testsAndMisc/focus_owner/lib/policy.dart

import 'dart:convert';

import 'package:flutter/services.dart' show AssetBundle, rootBundle;

part 'focus_policy.dart';

/// Schema version this build understands.
///
/// The asset is generated by `python3 -m python_pkg.focus_policy`, which is the
/// single source of truth. Refusing an unknown version is deliberate: silently
/// accepting a newer schema would mean enforcing a policy this code has
/// misread, and a misread allowlist is an allowlist that blocks the dialer.
const int kSupportedSchemaVersion = 1;

/// Raised when the bundled policy cannot be trusted.
class PolicyFormatException implements Exception {
  const PolicyFormatException(this.message);

  final String message;

  @override
  String toString() => 'PolicyFormatException: $message';
}

/// A nightly window that may wrap midnight (23:00 -> 05:00).
class CurfewWindow {
  const CurfewWindow({required this.startMinutes, required this.endMinutes});

  /// Parses an `{"start": "23:00", "end": "05:00"}` object.
  factory CurfewWindow.fromJson(Map<String, Object?> json) {
    return CurfewWindow(
      startMinutes: _parseHhMm(json['start'], 'curfew.start'),
      endMinutes: _parseHhMm(json['end'], 'curfew.end'),
    );
  }

  /// Minutes since midnight.
  final int startMinutes;
  final int endMinutes;

  /// Whether [minutesSinceMidnight] falls inside the window.
  ///
  /// Wrapping windows are the normal case here, so "inside" means at or after
  /// the start *or* before the end, not both.
  bool contains(int minutesSinceMidnight) {
    if (startMinutes <= endMinutes) {
      return minutesSinceMidnight >= startMinutes &&
          minutesSinceMidnight < endMinutes;
    }
    return minutesSinceMidnight >= startMinutes ||
        minutesSinceMidnight < endMinutes;
  }
}

/// The home anchor. Coordinates are null in a redacted policy.
class HomeLocation {
  const HomeLocation({
    required this.latitude,
    required this.longitude,
    required this.radiusM,
    required this.hysteresisM,
  });

  /// Parses the `home` object.
  factory HomeLocation.fromJson(Map<String, Object?> json) {
    return HomeLocation(
      latitude: (json['latitude'] as num?)?.toDouble(),
      longitude: (json['longitude'] as num?)?.toDouble(),
      radiusM: _requireNum(json['radius_m'], 'home.radius_m'),
      hysteresisM: _requireNum(json['hysteresis_m'], 'home.hysteresis_m'),
    );
  }

  final double? latitude;
  final double? longitude;
  final double radiusM;
  final double hysteresisM;

  /// Whether this policy carries real coordinates.
  ///
  /// The committed asset is redacted, so the location gate cannot run against
  /// it. Enforcement must check this rather than treating a missing coordinate
  /// as (0, 0), which would put "home" in the Atlantic.
  bool get hasCoordinates => latitude != null && longitude != null;
}