct Position {
+        /// @notice Time when the position matures.
+        uint128 maturityTime;
+        /// @notice Quantity of bonds in the position.
+        uint128 bondAmount;
+        /// @notice Vault share price at time of purchase.
+        uint128 vaultSharePrice;
+    }
+
     // ╭─────────────────────────────────────────────────────────╮
     // │ Getters                                                 │
     // ╰─────────────────────────────────────────────────────────╯
 
     /// @notice Gets the address of the underlying Hyperdrive Instance
-    function hyperdrive() external view returns (address);
+    function hyperdrive() external view virtual returns (address);
 
     /// @notice Gets the Everlong instance's kind.
     /// @return The Everlong instance's kind.
-    function kind() external pure returns (string memory);
+    function kind() external pure virtual returns (string memory);
 
     /// @notice Gets the Everlong instance's version.
     /// @return The Everlong instance's version.
-    function version() external pure returns (string memory);
+    function version() external pure virtual returns (string memory);
 
     // ╭─────────────────────────────────────────────────────────╮
     // │ Errors                                                  │

contracts/interfaces/IEverlongPositions.sol → contracts/interfaces/IEverlongPortfolio.sol

@@ -1,9 +1,9 @@
 // SPDX-License-Identifier: Apache-2.0
 pragma solidity ^0.8.20;
 
-import { Position } from "../types/Position.sol";
+import { IEverlong } from "./IEverlong.sol";
 
-interface IEverlongPositions {
+interface IEverlongPortfolio {
     // ╭─────────────────────────────────────────────────────────╮
     // │ Stateful                                                │
     // ╰─────────────────────────────────────────────────────────╯
@@ -17,15 +17,15 @@ interface IEverlongPositions {
 
     /// @notice Gets the number of positions managed by the Everlong instance.
     /// @return The number of positions.
-    function getPositionCount() external view returns (uint256);
+    function positionCount() external view returns (uint256);
 
     /// @notice Gets the position at an index.
     ///         Position `maturityTime` increases with each index.
     /// @param _index The index of the position.
     /// @return The position.
-    function getPosition(
+    function positionAt(
         uint256 _index
-    ) external view returns (Position memory);
+    ) external view returns (IEverlong.Position memory);
 
     /// @notice Determines whether any positions are matured.
     /// @return True if any positions are matured, false otherwise.
@@ -34,7 +34,7 @@ interface IEverlongPositions {
     /// @notice Determines whether Everlong has sufficient excess liquidity
     ///         for opening a long.
     /// @return True if sufficient excess liquidity, false otherwise.
-    function hasSufficientExcessLiquidity() external view returns (bool);
+    // function hasSufficientExcessLiquidity() external view returns (bool);
 
     /// @notice Determines whether Everlong's portfolio can currently be rebalanced.
     /// @return True if the portfolio can be rebalanced, false otherwise.