Add activity module with milk tea event

src/main/java/com/openisle/controller/ActivityController.java

@@ -0,0 +1,57 @@
+package com.openisle.controller;
+
+import com.openisle.model.Activity;
+import com.openisle.model.ActivityType;
+import com.openisle.model.User;
+import com.openisle.service.ActivityService;
+import com.openisle.service.UserService;
+import lombok.Data;
+import lombok.RequiredArgsConstructor;
+import org.springframework.security.core.Authentication;
+import org.springframework.web.bind.annotation.*;
+
+import java.util.List;
+
+@RestController
+@RequestMapping("/api/activities")
+@RequiredArgsConstructor
+public class ActivityController {
+    private final ActivityService activityService;
+    private final UserService userService;
+
+    @GetMapping
+    public List<Activity> list() {
+        return activityService.list();
+    }
+
+    @GetMapping("/milk-tea")
+    public MilkTeaInfo milkTea() {
+        Activity a = activityService.getByType(ActivityType.MILK_TEA);
+        long count = activityService.countLevel1Users();
+        if (!a.isEnded() && count > 50) {
+            activityService.end(a);
+        }
+        MilkTeaInfo info = new MilkTeaInfo();
+        info.setLevel1Count(count);
+        info.setEnded(a.isEnded());
+        return info;
+    }
+
+    @PostMapping("/milk-tea/redeem")
+    public void redeemMilkTea(@RequestBody RedeemRequest req, Authentication auth) {
+        User user = userService.findByIdentifier(auth.getName()).orElseThrow();
+        Activity a = activityService.getByType(ActivityType.MILK_TEA);
+        activityService.redeem(a, user, req.getContact());
+    }
+
+    @Data
+    private static class MilkTeaInfo {
+        private long level1Count;
+        private boolean ended;
+    }
+
+    @Data
+    private static class RedeemRequest {
+        private String contact;
+    }
+}