design.pattern.practices/behavioral.patterns/chain.of.responsibility.pattern/ExpenseHandler.cs at master · arslanaybars/design.pattern.practices · GitHub

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namespace chain.of.responsibility.pattern
{
    public interface IExpenseHandler
    {
        ApprovalResponse Approve(IExpenseReport expenseReport);
        void RegisterNext(IExpenseHandler next);
    }

    public class ExpenseHandler : IExpenseHandler
    {
        private readonly IExpenseApprover _approver;
        private IExpenseHandler _next;

        public ExpenseHandler(IExpenseApprover expenseApprover)
        {
            _approver = expenseApprover;
            _next = EndOfChainExpenseHandler.Instance;
        }

        public ApprovalResponse Approve(IExpenseReport expenseReport)
        {
            ApprovalResponse response = _approver.ApproveExpense(expenseReport);

            if (response == ApprovalResponse.BeyondApprovalLimit)
            {
                return _next.Approve(expenseReport);
            }

            return response;
        }

        public void RegisterNext(IExpenseHandler next)
        {
            _next = next;
        }
    }

}