It is recommended to emit all the critical parameter changes in the contract.

The function only checks the amount upper limit but does not verify Whether the user is eligible to participate. Also, the amount is non-zero (e.g., someone could call with 0, wasting gas and polluting data structures). This could lead to incorrect state changes or unnecessary gas costs. To mitigate this, Add a lower-bound validation, e.g., require(amount > 0, "amount must be greater than zero");. Also, Validate user eligibility, if applicable.

The contract defines an admin role with a setter function to update the admin address, but it is underutilized. The onlyAdmin modifier is included but only used in a placeholder function, with no meaningful admin-specific functionality implemented. This redundancy adds unnecessary complexity and risks, such as granting unused power to an admin without a clear purpose. To improve the contract, either fully integrate admin functionality with specific responsibilities (e.g., managing operations distinct from the owner) or remove it entirely to simplify the code. This ensures clarity, reduces attack surface, and avoids confusion about roles and permissions.

The _totalWithdraw variable is defined to track the total amount of tokens withdrawn across all users but is not updated or used anywhere in the contract. This makes it redundant and unnecessary, adding clutter to the code. To improve the contract, either integrate _totalWithdraw into the logic (e.g., increment it during withdrawals to maintain a total withdrawal record) or remove it entirely if it's not required for functionality or reporting. Simplifying unused variables improves code clarity, reduces gas costs, and minimizes potential confusion or errors during contract deployment and use.

Make sure to emit events for all the critical parameter changes in the contract to ensure the transparency and trackability of all the state variable changes.

The withdraw function uses int for calculations involving _curPeriod and _pullPeriod, likely to handle potential negative values. However, this is unnecessary since these values should always increase or remain constant. Using int introduces risks like negative values and higher gas costs, complicating logic unnecessarily. Switching to uint ensures safer and more efficient calculations, as unsigned integers inherently prevent negative values. Logical safeguards should also be implemented to prevent _curPeriod and _pullPeriod from decreasing, ensuring validity. Simplifying conditional logic by removing unnecessary checks further enhances clarity, reliability, and performance of the contract.