aded k6 and script and updated code with better logic and indexing on schema

.gitignore

@@ -1,2 +1,3 @@
 .env
 node_modules
+dist

Dockerfile

@@ -0,0 +1,25 @@
+FROM node:22-bookworm-slim AS build
+
+WORKDIR /app
+
+COPY package.json ./
+RUN npm install
+
+COPY tsconfig.json ./
+COPY src ./src
+
+RUN npm run build
+
+FROM node:22-bookworm-slim AS runtime
+
+ENV NODE_ENV=production
+WORKDIR /app
+
+COPY package.json ./
+RUN npm install --omit=dev
+
+COPY --from=build /app/dist ./dist
+
+EXPOSE 3000
+
+CMD ["node", "dist/index.js"]

compose.yml

@@ -0,0 +1,68 @@
+services:
+  mongo:
+    image: mongo:7.0.41
+    container_name: node-ass1-mongo
+    restart: unless-stopped
+    command: ["mongod", "--bind_ip_all"]
+    environment:
+      MONGO_INITDB_DATABASE: node_ass1
+    volumes:
+      - mongo_data:/data/db
+    networks:
+      - testnet
+    mem_limit: 2g
+    cpus: 1.0
+    healthcheck:
+      test:
+        [
+          "CMD",
+          "mongosh",
+          "--quiet",
+          "mongodb://127.0.0.1:27017/node_ass1",
+          "--eval",
+          "db.runCommand({ ping: 1 }).ok"
+        ]
+      interval: 5s
+      timeout: 3s
+      retries: 15
+
+  app:
+    build:
+      context: .
+      dockerfile: Dockerfile
+    container_name: node-ass1-app
+    init: true
+    environment:
+      NODE_ENV: production
+      PORT: 3000
+      MONGO_URI: mongodb://mongo:27017/node_ass1
+    ports:
+      - "127.0.0.1:3000:3000"
+    depends_on:
+      mongo:
+        condition: service_healthy
+    networks:
+      - testnet
+    mem_limit: 1g
+    cpus: 1.5
+
+  k6:
+    image: grafana/k6:latest
+    container_name: node-ass1-k6
+    profiles: ["testing"]
+    working_dir: /scripts
+    volumes:
+      - ./k6:/scripts:ro
+      - ./results:/results
+    networks:
+      - testnet
+    mem_limit: 2g
+    cpus: 1.0
+    entrypoint: ["k6"]
+
+networks:
+  testnet:
+    driver: bridge
+
+volumes:
+  mongo_data:

k6/booking-race.js

@@ -0,0 +1,49 @@
+import http from 'k6/http';
+import { check } from 'k6';
+import { Counter } from 'k6/metrics';
+
+const seed = JSON.parse(open('./seed-data.json'));
+const BASE_URL = __ENV.BASE_URL || 'http://app:3000';
+
+const successfulBookings = new Counter('successful_bookings');
+
+export const options = {
+  scenarios: {
+    concurrent_booking: {
+      executor: 'per-vu-iterations',
+      vus: 10,
+      iterations: 1,
+      maxDuration: '30s',
+    },
+  },
+  thresholds: {
+    successful_bookings: ['count==1'],
+  },
+};
+
+export default function () {
+  const session = seed.sessions[0];
+  const user = seed.users[__VU - 1];
+
+  const response = http.post(
+    `${BASE_URL}/sessions/${session.id}/book`,
+    JSON.stringify({ userId: user.id }),
+    {
+      headers: { 'Content-Type': 'application/json' },
+      responseCallback: http.expectedStatuses(200, 400),
+    }
+  );
+
+  if (response.status === 200) {
+    successfulBookings.add(1);
+  }
+
+  check(response, {
+    'booking returned expected status': (r) =>
+      r.status === 200 || r.status === 400,
+  });
+
+  console.log(
+    `VU ${__VU}: status=${response.status}, session=${session.id}`
+  );
+}

k6/load.js

@@ -0,0 +1,50 @@
+import http from 'k6/http';
+import { check, sleep } from 'k6';
+
+const BASE_URL = __ENV.BASE_URL || 'http://app:3000';
+const seed = JSON.parse(open('./seed-data.json'));
+
+export const options = {
+  stages: [
+    { duration: '15s', target: 1 },
+    { duration: '20s', target: 3 },
+    { duration: '20s', target: 5 },
+    { duration: '10s', target: 0 },
+  ],
+  thresholds: {
+    http_req_failed: ['rate<0.01'],
+    http_req_duration: ['p(95)<500'],
+    checks: ['rate>0.99'],
+  },
+};
+
+export default function () {
+  const user = seed.users[(__VU + __ITER) % seed.users.length];
+  const session =
+    seed.sessions[(__VU + __ITER) % seed.sessions.length];
+
+  const requests = [
+    ['users', `${BASE_URL}/users/`],
+    ['teachers', `${BASE_URL}/teachers/`],
+    [
+      'available sessions',
+      `${BASE_URL}/sessions/available?dateTimestamp=${encodeURIComponent(session.dateTimestamp)}`,
+    ],
+    [
+      'user session history',
+      `${BASE_URL}/sessions/${user.id}/sessions`,
+    ],
+  ];
+
+  for (const [name, url] of requests) {
+    const response = http.get(url);
+
+    check(response, {
+      [`${name}: HTTP 200`]: (r) => r.status === 200,
+      [`${name}: JSON response`]: (r) =>
+        r.headers['Content-Type']?.includes('application/json'),
+    });
+  }
+
+  sleep(1);
+}

k6/mixed-workload.js

@@ -0,0 +1,127 @@
+import http from 'k6/http';
+import { check, sleep } from 'k6';
+import { Counter } from 'k6/metrics';
+
+const BASE_URL = __ENV.BASE_URL || 'http://app:3000';
+const seed = JSON.parse(open('./seed-data.json'));
+
+const writeFailures = new Counter('write_failures');
+
+export const options = {
+  stages: [
+    { duration: '20s', target: 50 },
+    { duration: '20s', target: 100 },
+    { duration: '30s', target: 150 },
+    { duration: '30s', target: 200 },
+    { duration: '30s', target: 250 },
+    { duration: '30s', target: 300 },
+    { duration: '30s', target: 350 },
+    { duration: '30s', target: 400 },
+    { duration: '20s', target: 0 },
+  ],
+  thresholds: {
+    http_req_failed: ['rate<0.02'],
+    http_req_duration: ['p(95)<500'],
+    write_failures: ['count==0'],
+  },
+};
+
+export default function () {
+  const unique = `${__VU}-${__ITER}-${Date.now()}`;
+  const startTime = new Date(Date.now() + 60 * 60 * 1000);
+  const endTime = new Date(startTime.getTime() + 30 * 60 * 1000);
+
+  // 1. Insert a new user
+  const userResponse = http.post(
+    `${BASE_URL}/users/`,
+    JSON.stringify({
+      fullName: `Load Test ${unique}`,
+      email: `load-${unique}@example.invalid`,
+      phone: `9${String(__VU).padStart(1, '0')}${String(__ITER).padStart(8, '0')}`.slice(0, 10),
+    }),
+    { headers: { 'Content-Type': 'application/json' }, tags: { name: 'POST /users' } }
+  );
+
+  const userOk = check(userResponse, {
+    'user inserted (201)': (r) => r.status === 201,
+  });
+
+  if (!userOk) {
+    writeFailures.add(1);
+    return;
+  }
+
+  const userId = userResponse.json('result._id');
+
+  // 2. Insert a session for the existing seeded teacher
+  const sessionResponse = http.post(
+    `${BASE_URL}/sessions/`,
+    JSON.stringify({
+      teacherId: seed.teacher.id,
+      startTime: startTime.toISOString(),
+      endTime: endTime.toISOString(),
+    }),
+    { headers: { 'Content-Type': 'application/json' }, tags: { name: 'POST /sessions' } }
+  );
+
+  const sessionOk = check(sessionResponse, {
+    'session inserted (201)': (r) => r.status === 201,
+  });
+
+  if (!sessionOk) {
+    writeFailures.add(1);
+    return;
+  }
+
+  const sessionId = sessionResponse.json('result._id');
+
+  // 3. Book the newly created session
+  const bookingResponse = http.post(
+    `${BASE_URL}/sessions/${sessionId}/book`,
+    JSON.stringify({ userId }),
+    { headers: { 'Content-Type': 'application/json' }, tags: { name: 'POST /sessions/:id/book' } }
+  );
+
+  const bookingOk = check(bookingResponse, {
+    'session booked (200)': (r) => r.status === 200,
+  });
+
+  if (!bookingOk) {
+    writeFailures.add(1);
+    return;
+  }
+
+  // 4. Complete the booked session
+  const completeResponse = http.patch(
+    `${BASE_URL}/sessions/${sessionId}/complete`,
+    null,
+    { tags: { name: 'PATCH /sessions/:id/complete' } }
+  );
+
+  const completeOk = check(completeResponse, {
+    'session completed (200)': (r) => r.status === 200,
+  });
+
+  if (!completeOk) {
+    writeFailures.add(1);
+    return;
+  }
+
+  // 5. Read user session history
+  const historyResponse = http.get(
+    `${BASE_URL}/sessions/${userId}/sessions`,
+    { tags: { name: 'GET /sessions/:userId/sessions' } }
+  );
+
+  check(historyResponse, {
+    'user history returned (200)': (r) => r.status === 200,
+  });
+
+  sleep(1);
+}
+
+export function handleSummary(data) {
+  return {
+    '/results/endpoint-summary.json': JSON.stringify(data, null, 2),
+  };
+}

k6/mixed-workload.js.bak

@@ -0,0 +1,128 @@
+
+import http from 'k6/http';
+import { check, sleep } from 'k6';
+import { Counter } from 'k6/metrics';
+
+const BASE_URL = __ENV.BASE_URL || 'http://app:3000';
+const seed = JSON.parse(open('./seed-data.json'));
+
+const writeFailures = new Counter('write_failures');
+
+export const options = {
+  stages: [
+    { duration: '20s', target: 50 },
+    { duration: '20s', target: 100 },
+    { duration: '30s', target: 150 },
+    { duration: '30s', target: 200 },
+    { duration: '30s', target: 250 },
+    { duration: '30s', target: 300 },
+    { duration: '30s', target: 350 },
+    { duration: '30s', target: 400 },
+    { duration: '20s', target: 0 },
+  ],
+  thresholds: {
+    http_req_failed: ['rate<0.02'],
+    http_req_duration: ['p(95)<500'],
+    write_failures: ['count==0'],
+  },
+};
+
+export default function () {
+  const unique = `${__VU}-${__ITER}-${Date.now()}`;
+  const startTime = new Date(Date.now() + 60 * 60 * 1000);
+  const endTime = new Date(startTime.getTime() + 30 * 60 * 1000);
+
+  // 1. Insert a new user
+  const userResponse = http.post(
+    `${BASE_URL}/users/`,
+    JSON.stringify({
+      fullName: `Load Test ${unique}`,
+      email: `load-${unique}@example.invalid`,
+      phone: `9${String(__VU).padStart(1, '0')}${String(__ITER).padStart(8, '0')}`.slice(0, 10),
+    }),
+    { headers: { 'Content-Type': 'application/json' }, tags: { name: 'POST /users' } }
+  );
+
+  const userOk = check(userResponse, {
+    'user inserted (201)': (r) => r.status === 201,
+  });
+
+  if (!userOk) {
+    writeFailures.add(1);
+    return;
+  }
+
+  const userId = userResponse.json('result._id');
+
+  // 2. Insert a session for the existing seeded teacher
+  const sessionResponse = http.post(
+    `${BASE_URL}/sessions/`,
+    JSON.stringify({
+      teacherId: seed.teacher.id,
+      startTime: startTime.toISOString(),
+      endTime: endTime.toISOString(),
+    }),
+    { headers: { 'Content-Type': 'application/json' }, tags: { name: 'POST /sessions' } }
+  );
+
+  const sessionOk = check(sessionResponse, {
+    'session inserted (201)': (r) => r.status === 201,
+  });
+
+  if (!sessionOk) {
+    writeFailures.add(1);
+    return;
+  }
+
+  const sessionId = sessionResponse.json('result._id');
+
+  // 3. Book the newly created session
+  const bookingResponse = http.post(
+    `${BASE_URL}/sessions/${sessionId}/book`,
+    JSON.stringify({ userId }),
+    { headers: { 'Content-Type': 'application/json' }, tags: { name: 'POST /sessions/:id/book' } }
+  );
+
+  const bookingOk = check(bookingResponse, {
+    'session booked (200)': (r) => r.status === 200,
+  });
+
+  if (!bookingOk) {
+    writeFailures.add(1);
+    return;
+  }
+
+  // 4. Complete the booked session
+  const completeResponse = http.patch(
+    `${BASE_URL}/sessions/${sessionId}/complete`,
+    null,
+    { tags: { name: 'PATCH /sessions/:id/complete' } }
+  );
+
+  const completeOk = check(completeResponse, {
+    'session completed (200)': (r) => r.status === 200,
+  });
+
+  if (!completeOk) {
+    writeFailures.add(1);
+    return;
+  }
+
+  // 5. Read user session history
+  const historyResponse = http.get(
+    `${BASE_URL}/sessions/${userId}/sessions`,
+    { tags: { name: 'GET /sessions/:userId/sessions' } }
+  );
+
+  check(historyResponse, {
+    'user history returned (200)': (r) => r.status === 200,
+  });
+
+  sleep(1);
+}
+
+export function handleSummary(data) {
+  return {
+    '/results/endpoint-summary.json': JSON.stringify(data, null, 2),
+  };
+}

k6/mixed-workload.js.before-endpoint-metrics

@@ -0,0 +1,130 @@
+
+import http from 'k6/http';
+import { check, sleep } from 'k6';
+import { Counter } from 'k6/metrics';
+import { textSummary } from 'https://jslib.k6.io/k6-summary/0.0.1/index.js';
+
+const BASE_URL = __ENV.BASE_URL || 'http://app:3000';
+const seed = JSON.parse(open('./seed-data.json'));
+
+const writeFailures = new Counter('write_failures');
+
+export const options = {
+  stages: [
+    { duration: '20s', target: 100 },
+    { duration: '20s', target: 200 },
+    { duration: '30s', target: 300 },
+    { duration: '30s', target: 400 },
+    { duration: '30s', target: 450 },
+    { duration: '30s', target: 500 },
+    { duration: '30s', target: 550 },
+    { duration: '30s', target: 600 },
+    { duration: '20s', target: 0 },
+  ],
+  thresholds: {
+    http_req_failed: ['rate<0.02'],
+    http_req_duration: ['p(95)<500'],
+    write_failures: ['count==0'],
+  },
+};
+
+export default function () {
+  const unique = `${__VU}-${__ITER}-${Date.now()}`;
+  const startTime = new Date(Date.now() + 60 * 60 * 1000);
+  const endTime = new Date(startTime.getTime() + 30 * 60 * 1000);
+
+  // 1. Insert a new user
+  const userResponse = http.post(
+    `${BASE_URL}/users/`,
+    JSON.stringify({
+      fullName: `Load Test ${unique}`,
+      email: `load-${unique}@example.invalid`,
+      phone: `9${String(__VU).padStart(1, '0')}${String(__ITER).padStart(8, '0')}`.slice(0, 10),
+    }),
+    { headers: { 'Content-Type': 'application/json' }, tags: { name: 'POST /users' } }
+  );
+
+  const userOk = check(userResponse, {
+    'user inserted (201)': (r) => r.status === 201,
+  });
+
+  if (!userOk) {
+    writeFailures.add(1);
+    return;
+  }
+
+  const userId = userResponse.json('result._id');
+
+  // 2. Insert a session for the existing seeded teacher
+  const sessionResponse = http.post(
+    `${BASE_URL}/sessions/`,
+    JSON.stringify({
+      teacherId: seed.teacher.id,
+      startTime: startTime.toISOString(),
+      endTime: endTime.toISOString(),
+    }),
+    { headers: { 'Content-Type': 'application/json' }, tags: { name: 'POST /sessions' } }
+  );
+
+  const sessionOk = check(sessionResponse, {
+    'session inserted (201)': (r) => r.status === 201,
+  });
+
+  if (!sessionOk) {
+    writeFailures.add(1);
+    return;
+  }
+
+  const sessionId = sessionResponse.json('result._id');
+
+  // 3. Book the newly created session
+  const bookingResponse = http.post(
+    `${BASE_URL}/sessions/${sessionId}/book`,
+    JSON.stringify({ userId }),
+    { headers: { 'Content-Type': 'application/json' }, tags: { name: 'POST /sessions/:id/book' } }
+  );
+
+  const bookingOk = check(bookingResponse, {
+    'session booked (200)': (r) => r.status === 200,
+  });
+
+  if (!bookingOk) {
+    writeFailures.add(1);
+    return;
+  }
+
+  // 4. Complete the booked session
+  const completeResponse = http.patch(
+    `${BASE_URL}/sessions/${sessionId}/complete`,
+    null,
+    { tags: { name: 'PATCH /sessions/:id/complete' } }
+  );
+
+  const completeOk = check(completeResponse, {
+    'session completed (200)': (r) => r.status === 200,
+  });
+
+  if (!completeOk) {
+    writeFailures.add(1);
+    return;
+  }
+
+  // 5. Read user session history
+  const historyResponse = http.get(
+    `${BASE_URL}/sessions/${userId}/sessions`,
+    { tags: { name: 'GET /sessions/:userId/sessions' } }
+  );
+
+  check(historyResponse, {
+    'user history returned (200)': (r) => r.status === 200,
+  });
+
+  sleep(1);
+}
+
+export function handleSummary(data) {
+  return {
+    stdout: textSummary(data, { indent: ' ', enableColors: true }),
+    '/results/endpoint-summary.json': JSON.stringify(data, null, 2),
+  };
+}

k6/seed-data.json

@@ -0,0 +1,392 @@
+{
+  "generatedAt": "2026-10-21T18:53:24.974Z",
+  "runId": "1792608804974",
+  "teacher": {
+    "id": "6ad90a253d51b696cdc51357",
+    "email": "teacher-1792608804974@example.invalid"
+  },
+  "users": [
+    {
+      "id": "6ad90a253d51b696cdc51358",
+      "email": "user-1792608804974-1@example.invalid"
+    },
+    {
+      "id": "6ad90a253d51b696cdc51359",
+      "email": "user-1792608804974-2@example.invalid"
+    },
+    {
+      "id": "6ad90a253d51b696cdc5135a",
+      "email": "user-1792608804974-3@example.invalid"
+    },
+    {
+      "id": "6ad90a253d51b696cdc5135b",
+      "email": "user-1792608804974-4@example.invalid"
+    },
+    {
+      "id": "6ad90a253d51b696cdc5135c",
+      "email": "user-1792608804974-5@example.invalid"
+    },
+    {
+      "id": "6ad90a253d51b696cdc5135d",
+      "email": "user-1792608804974-6@example.invalid"
+    },
+    {
+      "id": "6ad90a253d51b696cdc5135e",
+      "email": "user-1792608804974-7@example.invalid"
+    },
+    {
+      "id": "6ad90a253d51b696cdc5135f",
+      "email": "user-1792608804974-8@example.invalid"
+    },
+    {
+      "id": "6ad90a253d51b696cdc51360",
+      "email": "user-1792608804974-9@example.invalid"
+    },
+    {
+      "id": "6ad90a253d51b696cdc51361",
+      "email": "user-1792608804974-10@example.invalid"
+    },
+    {
+      "id": "6ad90a253d51b696cdc51362",
+      "email": "user-1792608804974-11@example.invalid"
+    },
+    {
+      "id": "6ad90a253d51b696cdc51363",
+      "email": "user-1792608804974-12@example.invalid"
+    },
+    {
+      "id": "6ad90a253d51b696cdc51364",
+      "email": "user-1792608804974-13@example.invalid"
+    },
+    {
+      "id": "6ad90a253d51b696cdc51365",
+      "email": "user-1792608804974-14@example.invalid"
+    },
+    {
+      "id": "6ad90a253d51b696cdc51366",
+      "email": "user-1792608804974-15@example.invalid"
+    },
+    {
+      "id": "6ad90a253d51b696cdc51367",
+      "email": "user-1792608804974-16@example.invalid"
+    },
+    {
+      "id": "6ad90a253d51b696cdc51368",
+      "email": "user-1792608804974-17@example.invalid"
+    },
+    {
+      "id": "6ad90a253d51b696cdc51369",
+      "email": "user-1792608804974-18@example.invalid"
+    },
+    {
+      "id": "6ad90a253d51b696cdc5136a",
+      "email": "user-1792608804974-19@example.invalid"
+    },
+    {
+      "id": "6ad90a253d51b696cdc5136b",
+      "email": "user-1792608804974-20@example.invalid"
+    }
+  ],
+  "sessions": [
+    {
+      "id": "6ad90a253d51b696cdc5136c",
+      "startTime": "2026-10-22T18:53:25.235Z",
+      "endTime": "2026-10-22T19:23:25.235Z",
+      "dateTimestamp": "2026-10-22T18:53:25.235Z"
+    },
+    {
+      "id": "6ad90a253d51b696cdc5136d",
+      "startTime": "2026-10-22T19:53:25.235Z",
+      "endTime": "2026-10-22T20:23:25.235Z",
+      "dateTimestamp": "2026-10-22T19:53:25.235Z"
+    },
+    {
+      "id": "6ad90a253d51b696cdc5136e",
+      "startTime": "2026-10-22T20:53:25.235Z",
+      "endTime": "2026-10-22T21:23:25.235Z",
+      "dateTimestamp": "2026-10-22T20:53:25.235Z"
+    },
+    {
+      "id": "6ad90a253d51b696cdc5136f",
+      "startTime": "2026-10-22T21:53:25.235Z",
+      "endTime": "2026-10-22T22:23:25.235Z",
+      "dateTimestamp": "2026-10-22T21:53:25.235Z"
+    },
+    {
+      "id": "6ad90a253d51b696cdc51370",
+      "startTime": "2026-10-22T22:53:25.235Z",
+      "endTime": "2026-10-22T23:23:25.235Z",
+      "dateTimestamp": "2026-10-22T22:53:25.235Z"
+    },
+    {
+      "id": "6ad90a253d51b696cdc51371",
+      "startTime": "2026-10-22T23:53:25.235Z",
+      "endTime": "2026-10-23T00:23:25.235Z",
+      "dateTimestamp": "2026-10-22T23:53:25.235Z"
+    },
+    {
+      "id": "6ad90a253d51b696cdc51372",
+      "startTime": "2026-10-23T00:53:25.235Z",
+      "endTime": "2026-10-23T01:23:25.235Z",
+      "dateTimestamp": "2026-10-23T00:53:25.235Z"
+    },
+    {
+      "id": "6ad90a253d51b696cdc51373",
+      "startTime": "2026-10-23T01:53:25.235Z",
+      "endTime": "2026-10-23T02:23:25.235Z",
+      "dateTimestamp": "2026-10-23T01:53:25.235Z"
+    },
+    {
+      "id": "6ad90a253d51b696cdc51374",
+      "startTime": "2026-10-23T02:53:25.235Z",
+      "endTime": "2026-10-23T03:23:25.235Z",
+      "dateTimestamp": "2026-10-23T02:53:25.235Z"
+    },
+    {
+      "id": "6ad90a253d51b696cdc51375",
+      "startTime": "2026-10-23T03:53:25.235Z",
+      "endTime": "2026-10-23T04:23:25.235Z",
+      "dateTimestamp": "2026-10-23T03:53:25.235Z"
+    },
+    {
+      "id": "6ad90a253d51b696cdc51376",
+      "startTime": "2026-10-23T04:53:25.235Z",
+      "endTime": "2026-10-23T05:23:25.235Z",
+      "dateTimestamp": "2026-10-23T04:53:25.235Z"
+    },
+    {
+      "id": "6ad90a253d51b696cdc51377",
+      "startTime": "2026-10-23T05:53:25.235Z",
+      "endTime": "2026-10-23T06:23:25.235Z",
+      "dateTimestamp": "2026-10-23T05:53:25.235Z"
+    },
+    {
+      "id": "6ad90a253d51b696cdc51378",
+      "startTime": "2026-10-23T06:53:25.235Z",
+      "endTime": "2026-10-23T07:23:25.235Z",
+      "dateTimestamp": "2026-10-23T06:53:25.235Z"
+    },
+    {
+      "id": "6ad90a253d51b696cdc51379",
+      "startTime": "2026-10-23T07:53:25.235Z",
+      "endTime": "2026-10-23T08:23:25.235Z",
+      "dateTimestamp": "2026-10-23T07:53:25.235Z"
+    },
+    {
+      "id": "6ad90a253d51b696cdc5137a",
+      "startTime": "2026-10-23T08:53:25.235Z",
+      "endTime": "2026-10-23T09:23:25.235Z",
+      "dateTimestamp": "2026-10-23T08:53:25.235Z"
+    },
+    {
+      "id": "6ad90a253d51b696cdc5137b",
+      "startTime": "2026-10-23T09:53:25.235Z",
+      "endTime": "2026-10-23T10:23:25.235Z",
+      "dateTimestamp": "2026-10-23T09:53:25.235Z"
+    },
+    {
+      "id": "6ad90a253d51b696cdc5137c",
+      "startTime": "2026-10-23T10:53:25.235Z",
+      "endTime": "2026-10-23T11:23:25.235Z",
+      "dateTimestamp": "2026-10-23T10:53:25.235Z"
+    },
+    {
+      "id": "6ad90a253d51b696cdc5137d",
+      "startTime": "2026-10-23T11:53:25.235Z",
+      "endTime": "2026-10-23T12:23:25.235Z",
+      "dateTimestamp": "2026-10-23T11:53:25.235Z"
+    },
+    {
+      "id": "6ad90a253d51b696cdc5137e",
+      "startTime": "2026-10-23T12:53:25.235Z",
+      "endTime": "2026-10-23T13:23:25.235Z",
+      "dateTimestamp": "2026-10-23T12:53:25.235Z"
+    },
+    {
+      "id": "6ad90a253d51b696cdc5137f",
+      "startTime": "2026-10-23T13:53:25.235Z",
+      "endTime": "2026-10-23T14:23:25.235Z",
+      "dateTimestamp": "2026-10-23T13:53:25.235Z"
+    },
+    {
+      "id": "6ad90a253d51b696cdc51380",
+      "startTime": "2026-10-23T14:53:25.235Z",
+      "endTime": "2026-10-23T15:23:25.235Z",
+      "dateTimestamp": "2026-10-23T14:53:25.235Z"
+    },
+    {
+      "id": "6ad90a253d51b696cdc51381",
+      "startTime": "2026-10-23T15:53:25.235Z",
+      "endTime": "2026-10-23T16:23:25.235Z",
+      "dateTimestamp": "2026-10-23T15:53:25.235Z"
+    },
+    {
+      "id": "6ad90a253d51b696cdc51382",
+      "startTime": "2026-10-23T16:53:25.235Z",
+      "endTime": "2026-10-23T17:23:25.235Z",
+      "dateTimestamp": "2026-10-23T16:53:25.235Z"
+    },
+    {
+      "id": "6ad90a253d51b696cdc51383",
+      "startTime": "2026-10-23T17:53:25.235Z",
+      "endTime": "2026-10-23T18:23:25.235Z",
+      "dateTimestamp": "2026-10-23T17:53:25.235Z"
+    },
+    {
+      "id": "6ad90a253d51b696cdc51384",
+      "startTime": "2026-10-23T18:53:25.235Z",
+      "endTime": "2026-10-23T19:23:25.235Z",
+      "dateTimestamp": "2026-10-23T18:53:25.235Z"
+    },
+    {
+      "id": "6ad90a253d51b696cdc51385",
+      "startTime": "2026-10-23T19:53:25.235Z",
+      "endTime": "2026-10-23T20:23:25.235Z",
+      "dateTimestamp": "2026-10-23T19:53:25.235Z"
+    },
+    {
+      "id": "6ad90a253d51b696cdc51386",
+      "startTime": "2026-10-23T20:53:25.235Z",
+      "endTime": "2026-10-23T21:23:25.235Z",
+      "dateTimestamp": "2026-10-23T20:53:25.235Z"
+    },
+    {
+      "id": "6ad90a253d51b696cdc51387",
+      "startTime": "2026-10-23T21:53:25.235Z",
+      "endTime": "2026-10-23T22:23:25.235Z",
+      "dateTimestamp": "2026-10-23T21:53:25.235Z"
+    },
+    {
+      "id": "6ad90a253d51b696cdc51388",
+      "startTime": "2026-10-23T22:53:25.235Z",
+      "endTime": "2026-10-23T23:23:25.235Z",
+      "dateTimestamp": "2026-10-23T22:53:25.235Z"
+    },
+    {
+      "id": "6ad90a253d51b696cdc51389",
+      "startTime": "2026-10-23T23:53:25.235Z",
+      "endTime": "2026-10-24T00:23:25.235Z",
+      "dateTimestamp": "2026-10-23T23:53:25.235Z"
+    },
+    {
+      "id": "6ad90a253d51b696cdc5138a",
+      "startTime": "2026-10-24T00:53:25.235Z",
+      "endTime": "2026-10-24T01:23:25.235Z",
+      "dateTimestamp": "2026-10-24T00:53:25.235Z"
+    },
+    {
+      "id": "6ad90a253d51b696cdc5138b",
+      "startTime": "2026-10-24T01:53:25.235Z",
+      "endTime": "2026-10-24T02:23:25.235Z",
+      "dateTimestamp": "2026-10-24T01:53:25.235Z"
+    },
+    {
+      "id": "6ad90a253d51b696cdc5138c",
+      "startTime": "2026-10-24T02:53:25.235Z",
+      "endTime": "2026-10-24T03:23:25.235Z",
+      "dateTimestamp": "2026-10-24T02:53:25.235Z"
+    },
+    {
+      "id": "6ad90a253d51b696cdc5138d",
+      "startTime": "2026-10-24T03:53:25.235Z",
+      "endTime": "2026-10-24T04:23:25.235Z",
+      "dateTimestamp": "2026-10-24T03:53:25.235Z"
+    },
+    {
+      "id": "6ad90a253d51b696cdc5138e",
+      "startTime": "2026-10-24T04:53:25.235Z",
+      "endTime": "2026-10-24T05:23:25.235Z",
+      "dateTimestamp": "2026-10-24T04:53:25.235Z"
+    },
+    {
+      "id": "6ad90a253d51b696cdc5138f",
+      "startTime": "2026-10-24T05:53:25.235Z",
+      "endTime": "2026-10-24T06:23:25.235Z",
+      "dateTimestamp": "2026-10-24T05:53:25.235Z"
+    },
+    {
+      "id": "6ad90a253d51b696cdc51390",
+      "startTime": "2026-10-24T06:53:25.235Z",
+      "endTime": "2026-10-24T07:23:25.235Z",
+      "dateTimestamp": "2026-10-24T06:53:25.235Z"
+    },
+    {
+      "id": "6ad90a253d51b696cdc51391",
+      "startTime": "2026-10-24T07:53:25.235Z",
+      "endTime": "2026-10-24T08:23:25.235Z",
+      "dateTimestamp": "2026-10-24T07:53:25.235Z"
+    },
+    {
+      "id": "6ad90a253d51b696cdc51392",
+      "startTime": "2026-10-24T08:53:25.235Z",
+      "endTime": "2026-10-24T09:23:25.235Z",
+      "dateTimestamp": "2026-10-24T08:53:25.235Z"
+    },
+    {
+      "id": "6ad90a253d51b696cdc51393",
+      "startTime": "2026-10-24T09:53:25.235Z",
+      "endTime": "2026-10-24T10:23:25.235Z",
+      "dateTimestamp": "2026-10-24T09:53:25.235Z"
+    },
+    {
+      "id": "6ad90a253d51b696cdc51394",
+      "startTime": "2026-10-24T10:53:25.235Z",
+      "endTime": "2026-10-24T11:23:25.235Z",
+      "dateTimestamp": "2026-10-24T10:53:25.235Z"
+    },
+    {
+      "id": "6ad90a253d51b696cdc51395",
+      "startTime": "2026-10-24T11:53:25.235Z",
+      "endTime": "2026-10-24T12:23:25.235Z",
+      "dateTimestamp": "2026-10-24T11:53:25.235Z"
+    },
+    {
+      "id": "6ad90a253d51b696cdc51396",
+      "startTime": "2026-10-24T12:53:25.235Z",
+      "endTime": "2026-10-24T13:23:25.235Z",
+      "dateTimestamp": "2026-10-24T12:53:25.235Z"
+    },
+    {
+      "id": "6ad90a253d51b696cdc51397",
+      "startTime": "2026-10-24T13:53:25.235Z",
+      "endTime": "2026-10-24T14:23:25.235Z",
+      "dateTimestamp": "2026-10-24T13:53:25.235Z"
+    },
+    {
+      "id": "6ad90a253d51b696cdc51398",
+      "startTime": "2026-10-24T14:53:25.235Z",
+      "endTime": "2026-10-24T15:23:25.235Z",
+      "dateTimestamp": "2026-10-24T14:53:25.235Z"
+    },
+    {
+      "id": "6ad90a253d51b696cdc51399",
+      "startTime": "2026-10-24T15:53:25.235Z",
+      "endTime": "2026-10-24T16:23:25.235Z",
+      "dateTimestamp": "2026-10-24T15:53:25.235Z"
+    },
+    {
+      "id": "6ad90a253d51b696cdc5139a",
+      "startTime": "2026-10-24T16:53:25.235Z",
+      "endTime": "2026-10-24T17:23:25.235Z",
+      "dateTimestamp": "2026-10-24T16:53:25.235Z"
+    },
+    {
+      "id": "6ad90a253d51b696cdc5139b",
+      "startTime": "2026-10-24T17:53:25.235Z",
+      "endTime": "2026-10-24T18:23:25.235Z",
+      "dateTimestamp": "2026-10-24T17:53:25.235Z"
+    },
+    {
+      "id": "6ad90a253d51b696cdc5139c",
+      "startTime": "2026-10-24T18:53:25.235Z",
+      "endTime": "2026-10-24T19:23:25.235Z",
+      "dateTimestamp": "2026-10-24T18:53:25.235Z"
+    },
+    {
+      "id": "6ad90a253d51b696cdc5139d",
+      "startTime": "2026-10-24T19:53:25.235Z",
+      "endTime": "2026-10-24T20:23:25.235Z",
+      "dateTimestamp": "2026-10-24T19:53:25.235Z"
+    }
+  ]
+}

k6/smoke.js

@@ -0,0 +1,23 @@
+import http from 'k6/http';
+import { check, sleep } from 'k6';
+
+export const options = {
+  vus: 1,
+  iterations: 10,
+  thresholds: {
+    http_req_failed: ['rate<0.01'],
+    http_req_duration: ['p(95)<500'],
+  },
+};
+
+export default function () {
+  const response = http.get('http://app:3000/users/');
+
+  check(response, {
+    'status is 200': (r) => r.status === 200,
+    'response is JSON': (r) =>
+      r.headers['Content-Type']?.includes('application/json'),
+  });
+
+  sleep(1);
+}

k6/stress.js

@@ -0,0 +1,37 @@
+import http from 'k6/http';
+import { check } from 'k6';
+
+const BASE_URL = __ENV.BASE_URL || 'http://app:3000';
+
+export const options = {
+  stages: [
+    { duration: '20s', target: 5 },
+    { duration: '20s', target: 10 },
+    { duration: '20s', target: 20 },
+    { duration: '20s', target: 30 },
+    { duration: '20s', target: 40 },
+    { duration: '20s', target: 50 },
+    { duration: '15s', target: 0 },
+  ],
+  thresholds: {
+    http_req_failed: ['rate<0.01'],
+    http_req_duration: ['p(95)<500'],
+    checks: ['rate>0.99'],
+  },
+};
+
+export default function () {
+  const endpoints = [
+    '/users/',
+    '/teachers/',
+    '/sessions/available?dateTimestamp=2026-10-25T10%3A00%3A00.000Z',
+  ];
+
+  for (const endpoint of endpoints) {
+    const response = http.get(`${BASE_URL}${endpoint}`);
+
+    check(response, {
+      [`${endpoint}: status 200`]: (r) => r.status === 200,
+    });
+  }
+}

scripts/seed.mjs

@@ -0,0 +1,126 @@
+import { writeFile } from 'node:fs/promises';
+
+const BASE_URL = process.env.API_BASE_URL || 'http://localhost:3000';
+const USER_COUNT = Number(process.env.SEED_USERS || 20);
+const SESSION_COUNT = Number(process.env.SEED_SESSIONS || 50);
+
+const runId = `${Date.now()}`;
+const generated = {
+  generatedAt: new Date().toISOString(),
+  runId,
+  teacher: null,
+  users: [],
+  sessions: [],
+};
+
+async function request(path, method = 'GET', body) {
+  const response = await fetch(`${BASE_URL}${path}`, {
+    method,
+    headers: { 'Content-Type': 'application/json' },
+    ...(body ? { body: JSON.stringify(body) } : {}),
+  });
+
+  const text = await response.text();
+  let data;
+
+  try {
+    data = JSON.parse(text);
+  } catch {
+    throw new Error(`${method} ${path}: Invalid JSON response: ${text}`);
+  }
+
+  if (!response.ok) {
+    throw new Error(
+      `${method} ${path} failed (${response.status}): ${JSON.stringify(data)}`
+    );
+  }
+
+  return data;
+}
+
+function entityId(data) {
+  const entity = data.result ?? data.data ?? data;
+  const id = entity._id ?? entity.id;
+
+  if (!id) {
+    throw new Error(`Could not find created record ID: ${JSON.stringify(data)}`);
+  }
+
+  return id;
+}
+
+async function main() {
+  console.log(`Seeding ${BASE_URL}`);
+
+  const teacherResponse = await request('/teachers/', 'POST', {
+    fullName: `Load Test Teacher ${runId}`,
+    email: `teacher-${runId}@example.invalid`,
+    specialization: 'Mathematics',
+    experience: '5 years',
+  });
+
+  generated.teacher = {
+    id: entityId(teacherResponse),
+    email: `teacher-${runId}@example.invalid`,
+  };
+
+  for (let i = 1; i <= USER_COUNT; i++) {
+    const email = `user-${runId}-${i}@example.invalid`;
+
+    const response = await request('/users/', 'POST', {
+      fullName: `Load Test User ${i}`,
+      email,
+      phone: String(9000000000 + i),
+    });
+
+    generated.users.push({
+      id: entityId(response),
+      email,
+    });
+
+    if (i % 10 === 0 || i === USER_COUNT) {
+      console.log(`Created ${i}/${USER_COUNT} users`);
+    }
+  }
+
+  // Start tomorrow and spread sessions one hour apart.
+  const firstStart = Date.now() + 24 * 60 * 60 * 1000;
+
+  for (let i = 0; i < SESSION_COUNT; i++) {
+    const start = new Date(firstStart + i * 60 * 60 * 1000);
+    const end = new Date(start.getTime() + 30 * 60 * 1000);
+
+    const response = await request('/sessions/', 'POST', {
+      teacherId: generated.teacher.id,
+      startTime: start.toISOString(),
+      endTime: end.toISOString(),
+    });
+
+    generated.sessions.push({
+      id: entityId(response),
+      startTime: start.toISOString(),
+      endTime: end.toISOString(),
+      dateTimestamp: start.toISOString(),
+    });
+
+    if ((i + 1) % 10 === 0 || i + 1 === SESSION_COUNT) {
+      console.log(`Created ${i + 1}/${SESSION_COUNT} sessions`);
+    }
+  }
+
+  await writeFile(
+    new URL('../k6/seed-data.json', import.meta.url),
+    JSON.stringify(generated, null, 2) + '\n'
+  );
+
+  console.log('\nSeeding completed successfully.');
+  console.log(`Teacher: 1`);
+  console.log(`Users: ${generated.users.length}`);
+  console.log(`Sessions: ${generated.sessions.length}`);
+  console.log('Saved IDs to k6/seed-data.json');
+}
+
+main().catch((error) => {
+  console.error('\nSeeding failed:', error.message);
+  process.exitCode = 1;
+});

src/Sessions/Schema/sessions.schema.ts

@@ -27,5 +27,8 @@ const SessionsSchema = new Schema({
   }
 }, { timestamps: true });
 
+SessionsSchema.index({ userId: 1 });
+SessionsSchema.index({ status: 1, startTime: 1 });
+
 const Sessions = mongoose.model('sessions', SessionsSchema);
 export default Sessions;

src/Sessions/sessions.routes.ts

@@ -58,38 +58,78 @@ SessionsRoutes.get('/available', async(req: any, res) => {
 
 
 // Book Available Sessions 
-SessionsRoutes.post('/:id/book', async(req: any, res) => {
+// SessionsRoutes.post('/:id/book', async(req: any, res) => {
+//
+//     const {id} = req.params;
+//     const {userId} = req.body;
+//
+//     const existingSession = await Sessions.findOne({_id: id});
+//
+//     if(!existingSession) {
+//         return res.status(400).send({message: 'Session does not exist.'})
+//     }
+//     if(existingSession.status !== 'AVAILABLE') {
+//         return res.status(400).send({message: 'This session is not Available'});
+//     }
+//
+//     const result = await Sessions.findByIdAndUpdate(
+//         id,
+//         { status: "BOOKED", userId: userId },
+//         { new: true }
+//     );
+//
+//     // console.log('re-------', result)
+//
+//     if(result?.status === 'BOOKED') {
+//         return res.status(200).send({message: 'Session Booked', result})
+//     } else {
+//         return res.status(400).send({message: 'Error during Booking session.'})
+//     }
+//
+//
+//
+// })
 
+// Book Available Sessions atomically
+SessionsRoutes.post('/:id/book', async (req: any, res) => {
   const { id } = req.params;
   const { userId } = req.body;
 
-    const existingSession = await Sessions.findOne({_id: id});
+  // Atomically book only if the session is still AVAILABLE
-    
+  const result = await Sessions.findOneAndUpdate(
-    if(!existingSession) {
+    { _id: id, status: 'AVAILABLE' },
-        return res.status(400).send({message: 'Session does not exist.'})
+    {
+      $set: {
+        status: 'BOOKED',
+        userId: userId
       }
-    if(existingSession.status !== 'AVAILABLE') {
+    },
-        return res.status(400).send({message: 'This session is not Available'});
+    {
+      new: true,
+      runValidators: true
     }
-
-    const result = await Sessions.findByIdAndUpdate(
-        id,
-        { status: "BOOKED", userId: userId },
-        { new: true }
   );
 
-    // console.log('re-------', result)
+  if (result) {
-
+    return res.status(200).send({
-    if(result?.status === 'BOOKED') {
+      message: 'Session Booked',
-        return res.status(200).send({message: 'Session Booked', result})
+      result
-    } else {
+    });
-        return res.status(400).send({message: 'Error during Booking session.'})
   }
 
+  // Determine why the booking failed
+  const existingSession = await Sessions.findById(id);
 
+  if (!existingSession) {
+    return res.status(400).send({
+      message: 'Session does not exist.'
+    });
+  }
 
-})
+  return res.status(400).send({
-
+    message: 'This session is not Available'
+  });
+});
 // Update Available Sessions To Complete : User Id also needed to update
 SessionsRoutes.patch('/:id/complete', async (req: any, res) => {
 

src/Users/users.routes.ts

@@ -1,34 +1,45 @@
 import express from 'express';
-import Users from './Schema/users.schema.js'
+import Users from './Schema/users.schema.js';
-
+import mongoose from 'mongoose';
 
 const UsersRoutes = express.Router();
 
-// Get All Users
+// Get all users
-UsersRoutes.get('/', async(req, res) => {
+UsersRoutes.get('/', async (_req, res, next) => {
+  try {
     const users = await Users.find();
-    return res.status(200).send({'messesage': 'success', data: {users}})
+    return res.status(200).send({
-})
+      message: 'success',
+      data: { users }
+    });
+  } catch (error) {
+    next(error);
+  }
+});
 
-// Add New User
+// Add a new user
-UsersRoutes.post('/', async(req, res) => {
+UsersRoutes.post('/', async (req, res, next) => {
+  try {
     const { fullName, email, phone } = req.body;
 
-    //Check for email uniqeness
+    const result = await Users.create({ fullName, email, phone });
-    const existingUser = await Users.find({email});
+
-    console.log('existingUser', existingUser)
+    return res.status(201).send({
-    if(existingUser.length){
+      message: 'User added successfully',
-        return res.status(400).send({message: 'User already exist with this email. Please Use Correct Email Address.'})
+      result
+    });
+  } catch (error: unknown) {
+    if (
+      error instanceof mongoose.mongo.MongoServerError &&
+      error.code === 11000
+    ) {
+      return res.status(400).send({
+        message: 'A user already exists with this email.'
+      });
     }
 
-    const newTeacher = new Users({fullName, email, phone });
+    next(error);
-    const result = await newTeacher.save();
-
-    if(result) {
-        return res.status(201).send({message: 'Teacher Added Successfully', result})
   }
-
+});
-})
-
 
 export default UsersRoutes;

tsconfig.json

@@ -2,8 +2,8 @@
   // Visit https://aka.ms/tsconfig to read more about this file
   "compilerOptions": {
     // File Layout
-    // "rootDir": "./src",
+    "rootDir": "./src",
-    // "outDir": "./dist",
+    "outDir": "./dist",
 
     // Environment Settings
     // See also https://aka.ms/tsconfig/module