import 'package:flutter/foundation.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';

import '../../../../core/platform/health_gateway.dart';
import '../../../health_sync/presentation/controllers/biometric_controller.dart';

/// Immutable snapshot of the integrations toggles shown on the Settings
/// screen.
///
/// Native health toggles are gated by the platform actually backing the
/// gateway (HealthKit on iOS, Health Connect on Android); the HealthGateway
/// connector (cloud partner REST sync) is available everywhere and reports
/// manual-entry fallback on Web/Windows/macOS.
class IntegrationsState {
  const IntegrationsState({
    this.appleHealthEnabled = false,
    this.healthConnectEnabled = false,
    this.healthGatewayEnabled = false,
    this.isRequestingPermissions = false,
    this.errorMessage,
  });

  /// Sentinel allowing `copyWith` to explicitly reset a field to `null`.
  static const Object _keep = Object();

  /// Apple HealthKit sync armed (iOS only).
  final bool appleHealthEnabled;

  /// Google Health Connect sync armed (Android only).
  final bool healthConnectEnabled;

  /// HealthGateway (cloud partner / manual-entry fallback) sync armed.
  final bool healthGatewayEnabled;

  /// `true` while a native permission round-trip is in flight.
  final bool isRequestingPermissions;

  /// Last permission/persistence failure, surfaced inline.
  final String? errorMessage;

  IntegrationsState copyWith({
    bool? appleHealthEnabled,
    bool? healthConnectEnabled,
    bool? healthGatewayEnabled,
    bool? isRequestingPermissions,
    Object? errorMessage = _keep,
  }) =>
      IntegrationsState(
        appleHealthEnabled: appleHealthEnabled ?? this.appleHealthEnabled,
        healthConnectEnabled: healthConnectEnabled ?? this.healthConnectEnabled,
        healthGatewayEnabled: healthGatewayEnabled ?? this.healthGatewayEnabled,
        isRequestingPermissions:
            isRequestingPermissions ?? this.isRequestingPermissions,
        errorMessage: identical(errorMessage, _keep)
            ? this.errorMessage
            : errorMessage as String?,
      );
}

/// Orchestrates the integrations toggles: requests native health
/// permissions through the cross-platform [IHealthGateway] before arming a
/// toggle, and degrades gracefully on platforms without native support.
class IntegrationsController extends Notifier<IntegrationsState> {
  @override
  IntegrationsState build() {
    final gateway = ref.read(healthGatewayProvider);
    return IntegrationsState(
      // Toggles start disarmed; enabling requests fresh permissions.
      appleHealthEnabled: false,
      healthConnectEnabled: false,
      healthGatewayEnabled: false,
      errorMessage:
          gateway.supportsNativeHealth ? null : _fallbackNotice(gateway),
    );
  }

  /// Human-readable capability notice for platforms without native health
  /// SDKs (Web / Windows / macOS fallback driver).
  static String? _fallbackNotice(IHealthGateway gateway) {
    if (gateway.supportsNativeHealth) return null;
    return 'Native health SDKs are unavailable on this platform — '
        'HealthGateway runs in manual-entry mode.';
  }

  /// Arms/disarms the Apple Health toggle. Enabling requests native
  /// permission; denial reverts the toggle and records a message.
  Future<void> setAppleHealthEnabled(bool enabled) =>
      _setNative(enabled: enabled, isApple: true);

  /// Arms/disarms the Health Connect toggle (same permission contract as
  /// Apple Health; the gateway routes to the right SDK per platform).
  Future<void> setHealthConnectEnabled(bool enabled) =>
      _setNative(enabled: enabled, isApple: false);

  /// Arms/disarms the HealthGateway connector (no native permission needed).
  void setHealthGatewayEnabled(bool enabled) {
    state = state.copyWith(healthGatewayEnabled: enabled, errorMessage: null);
  }

  /// Clears the transient error banner.
  void clearError() {
    if (state.errorMessage != null) {
      state = state.copyWith(errorMessage: null);
    }
  }

  Future<void> _setNative({required bool enabled, required bool isApple}) async {
    if (!enabled) {
      state = state.copyWith(
        appleHealthEnabled: isApple ? false : state.appleHealthEnabled,
        healthConnectEnabled: isApple ? state.healthConnectEnabled : false,
        errorMessage: null,
      );
      return;
    }

    state = state.copyWith(isRequestingPermissions: true, errorMessage: null);
    try {
      final granted = await ref.read(healthGatewayProvider).requestPermissions();
      if (granted) {
        state = state.copyWith(
          appleHealthEnabled: isApple ? true : state.appleHealthEnabled,
          healthConnectEnabled: isApple ? state.healthConnectEnabled : true,
          isRequestingPermissions: false,
        );
      } else {
        state = state.copyWith(
          isRequestingPermissions: false,
          errorMessage:
              'Health permissions were denied. Enable them in your device '
              'settings to sync biometrics.',
        );
      }
    } catch (error, stackTrace) {
      debugPrintStack(
        stackTrace: stackTrace,
        label: 'health permission request failed',
      );
      state = state.copyWith(
        isRequestingPermissions: false,
        errorMessage: 'Could not request health permissions: $error',
      );
    }
  }
}

/// Exposes the [IntegrationsController] to the widget tree.
final integrationsControllerProvider =
    NotifierProvider<IntegrationsController, IntegrationsState>(
  IntegrationsController.new,
);