# Halcyon belt

A once-a-day asteroid-belt simulator. Players cannot fly their ships: they write a
program for the ship's flight computer, launch it, and then exchange 1 KB a day with
it over a "wormhole" link. The belt is simulated once a day, deterministically.

- `docs/manual.txt` -- the HC-33 flight computer programmer's manual (also served at `/manual.txt`)
- `examples/programs/` -- sample ship programs (assembly)

## Run it

```sh
go run ./cmd/server -db sqlite:wh.db            # API + website on :8080
go run ./cmd/daily  -db sqlite:wh.db            # simulate one day (run once a day, e.g. from cron)
```

`-db` is `sqlite:<path>` or a `postgres://` URL. The world parameters (`-seed`,
`-ticks-per-day`, `-asteroids`, ...) or their `WH_*` variables must be the same for `server` and
`daily`, and cannot be changed for an existing database.

Open <http://localhost:8080/>, create an account (you are shown an access key once;
it is your login), write a program, seal it into your ship, launch it, then run `daily`.

## Docker

```sh
docker build -t halcyon .
docker run -d -p 8080:8080 -v whdata:/data halcyon                       # SQLite on a volume
docker run --rm -v whdata:/data halcyon daily                            # simulate one day
docker run -d -p 8080:8080 -e DATABASE_URL=postgres://user:pw@db/wh halcyon   # or Postgres
docker build --target test .                                             # run the tests
```

With Compose, Caddy serves the site over HTTPS at `sandbox.clearsky.dev` (edit `caddy/Caddyfile`
for another name; DNS must point at the host and ports 80/443 must be open). The app itself is
also on <http://localhost:8070>, bound to localhost only. SQLite lives in the `halcyon-data` volume:

```sh
docker compose up -d --build
scripts/daily.sh          # one simulated day via `docker exec`; schedule it once a day
```

The world settings are environment variables (`WH_SEED`, `WH_TICKS_PER_DAY`, `WH_CYCLES_PER_TICK`,
`WH_PROGRAM_BYTES`, `WH_RAM_BYTES`, `WH_COMM_BYTES`, `WH_ASTEROIDS`); flags of the same name override
them. In Compose they are set once on the `web` service, so `scripts/daily.sh` always matches the
server. Change them only before a world has run.

`DATABASE_URL` sets the database for both `server` and `daily` (default in the image:
`sqlite:/data/wh.db`); the `-db` flag overrides it. The image also contains `asm`.

## Layout

| path | what |
|---|---|
| `fixed`, `rng` | deterministic Q32.32 maths and PRNG |
| `vm` | the ship CPU and its assembler (`cmd/asm`) |
| `world`, `sim`, `market` | belt generation, the daily simulation, ore prices |
| `store`, `runner` | SQLite/Postgres persistence and the daily run |
| `api`, `web`, `cmd/server` | HTTP API and the browser front end |
| `examples`, `docs` | embedded sample programs and manual |

## Tests

`go test ./...` covers everything; set `WH_TEST_PG=postgres://...` to also run the API
test against PostgreSQL (it wipes that database's `public` schema).