# LAS Stream Viewer

Stream very large (10 GB+) LAS well-log files **line by line** in the browser. A Java 21 /
Quarkus backend indexes and streams the file with a constant, tiny memory footprint; a React +
Vite UI renders millions of lines via virtualization and plays them back as a live SSE stream.

Built for the Pason-style LAS 2.0 logs in `Desktop\LAS files` (up to ~12.5 GB, 426 curves,
~2.5 M rows). Nothing about the design assumes the file fits in memory.

## Why it scales

| Concern | Approach |
|---|---|
| Open a 12.5 GB file | **Open-in-place** (no copy) — or resumable chunked upload for remote files |
| Random access into the file | One-pass **sparse byte-offset index** (a checkpoint every 256 lines ≈ 80 KB for 2.5 M lines) |
| Indexing memory | Single streaming pass, 1 MiB buffer — independent of file size |
| Streaming memory | One `BufferedReader` advanced sequentially; lines pushed over **SSE** with backpressure |
| Browser memory | Virtualized list (only visible rows in the DOM) + a capped (20 K-line) LRU cache |
| Reading a line range | Seek to nearest checkpoint, skip ≤ 255 lines — effectively O(1) |

## Layout

```
las-stream-viewer/
├─ pom.xml                      Quarkus 3.34.3, Java 21
├─ run.ps1                      dev: Vite (:5173) + Quarkus (:8090)
├─ build.ps1                    prod: bundle UI into the jar, serve on :8090
├─ src/main/java/com/oiusa/las/
│  ├─ model/                    LasFile, Curve, HeaderSection
│  ├─ index/                    LineIndex (sparse offsets), LineReader (random access)
│  ├─ service/                  FileStore, IndexService (one-pass scan), LasHeaderParser, UploadService
│  └─ web/                      File / Lines / Stream(SSE) / Search(SSE) / Upload resources
└─ frontend/                    React + Vite + TS, @tanstack/react-virtual
```

## Run (dev)

```powershell
cd C:\Users\Dell\Desktop\las-stream-viewer
.\run.ps1
```

This installs UI deps on first run, starts Vite in a new window, and runs the Quarkus dev server.
Open **http://localhost:5173**.

To run the pieces by hand:

```powershell
# backend
$env:JAVA_HOME="C:\Program Files\Java\jdk-21.0.11"
$mvn = "C:\Users\Dell\.m2\wrapper\dists\apache-maven-3.9.9-bin\4nf9hui3q3djbarqar9g711ggc\apache-maven-3.9.9\bin\mvn.cmd"
& $mvn quarkus:dev
# frontend (separate window)
cd frontend; npm install; npm run dev
```

## Run (production, single port)

```powershell
.\build.ps1
$env:JAVA_HOME="C:\Program Files\Java\jdk-21.0.11"
java -jar target\quarkus-app\quarkus-run.jar
# open http://localhost:8090
```

## Using it

1. **Open on disk** — browse the server filesystem (constrained to `las.allowed-roots`, default your
   home dir) and click a `.las` file. It opens in place; indexing starts immediately and the header
   appears as soon as it's parsed.
2. **Upload** — drag a file in; it's streamed to the server in 16 MiB chunks.
3. Watch the **LAS header** (version/well/curve metadata) populate in the sidebar.
4. In the viewer: **▶ Stream** plays lines server-side over SSE (speed slider = lines/sec), scroll
   freely through all lines (ranges fetched on demand), jump to **Top / Data / End** or any line,
   and **Search** the whole file (streamed matches, click to jump).

## Configuration (`src/main/resources/application.properties`)

| Key | Default | Notes |
|---|---|---|
| `quarkus.http.port` | `8090` | API (and prod UI) port |
| `las.data-dir` | `${user.home}/.las-stream-viewer` | where uploads live |
| `las.allowed-roots` | `${user.home}` | local files may only be opened from under these roots |
| `las.index-stride` | `256` | lines per index checkpoint (smaller = faster seeks, larger index) |
| `las.upload-chunk-size` | `16777216` | upload chunk size hint (16 MiB) |
```