# System Architecture Diagrams

This document explains the physical and logical architecture design of the Nigeria Immigration Service Hospital Management System (NIS HMS).

## Architectural Overview

The application follows the **Clean Architecture** principles to separate concerns into decoupled layers, enhancing maintainability and testability.

```mermaid
graph TD
    subgraph Presentation Layer
        React[React 19 Frontend]
        Vite[Vite Bundler]
        Tailwind[Tailwind CSS v4]
        Controllers[Laravel API Controllers]
        Resources[API JSON Resources]
    end

    subgraph Business Layer
        Services[Service Layer]
        DTOs[Data Transfer Objects]
    end

    subgraph Repository Layer
        Contracts[Repository Interfaces]
        Eloquent[Eloquent Implementations]
    end

    subgraph Database Layer
        Postgres[(PostgreSQL 15)]
        Redis[(Redis Cache)]
    end

    React -->|REST HTTPS Requests| Controllers
    Controllers --> DTOs
    Controllers --> Services
    Services --> Contracts
    Eloquent -->|Implements| Contracts
    Eloquent --> Postgres
    Services --> Redis
```

## Relational Data Flow

1. **Patient Registration**: Demographics are requested via a `RegisterPatientDTO` form, written to PostgreSQL, and logged in the Audit Trail.
2. **Clinical Triage**: Nurses input vital sign metrics, creating a `Visit` object.
3. **Medical Consultation**: Doctors fetch patient files, write SOAP notes, input ICD-10 diagnoses, and trigger lab tests or drug prescriptions.
4. **Billing & cashier Checkout**: Total balances are calculated, invoices are generated, cashier captures payments, and issues official receipts.