# Drizz.li

An open-source, high-performance weather forecast website built with SvelteKit and powered by the [Open-Meteo APIs](https://open-meteo.com/).

## Goals

Our objective is to provide a comprehensive, user-friendly weather platform for end-users. We aim to offer professional-grade weather visualizations and detailed meteorological data while maintaining the transparency and community-driven nature of open-source software.

## Tech Stack

- **Framework**: [SvelteKit](https://kit.svelte.dev/)
- **Language**: [TypeScript](https://www.typescriptlang.org/)
- **Data Source**: [Open-Meteo API](https://open-meteo.com/)
- **Visualization**: custom canvas charts (`src/lib/charts`)

## Developing

Once you've cloned the project and installed dependencies with `npm install`:

```sh
npm run dev

# or start the server and open the app in a new browser tab
npm run dev -- --open
```

## Building

To create a production version of your app:

```sh
npm run build
```

You can preview the production build with `npm run preview`.

## Deployment (static hosting)

The build output in `build/` is a fully static site. Two pieces of server
configuration are needed:

### 1. SPA fallback

Pages that are not prerendered (unlisted cities, GPS coordinate routes like
`/weather/week/52.09N5.12E/`) are served by `404.html`, which boots the app
and resolves the location client-side. Configure the server to serve
`404.html` for unknown paths.

Serve it as an **internal rewrite (200)**, not as an error page. `error_page
404 /404.html` sends the right body with a 404 status: the page works, but
every hard reload of an unprerendered URL logs a 404 in the network panel and
tells crawlers the page does not exist. `try_files` with a URI as its last
argument does an internal redirect instead, and answers 200.

### 2. Cross-origin isolation (SharedArrayBuffer for the embedded map)

The `/weather/maps/` page embeds `maps.open-meteo.com`, which uses
`SharedArrayBuffer` for its decoding worker pool. A cross-origin iframe only
gets `SharedArrayBuffer` when the **embedding** page is cross-origin
isolated, so this site must be served with:

```
Cross-Origin-Opener-Policy: same-origin
Cross-Origin-Embedder-Policy: require-corp
```

(The map already serves `Cross-Origin-Resource-Policy: cross-origin` and its
own COOP/COEP, so it is embeddable under these headers. All other assets are
same-origin and the weather APIs are CORS requests, so `require-corp` is safe
here.)

### Example: Caddy

```caddy
drizzli.example.com {
	root * /srv/drizzli
	file_server
	try_files {path} {path}/ /404.html
	header {
		Cross-Origin-Opener-Policy "same-origin"
		Cross-Origin-Embedder-Policy "require-corp"
	}
}
```

### Example: nginx

```nginx
server {
	server_name drizzli.example.com;
	root /srv/drizzli;
	add_header Cross-Origin-Opener-Policy "same-origin" always;
	add_header Cross-Origin-Embedder-Policy "require-corp" always;
	location / {
		# the trailing /404.html is a URI, so nginx rewrites internally and
		# answers 200 - `error_page 404 /404.html` would answer 404 instead
		try_files $uri $uri/index.html /404.html;
	}
}
```
