# Interval Timer

A mobile-first interval training timer that installs as a Progressive Web App.
No build step, no dependencies, no network calls — just static files.

## The cycle

For every set, each exercise gets a **pause** followed by a **training** block:

```
for each set:
  for each exercise:
    pause    (default 15s)   text is grey
    training (default 45s)   text turns red
```

- **Start** rings a bell, shows the first exercise in grey and runs the pause.
- When the pause ends a beep plays and the text turns **red** for the training block.
- When training ends another beep plays, the next exercise appears and its pause begins.
- After the last exercise of the last set, a triple bell rings and the screen shows *Workout complete*.

`Pause` / `Resume` freezes the clock; `Reset` returns to the start. The screen is kept
awake during a session via the Screen Wake Lock API.

## Files

| Path | Purpose |
| --- | --- |
| `index.html` | Markup: stage, controls, settings |
| `styles.css` | Dark theme; grey/red phase colours |
| `app.js` | Timer state machine, Web Audio bell/beep, exercise list |
| `manifest.webmanifest` | PWA metadata and icons |
| `sw.js` | Service worker — app shell cached for offline use |
| `icons/` | Generated app icons |
| `tools/make_icons.py` | Regenerates the icons (needs Pillow) |
| `tools/smoke_test.mjs` | Headless-Chrome test of the whole cycle |
| `start` | Your local live-server launcher (port 8080) |

Settings and the exercise list are stored in `localStorage`, so they survive a reload.

## Running it on your phone

PWA installation and offline caching require a **secure context** (HTTPS, or
`localhost`). A plain `http://<laptop-ip>:8080` URL works as a normal web page but
will not be installable and will not cache offline.

### 1. Serve the files

```sh
cd timer
python3 -m http.server 8080
# or, using the ./start script (Node + live-server, auto-reload)
./start
```

### 2. Give your phone an HTTPS URL

Either expose the local server through a tunnel, for example:

```sh
cloudflared tunnel --url http://localhost:8080
# or: npx localtunnel --port 8080
```

or upload the folder as-is to any static host (GitHub Pages, Netlify, Cloudflare
Pages, Vercel). There is nothing to compile.

### 3. Install

Open the HTTPS URL on the phone and use **Add to Home Screen** (Safari: Share
menu; Chrome: banner or the ⋮ menu → *Install app*). It then launches fullscreen
and works offline.

### Audio notes

- The bell and beeps are synthesised with the Web Audio API, so there are no sound
  files to download and they work offline.
- Audio is unlocked by the first tap on **Start**, as mobile browsers require.
- On iOS the ringer/silent switch still mutes Web Audio playback — turn silent mode
  off for a workout.

## Tests

With a server on `127.0.0.1:8765` and Chrome running with `--remote-debugging-port=9222`:

```sh
cd timer
node tools/smoke_test.mjs
```

The test drives the real page and asserts the exact pause/training sequence for
2 sets × 3 exercises, the grey→red colour switch, phase durations, the frozen clock
while paused, reset/restart behaviour and settings persistence.