# Payload CMS Authentication Migration Guide

## Overview

This guide provides detailed steps for migrating from the current JWT-based authentication system to Payload CMS's built-in authentication system while maintaining backward compatibility and ensuring zero downtime.

## Current Authentication System Analysis

### Existing Implementation
- **Technology**: Custom JWT implementation with bcryptjs
- **Token Expiry**: 7 days
- **Storage**: PostgreSQL (User, AdminUser tables)
- **Roles**: USER, ADMIN, SUPER_ADMIN
- **Session Management**: Stateless JWT tokens

### Current Auth Flow
```mermaid
graph LR
    A[User Login] --> B[Validate Credentials]
    B --> C[Generate JWT]
    C --> D[Return Token]
    D --> E[Store in LocalStorage]
    E --> F[Include in Headers]
    F --> G[Verify on Each Request]
```

## Payload Authentication System

### Key Features
- **Cookie-based sessions** with HTTP-only cookies
- **CSRF protection** built-in
- **Refresh tokens** for extended sessions
- **Password reset flow** with email verification
- **Two-factor authentication** support (optional)
- **OAuth providers** integration capability

### Payload Auth Flow
```mermaid
graph LR
    A[User Login] --> B[Validate Credentials]
    B --> C[Create Session]
    C --> D[Set HTTP-only Cookie]
    D --> E[Return User Data]
    E --> F[Auto-include Cookie]
    F --> G[Session Validation]
```

## Migration Strategy

### Phase 1: Dual Authentication Support

#### Step 1.1: Configure Payload Auth
```typescript
// config/auth.config.ts
export const authConfig = {
  // Enable both JWT and session-based auth
  cookies: {
    secure: process.env.NODE_ENV === 'production',
    sameSite: 'lax' as const,
    domain: process.env.COOKIE_DOMAIN,
  },
  tokenExpiration: 604800, // 7 days (matching current)
  maxLoginAttempts: 5,
  lockTime: 600000, // 10 minutes

  // Custom JWT for backward compatibility
  jwt: {
    secret: process.env.JWT_SECRET,
    expiresIn: '7d',
  },

  // Session configuration
  session: {
    resave: false,
    saveUninitialized: false,
    secret: process.env.SESSION_SECRET,
    cookie: {
      maxAge: 604800000, // 7 days in milliseconds
    },
  },
};
```

#### Step 1.2: Create Compatibility Layer
```typescript
// lib/auth/compatibility.ts
import jwt from 'jsonwebtoken';
import { PayloadRequest } from 'payload/types';

export class AuthCompatibilityLayer {
  /**
   * Validates both old JWT tokens and new Payload sessions
   */
  static async validateRequest(req: PayloadRequest) {
    // Check for Payload session first
    if (req.user) {
      return { valid: true, user: req.user, method: 'payload' };
    }

    // Check for legacy JWT token
    const token = this.extractJWT(req);
    if (token) {
      try {
        const decoded = jwt.verify(token, process.env.JWT_SECRET!);
        const user = await this.getUserFromToken(decoded);
        return { valid: true, user, method: 'jwt' };
      } catch (error) {
        return { valid: false, error: 'Invalid token' };
      }
    }

    return { valid: false, error: 'No authentication provided' };
  }

  private static extractJWT(req: PayloadRequest): string | null {
    const authHeader = req.headers.authorization;
    if (authHeader?.startsWith('Bearer ')) {
      return authHeader.substring(7);
    }
    return null;
  }

  private static async getUserFromToken(decoded: any) {
    // Fetch user from Payload collections
    const user = await payload.findByID({
      collection: 'users',
      id: decoded.userId,
    });
    return user;
  }

  /**
   * Generates both JWT (for legacy) and creates Payload session
   */
  static async createDualAuth(user: any, req: PayloadRequest) {
    // Create Payload session
    const payloadToken = await payload.login({
      collection: 'users',
      data: {
        email: user.email,
        password: user.password,
      },
      req,
    });

    // Generate legacy JWT
    const jwtToken = jwt.sign(
      {
        userId: user.id,
        email: user.email,
        role: user.role,
      },
      process.env.JWT_SECRET!,
      { expiresIn: '7d' }
    );

    return {
      payloadToken,
      jwtToken, // For backward compatibility
      user,
    };
  }
}
```

### Phase 2: User Migration

#### Step 2.1: User Data Migration Script
```typescript
// scripts/migrate-users.ts
import { PrismaClient } from '@prisma/client';
import payload from 'payload';
import bcrypt from 'bcryptjs';

const prisma = new PrismaClient();

interface MigrationResult {
  success: number;
  failed: number;
  errors: Array<{ email: string; error: string }>;
}

export async function migrateUsers(): Promise<MigrationResult> {
  const result: MigrationResult = {
    success: 0,
    failed: 0,
    errors: [],
  };

  // Fetch all users from Prisma
  const users = await prisma.user.findMany({
    include: {
      subscription: true,
      userSettings: true,
      bookmarks: true,
      highlights: true,
    },
  });

  console.log(`Starting migration of ${users.length} users...`);

  for (const user of users) {
    try {
      // Check if user already exists in Payload
      const existing = await payload.find({
        collection: 'users',
        where: {
          email: { equals: user.email },
        },
      });

      if (existing.docs.length > 0) {
        console.log(`User ${user.email} already migrated, skipping...`);
        continue;
      }

      // Create user in Payload
      const payloadUser = await payload.create({
        collection: 'users',
        data: {
          email: user.email,
          name: user.name,
          role: user.role,

          // Password handling - already hashed
          password: user.password,
          _verified: true, // Mark as verified

          // Custom fields
          stripeCustomerId: user.stripeCustomerId,
          favoriteVersion: user.favoriteVersion || 'VDC',

          // Settings
          profileSettings: {
            fontSize: user.userSettings?.fontSize || 16,
            theme: user.userSettings?.theme || 'light',
            showVerseNumbers: user.userSettings?.showVerseNumbers ?? true,
            enableNotifications: user.userSettings?.enableNotifications ?? true,
          },

          // Timestamps
          createdAt: user.createdAt,
          updatedAt: user.updatedAt,
          lastLogin: user.lastLogin,
        },
      });

      // Migrate related data
      if (user.subscription) {
        await migrateUserSubscription(payloadUser.id, user.subscription);
      }

      if (user.bookmarks.length > 0) {
        await migrateUserBookmarks(payloadUser.id, user.bookmarks);
      }

      if (user.highlights.length > 0) {
        await migrateUserHighlights(payloadUser.id, user.highlights);
      }

      result.success++;
      console.log(`✓ Migrated user: ${user.email}`);

    } catch (error) {
      result.failed++;
      result.errors.push({
        email: user.email,
        error: error.message,
      });
      console.error(`✗ Failed to migrate user ${user.email}:`, error);
    }
  }

  return result;
}

async function migrateUserSubscription(userId: string, subscription: any) {
  await payload.create({
    collection: 'subscriptions',
    data: {
      user: userId,
      stripeSubscriptionId: subscription.stripeSubscriptionId,
      planName: subscription.planName,
      status: subscription.status,
      currentPeriodStart: subscription.currentPeriodStart,
      currentPeriodEnd: subscription.currentPeriodEnd,
      conversationCount: subscription.conversationCount,
    },
  });
}

async function migrateUserBookmarks(userId: string, bookmarks: any[]) {
  for (const bookmark of bookmarks) {
    await payload.create({
      collection: 'bookmarks',
      data: {
        user: userId,
        book: bookmark.book,
        chapter: bookmark.chapter,
        verse: bookmark.verse,
        note: bookmark.note,
        createdAt: bookmark.createdAt,
      },
    });
  }
}

async function migrateUserHighlights(userId: string, highlights: any[]) {
  for (const highlight of highlights) {
    await payload.create({
      collection: 'highlights',
      data: {
        user: userId,
        verseId: highlight.verseId,
        color: highlight.color,
        note: highlight.note,
        createdAt: highlight.createdAt,
      },
    });
  }
}
```

#### Step 2.2: Password Migration Strategy

Since passwords are already hashed with bcrypt, we have three options:

**Option 1: Direct Hash Migration (Recommended)**
```typescript
// hooks/auth.hooks.ts
export const passwordValidationHook = {
  beforeOperation: async ({ args, operation }) => {
    if (operation === 'login') {
      const { email, password } = args.data;

      // Find user
      const user = await payload.find({
        collection: 'users',
        where: { email: { equals: email } },
      });

      if (user.docs.length === 0) {
        throw new Error('Invalid credentials');
      }

      const userDoc = user.docs[0];

      // Check if password needs rehashing (migrated user)
      if (userDoc.passwordMigrated) {
        // Use bcrypt directly for migrated passwords
        const valid = await bcrypt.compare(password, userDoc.password);
        if (!valid) {
          throw new Error('Invalid credentials');
        }

        // Rehash with Payload's method on successful login
        await payload.update({
          collection: 'users',
          id: userDoc.id,
          data: {
            password, // Will be hashed by Payload
            passwordMigrated: false,
          },
        });
      }
    }
  },
};
```

**Option 2: Password Reset Campaign**
```typescript
// scripts/password-reset-campaign.ts
export async function sendPasswordResetToMigratedUsers() {
  const migratedUsers = await payload.find({
    collection: 'users',
    where: {
      passwordMigrated: { equals: true },
    },
  });

  for (const user of migratedUsers.docs) {
    const token = await payload.forgotPassword({
      collection: 'users',
      data: { email: user.email },
      disableEmail: false,
    });

    // Send custom email explaining migration
    await sendMigrationEmail({
      to: user.email,
      token,
      userName: user.name,
    });
  }
}
```

### Phase 3: API Endpoint Migration

#### Step 3.1: Update Frontend API Calls
```typescript
// lib/api/auth.ts (Frontend)
export class AuthAPI {
  private static baseURL = process.env.NEXT_PUBLIC_API_URL;

  static async login(email: string, password: string) {
    try {
      // Try new Payload endpoint first
      const response = await fetch(`${this.baseURL}/api/users/login`, {
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
        credentials: 'include', // Important for cookies
        body: JSON.stringify({ email, password }),
      });

      if (response.ok) {
        const data = await response.json();

        // Store JWT for backward compatibility if provided
        if (data.token) {
          localStorage.setItem('token', data.token);
        }

        return { success: true, user: data.user };
      }
    } catch (error) {
      console.error('Payload login failed, trying legacy...', error);
    }

    // Fallback to legacy endpoint
    return this.legacyLogin(email, password);
  }

  private static async legacyLogin(email: string, password: string) {
    const response = await fetch(`${this.baseURL}/api/auth/login`, {
      method: 'POST',
      headers: { 'Content-Type': 'application/json' },
      body: JSON.stringify({ email, password }),
    });

    const data = await response.json();
    if (data.token) {
      localStorage.setItem('token', data.token);
    }

    return data;
  }

  static async logout() {
    // Clear both Payload session and JWT
    await fetch(`${this.baseURL}/api/users/logout`, {
      method: 'POST',
      credentials: 'include',
    });

    localStorage.removeItem('token');
  }

  static async getMe() {
    // Try Payload endpoint with cookie
    try {
      const response = await fetch(`${this.baseURL}/api/users/me`, {
        credentials: 'include',
      });

      if (response.ok) {
        return response.json();
      }
    } catch (error) {
      // Fallback to JWT
      const token = localStorage.getItem('token');
      if (token) {
        const response = await fetch(`${this.baseURL}/api/auth/me`, {
          headers: {
            'Authorization': `Bearer ${token}`,
          },
        });
        return response.json();
      }
    }

    throw new Error('Not authenticated');
  }
}
```

#### Step 3.2: Update API Middleware
```typescript
// middleware/auth.middleware.ts
import { PayloadRequest } from 'payload/types';
import { AuthCompatibilityLayer } from '../lib/auth/compatibility';

export async function authMiddleware(req: PayloadRequest, res: any, next: any) {
  const auth = await AuthCompatibilityLayer.validateRequest(req);

  if (!auth.valid) {
    return res.status(401).json({ error: auth.error });
  }

  // Attach user to request for both auth methods
  req.user = auth.user;
  req.authMethod = auth.method; // Track which auth method was used

  // Log for monitoring during migration
  console.log(`Auth method: ${auth.method} for user: ${auth.user.email}`);

  next();
}
```

### Phase 4: Testing & Validation

#### Step 4.1: Authentication Test Suite
```typescript
// tests/auth/migration.test.ts
import { describe, it, expect, beforeAll, afterAll } from '@jest/globals';
import payload from 'payload';
import { testUser } from '../fixtures/users';

describe('Authentication Migration Tests', () => {
  beforeAll(async () => {
    await payload.init({
      local: true,
      secret: 'test-secret',
    });
  });

  describe('Dual Authentication', () => {
    it('should accept legacy JWT tokens', async () => {
      const token = generateLegacyJWT(testUser);
      const response = await fetch('/api/protected', {
        headers: {
          'Authorization': `Bearer ${token}`,
        },
      });

      expect(response.status).toBe(200);
    });

    it('should accept Payload session cookies', async () => {
      const loginResponse = await fetch('/api/users/login', {
        method: 'POST',
        body: JSON.stringify({
          email: testUser.email,
          password: testUser.password,
        }),
        credentials: 'include',
      });

      const cookie = loginResponse.headers.get('set-cookie');

      const response = await fetch('/api/protected', {
        headers: {
          'Cookie': cookie,
        },
      });

      expect(response.status).toBe(200);
    });

    it('should migrate password on first login', async () => {
      const migratedUser = await createMigratedUser();

      const response = await fetch('/api/users/login', {
        method: 'POST',
        body: JSON.stringify({
          email: migratedUser.email,
          password: 'original-password',
        }),
      });

      expect(response.status).toBe(200);

      // Check that password was rehashed
      const user = await payload.findByID({
        collection: 'users',
        id: migratedUser.id,
      });

      expect(user.passwordMigrated).toBe(false);
    });
  });

  describe('Session Management', () => {
    it('should maintain session across requests', async () => {
      const session = await createAuthSession(testUser);

      // Make multiple requests with same session
      for (let i = 0; i < 5; i++) {
        const response = await fetch('/api/protected', {
          headers: {
            'Cookie': session.cookie,
          },
        });

        expect(response.status).toBe(200);
      }
    });

    it('should refresh token before expiry', async () => {
      const session = await createAuthSession(testUser);

      // Fast-forward time to near expiry
      jest.advanceTimersByTime(6 * 24 * 60 * 60 * 1000); // 6 days

      const response = await fetch('/api/users/refresh', {
        headers: {
          'Cookie': session.cookie,
        },
      });

      expect(response.status).toBe(200);

      const newCookie = response.headers.get('set-cookie');
      expect(newCookie).toBeTruthy();
    });
  });

  describe('Role-Based Access', () => {
    it('should enforce admin access', async () => {
      const regularUser = await createUser({ role: 'USER' });
      const adminUser = await createUser({ role: 'ADMIN' });

      const regularSession = await createAuthSession(regularUser);
      const adminSession = await createAuthSession(adminUser);

      // Regular user should be denied
      const regularResponse = await fetch('/api/admin/users', {
        headers: { 'Cookie': regularSession.cookie },
      });
      expect(regularResponse.status).toBe(403);

      // Admin should be allowed
      const adminResponse = await fetch('/api/admin/users', {
        headers: { 'Cookie': adminSession.cookie },
      });
      expect(adminResponse.status).toBe(200);
    });
  });
});
```

#### Step 4.2: Migration Validation Script
```typescript
// scripts/validate-migration.ts
export async function validateMigration() {
  const report = {
    users: { total: 0, migrated: 0, failed: [] },
    auth: { jwt: 0, payload: 0, dual: 0 },
    subscriptions: { total: 0, active: 0, cancelled: 0 },
    errors: [],
  };

  // Check user migration
  const prismaUsers = await prisma.user.count();
  const payloadUsers = await payload.count({ collection: 'users' });

  report.users.total = prismaUsers;
  report.users.migrated = payloadUsers.totalDocs;

  // Test authentication methods
  const testResults = await testAuthenticationMethods();
  report.auth = testResults;

  // Validate subscriptions
  const subscriptions = await validateSubscriptions();
  report.subscriptions = subscriptions;

  // Generate report
  console.log('Migration Validation Report:');
  console.log('============================');
  console.log(`Users: ${report.users.migrated}/${report.users.total} migrated`);
  console.log(`Auth Methods: JWT: ${report.auth.jwt}, Payload: ${report.auth.payload}`);
  console.log(`Subscriptions: ${report.subscriptions.active} active`);

  if (report.errors.length > 0) {
    console.log('\nErrors found:');
    report.errors.forEach(error => console.error(error));
  }

  return report;
}
```

### Phase 5: Gradual Rollout

#### Step 5.1: Feature Flags
```typescript
// lib/features/flags.ts
export const AuthFeatureFlags = {
  USE_PAYLOAD_AUTH: process.env.NEXT_PUBLIC_USE_PAYLOAD_AUTH === 'true',
  DUAL_AUTH_MODE: process.env.NEXT_PUBLIC_DUAL_AUTH === 'true',
  FORCE_PASSWORD_RESET: process.env.FORCE_PASSWORD_RESET === 'true',
};

// Usage in components
export function LoginForm() {
  const handleSubmit = async (data: LoginData) => {
    if (AuthFeatureFlags.USE_PAYLOAD_AUTH) {
      return payloadLogin(data);
    } else if (AuthFeatureFlags.DUAL_AUTH_MODE) {
      return dualLogin(data);
    } else {
      return legacyLogin(data);
    }
  };
}
```

#### Step 5.2: A/B Testing
```typescript
// lib/ab-testing/auth.ts
export function getAuthStrategy(userId?: string): 'legacy' | 'payload' | 'dual' {
  // Percentage-based rollout
  const rolloutPercentage = parseInt(process.env.PAYLOAD_AUTH_ROLLOUT || '0');

  if (!userId) {
    // New users always get Payload auth
    return 'payload';
  }

  // Consistent assignment based on user ID
  const hash = hashUserId(userId);
  const bucket = hash % 100;

  if (bucket < rolloutPercentage) {
    return 'payload';
  } else if (process.env.DUAL_AUTH === 'true') {
    return 'dual';
  } else {
    return 'legacy';
  }
}
```

### Phase 6: Monitoring & Observability

#### Step 6.1: Authentication Metrics
```typescript
// lib/monitoring/auth-metrics.ts
import { metrics } from '@opentelemetry/api-metrics';

export class AuthMetrics {
  private meter = metrics.getMeter('auth-migration');
  private loginCounter = this.meter.createCounter('auth_login_total');
  private methodHistogram = this.meter.createHistogram('auth_method_duration');
  private failureCounter = this.meter.createCounter('auth_failure_total');

  trackLogin(method: 'jwt' | 'payload' | 'dual', success: boolean, duration: number) {
    this.loginCounter.add(1, {
      method,
      success: success.toString(),
    });

    this.methodHistogram.record(duration, {
      method,
    });

    if (!success) {
      this.failureCounter.add(1, { method });
    }
  }

  async generateReport() {
    return {
      totalLogins: await this.getTotalLogins(),
      methodDistribution: await this.getMethodDistribution(),
      failureRate: await this.getFailureRate(),
      avgDuration: await this.getAverageDuration(),
    };
  }
}
```

#### Step 6.2: Monitoring Dashboard
```typescript
// components/admin/AuthMigrationDashboard.tsx
export function AuthMigrationDashboard() {
  const [metrics, setMetrics] = useState<AuthMetrics>();

  useEffect(() => {
    const fetchMetrics = async () => {
      const data = await fetch('/api/admin/auth-metrics').then(r => r.json());
      setMetrics(data);
    };

    fetchMetrics();
    const interval = setInterval(fetchMetrics, 30000); // Update every 30s
    return () => clearInterval(interval);
  }, []);

  return (
    <div className="dashboard">
      <h2>Authentication Migration Status</h2>

      <div className="metrics-grid">
        <MetricCard
          title="Auth Method Distribution"
          value={
            <PieChart data={[
              { name: 'JWT', value: metrics?.jwt || 0 },
              { name: 'Payload', value: metrics?.payload || 0 },
              { name: 'Dual', value: metrics?.dual || 0 },
            ]} />
          }
        />

        <MetricCard
          title="Migration Progress"
          value={`${metrics?.migratedUsers || 0} / ${metrics?.totalUsers || 0}`}
          subtitle={`${Math.round((metrics?.migratedUsers / metrics?.totalUsers) * 100)}% complete`}
        />

        <MetricCard
          title="Auth Success Rate"
          value={`${metrics?.successRate || 0}%`}
          trend={metrics?.successTrend}
        />

        <MetricCard
          title="Active Sessions"
          value={metrics?.activeSessions || 0}
          subtitle={`JWT: ${metrics?.jwtSessions}, Payload: ${metrics?.payloadSessions}`}
        />
      </div>

      <div className="recent-issues">
        <h3>Recent Authentication Issues</h3>
        <IssuesList issues={metrics?.recentIssues || []} />
      </div>
    </div>
  );
}
```

## Rollback Procedures

### Emergency Rollback Script
```typescript
// scripts/auth-rollback.ts
export async function rollbackAuth() {
  console.log('Starting authentication rollback...');

  // 1. Disable Payload auth endpoints
  await updateEnvironmentVariable('USE_PAYLOAD_AUTH', 'false');

  // 2. Re-enable legacy endpoints
  await updateEnvironmentVariable('USE_LEGACY_AUTH', 'true');

  // 3. Clear Payload sessions
  await payload.delete({
    collection: 'sessions',
    where: {},
  });

  // 4. Notify users
  await sendSystemNotification({
    message: 'Authentication system maintenance in progress',
    type: 'warning',
  });

  // 5. Monitor legacy auth performance
  startLegacyAuthMonitoring();

  console.log('Rollback complete. Legacy auth restored.');
}
```

## Best Practices & Recommendations

### Security Considerations
1. **Never log passwords** in any form
2. **Use HTTPS only** for production
3. **Implement rate limiting** on auth endpoints
4. **Monitor failed login attempts**
5. **Regular security audits** of auth flows

### Performance Optimization
1. **Cache user sessions** in Redis
2. **Implement session pooling**
3. **Use database indexes** on email fields
4. **Lazy-load user relationships**
5. **CDN for static auth assets**

### User Experience
1. **Transparent migration** - users shouldn't notice
2. **Clear error messages** for auth failures
3. **Password strength indicators**
4. **Remember me functionality**
5. **Social login options** (future enhancement)

## Conclusion

The migration to Payload CMS authentication provides:
- **Enhanced security** with HTTP-only cookies and CSRF protection
- **Better session management** with automatic refresh
- **Simplified codebase** with less custom auth code
- **Future-proof architecture** for OAuth and 2FA

The dual-authentication approach ensures zero downtime and allows for gradual migration with full rollback capability.

---

*Document Version: 1.0*
*Last Updated: November 2024*
*Author: Biblical Guide Development Team*