Chore: Automate end start swapping

contracts/lbp/LBPManager.sol

@@ -25,6 +25,12 @@ import "../utils/interface/ILBP.sol";
  */
 // solhint-disable-next-line max-states-count
 contract LBPManager {
+    enum TaskState {
+        Waiting,
+        Started,
+        Ended
+    }
+    TaskState public state;
     // Constants
     uint256 private constant HUNDRED_PERCENT = 1e18; // Used in calculating the fee.
 
@@ -192,7 +198,7 @@ contract LBPManager {
                 startWeights,
                 swapFeePercentage,
                 address(this),
-                true // SwapEnabled is set to true at pool creation.
+                false // SwapEnabled is set to true at pool creation.
             )
         );
 
@@ -234,6 +240,47 @@ contract LBPManager {
         vault.joinPool(lbp.getPoolId(), address(this), address(this), request);
     }
 
+    /**
+     * @dev start LBP just before one block
+     * @notice it can be invoked by anyone only once
+     */
+    function startLbp() external {
+        uint256 startTime;
+        uint256 blockTime = 5 minutes;
+        bool isSwapEnabled = lbp.getSwapEnabled();
+        (startTime, , ) = lbp.getGradualWeightUpdateParams();
+        require(
+            !isSwapEnabled && state == TaskState.Waiting,
+            "LBPManager: swapping already active"
+        );
+        require(
+            block.timestamp > startTime - blockTime,
+            "LBPManager: Only once block before start time"
+        );
+        state = TaskState.Started;
+        lbp.setSwapEnabled(true);
+    }
+
+    /**
+     * @dev ends LBP just after one block
+     * @notice it can be invoked by anyone only once
+     */
+    function endLbp() external {
+        uint256 endTime;
+        bool isSwapEnabled = lbp.getSwapEnabled();
+        (, endTime, ) = lbp.getGradualWeightUpdateParams();
+        require(
+            isSwapEnabled && state == TaskState.Started,
+            "LBPManager: swapping already active"
+        );
+        require(
+            block.timestamp > endTime,
+            "LBPManager: Only once block before start time"
+        );
+        state = TaskState.Ended;
+        lbp.setSwapEnabled(false);
+    }
+
     /**
      * @dev                             Exit pool or remove liquidity from pool.
      * @param _receiver                 Address of the liquidity receiver, after exiting the LBP.
@@ -302,6 +349,7 @@ contract LBPManager {
      * @param _swapEnabled              Enables/disables swapping.
      */
     function setSwapEnabled(bool _swapEnabled) external onlyAdmin {
+        require(TaskState.Ended != state, "LBPManager: LBP ended");
         lbp.setSwapEnabled(_swapEnabled);
     }