A production-quality Go-based platform for integrating with Electronic Health Record (EHR) systems using the SMART on FHIR protocol. This sandbox demonstrates authentication, persistence, and dashboarding for patient and practitioner data, serving as a robust starting point for healthcare applications.

Features

SMART on FHIR Launch: Supports the full SMART App Launch flow (EHR launch and standalone) with OAuth2 code exchange.
Identity Resolution: Correctly handles practitioner identification from both practitioner and user (Practitioner/ID) fields in OAuth2 token responses.
Comprehensive FHIR Sync: Automatically synchronizes and persists key clinical data:
- Patient Demographics
- Observations (Vitals, Labs)
- Conditions (Problems)
- DocumentReferences
- MedicationRequests
- AllergyIntolerances
SQLite Persistence: Persists all synced data using a pure-Go SQLite driver (modernc.org/sqlite), requiring no CGO or external database server.
Secure Session Management: Server-side sessions stored in SQLite with secure, HttpOnly cookies.
Responsive Dashboard: A modern UI built with Go html/template that displays patient demographics, clinical data, and practitioner details.
Extensible Architecture: Modular design with clean separation of concerns (handlers, db, fhir, models, middleware, config).

Architecture

The project is structured into modular packages under /app:

/config: Configuration structures and URL normalization.
/db: Database schema, versioned migrations, and CRUD operations using modernc.org/sqlite.
/fhir: FHIR R4 resource definitions, SMART discovery, and FHIR client logic.
/handlers: HTTP request handlers (launch, auth, dashboard, sync) and template rendering.
/middleware: Session management middleware (loading and hard-gate protection).
/models: Core domain models and context keys.
/templates: Embedded HTML templates with layout inheritance.

Prerequisites

Go 1.24+
No external database required (uses embedded SQLite)

Getting Started

Clone the repository:

git clone https://github.com/AmanTahiliani/FHIR-Sandbox.git
cd FHIR-Sandbox

Run the application:
```
go run app/main.go
```
The server starts on http://localhost:8080.
Test with a Sandbox: Use the SMART Health IT Sandbox:
- App Launch URL: http://localhost:8080/launch
- Redirect URL: http://localhost:8080/auth-redirect
The default configuration in main.go is pre-set to work with the SmartHealthIT sandbox.

Configuration

Configuration is currently managed in app/main.go via the config.AppConfig struct. You can define multiple EHRs, set your redirect URI, and required scopes directly in the code.

// Example configuration in app/main.go
cfg := &config.AppConfig{
    DBPath: "fhir_sandbox.db",
    Server: config.ServerConfig{
        Port: 8080,
    },
    SMART: config.SMARTConfig{
        RedirectURL: "http://localhost:8080/auth-redirect",
        Scopes:      []string{"openid", "profile", "launch", "patient/*.read", "user/*.read"},
    },
    EHRs: []config.EHRConfig{
        {
            Name:         "SmartHealthIT Sandbox (R4)",
            FHIRURL:      "https://launch.smarthealthit.org/v/r4/fhir",
            ClientID:     "your-client-id",
            ClientSecret: "your-client-secret", // Optional, depending on EHR
        },
    },
}

Testing

The project includes comprehensive unit tests for database logic, FHIR parsing, and clinical data handling.

Run all tests:
```
go test ./...
```
Run tests with coverage:
```
go test -cover ./...
```

Future Improvements

Configuration Loading: Implement a robust configuration loader (e.g., spf13/viper) to load settings from files or environment variables.
Structured Logging: Migrate to Go 1.21's log/slog for structured, leveled logging.
Refresh Tokens: Implement OAuth2 refresh token logic to maintain long-lived sessions.
Additional Resources: Add support for Encounters, Procedures, Immunizations, etc.
Frontend Enhancement: Evolve the UI with HTMX or a modern JS framework for better interactivity.
FHIR Type Safety: Adopt a comprehensive FHIR library (e.g., google/fhir/go) for stricter type safety.