# KiviCare REST API Plugin - Feature Specification

**Status**: Draft  
**Created**: 2025-09-12  
**Last Updated**: 2025-09-12  
**Branch**: spec/care-api  
**Assignee**: AikTop (ID: 25)

## 📋 Executive Summary

The KiviCare REST API Plugin provides comprehensive REST API access to all KiviCare healthcare management system functionality through a secure, authenticated WordPress plugin. This system enables third-party applications, mobile apps, and external integrations to programmatically interact with patient records, appointments, clinical data, and billing information while maintaining strict security and compliance standards.

## 🎯 Objectives

### Primary Objectives
- **Complete API Coverage**: Expose all 35 KiviCare database entities through REST endpoints
- **Enterprise Security**: Implement JWT authentication with role-based access control
- **WordPress Integration**: Native plugin architecture with hooks, filters, and admin interface
- **Developer Experience**: Comprehensive API documentation with SDK libraries

### Secondary Objectives
- **High Performance**: Sub-200ms response times with caching strategies
- **Audit Compliance**: Complete activity logging for healthcare compliance (HIPAA considerations)
- **Monitoring & Analytics**: Real-time API usage metrics and health monitoring
- **Multi-tenant Support**: Support multiple clinic installations

## 📖 User Stories

### As a Healthcare Application Developer
- **I want** to authenticate securely and access patient data via REST API
- **So that** I can build custom healthcare applications integrated with KiviCare
- **Given** I have valid API credentials
- **When** I make authenticated requests to patient endpoints
- **Then** I receive structured JSON data with proper HTTP status codes

### As a Clinic Administrator
- **I want** to control which external applications can access our data
- **So that** patient privacy and compliance requirements are maintained
- **Given** I have admin access to the WordPress dashboard
- **When** I configure API permissions and generate API keys
- **Then** only authorized applications can access specific data endpoints

### As a Mobile App Developer
- **I want** to access appointment scheduling and patient lookup functionality
- **So that** I can create mobile applications for patients and staff
- **Given** I have mobile app credentials
- **When** I integrate with appointment and patient endpoints
- **Then** I can build responsive mobile interfaces for healthcare workflows

## 🔧 Technical Requirements

### Functional Requirements
1. **Authentication System**: JWT-based authentication with refresh tokens and role-based access
2. **CRUD Operations**: Complete Create, Read, Update, Delete operations for all KiviCare entities
3. **Data Validation**: Comprehensive input validation and sanitization for all endpoints
4. **Error Handling**: Structured error responses with proper HTTP status codes
5. **Rate Limiting**: Configurable rate limiting to prevent API abuse
6. **Audit Logging**: Complete activity logs for compliance and monitoring

### Non-Functional Requirements
1. **Performance**: 95th percentile response time < 200ms under normal load
2. **Security**: OWASP Top 10 compliance, SQL injection prevention, XSS protection
3. **Scalability**: Support for 1000+ concurrent users with horizontal scaling capability
4. **Reliability**: 99.9% uptime with graceful failure handling and circuit breakers

### API Specification
```
Base URL: /wp-json/kivicare-api/v1/
Authentication: Bearer JWT Token
Content-Type: application/json
Rate Limit: 1000 requests/hour per API key
Response Format: JSON with consistent structure
Error Format: RFC 7807 Problem Details
```

## 📊 Database Schema

### No New Tables Required
The plugin integrates with existing KiviCare schema (35 tables):
- Core: `kc_patients`, `kc_doctors`, `kc_appointments`, `kc_clinics`
- Clinical: `kc_encounters`, `kc_prescriptions`, `kc_medical_records`
- Billing: `kc_bills`, `kc_services`, `kc_payments`
- System: `kc_users`, `kc_roles`, `kc_settings`

### Schema Enhancements
```sql
-- Add API tracking columns to existing tables (optional)
ALTER TABLE wp_kc_appointments ADD COLUMN api_created_at TIMESTAMP NULL;
ALTER TABLE wp_kc_appointments ADD COLUMN api_modified_at TIMESTAMP NULL;
ALTER TABLE wp_kc_appointments ADD COLUMN api_source VARCHAR(50) NULL;

-- API Keys table for authentication
CREATE TABLE wp_kc_api_keys (
    id BIGINT AUTO_INCREMENT PRIMARY KEY,
    user_id BIGINT NOT NULL,
    api_key VARCHAR(64) NOT NULL UNIQUE,
    secret_key VARCHAR(64) NOT NULL,
    name VARCHAR(100) NOT NULL,
    permissions JSON,
    last_used_at TIMESTAMP NULL,
    created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
    expires_at TIMESTAMP NULL,
    is_active BOOLEAN DEFAULT TRUE,
    INDEX idx_api_key (api_key),
    INDEX idx_user_id (user_id)
);
```

## 🏗️ Architecture

### System Components
- **Authentication Layer**: JWT token management, user validation, permission checking
- **API Controller Layer**: RESTful endpoint handlers, request routing, response formatting  
- **Service Layer**: Business logic, data validation, KiviCare integration
- **Data Access Layer**: WordPress database abstraction, query optimization
- **Security Layer**: Rate limiting, input sanitization, audit logging

### Data Flow
1. **Request Reception**: WordPress REST API receives authenticated request
2. **Authentication**: JWT token validation and user permission checking
3. **Route Processing**: Request routed to appropriate API controller
4. **Business Logic**: Service layer processes request with validation
5. **Data Access**: Secure database operations via WordPress $wpdb
6. **Response Formation**: Structured JSON response with proper HTTP codes

### Integration Points
- **WordPress Core**: Uses WP REST API framework and authentication hooks
- **KiviCare Plugin**: Integrates with existing KiviCare database schema and business logic
- **External Applications**: RESTful API consumption via HTTP/HTTPS protocols

## 🔒 Security Considerations

### Authentication & Authorization
- **JWT Authentication**: Secure token-based authentication with configurable expiration
- **Role-Based Access Control (RBAC)**: Granular permissions per user role and endpoint
- **API Key Management**: Secure API key generation, rotation, and revocation
- **Session Management**: Stateless authentication with refresh token capability

### Data Protection
- **Input Sanitization**: WordPress sanitization functions for all user inputs
- **SQL Injection Prevention**: Exclusive use of prepared statements via $wpdb
- **XSS Protection**: Output escaping and Content Security Policy headers
- **Data Encryption**: Sensitive data encryption at rest and in transit (HTTPS)

### Vulnerability Mitigation
- **Rate Limiting**: Prevents brute force attacks and API abuse
- **CORS Configuration**: Proper Cross-Origin Resource Sharing policies
- **Request Size Limits**: Protection against large payload attacks
- **Audit Logging**: Complete request/response logging for security monitoring

## 🧪 Testing Strategy

### Unit Tests
- **Model Layer Testing**: Test all KiviCare entity models and data validation
- **Service Layer Testing**: Business logic and KiviCare integration testing
- **Authentication Testing**: JWT token generation, validation, and expiration
- **API Controller Testing**: Endpoint routing, request handling, response formatting

### Integration Tests
- **Database Integration**: WordPress database operations and KiviCare schema interaction
- **WordPress Integration**: Plugin activation, deactivation, and REST API framework
- **Authentication Flow**: End-to-end authentication and authorization workflows
- **Permission Testing**: Role-based access control across all endpoints

### End-to-End Tests
- **API Workflow Testing**: Complete user journeys from authentication to data access
- **Multi-user Testing**: Concurrent access scenarios with different user roles
- **Error Scenario Testing**: Network failures, invalid data, and edge cases
- **Performance Testing**: Load testing with realistic healthcare data volumes

### Performance Tests
- **Load Testing**: 1000+ concurrent users with typical healthcare API usage patterns
- **Stress Testing**: System behavior under extreme load conditions
- **Endpoint Performance**: Individual endpoint response time optimization
- **Database Performance**: Query optimization and indexing validation

## 📋 Acceptance Criteria

### Must Have
- [ ] All 35 KiviCare entities accessible via REST API endpoints
- [ ] JWT authentication with role-based access control implemented
- [ ] Complete input validation and sanitization for all endpoints
- [ ] Comprehensive error handling with proper HTTP status codes
- [ ] PHPUnit test suite with 90%+ code coverage
- [ ] WordPress coding standards (WPCS) compliance
- [ ] API documentation with interactive examples
- [ ] Rate limiting and basic security measures implemented

### Should Have
- [ ] Real-time API monitoring dashboard
- [ ] Automated API key management interface
- [ ] Comprehensive audit logging system
- [ ] Performance optimization with caching
- [ ] Multi-language API documentation
- [ ] SDK libraries for PHP, JavaScript, Python
- [ ] Webhook support for real-time notifications
- [ ] Advanced search and filtering capabilities

### Could Have
- [ ] GraphQL endpoint alongside REST API
- [ ] API versioning strategy implementation
- [ ] Multi-tenant clinic support
- [ ] Advanced analytics and reporting features
- [ ] Integration with external healthcare systems (HL7, FHIR)
- [ ] Mobile SDK for iOS and Android
- [ ] Automated API testing in CI/CD pipeline
- [ ] Advanced security features (2FA, IP whitelisting)

## 🚀 Implementation Plan

### Phase 1: Foundation (Weeks 1-2)
- **Authentication System**: JWT implementation with user role integration
- **Core API Framework**: Base controller classes and response formatting
- **Security Layer**: Input sanitization and basic rate limiting
- **Testing Foundation**: PHPUnit setup and basic test structure

### Phase 2: Core Endpoints (Weeks 3-6)
- **Patient Management**: CRUD operations for patient data and medical history
- **Appointment System**: Scheduling, modification, and cancellation endpoints
- **Doctor Management**: Doctor profiles, availability, and specialization data
- **Clinic Operations**: Multi-clinic support and clinic-specific data access

### Phase 3: Advanced Features (Weeks 7-10)
- **Clinical Documentation**: Encounters, prescriptions, and medical records
- **Billing Integration**: Bills, services, payments, and insurance claims
- **Audit Logging**: Comprehensive activity tracking and compliance reporting
- **Performance Optimization**: Caching, query optimization, and monitoring

### Phase 4: Enhancement & Documentation (Weeks 11-12)
- **API Documentation**: Interactive documentation with Swagger/OpenAPI
- **SDK Development**: Client libraries for popular programming languages
- **Advanced Security**: Enhanced rate limiting, API key management
- **Production Deployment**: CI/CD pipeline and production monitoring

## 📊 Success Metrics

### Key Performance Indicators
- **API Response Time**: 95th percentile < 200ms
- **System Uptime**: 99.9% availability
- **Test Coverage**: 90%+ code coverage maintained
- **Security Compliance**: Zero critical security vulnerabilities
- **Developer Adoption**: 10+ active integrations within 6 months

### Success Criteria
- **Complete API Coverage**: All KiviCare entities accessible via REST endpoints
- **Production Readiness**: Deployed and stable in production environments
- **Developer Satisfaction**: Positive feedback from integration developers
- **Performance Targets**: All performance KPIs consistently met
- **Compliance Standards**: Healthcare data protection requirements satisfied

## 📚 Documentation Requirements

### Technical Documentation
- [ ] Complete API Reference with interactive examples (Swagger/OpenAPI)
- [ ] Database Schema Documentation with entity relationships
- [ ] Architecture Documentation with system diagrams
- [ ] Security Documentation including authentication flows
- [ ] Deployment Guide for various hosting environments

### User Documentation
- [ ] Developer Quick Start Guide with sample applications
- [ ] API Integration Tutorial with step-by-step examples
- [ ] Troubleshooting Guide with common issues and solutions
- [ ] Best Practices Guide for optimal API usage
- [ ] Migration Guide for existing KiviCare installations

## 🔄 Dependencies

### Internal Dependencies
- **KiviCare Plugin**: v3.0+ (core healthcare management system)
- **WordPress Core**: v6.0+ (REST API framework and authentication)
- **PHP Runtime**: 8.1+ (modern PHP features and performance)

### External Dependencies
- **Firebase JWT Library**: v6.0+ for secure JWT token handling
- **PHPUnit Testing Framework**: v9.0+ for comprehensive test coverage
- **WordPress Coding Standards**: Latest version for code quality
- **Composer**: Package management and PSR-4 autoloading

## ⚠️ Risks & Mitigation

### Technical Risks
- **Risk**: KiviCare schema changes breaking API compatibility
  - **Impact**: High - Could break all API integrations
  - **Mitigation**: Version-controlled API with backward compatibility strategy

- **Risk**: Performance degradation under high load
  - **Impact**: Medium - Could affect user experience
  - **Mitigation**: Comprehensive performance testing and caching implementation

### Business Risks
- **Risk**: Healthcare compliance and data privacy violations
  - **Impact**: Critical - Legal and regulatory consequences
  - **Mitigation**: Security-first design with audit logging and compliance review

- **Risk**: Limited adoption due to complex integration requirements
  - **Impact**: Medium - Reduces business value and ROI
  - **Mitigation**: Comprehensive documentation and SDK libraries

## 📅 Timeline

### Milestones
- **Foundation Complete**: Week 2 - Authentication and core framework ready
- **Core API Ready**: Week 6 - Primary endpoints functional with testing
- **Feature Complete**: Week 10 - All endpoints implemented with security
- **Production Ready**: Week 12 - Documentation, optimization, and deployment

### Critical Path
1. **Authentication System** → **Core API Framework** → **Security Implementation**
2. **Patient/Appointment Endpoints** → **Clinical Documentation** → **Billing Integration**
3. **Testing Infrastructure** → **Performance Optimization** → **Production Deployment**

## 🔗 Related Features

### Prerequisites
- **KiviCare Plugin Installation**: Active and configured
- **WordPress Environment**: Version 6.0+ with REST API enabled
- **SSL Certificate**: HTTPS required for secure API communication

### Follow-up Features
- **Mobile Application**: Native iOS and Android apps using the API
- **Third-party Integrations**: Integration with popular healthcare systems
- **Advanced Analytics**: Business intelligence dashboard for clinic operations
- **Telehealth Integration**: Video consultation booking and management

---

**Specification Version**: 1.0  
**Template Version**: Descomplicar® v2.0  
**Next Phase**: Implementation Planning (`/plan`)
