# JoykooScanner — Android Barcode Scanner Kiosk App

## What This Is

Native Android app (Kotlin) that wraps `https://smart.joykoo.mx/` in a fullscreen WebView for dedicated Chinese industrial handheld barcode scanners. The scanner operates in HID/keyboard-wedge mode — it sends Android key events like a physical keyboard.

## Critical Design Decision

The Android soft keyboard must NEVER appear. Keyboard suppression uses multiple layers — do not remove any of them:

1. `NoSoftKeyboardWebView.onCheckIsTextEditor()` → `false`
2. `EditorInfo` flags `IME_FLAG_NO_EXTRACT_UI | IME_FLAG_NO_FULLSCREEN` in `onCreateInputConnection()`
3. `InputMethodManager.hideSoftInputFromWindow()` posted after each InputConnection request and on page load / window focus
4. JavaScript injection setting `inputmode="none"` on all `<input>`, `<textarea>`, and `contenteditable` elements via `MutationObserver`
5. Manifest `windowSoftInputMode="stateAlwaysHidden|adjustNothing"`

The real `InputConnection` from `super.onCreateInputConnection()` **must be returned** — returning `null` breaks hardware key input from the barcode scanner on devices like the Urovo CT58C.

## Project Structure

```
app/src/main/java/mx/joykoo/scanner/
  AppConfig.kt              — URL, allowed hosts, admin triggers, scanner broadcasts (single config point)
  MainActivity.kt           — Fullscreen kiosk activity, WebView setup, navigation, lifecycle
  NoSoftKeyboardWebView.kt  — IME suppression via null InputConnection
  ScannerIntegration.kt     — Scanner lifecycle interface
  BroadcastScannerIntegration.kt — Intent-output scans → JS injection (React-safe value setter)
  KioskController.kt        — Lock Task kiosk toggle (session-only until KIOSK_PERSISTED); device-owner full lockdown + HOME alias, else screen pinning
  KioskAdminReceiver.kt     — DeviceAdminReceiver for `dpm set-device-owner`
  StatusStrip.kt            — App-drawn status strip (Wi-Fi + battery only); system bars stay hidden
  Permissions.kt            — Runtime permission prompts (camera, storage ≤ Android 9); asked at launch and on demand
  FileTransfers.kt          — Downloads → Downloads folder; file uploads with camera option; photos kept in Pictures/Joykoo
```

## Build

- **Language**: Kotlin, targeting JVM 1.8 bytecode
- **SDK**: compileSdk 34, minSdk 24, targetSdk 34
- **Dependencies**: androidx core-ktx, appcompat, webkit, swiperefreshlayout
- **Gradle**: 8.7 with Kotlin DSL, AGP 8.5.2, Kotlin 1.9.24
- **Package**: `mx.joykoo.scanner`

### Build prerequisites (not yet installed on this server)

1. `sudo dnf install java-17-openjdk-devel` — only the JRE is installed, need javac
2. Android SDK cmdline-tools — download to `~/Android/Sdk/`, then install:
   - `platform-tools`
   - `platforms;android-34`
   - `build-tools;34.0.0`
3. Set env vars:
   ```
   JAVA_HOME=/usr/lib/jvm/java-17-openjdk-17.0.20.1.1-1.2.el9.x86_64
   ANDROID_HOME=~/Android/Sdk
   ```
4. `./gradlew assembleDebug`

### Server environment (RHEL 9.8)

- JRE 17 installed at `/usr/lib/jvm/java-17-openjdk-17.0.20.1.1-1.2.el9.x86_64`
- 323 GB free on /home, 5.5 GB free on /
- curl, wget, unzip, zip available
- No Android SDK present anywhere

## Configuration

All configurable values are in `AppConfig.kt`:
- `HOME_URL` — the webpage to load
- `ALLOWED_HOSTS` — domains that stay inside the WebView
- `BACK_PRESS_EXIT_COUNT` / `BACK_PRESS_WINDOW_MS` — back-button exit guard
- `ADMIN_VOLUME_HOLD_MS` — hold Volume Up + Volume Down this long to open the admin dialog
- `ADMIN_BARCODE` — scanning this value (Intent mode) opens the admin dialog
- `KIOSK_BARCODE` — scanning this value (Intent mode) toggles kiosk lockdown
- `RENDERER_CRASH_LIMIT` / `RENDERER_CRASH_WINDOW_MS` — WebView crash auto-recovery limit
- `FILE_OPEN_FALLBACK_APPS` — app launched by a download's "Abrir" when nothing opens that file type (also add it to `<queries>` in the manifest)

## Navigation Rules

- URLs on `joykoo.mx` or `smart.joykoo.mx` (and subdomains) load inside the WebView
- All other URLs are silently blocked
- Back button goes back in WebView history; 3 rapid presses exits when no history
- Admin dialog (exit / toggle soft keyboard): hold both volume keys 3 s, or scan `ADMIN_BARCODE`. Volume keys are consumed and never reach the page. No touch gestures — corner taps leaked through to site UI

## Kiosk & Errors

- Kiosk mode (`KioskController`): **off by default and not persisted** while it is being tested (`AppConfig.KIOSK_PERSISTED = false`) — each launch starts unlocked and clears any leftover lockdown; scanning `KIOSK_BARCODE` toggles it for the session. When on, admin dialog hides "Salir" and Back never exits. Device owner required for real lockdown; the app can't be uninstalled while device owner, so set it only with the release-signed APK.
- Error overlay: per-cause messages (no Wi-Fi with auto-retry on reconnect, unreachable, 5xx, SSL, repeated renderer crash). 4xx responses are left to the site.
- Renderer crash (`onRenderProcessGone`): the WebView is replaced and the last URL (tracked via `doUpdateVisitedHistory`) reloaded.

## Files & Permissions

- Permissions are requested at first launch (camera; storage on Android ≤ 9) and again when a feature needs one.
- Downloads: https on allowed hosts via `DownloadManager` (session cookie forwarded); `data:` decoded natively; `blob:` read in-page and returned via `evaluateJavascript` polling (no JS interface). A document-start hook keeps blobs readable if the site revokes the URL immediately, and records the `<a download="name">` file name (WebView does not pass it on; without it files save as `downloadfile.csv`). Saved to Downloads, then an "Archivo guardado" dialog offers **Abrir**: the app registered for the type, else the app in `AppConfig.FILE_OPEN_FALLBACK_APPS` (CSV → CSV Editor from F-Droid, which has no open-with support) is launched. Fallback apps must also be declared under `<queries>` in the manifest (Android 11+ package visibility).
- Uploads: `<input type=file>` image fields show an in-app "Tomar foto / Elegir de la galería" dialog (the system chooser hid the camera behind the gallery picker); `capture` opens the camera directly. If camera permission is denied, a dialog offers app Settings or the file picker. Photos are saved to Pictures/Joykoo.
- In-page camera (`getUserMedia`) is granted to allowed hosts only, video only.

## Security

- HTTPS only, no cleartext, mixed content never allowed, no SSL error bypass
- No JavaScript interfaces exposed
- No file:// or content:// access
- Network security config enforces system trust anchors only
- Domain allowlist in WebViewClient

## UI Strings

Spanish (`es`) — this is for a Mexico-based company.