# nigig-system-prefs

Cross-platform reader for OS-level preferences (dark mode, locale, accent
color). Follows the `robius-sms` cross-platform pattern: a `cfg_if!` block
dispatches to a per-platform `sys/*.rs` submodule.

## Why this exists

Makepad's `Cx` does not expose `platform_is_dark_mode()` on all branches
of its public API, and even where it does the value is cached at window
creation time — it does not update when the user toggles dark mode while
the app is running. This crate queries the OS directly on every call.

## API

```rust
// Boolean convenience:
let dark: bool = nigig_system_prefs::is_dark_mode().unwrap_or(false);

// Three-way (Linux exposes "no preference"):
let scheme: ColorScheme = nigig_system_prefs::color_scheme()?;

// BCP-47 locale tag ("en-US", "sw-KE"):
let locale: String = nigig_system_prefs::system_locale()?;

// Language subtag only ("en", "sw"):
let lang: String = nigig_system_prefs::system_language()?;

// Accent color as [r, g, b, a] floats (macOS / Windows only):
let rgba: [f32; 4] = nigig_system_prefs::accent_color()?;
```

## Platform support

| Platform | Dark mode | Locale | Accent |
|---|---|---|---|
| Android  | ✅ `Configuration.uiMode`            | ✅ `Configuration.locales[0]`         | ❌ |
| macOS    | ✅ `NSUserDefaults`                  | ✅ `NSLocale.currentLocale`           | ✅ `NSColor.controlAccentColor` |
| iOS      | ⚠️ TODO (`UITraitCollection`)       | ✅ `NSLocale.currentLocale`           | ❌ |
| Windows  | ✅ registry `AppsUseLightTheme`     | ✅ `GetUserDefaultLocaleName`         | ✅ registry `AccentColor` |
| Linux    | ✅ `gsettings` (GNOME 42+)          | ✅ `$LANG` / `$LC_ALL`                | ❌ |
| Other    | ❌ `PermanentlyUnavailable`          | ❌                                    | ❌ |

## Layout

```
nigig-system-prefs/
├── Cargo.toml             # cfg-if + per-platform target deps
├── README.md
└── src/
    ├── lib.rs             # public API + tests
    ├── error.rs           # Error / Result
    └── sys/
        ├── mod.rs         # cfg_if! dispatch
        ├── android.rs     # JNI via robius-android-env
        ├── apple.rs       # objc2 + objc2-foundation (NSUserDefaults, NSLocale)
        ├── windows.rs     # windows crate (registry + Globalization)
        ├── linux.rs       # std::process::Command + std::env
        └── unsupported.rs # fallback
```

## objc2 feature notes (Apple targets)

`NSUserDefaults` and `NSLocale` are Foundation classes — their cargo
features live on `objc2-foundation`, NOT on `objc2-app-kit`.

```toml
[target.'cfg(target_vendor = "apple")'.dependencies]
objc2-foundation = { version = "0.3", default-features = false, features = [
    "std", "NSString", "NSArray", "NSObjCRuntime",
    "NSUserDefaults",   # ← Foundation feature
    "NSLocale",         # ← Foundation feature
] }

[target.'cfg(all(target_vendor = "apple", target_os = "macos"))'.dependencies]
objc2-app-kit = { version = "0.3", default-features = false, features = [
    "std", "NSColor", "NSApplication",
    # NOTE: objc2-app-kit 0.3.x does NOT have an NSUserDefaults feature.
    # If you add it here you'll get:
    #   error: failed to select a version for `objc2-app-kit`.
    #   package depends on `objc2-app-kit` with feature `NSUserDefaults`
    #   but `objc2-app-kit` does not have that feature.
] }
```

The `objc2-app-kit` 0.3.x feature list is large (NSColor, NSApplication,
NSWindow, NSView, ...) but `NSUserDefaults` is not on it.