[update feature] 극장 Service 추가

src/main/java/study/book/object/ticket/service/Theater.java

@@ -0,0 +1,25 @@
+package study.book.object.ticket.service;
+
+import study.book.object.ticket.model.Audience;
+import study.book.object.ticket.model.Ticket;
+import study.book.object.ticket.model.TicketSeller;
+
+public class Theater {
+    private TicketSeller ticketSeller;
+
+    public Theater(TicketSeller ticketSeller) {
+        this.ticketSeller = ticketSeller;
+    }
+
+    public void enter(Audience audience) {
+        if(audience.getBag().hasInvitation()) {
+            Ticket ticket = ticketSeller.getTicketOffice().getTicket();
+            audience.getBag().setTicket(ticket);
+        } else {
+            Ticket ticket = ticketSeller.getTicketOffice().getTicket();
+            audience.getBag().minusAmount(ticket.getFee());
+            ticketSeller.getTicketOffice().plusAmount(ticket.getFee());
+            audience.getBag().setTicket(ticket);
+        }
+    }
+}