import 'package:flutter/foundation.dart';

/// Supported commercial product plans for MotorSignal.
enum MotorSignalPlan { free, proMonthly, proLifetime }

/// Lifecycle and billing entitlement states.
enum MotorSignalEntitlementStatus {
  free,
  proMonthlyActive,
  proMonthlyGrace,
  proMonthlyAccountHold,
  proMonthlyExpired,
  proLifetime,
  unknown,
  syncPending,
}

/// Verification / freshness state of store-asserted entitlement.
enum EntitlementVerificationStatus {
  /// Unverified or default state before store inquiry.
  unverified,

  /// Confirmed valid by app store or server verification.
  verified,

  /// Validated locally under defined offline grace rules.
  offlineGrace,

  /// Explicitly expired subscription.
  expired,

  /// Revoked or refunded by store/issuer.
  revoked,
}

/// Origin of purchase assertion.
enum PurchaseSource { none, googlePlay, offlineCache }

/// Central capability model and immutable entitlement state.
/// UI and services depend on capabilities, not store product IDs or scattered checks.
@immutable
class EntitlementState {
  final MotorSignalPlan plan;
  final MotorSignalEntitlementStatus status;
  final EntitlementVerificationStatus verificationStatus;
  final PurchaseSource source;
  final String? productId;
  final String? purchaseTokenHash;
  final DateTime? expiresAt;
  final DateTime? lastVerifiedAt;

  const EntitlementState({
    this.plan = MotorSignalPlan.free,
    this.status = MotorSignalEntitlementStatus.free,
    this.verificationStatus = EntitlementVerificationStatus.unverified,
    this.source = PurchaseSource.none,
    this.productId,
    this.purchaseTokenHash,
    this.expiresAt,
    this.lastVerifiedAt,
  });

  /// Factory creating normalized default Free tier.
  const EntitlementState.free()
    : plan = MotorSignalPlan.free,
      status = MotorSignalEntitlementStatus.free,
      verificationStatus = EntitlementVerificationStatus.verified,
      source = PurchaseSource.none,
      productId = null,
      purchaseTokenHash = null,
      expiresAt = null,
      lastVerifiedAt = null;

  /// Factory creating normalized active Pro Monthly tier.
  EntitlementState.proMonthlyActive({
    this.productId,
    this.purchaseTokenHash,
    this.expiresAt,
    DateTime? lastVerifiedAt,
    this.source = PurchaseSource.googlePlay,
  }) : plan = MotorSignalPlan.proMonthly,
       status = MotorSignalEntitlementStatus.proMonthlyActive,
       verificationStatus = EntitlementVerificationStatus.verified,
       lastVerifiedAt = lastVerifiedAt ?? DateTime.now();

  /// Factory creating normalized active Pro Lifetime tier.
  EntitlementState.proLifetime({
    this.productId,
    this.purchaseTokenHash,
    DateTime? lastVerifiedAt,
    this.source = PurchaseSource.googlePlay,
  }) : plan = MotorSignalPlan.proLifetime,
       status = MotorSignalEntitlementStatus.proLifetime,
       verificationStatus = EntitlementVerificationStatus.verified,
       expiresAt = null,
       lastVerifiedAt = lastVerifiedAt ?? DateTime.now();

  /// Factory normalizing raw inputs to prevent invalid or contradictory combinations.
  factory EntitlementState.normalized({
    required MotorSignalPlan plan,
    required MotorSignalEntitlementStatus status,
    EntitlementVerificationStatus verificationStatus =
        EntitlementVerificationStatus.unverified,
    PurchaseSource source = PurchaseSource.none,
    String? productId,
    String? purchaseTokenHash,
    DateTime? expiresAt,
    DateTime? lastVerifiedAt,
  }) {
    // Normalization rules:
    // 1. Free plan must not possess Pro status, active expiration, or Pro product IDs.
    if (plan == MotorSignalPlan.free) {
      return EntitlementState(
        plan: MotorSignalPlan.free,
        status: MotorSignalEntitlementStatus.free,
        verificationStatus:
            verificationStatus == EntitlementVerificationStatus.revoked
            ? EntitlementVerificationStatus.revoked
            : EntitlementVerificationStatus.verified,
        source: PurchaseSource.none,
        productId: null,
        purchaseTokenHash: null,
        expiresAt: null,
        lastVerifiedAt: lastVerifiedAt,
      );
    }

    // 2. Revoked verification forces expired/revoked standing regardless of plan.
    if (verificationStatus == EntitlementVerificationStatus.revoked) {
      return EntitlementState(
        plan: plan,
        status: plan == MotorSignalPlan.proLifetime
            ? MotorSignalEntitlementStatus.unknown
            : MotorSignalEntitlementStatus.proMonthlyExpired,
        verificationStatus: EntitlementVerificationStatus.revoked,
        source: source,
        productId: productId,
        purchaseTokenHash: purchaseTokenHash,
        expiresAt: expiresAt,
        lastVerifiedAt: lastVerifiedAt,
      );
    }

    // 3. Lifetime plan normalization: status must be proLifetime, expiresAt is null.
    if (plan == MotorSignalPlan.proLifetime) {
      final isSyncPending = status == MotorSignalEntitlementStatus.syncPending;
      return EntitlementState(
        plan: MotorSignalPlan.proLifetime,
        status: isSyncPending
            ? MotorSignalEntitlementStatus.syncPending
            : MotorSignalEntitlementStatus.proLifetime,
        verificationStatus: verificationStatus,
        source: source,
        productId: productId,
        purchaseTokenHash: purchaseTokenHash,
        expiresAt: null,
        lastVerifiedAt: lastVerifiedAt,
      );
    }

    // 4. Pro Monthly: check explicit expiration if past expiresAt.
    final now = DateTime.now();
    var resolvedStatus = status;
    var resolvedVerification = verificationStatus;

    if (expiresAt != null && now.isAfter(expiresAt)) {
      if (status == MotorSignalEntitlementStatus.proMonthlyActive) {
        // Expired active subscription
        resolvedStatus = MotorSignalEntitlementStatus.proMonthlyExpired;
        resolvedVerification = EntitlementVerificationStatus.expired;
      }
    }

    return EntitlementState(
      plan: MotorSignalPlan.proMonthly,
      status: resolvedStatus,
      verificationStatus: resolvedVerification,
      source: source,
      productId: productId,
      purchaseTokenHash: purchaseTokenHash,
      expiresAt: expiresAt,
      lastVerifiedAt: lastVerifiedAt,
    );
  }

  /// Whether user currently holds effective Pro entitlement.
  /// Free plan, expired subscription, revoked verification, or account hold do NOT grant Pro access.
  bool get isPro {
    if (plan == MotorSignalPlan.free) return false;
    if (verificationStatus == EntitlementVerificationStatus.revoked) {
      return false;
    }
    if (verificationStatus == EntitlementVerificationStatus.expired) {
      return false;
    }
    if (status == MotorSignalEntitlementStatus.proMonthlyExpired) return false;
    if (status == MotorSignalEntitlementStatus.proMonthlyAccountHold) {
      return false;
    }
    if (status == MotorSignalEntitlementStatus.free) return false;
    if (status == MotorSignalEntitlementStatus.unknown) return false;

    // Active or grace period allows effective access
    return status == MotorSignalEntitlementStatus.proMonthlyActive ||
        status == MotorSignalEntitlementStatus.proMonthlyGrace ||
        status == MotorSignalEntitlementStatus.proLifetime;
  }

  // Capability mapping conforming to MOTORSIGNAL_FREE_PRO_SPEC.md
  bool get canCloudBackup => true;
  bool get canUnlimitedCloudHistory => isPro;
  bool get canMultiDeviceRestore => isPro;
  bool get canAdvancedTelemetry => isPro;
  bool get canAdvancedAcceleration => isPro;
  bool get canAdvancedBraking => isPro;
  bool get canAdvancedLean => isPro;
  bool get canAdvancedAnalytics => isPro;
  bool get canUnlimitedHistory => isPro;
  bool get canExportCsv => isPro;
  bool get canExportPdf => isPro;
  bool get canUseMultipleMotorcycles => isPro;
  bool get canPlanTrips => isPro;
  bool get canCreateGroupRides => isPro;
  bool get canUseAdvancedGroupRideFeatures => isPro;

  /// Free cloud allowance quota. null indicates unconstrained (Pro) or to be determined by backend.
  int? get cloudRideAllowance => isPro ? null : null;

  EntitlementState copyWith({
    MotorSignalPlan? plan,
    MotorSignalEntitlementStatus? status,
    EntitlementVerificationStatus? verificationStatus,
    PurchaseSource? source,
    String? productId,
    String? purchaseTokenHash,
    DateTime? expiresAt,
    DateTime? lastVerifiedAt,
  }) => EntitlementState(
    plan: plan ?? this.plan,
    status: status ?? this.status,
    verificationStatus: verificationStatus ?? this.verificationStatus,
    source: source ?? this.source,
    productId: productId ?? this.productId,
    purchaseTokenHash: purchaseTokenHash ?? this.purchaseTokenHash,
    expiresAt: expiresAt ?? this.expiresAt,
    lastVerifiedAt: lastVerifiedAt ?? this.lastVerifiedAt,
  );

  Map<String, dynamic> toJson() => {
    'version': 1,
    'plan': plan.name,
    'status': status.name,
    'verificationStatus': verificationStatus.name,
    'source': source.name,
    'productId': productId,
    'purchaseTokenHash': purchaseTokenHash,
    'expiresAt': expiresAt?.toIso8601String(),
    'lastVerifiedAt': lastVerifiedAt?.toIso8601String(),
  };

  factory EntitlementState.fromJson(Map<String, dynamic> json) {
    final version = json['version'] as int? ?? 1;
    if (version > 1) {
      // Forward-compatibility safeguard for future cache schema versions
      throw const FormatException('Unsupported entitlement cache version');
    }

    final plan = MotorSignalPlan.values.firstWhere(
      (e) => e.name == json['plan'],
      orElse: () => MotorSignalPlan.free,
    );

    final status = MotorSignalEntitlementStatus.values.firstWhere(
      (e) => e.name == json['status'],
      orElse: () => MotorSignalEntitlementStatus.free,
    );

    final verificationStatus = EntitlementVerificationStatus.values.firstWhere(
      (e) => e.name == json['verificationStatus'],
      orElse: () => EntitlementVerificationStatus.unverified,
    );

    final source = PurchaseSource.values.firstWhere(
      (e) => e.name == json['source'],
      orElse: () => PurchaseSource.none,
    );

    final expiresAt = json['expiresAt'] != null
        ? DateTime.tryParse(json['expiresAt'] as String)
        : null;

    final lastVerifiedAt = json['lastVerifiedAt'] != null
        ? DateTime.tryParse(json['lastVerifiedAt'] as String)
        : null;

    return EntitlementState.normalized(
      plan: plan,
      status: status,
      verificationStatus: verificationStatus,
      source: source,
      productId: json['productId'] as String?,
      purchaseTokenHash: json['purchaseTokenHash'] as String?,
      expiresAt: expiresAt,
      lastVerifiedAt: lastVerifiedAt,
    );
  }

  @override
  bool operator ==(Object other) =>
      identical(this, other) ||
      other is EntitlementState &&
          runtimeType == other.runtimeType &&
          plan == other.plan &&
          status == other.status &&
          verificationStatus == other.verificationStatus &&
          source == other.source &&
          productId == other.productId &&
          purchaseTokenHash == other.purchaseTokenHash &&
          expiresAt == other.expiresAt &&
          lastVerifiedAt == other.lastVerifiedAt;

  @override
  int get hashCode =>
      plan.hashCode ^
      status.hashCode ^
      verificationStatus.hashCode ^
      source.hashCode ^
      productId.hashCode ^
      purchaseTokenHash.hashCode ^
      expiresAt.hashCode ^
      lastVerifiedAt.hashCode;
}