import 'state/aircraft_state.dart';
import 'state/alert_state.dart';

/// How the status chip is coloured, worst last.
enum StatusLevel { neutral, ready, caution, danger }

/// The status chip at the left of the HUD's top bar (GO 4's "Ready to Go (GPS)").
class FlightStatus {
  const FlightStatus(this.text, this.level);

  final String text;
  final StatusLevel level;

  /// GPS level the flight controller needs before it will record a home point.
  static const int minGpsLevel = 3;

  /// Reads the chip off the flight controller state and the live diagnostics.
  /// Ordered by what the pilot most needs to know: an automatic manoeuvre in
  /// progress first, then battery, then faults, then the plain flight state.
  static FlightStatus of({required bool connected, required AircraftState a, AlertState? alerts}) {
    if (!connected) return const FlightStatus('Disconnected', StatusLevel.neutral);
    if (a.updatedAt == null) return const FlightStatus('Connecting…', StatusLevel.neutral);

    final String mode = a.flightModeEnum ?? '';
    final bool flying = a.isFlying == true;
    final AlertSeverity? worst = alerts?.worst;

    if (a.landingConfirmationNeeded == true) return const FlightStatus('Confirm landing', StatusLevel.caution);
    if (a.goingHome == true || mode == 'GO_HOME') {
      return const FlightStatus('Returning to Home', StatusLevel.caution);
    }
    if (mode == 'AUTO_LANDING' || mode == 'CONFIRM_LANDING') return const FlightStatus('Landing', StatusLevel.caution);
    if (mode == 'AUTO_TAKEOFF' || mode == 'ASSISTED_TAKEOFF') return const FlightStatus('Taking off', StatusLevel.ready);
    if (a.seriousLowBattery == true) return const FlightStatus('Battery critical', StatusLevel.danger);
    if (a.lowBattery == true) return const FlightStatus('Low battery', StatusLevel.caution);
    if (worst == AlertSeverity.critical) {
      return FlightStatus(flying ? 'Warning' : 'Cannot take off', StatusLevel.danger);
    }
    if (a.imuPreheating == true) return const FlightStatus('IMU preheating', StatusLevel.caution);

    final String fix = _positioning(a);
    if (flying) {
      return FlightStatus('In Flight ($fix)', worst == AlertSeverity.warning ? StatusLevel.caution : StatusLevel.ready);
    }
    final bool noFix = fix == 'ATTI';
    return FlightStatus(
      'Ready to Go ($fix)',
      noFix || worst == AlertSeverity.warning ? StatusLevel.caution : StatusLevel.ready,
    );
  }

  /// What the aircraft is holding position with: GPS, the vision system, or nothing.
  static String _positioning(AircraftState a) {
    if ((a.gpsSignalLevel ?? 0) >= minGpsLevel) return 'GPS';
    if (a.visionPositioningBeingUsed == true) return 'Vision';
    return 'ATTI';
  }

  @override
  bool operator ==(Object other) => other is FlightStatus && other.text == text && other.level == level;

  @override
  int get hashCode => Object.hash(text, level);

  @override
  String toString() => 'FlightStatus($text, $level)';
}