# harbour-tide

**Universal tide predictions** for Sailfish OS — native Silica client with a
local harmonic engine (no tide API: offline computation, forever).

## Features

- **7-constituent harmonic engine** (M2, S2, N2, K1, O1, P1, K2):
  `h(t) = Z₀ + Σ Aᵢ·cos(ωᵢt + φᵢ)`, computed locally
- **503 ports** (Italy majors + minor harbours, all Europe from the World Port
  Index (NGA) with zone tide constants, plus London, New York, San Francisco,
  Tokyo, Sydney, Honolulu)
- **Free city search**: OpenStreetMap geocoding via Photon with offline
  fallback on the local dataset; constants are taken from the known port
  within 222 km, otherwise from a synthetic lat/lon estimate (labelled)
- **"Nearest port" card** highlighted when opening a searched city
- **24/48/72 h chart** with high/low tides marked with times, tap for the
  height at a given point
- **Moon phase and sunrise/sunset** computed
- **English by default, Italian and English** (language selector in settings:
  English / Italiano / System; `.qm` catalogue in the app data dir)
- **Saved preferences**: language, preferred port (opened at startup and
  shown on the cover), unit (m/ft), chart range

## Build

Requires the [Sailfish SDK](https://sailfishos.org/wiki/Sailfish_SDK).

```sh
sfdk target install SailfishOS-5.0.0.62-aarch64   # or your device target
sfdk target use SailfishOS-5.0.0.62-aarch64
sfdk build            # produces the RPM in RPMS/
sfdk deploy           # installs on the connected device
```

Recommended targets: `aarch64` (Jolla Phone 2026, Xperia 10 II/III),
`armv7hl` (Xperia X, Jolla C), `x86_64` (emulator).

## Structure

```
src/                C++: main.cpp (language + translator), settings
                    (QSettings: language, preferredPort, unit, days)
qml/js/tides.js     harmonic engine (pure ES5, Qt 5.6 compatible):
                    constants, prediction, extrema, synthetic estimate,
                    local geocoding, moon, sun
qml/pages/          MainPage (ports + free city search), DetailPage
                    (canvas chart, events, nearest-port card, astro),
                    SettingsPage (language, unit, range, port)
qml/cover/          cover with preferred port and next tide
translations/       harbour-tide.ts (EN source), harbour-tide_it.ts
icons/              icons 86/108/128/172 (make_icons.py, harbour style)
rpm/                spec and desktop file (SailJail: Internet)
```

## Configuration

File: `~/.config/harbour/tide/tide.conf` (QSettings, persistent zone of the
SailJail sandbox). Keys: `language` (system/en/it), `preferredPort`,
`unit` (m/ft), `days` (1/2/3).

## Known limitations

- Port constants are synthetic but realistic; the lat/lon estimate does not
  distinguish closed basins (Mediterranean) from open ocean.
- Accuracy of a real global model (FES2014/TPXO9): ~10–20 cm in open ocean;
  the engine is ready to receive grid constants.
- Not for navigation.
- Language is applied on app restart.

## License

MIT