Improve student activity registration system

pytest.ini

@@ -1,2 +1,4 @@
 [pytest]
 pythonpath = .
+testpaths = tests
+python_files = test_*.py

requirements.txt

@@ -1,4 +1,5 @@
 fastapi
 uvicorn
 httpx
-watchfiles
+watchfiles
+pytest

src/app.py

@@ -38,6 +38,42 @@
         "schedule": "Mondays, Wednesdays, Fridays, 2:00 PM - 3:00 PM",
         "max_participants": 30,
         "participants": ["john@mergington.edu", "olivia@mergington.edu"]
+    },
+    "Basketball Team": {
+        "description": "Competitive basketball team for interscholastic play",
+        "schedule": "Mondays and Wednesdays, 4:00 PM - 5:30 PM",
+        "max_participants": 15,
+        "participants": ["alex@mergington.edu"]
+    },
+    "Tennis Club": {
+        "description": "Learn tennis skills and compete in matches",
+        "schedule": "Tuesdays and Thursdays, 3:30 PM - 5:00 PM",
+        "max_participants": 16,
+        "participants": ["ava@mergington.edu"]
+    },
+    "Art Studio": {
+        "description": "Explore painting, drawing, and mixed media techniques",
+        "schedule": "Wednesdays, 3:30 PM - 5:00 PM",
+        "max_participants": 18,
+        "participants": ["isabella@mergington.edu", "lucas@mergington.edu"]
+    },
+    "Drama Club": {
+        "description": "Perform in theatrical productions and develop acting skills",
+        "schedule": "Thursdays, 4:00 PM - 5:30 PM",
+        "max_participants": 25,
+        "participants": ["noah@mergington.edu"]
+    },
+    "Debate Team": {
+        "description": "Engage in competitive debate and public speaking",
+        "schedule": "Mondays and Fridays, 3:30 PM - 4:30 PM",
+        "max_participants": 14,
+        "participants": ["mia@mergington.edu", "ethan@mergington.edu"]
+    },
+    "Science Club": {
+        "description": "Conduct experiments and explore advanced scientific concepts",
+        "schedule": "Tuesdays, 3:30 PM - 5:00 PM",
+        "max_participants": 20,
+        "participants": ["charlotte@mergington.edu"]
     }
 }
 
@@ -61,7 +97,26 @@ def signup_for_activity(activity_name: str, email: str):
 
     # Get the specific activity
     activity = activities[activity_name]
-
+    # Validate student is not already signed up
+    if email in activity["participants"]:
+        raise HTTPException(status_code=400, detail="Student already signed up for this activity")
     # Add student
     activity["participants"].append(email)
     return {"message": f"Signed up {email} for {activity_name}"}
+
+
+@app.delete("/activities/{activity_name}/participants/{email}")
+def unregister_from_activity(activity_name: str, email: str):
+    """Unregister a student from an activity"""
+    # Validate activity exists
+    if activity_name not in activities:
+        raise HTTPException(status_code=404, detail="Activity not found")
+
+    activity = activities[activity_name]
+
+    # Validate student is currently signed up
+    if email not in activity["participants"]:
+        raise HTTPException(status_code=404, detail="Student is not signed up for this activity")
+
+    activity["participants"].remove(email)
+    return {"message": f"Unregistered {email} from {activity_name}"}

src/static/app.js

@@ -4,27 +4,71 @@ document.addEventListener("DOMContentLoaded", () => {
   const signupForm = document.getElementById("signup-form");
   const messageDiv = document.getElementById("message");
 
+  function escapeHtml(value) {
+    return String(value)
+      .replaceAll("&", "&")
+      .replaceAll("<", "&lt;")
+      .replaceAll(">", "&gt;")
+      .replaceAll('"', "&quot;")
+      .replaceAll("'", "&#39;");
+  }
+
   // Function to fetch activities from API
   async function fetchActivities() {
     try {
-      const response = await fetch("/activities");
+      const response = await fetch("/activities", { cache: "no-store" });
       const activities = await response.json();
 
       // Clear loading message
       activitiesList.innerHTML = "";
+      activitySelect.innerHTML = '<option value="">-- Select an activity --</option>';
 
       // Populate activities list
       Object.entries(activities).forEach(([name, details]) => {
         const activityCard = document.createElement("div");
         activityCard.className = "activity-card";
 
-        const spotsLeft = details.max_participants - details.participants.length;
+        const participants = Array.isArray(details.participants) ? details.participants : [];
+        const maxParticipants = details.max_participants || 0;
+        const spotsLeft = maxParticipants - participants.length;
+        const encodedActivity = encodeURIComponent(name);
+        const participantItems = participants.length
+          ? participants
+              .map((participant) => {
+                const encodedParticipant = encodeURIComponent(participant);
+                const safeParticipant = escapeHtml(participant);
+
+                return `
+                  <li class="participant-item">
+                    <span class="participant-email">${safeParticipant}</span>
+                    <button
+                      type="button"
+                      class="delete-participant-btn"
+                      data-activity="${encodedActivity}"
+                      data-email="${encodedParticipant}"
+                      aria-label="Unregister ${safeParticipant} from ${escapeHtml(name)}"
+                      title="Unregister participant"
+                    >
+                      <span aria-hidden="true">&#128465;</span>
+                    </button>
+                  </li>
+                `;
+              })
+              .join("")
+          : '<li class="empty-participant">No students signed up yet</li>';
 
         activityCard.innerHTML = `
           <h4>${name}</h4>
           <p>${details.description}</p>
           <p><strong>Schedule:</strong> ${details.schedule}</p>
           <p><strong>Availability:</strong> ${spotsLeft} spots left</p>
+          <div class="participants-section">
+            <p class="participants-title">Participants</p>
+            <p class="participants-meta">${participants.length}/${maxParticipants} students enrolled</p>
+            <ul class="participants-list">
+              ${participantItems}
+            </ul>
+          </div>
         `;
 
         activitiesList.appendChild(activityCard);
@@ -62,6 +106,7 @@ document.addEventListener("DOMContentLoaded", () => {
         messageDiv.textContent = result.message;
         messageDiv.className = "success";
         signupForm.reset();
+        await fetchActivities();
       } else {
         messageDiv.textContent = result.detail || "An error occurred";
         messageDiv.className = "error";
@@ -81,6 +126,48 @@ document.addEventListener("DOMContentLoaded", () => {
     }
   });
 
+  activitiesList.addEventListener("click", async (event) => {
+    const button = event.target.closest(".delete-participant-btn");
+    if (!button) {
+      return;
+    }
+
+    const activity = button.dataset.activity;
+    const email = button.dataset.email;
+
+    if (!activity || !email) {
+      return;
+    }
+
+    try {
+      const response = await fetch(`/activities/${activity}/participants/${email}`, {
+        method: "DELETE",
+      });
+
+      const result = await response.json();
+
+      if (response.ok) {
+        messageDiv.textContent = result.message;
+        messageDiv.className = "success";
+        await fetchActivities();
+      } else {
+        messageDiv.textContent = result.detail || "Failed to unregister participant";
+        messageDiv.className = "error";
+      }
+
+      messageDiv.classList.remove("hidden");
+
+      setTimeout(() => {
+        messageDiv.classList.add("hidden");
+      }, 5000);
+    } catch (error) {
+      messageDiv.textContent = "Failed to unregister participant. Please try again.";
+      messageDiv.className = "error";
+      messageDiv.classList.remove("hidden");
+      console.error("Error unregistering participant:", error);
+    }
+  });
+
   // Initialize app
   fetchActivities();
 });

src/static/index.html

@@ -4,7 +4,7 @@
     <meta charset="UTF-8" />
     <meta name="viewport" content="width=device-width, initial-scale=1.0" />
     <title>Mergington High School Activities</title>
-    <link rel="stylesheet" href="styles.css" />
+    <link rel="stylesheet" href="styles.css?v=participants2" />
   </head>
   <body>
     <header>
@@ -45,6 +45,6 @@ <h3>Sign Up for an Activity</h3>
       <p>&copy; 2023 Mergington High School</p>
     </footer>
 
-    <script src="app.js"></script>
+    <script src="app.js?v=participants2"></script>
   </body>
 </html>

src/static/styles.css

@@ -63,6 +63,8 @@ section h3 {
   border: 1px solid #ddd;
   border-radius: 5px;
   background-color: #f9f9f9;
+  border-left: 4px solid #3949ab;
+  box-shadow: 0 4px 12px rgba(26, 35, 126, 0.08);
 }
 
 .activity-card h4 {
@@ -74,6 +76,93 @@ section h3 {
   margin-bottom: 8px;
 }
 
+.participants-section {
+  margin-top: 12px;
+  padding: 12px;
+  border-radius: 8px;
+  border: 1px solid #c5cae9;
+  background: linear-gradient(180deg, #eef1ff 0%, #f7f8ff 100%);
+  border-left: 5px solid #1a237e;
+}
+
+.participants-title {
+  margin-bottom: 4px;
+  color: #1a237e;
+  font-size: 0.98rem;
+  font-weight: 700;
+  text-transform: uppercase;
+  letter-spacing: 0.04em;
+}
+
+.participants-meta {
+  margin-bottom: 8px;
+  color: #3a4673;
+  font-size: 0.9rem;
+}
+
+.participants-list {
+  margin: 0;
+  padding-left: 0;
+  list-style: none;
+  display: grid;
+  gap: 8px;
+}
+
+.participant-item {
+  display: flex;
+  align-items: center;
+  justify-content: space-between;
+  gap: 10px;
+  padding: 8px 10px;
+  border-radius: 6px;
+  background-color: #ffffff;
+  border: 1px solid #d7dcf5;
+}
+
+.participant-email {
+  color: #2f3b63;
+  line-height: 1.4;
+  word-break: break-word;
+  font-size: 0.95rem;
+}
+
+.delete-participant-btn {
+  border: 1px solid #f3b5b5;
+  background-color: #fff3f3;
+  color: #b42323;
+  width: 30px;
+  height: 30px;
+  border-radius: 50%;
+  display: inline-flex;
+  align-items: center;
+  justify-content: center;
+  cursor: pointer;
+  font-size: 14px;
+  padding: 0;
+  transition: background-color 0.2s, transform 0.15s;
+}
+
+.delete-participant-btn:hover {
+  background-color: #ffe4e4;
+  transform: scale(1.05);
+}
+
+.delete-participant-btn:focus-visible {
+  outline: 2px solid #b42323;
+  outline-offset: 2px;
+}
+
+.empty-participant {
+  list-style: none;
+  margin-left: -1.2rem;
+  padding: 6px 8px;
+  border: 1px dashed #9fa8da;
+  border-radius: 6px;
+  background-color: #ffffff;
+  color: #5f6b8b;
+  font-style: italic;
+}
+
 .form-group {
   margin-bottom: 15px;
 }

tests/conftest.py

@@ -0,0 +1,24 @@
+import copy
+
+import pytest
+from fastapi.testclient import TestClient
+
+from src import app as app_module
+
+INITIAL_ACTIVITIES = copy.deepcopy(app_module.activities)
+
+
+@pytest.fixture(autouse=True)
+def reset_activities():
+    """Reset in-memory state so tests remain isolated and deterministic."""
+    app_module.activities.clear()
+    app_module.activities.update(copy.deepcopy(INITIAL_ACTIVITIES))
+    yield
+    app_module.activities.clear()
+    app_module.activities.update(copy.deepcopy(INITIAL_ACTIVITIES))
+
+
+@pytest.fixture
+def client():
+    with TestClient(app_module.app) as test_client:
+        yield test_client