# rtx-hemodynamics-server

Server layer for the RustyTorch++ hemodynamics demo.

## Overview

This crate provides the API layer between the Tauri frontend and the hemodynamics PINN backend. It manages simulation state, handles inference requests, and provides a clean interface for IPC commands.

## Architecture

```
Tauri IPC
    ↓
HemodynamicsService  ← ServiceConfig
    ↓
SimulationHandle     ← manages state
    ↓
rtx-hemodynamics     ← PINN backend
```

## Modules

| Module | Description |
|--------|-------------|
| `service` | Main API: `HemodynamicsService` |
| `state` | Simulation state: `SimulationHandle`, `SimulationStatus` |
| `error` | Error types: `ServerError`, `ServerResult` |

## Usage

```rust
use rtx_hemodynamics_server::{HemodynamicsService, ServiceConfig};
use rtx_hemodynamics_shared::params::VesselParams;

// Create service
let service = HemodynamicsService::new(ServiceConfig::default()).unwrap();

// Initialize simulation
service.initialize(VesselParams::default()).await.unwrap();

// Query fields at points
let fields = service.query_fields(&points, 0.0).await.unwrap();

// Query on a grid
let grid = service.query_grid(100, 40, 0.0).await.unwrap();

// Modify geometry
service.add_stenosis(stenosis_params).await.unwrap();

// Get status
let status = service.get_status().await.unwrap();

// Get metrics
let metrics = service.get_metrics().await.unwrap();
```

## API Methods

### Initialization

| Method | Description |
|--------|-------------|
| `initialize(params)` | Initialize simulation with vessel parameters |
| `reset()` | Reset simulation to initial state |

### Inference

| Method | Description |
|--------|-------------|
| `query_fields(points, time)` | Query (u, v, p) at specific points |
| `query_grid(nx, ny, time)` | Query fields on a regular grid |

### Geometry

| Method | Description |
|--------|-------------|
| `add_stenosis(params)` | Add stenosis to vessel |
| `add_aneurysm(params)` | Add aneurysm to vessel |
| `place_stent(params)` | Place virtual stent |
| `reset_geometry()` | Reset to original geometry |

### Status

| Method | Description |
|--------|-------------|
| `get_status()` | Get simulation status |
| `get_metrics()` | Get performance metrics |

## State Management

The service maintains:
- **SimulationHandle**: Wraps the PINN model and manages GPU resources
- **SimulationStatus**: Tracks initialization, training progress, inference count
- **Metrics**: FPS, inference latency, GPU utilization

## Error Handling

```rust
pub enum ServerError {
    NotInitialized,
    InvalidParameters(String),
    InferenceError(String),
    GeometryError(String),
    InternalError(String),
}
```

All public methods return `ServerResult<T>`.

## Thread Safety

`HemodynamicsService` is `Send + Sync` and can be shared across async tasks using `Arc`. Internal state is protected by appropriate synchronization primitives.

## Configuration

```rust
pub struct ServiceConfig {
    pub max_query_points: usize,      // Default: 50000
    pub default_grid_nx: usize,       // Default: 100
    pub default_grid_ny: usize,       // Default: 40
    pub enable_cuda_graphs: bool,     // Default: true
    pub cache_inference: bool,        // Default: true
}
```

## Tests

```bash
cargo test
```

Integration tests verify:
- Service lifecycle (init → query → reset)
- Geometry modification flow
- Error handling for invalid states
- Concurrent access safety