# Implementation Tasks

## 1. Database Schema Redesign
- [ ] 1.1 Backup existing database (for reference)
  - Export current schema and data
  - Document any important data to preserve
- [ ] 1.2 Drop old tables
  - Remove existing users table
  - Remove any related tables
  - Clear database for fresh start
- [ ] 1.3 Create new database schema
  - Create new `users` table (email as primary identifier)
  - Create `ocr_tasks` table with user association
  - Create `task_files` table for file tracking
  - Add proper indexes for performance
- [ ] 1.4 Create SQLAlchemy models
  - User model (simplified)
  - Task model with user relationship
  - TaskFile model with cascade delete
- [ ] 1.5 Generate Alembic migration
  - Create initial migration for new schema
  - Test migration script

## 2. Configuration Management
- [ ] 2.1 Update environment configuration
  - Add `EXTERNAL_AUTH_API_URL` to `.env.local`
  - Add `EXTERNAL_AUTH_ENDPOINT` configuration
  - Add `EXTERNAL_AUTH_TIMEOUT` setting
  - Add `TOKEN_REFRESH_BUFFER` setting
  - Add `TASK_RETENTION_DAYS` for auto-cleanup
  - Add `MAX_TASKS_PER_USER` for limits
  - Add `ENABLE_TASK_HISTORY` feature flag
- [ ] 2.2 Update Settings class
  - Add external auth settings to `backend/app/core/config.py`
  - Add task management settings
  - Add validation for new configuration values
  - Remove old authentication settings

## 3. External API Integration Service
- [ ] 3.1 Create auth API client
  - Implement `backend/app/services/external_auth_service.py`
  - Create async HTTP client for API calls
  - Implement request/response models
  - Add proper error handling and logging
- [ ] 3.2 Implement authentication methods
  - `authenticate_user()` - Call external API
  - `validate_token()` - Verify token validity
  - `refresh_token()` - Handle token refresh
  - `get_user_info()` - Fetch user details
- [ ] 3.3 Add resilience patterns
  - Implement retry logic with exponential backoff
  - Add circuit breaker pattern
  - Implement timeout handling
  - Add fallback mechanisms

## 4. Backend Authentication Updates
- [ ] 4.1 Modify login endpoint
  - Update `backend/app/api/v1/endpoints/auth.py`
  - Route to external API based on feature flag
  - Handle both authentication modes during transition
  - Return appropriate token format
- [ ] 4.2 Update token validation
  - Modify `backend/app/core/security.py`
  - Support both local and external tokens
  - Implement token type detection
  - Update JWT validation logic
- [ ] 4.3 Update authentication dependencies
  - Modify `backend/app/core/auth.py`
  - Update `get_current_user()` dependency
  - Handle external user information
  - Implement proper user context

## 5. Session and Token Management
- [ ] 5.1 Implement token storage
  - Store external tokens securely
  - Implement token encryption at rest
  - Handle multiple token types (access, ID, refresh)
- [ ] 5.2 Create token refresh mechanism
  - Background task for token refresh
  - Refresh tokens before expiration
  - Update stored tokens atomically
  - Handle refresh failures gracefully
- [ ] 5.3 Session invalidation
  - Clear tokens on logout
  - Handle token revocation
  - Implement session timeout

## 6. Frontend Updates
- [ ] 6.1 Update authentication service
  - Modify `frontend/src/services/authService.ts`
  - Handle new token format
  - Store user display information
  - Implement token refresh on client side
- [ ] 6.2 Update auth store
  - Modify `frontend/src/stores/authStore.ts`
  - Store external user information
  - Update user display logic
  - Handle token expiration
- [ ] 6.3 Update UI components
  - Modify `frontend/src/components/Header.tsx`
  - Display user `name` instead of username
  - Show additional user information
  - Update login form if needed
- [ ] 6.4 Error handling
  - Handle external API errors
  - Display appropriate error messages
  - Implement retry UI for failures
  - Add loading states

## 7. Task Management System (NEW)
- [ ] 7.1 Create task management backend
  - Implement `backend/app/models/task.py`
  - Implement `backend/app/models/task_file.py`
  - Create `backend/app/services/task_service.py`
  - Add task CRUD operations with user isolation
- [ ] 7.2 Implement task APIs
  - Create `backend/app/api/v1/endpoints/tasks.py`
  - GET /tasks (list user's tasks with pagination)
  - GET /tasks/{id} (get specific task)
  - DELETE /tasks/{id} (delete task)
  - POST /tasks/{id}/retry (retry failed task)
- [ ] 7.3 Create task history endpoints
  - Create `backend/app/api/v1/endpoints/task_history.py`
  - GET /history (query with filters)
  - GET /history/stats (user statistics)
  - POST /history/export (export history)
- [ ] 7.4 Implement file access control
  - Create `backend/app/services/file_access_service.py`
  - Validate user ownership before file access
  - Restrict download to user's own files
  - Add audit logging for file access
- [ ] 7.5 Update OCR service integration
  - Link OCR tasks to user accounts
  - Save task records in database
  - Update task status during processing
  - Store result file paths

## 8. Frontend Task Management UI (NEW)
- [ ] 8.1 Create task history page
  - Implement `frontend/src/pages/TaskHistory.tsx`
  - Display task list with status indicators
  - Add pagination controls
  - Show task details modal
- [ ] 8.2 Build task list component
  - Implement `frontend/src/components/TaskList.tsx`
  - Display task table with columns
  - Add sorting capabilities
  - Implement action buttons
- [ ] 8.3 Create filter components
  - Implement `frontend/src/components/TaskFilters.tsx`
  - Date range picker
  - Status filter dropdown
  - Search by filename
  - Clear filters button
- [ ] 8.4 Add task management store
  - Implement `frontend/src/stores/taskStore.ts`
  - Manage task list state
  - Handle filter state
  - Cache task data
- [ ] 8.5 Create task service client
  - Implement `frontend/src/services/taskService.ts`
  - API methods for task operations
  - Handle pagination
  - Implement retry logic
- [ ] 8.6 Update navigation
  - Add "Task History" menu item
  - Update router configuration
  - Add task count badge
  - Implement user menu with stats

## 9. User Isolation and Security
- [ ] 9.1 Implement user context middleware
  - Create middleware to inject user context
  - Validate user in all requests
  - Add user_id to logging context
- [ ] 9.2 Database query isolation
  - Add user_id filter to all task queries
  - Prevent cross-user data access
  - Implement row-level security
- [ ] 9.3 File system isolation
  - Organize files by user directory
  - Validate file paths before access
  - Implement cleanup for deleted users
- [ ] 9.4 API authorization
  - Add @require_user decorator
  - Validate ownership in endpoints
  - Return 403 for unauthorized access

## 10. Testing
- [ ] 10.1 Unit tests
  - Test external auth service
  - Test token validation
  - Test task isolation logic
  - Test file access control
- [ ] 10.2 Integration tests
  - Test full authentication flow
  - Test task management flow
  - Test user isolation between accounts
  - Test file download restrictions
- [ ] 10.3 Load testing
  - Test external API response times
  - Test system with many concurrent users
  - Test large task history queries
  - Measure database query performance
- [ ] 10.4 Security testing
  - Test token security
  - Verify user isolation
  - Test unauthorized access attempts
  - Validate SQL injection prevention

## 11. Migration Execution (Simplified)
- [ ] 11.1 Pre-migration preparation
  - Backup existing database (reference only)
  - Prepare deployment package
  - Set up monitoring
- [ ] 11.2 Execute migration
  - Drop old database tables
  - Create new schema
  - Deploy new code
  - Verify system startup
- [ ] 11.3 Post-migration validation
  - Test authentication with real users
  - Verify task isolation works
  - Check task history functionality
  - Validate file access controls

## 12. Documentation
- [ ] 12.1 Technical documentation
  - Update API documentation with new endpoints
  - Document authentication flow
  - Document task management APIs
  - Create troubleshooting guide
- [ ] 12.2 User documentation
  - Update login instructions
  - Document task history features
  - Explain user isolation
  - Create user guide for new UI
- [ ] 12.3 Developer documentation
  - Document database schema
  - Explain security model
  - Provide integration examples

## 13. Monitoring and Observability
- [ ] 13.1 Add monitoring metrics
  - Authentication success/failure rates
  - Task creation/completion rates
  - User activity metrics
  - File storage usage
- [ ] 13.2 Implement logging
  - Log all authentication attempts
  - Log task operations
  - Log file access attempts
  - Structured logging for analysis
- [ ] 13.3 Create alerts
  - Alert on authentication failures
  - Alert on high error rates
  - Alert on storage issues
  - Alert on performance degradation

## 14. Performance Optimization (Post-Launch)
- [ ] 14.1 Database optimization
  - Analyze query patterns
  - Add missing indexes
  - Optimize slow queries
- [ ] 14.2 Caching implementation
  - Cache user information
  - Cache task lists
  - Implement Redis if needed
- [ ] 14.3 File management
  - Implement automatic cleanup
  - Optimize storage structure
  - Add compression if needed