# Changes Summary - Dynamic Application System

## Overview
The application system has been completely redesigned to be fully dynamic and configurable. All application types, fields, statuses, and workflows are now defined in the database rather than hardcoded.

## Major Changes

### 1. Database Architecture

#### New Tables
- `application_types` - Defines application type templates
- `application_fields` - Field definitions for each type
- `application_type_statuses` - Status definitions per type
- `status_transitions` - Workflow transition rules
- `dynamic_applications` - Application instances
- `application_history_v2` - Complete audit trail
- `application_attachments_v2` - File attachments
- `application_transition_logs` - Status change tracking
- `application_approvals` - Approval decisions

#### Removed Tables
- `applications` (old fixed structure)
- `form_templates` (replaced by application_types)
- `field_mappings` (integrated into application_fields)

### 2. Core Features

#### Dynamic Field System
- 18+ field types (text, date, amount, etc.)
- Conditional display rules
- Custom validation per field
- Section grouping
- Default values and placeholders

#### Flexible Workflow
- Custom statuses with colors/icons
- Configurable transitions between statuses
- Multiple trigger types:
  - User approval (with role requirements)
  - Applicant actions
  - Time-based triggers
  - Condition-based triggers
  - Automatic transitions

#### Enhanced Cost Management
- Up to 100 cost positions (previously 24)
- Up to 100 comparison offers (previously 24)
- Categories and notes per position
- Automatic total calculation

### 3. API Changes

#### New Endpoints

**Application Types:**
- `GET /api/application-types` - List all types
- `GET /api/application-types/{id}` - Get specific type
- `POST /api/application-types` - Create new type (admin)
- `PUT /api/application-types/{id}` - Update type (admin)
- `DELETE /api/application-types/{id}` - Delete/deactivate type
- `POST /api/application-types/{id}/pdf-template` - Upload PDF

**Dynamic Applications:**
- `GET /api/applications` - List with advanced filtering
- `GET /api/applications/{id}` - Get with access key support
- `POST /api/applications` - Create with type selection
- `PUT /api/applications/{id}` - Update with validation
- `POST /api/applications/{id}/submit` - Submit for review
- `POST /api/applications/{id}/transition` - Status change
- `POST /api/applications/{id}/approve` - Approval actions
- `GET /api/applications/{id}/history` - Audit trail
- `POST /api/applications/{id}/generate-pdf` - PDF generation

#### Removed Endpoints
- All QSM/VSM specific endpoints
- Fixed form template endpoints
- Legacy PDF processing endpoints

### 4. Models & Types

#### New TypeScript Types (`frontend/src/types/dynamic.ts`)
- `ApplicationType` - Type definition
- `FieldDefinition` - Field configuration
- `StatusDefinition` - Status configuration
- `TransitionDefinition` - Workflow rules
- `DynamicApplication` - Application instance
- `CostPosition` - Cost item structure
- `ComparisonOffer` - Vendor offer structure

#### New Python Models (`backend/src/models/application_type.py`)
- `ApplicationType` - Type ORM model
- `ApplicationField` - Field ORM model
- `ApplicationTypeStatus` - Status ORM model
- `StatusTransition` - Transition ORM model
- `DynamicApplication` - Application ORM model
- Supporting models for history, attachments, approvals

### 5. Services

#### New Services
- `NotificationService` - Email notifications with templates
- `PDFService` - Dynamic PDF generation
- `AuthService` - Enhanced authentication with roles

#### Enhanced Services
- Field validation with type-specific rules
- PDF template mapping and filling
- Workflow engine for transitions
- Audit logging for all changes

### 6. Frontend Updates

#### New Components (to be implemented)
- Dynamic field renderer
- Visual workflow designer
- Application type builder
- Status badge with colors
- Cost position manager (100 items)
- Comparison offer manager (100 items)

#### API Client (`frontend/src/api/dynamicClient.ts`)
- Full TypeScript support
- Automatic token refresh
- Public access support
- Error handling
- File upload support

### 7. Migration

#### Data Migration (`backend/scripts/migrate_to_dynamic.py`)
- Creates QSM and VSM as dynamic types
- Migrates existing applications
- Preserves all data and relationships
- Maintains audit trail

#### Migration Steps
1. Run database migration to create new tables
2. Execute migration script to create default types
3. Verify data integrity
4. Update frontend to use new endpoints
5. Remove old code and tables

### 8. Configuration

#### Environment Variables
```env
# New/Updated
MAX_COST_POSITIONS=100
MAX_COMPARISON_OFFERS=100
PDF_TEMPLATE_STORAGE=database
DYNAMIC_FIELD_VALIDATION=true
WORKFLOW_ENGINE_ENABLED=true
AUDIT_LOGGING_LEVEL=detailed
```

### 9. Benefits

#### For Administrators
- Create new application types without coding
- Visual workflow designer
- Flexible field configuration
- PDF template management
- Role-based access control

#### For Users
- Consistent interface across all types
- Better validation and help text
- Public access with keys
- Enhanced cost management
- Real-time status tracking

#### For Developers
- No hardcoded logic
- Extensible field types
- Clean separation of concerns
- Full TypeScript support
- Comprehensive audit trail

### 10. Breaking Changes

#### Backend
- All application endpoints changed
- Database schema completely redesigned
- Old models removed
- API response format changed

#### Frontend
- New type system required
- API client rewritten
- Component props changed
- State management updated

### 11. Upgrade Path

1. **Backup** all existing data
2. **Deploy** new backend with migrations
3. **Run** migration script
4. **Update** frontend to new API
5. **Test** thoroughly
6. **Remove** old code and tables

### 12. Future Enhancements

- Form templates and presets
- Batch operations
- Advanced reporting
- Mobile app support
- Webhook integrations
- Custom field types via plugins
- Multi-language support
- Advanced PDF templates with conditionals

## Summary

This update transforms the application system from a fixed, hardcoded structure to a fully dynamic, database-driven system. While this is a major breaking change, it provides unlimited flexibility for future requirements without code changes.