feat(shopinbit): add ShopInBit API data models

diff --git a/lib/services/shopinbit/src/api_exception.dart b/lib/services/shopinbit/src/api_exception.dart
new file mode 100644
index 0000000..6e35192
--- /dev/null
+++ b/lib/services/shopinbit/src/api_exception.dart
@@ -0,0 +1,24 @@
+class ApiException implements Exception {
+  final String message;
+  final int? statusCode;
+  final String? responseBody;
+
+  ApiException(this.message, {this.statusCode, this.responseBody});
+
+  factory ApiException.fromResponse(int statusCode, String body) {
+    return ApiException(
+      'HTTP $statusCode',
+      statusCode: statusCode,
+      responseBody: body,
+    );
+  }
+
+  factory ApiException.network(Object error) {
+    return ApiException('Network error: $error');
+  }
+
+  @override
+  String toString() =>
+      'ApiException: $message'
+      '${statusCode != null ? ' (status: $statusCode)' : ''}';
+}
diff --git a/lib/services/shopinbit/src/api_response.dart b/lib/services/shopinbit/src/api_response.dart
new file mode 100644
index 0000000..a1e9135
--- /dev/null
+++ b/lib/services/shopinbit/src/api_response.dart
@@ -0,0 +1,18 @@
+import 'api_exception.dart';
+
+class ApiResponse<T> {
+  final T? value;
+  final ApiException? exception;
+
+  ApiResponse({this.value, this.exception});
+
+  bool get hasError => exception != null;
+
+  T get valueOrThrow {
+    if (exception != null) throw exception!;
+    return value as T;
+  }
+
+  @override
+  String toString() => '{error: $exception, value: $value}';
+}
diff --git a/lib/services/shopinbit/src/endpoints.dart b/lib/services/shopinbit/src/endpoints.dart
new file mode 100644
index 0000000..00a18f6
--- /dev/null
+++ b/lib/services/shopinbit/src/endpoints.dart
@@ -0,0 +1,3 @@
+class Endpoints {
+  static const production = 'https://api.shopinbit.com';
+}
diff --git a/lib/services/shopinbit/src/models/address.dart b/lib/services/shopinbit/src/models/address.dart
new file mode 100644
index 0000000..5371a37
--- /dev/null
+++ b/lib/services/shopinbit/src/models/address.dart
@@ -0,0 +1,49 @@
+class Address {
+  final String? company;
+  final String? vat;
+  final String firstName;
+  final String lastName;
+  final String street;
+  final String zip;
+  final String city;
+  final String country;
+  final String? state;
+
+  Address({
+    this.company,
+    this.vat,
+    required this.firstName,
+    required this.lastName,
+    required this.street,
+    required this.zip,
+    required this.city,
+    required this.country,
+    this.state,
+  });
+
+  Map<String, dynamic> toJson() => {
+    'company': company,
+    'vat': vat,
+    'firstName': firstName,
+    'lastName': lastName,
+    'street': street,
+    'zip': zip,
+    'city': city,
+    'country': country,
+    'state': state,
+  };
+
+  factory Address.fromJson(Map<String, dynamic> json) {
+    return Address(
+      company: json['company'] as String?,
+      vat: json['vat'] as String?,
+      firstName: json['firstName'] as String,
+      lastName: json['lastName'] as String,
+      street: json['street'] as String,
+      zip: json['zip'] as String,
+      city: json['city'] as String,
+      country: json['country'] as String,
+      state: json['state'] as String?,
+    );
+  }
+}
diff --git a/lib/services/shopinbit/src/models/auth_token.dart b/lib/services/shopinbit/src/models/auth_token.dart
new file mode 100644
index 0000000..af7816a
--- /dev/null
+++ b/lib/services/shopinbit/src/models/auth_token.dart
@@ -0,0 +1,25 @@
+class AuthToken {
+  final String accessToken;
+  final String tokenType;
+  final DateTime expiresAt;
+
+  AuthToken({
+    required this.accessToken,
+    required this.tokenType,
+    required this.expiresAt,
+  });
+
+  factory AuthToken.fromJson(Map<String, dynamic> json) {
+    return AuthToken(
+      accessToken: json['access_token'] as String,
+      tokenType: json['token_type'] as String,
+      // Tokens valid for 10 minutes per API docs.
+      expiresAt: DateTime.now().add(const Duration(minutes: 10)),
+    );
+  }
+
+  bool get isExpired => DateTime.now().isAfter(expiresAt);
+
+  bool get expiresSoon =>
+      DateTime.now().isAfter(expiresAt.subtract(const Duration(minutes: 1)));
+}
diff --git a/lib/services/shopinbit/src/models/car_research.dart b/lib/services/shopinbit/src/models/car_research.dart
new file mode 100644
index 0000000..ea1eceb
--- /dev/null
+++ b/lib/services/shopinbit/src/models/car_research.dart
@@ -0,0 +1,43 @@
+class CarResearchInvoice {
+  final String btcpayInvoice;
+  final DateTime expiresAt;
+  final Map<String, String> paymentLinks;
+
+  CarResearchInvoice({
+    required this.btcpayInvoice,
+    required this.expiresAt,
+    required this.paymentLinks,
+  });
+
+  factory CarResearchInvoice.fromJson(Map<String, dynamic> json) {
+    final linksRaw = json['payment_links'] as Map<String, dynamic>? ?? {};
+    return CarResearchInvoice(
+      btcpayInvoice: json['btcpay_invoice'] as String,
+      expiresAt: DateTime.parse(json['expires_at'] as String),
+      paymentLinks: linksRaw.map((k, v) => MapEntry(k, v as String)),
+    );
+  }
+}
+
+class CarResearchPaymentResult {
+  final String status;
+  final int ticketId;
+  final String ticketNumber;
+  final String externalCustomerKey;
+
+  CarResearchPaymentResult({
+    required this.status,
+    required this.ticketId,
+    required this.ticketNumber,
+    required this.externalCustomerKey,
+  });
+
+  factory CarResearchPaymentResult.fromJson(Map<String, dynamic> json) {
+    return CarResearchPaymentResult(
+      status: json['status'] as String,
+      ticketId: json['ticket_id'] as int,
+      ticketNumber: json['ticket_number'] as String,
+      externalCustomerKey: json['external_customer_key'] as String,
+    );
+  }
+}
diff --git a/lib/services/shopinbit/src/models/message.dart b/lib/services/shopinbit/src/models/message.dart
new file mode 100644
index 0000000..2048b72
--- /dev/null
+++ b/lib/services/shopinbit/src/models/message.dart
@@ -0,0 +1,19 @@
+class TicketMessage {
+  final DateTime timestamp;
+  final bool fromAgent;
+  final String content;
+
+  TicketMessage({
+    required this.timestamp,
+    required this.fromAgent,
+    required this.content,
+  });
+
+  factory TicketMessage.fromJson(Map<String, dynamic> json) {
+    return TicketMessage(
+      timestamp: DateTime.parse(json['timestamp'] as String),
+      fromAgent: json['from_agent'] as bool,
+      content: json['content'] as String,
+    );
+  }
+}
diff --git a/lib/services/shopinbit/src/models/models.dart b/lib/services/shopinbit/src/models/models.dart
new file mode 100644
index 0000000..7d4208c
--- /dev/null
+++ b/lib/services/shopinbit/src/models/models.dart
@@ -0,0 +1,8 @@
+export 'auth_token.dart';
+export 'ticket.dart';
+export 'message.dart';
+export 'address.dart';
+export 'payment.dart';
+export 'car_research.dart';
+export 'voucher.dart';
+export 'webhook_event.dart';
diff --git a/lib/services/shopinbit/src/models/payment.dart b/lib/services/shopinbit/src/models/payment.dart
new file mode 100644
index 0000000..bd0938d
--- /dev/null
+++ b/lib/services/shopinbit/src/models/payment.dart
@@ -0,0 +1,44 @@
+class PaymentInfo {
+  final String status;
+  final String customerPrice;
+  final String partnerPrice;
+  final int vatRate;
+  final String currency;
+  final DateTime? rateLockedUntil;
+  final Map<String, String> paymentLinks;
+  final String? due;
+
+  PaymentInfo({
+    required this.status,
+    required this.customerPrice,
+    required this.partnerPrice,
+    required this.vatRate,
+    required this.currency,
+    this.rateLockedUntil,
+    required this.paymentLinks,
+    this.due,
+  });
+
+  factory PaymentInfo.fromJson(Map<String, dynamic> json) {
+    final linksRaw = json['payment_links'] as Map<String, dynamic>? ?? {};
+    return PaymentInfo(
+      status: json['status'] as String,
+      customerPrice: (json['customer_price'] ?? '') as String,
+      partnerPrice: (json['partner_price'] ?? '') as String,
+      vatRate: _toInt(json['vat_rate']),
+      currency: (json['currency'] ?? 'EUR') as String,
+      rateLockedUntil: json['rate_locked_until'] != null
+          ? DateTime.parse(json['rate_locked_until'] as String)
+          : null,
+      paymentLinks: linksRaw.map((k, v) => MapEntry(k, v as String)),
+      due: json['due'] as String?,
+    );
+  }
+}
+
+int _toInt(dynamic v) {
+  if (v is int) return v;
+  if (v is String) return int.parse(v);
+  if (v is double) return v.toInt();
+  return 0;
+}
diff --git a/lib/services/shopinbit/src/models/ticket.dart b/lib/services/shopinbit/src/models/ticket.dart
new file mode 100644
index 0000000..eec6dd3
--- /dev/null
+++ b/lib/services/shopinbit/src/models/ticket.dart
@@ -0,0 +1,112 @@
+enum TicketState {
+  newTicket('NEW'),
+  checking('CHECKING'),
+  inProgress('IN PROGRESS'),
+  offerAvailable('OFFER AVAILABLE'),
+  clearing('CLEARING'),
+  shipped('SHIPPED'),
+  refunded('REFUNDED'),
+  fulfilled('FULFILLED'),
+  pendingClose('PENDING CLOSE'),
+  replyNeeded('REPLY NEEDED'),
+  closed('CLOSED'),
+  closedCancelled('CLOSED/CANCELLED'),
+  merged('MERGED');
+
+  final String value;
+  const TicketState(this.value);
+
+  static TicketState fromString(String s) {
+    return TicketState.values.firstWhere(
+      (e) => e.value == s,
+      orElse: () => TicketState.newTicket,
+    );
+  }
+}
+
+class TicketRef {
+  final int id;
+  final String number;
+
+  TicketRef({required this.id, required this.number});
+
+  factory TicketRef.fromJson(Map<String, dynamic> json) {
+    return TicketRef(id: _toInt(json['id']), number: json['number'].toString());
+  }
+}
+
+class TicketStatus {
+  final int ticketId;
+  final TicketState state;
+  final DateTime updatedAt;
+  final DateTime? lastAgentMessageAt;
+  final String? paymentInvoiceStatus;
+  final String? trackingLink;
+
+  TicketStatus({
+    required this.ticketId,
+    required this.state,
+    required this.updatedAt,
+    this.lastAgentMessageAt,
+    this.paymentInvoiceStatus,
+    this.trackingLink,
+  });
+
+  factory TicketStatus.fromJson(Map<String, dynamic> json) {
+    return TicketStatus(
+      ticketId: _toInt(json['ticket_id']),
+      state: TicketState.fromString(json['state'] as String),
+      updatedAt: DateTime.parse(json['updated_at'] as String),
+      lastAgentMessageAt: json['last_agent_message_at'] != null
+          ? DateTime.parse(json['last_agent_message_at'] as String)
+          : null,
+      paymentInvoiceStatus: json['payment_invoice_status'] as String?,
+      trackingLink: json['tracking_link'] as String?,
+    );
+  }
+}
+
+class TicketFull {
+  final int id;
+  final String number;
+  final String productName;
+  final String customerPrice;
+  final String partnerPrice;
+  final String partnerCommission;
+  final String netPurchasePrice;
+  final String netShippingCosts;
+  final int vatRate;
+
+  TicketFull({
+    required this.id,
+    required this.number,
+    required this.productName,
+    required this.customerPrice,
+    required this.partnerPrice,
+    required this.partnerCommission,
+    required this.netPurchasePrice,
+    required this.netShippingCosts,
+    required this.vatRate,
+  });
+
+  factory TicketFull.fromJson(Map<String, dynamic> json) {
+    return TicketFull(
+      id: _toInt(json['id']),
+      number: json['number'].toString(),
+      productName: (json['product_name'] ?? '').toString(),
+      customerPrice: (json['customer_price'] ?? '').toString(),
+      partnerPrice: (json['partner_price'] ?? '').toString(),
+      partnerCommission: (json['partner_commission'] ?? '').toString(),
+      netPurchasePrice: (json['net_purchase_price'] ?? '').toString(),
+      netShippingCosts: (json['net_shipping_costs'] ?? '').toString(),
+      vatRate: _toInt(json['vat_rate']),
+    );
+  }
+}
+
+int _toInt(dynamic v) {
+  if (v is int) return v;
+  if (v is String) return int.parse(v);
+  if (v is double) return v.toInt();
+  return 0;
+}
diff --git a/lib/services/shopinbit/src/models/voucher.dart b/lib/services/shopinbit/src/models/voucher.dart
new file mode 100644
index 0000000..97d048a
--- /dev/null
+++ b/lib/services/shopinbit/src/models/voucher.dart
@@ -0,0 +1,71 @@
+class VoucherInfo {
+  final bool valid;
+  final String? voucherCode;
+  final double? discountAmount;
+  final String? voucherType;
+  final int? priorityLevel;
+  final int? usageCount;
+  final int? maxUsage;
+  final bool? isUnlimited;
+  final int? remainingUses;
+  final String? validFrom;
+  final String? validUntil;
+  final String? error;
+
+  VoucherInfo({
+    required this.valid,
+    this.voucherCode,
+    this.discountAmount,
+    this.voucherType,
+    this.priorityLevel,
+    this.usageCount,
+    this.maxUsage,
+    this.isUnlimited,
+    this.remainingUses,
+    this.validFrom,
+    this.validUntil,
+    this.error,
+  });
+
+  factory VoucherInfo.fromJson(Map<String, dynamic> json) {
+    return VoucherInfo(
+      valid: json['valid'] as bool? ?? false,
+      voucherCode: json['voucher_code'] as String?,
+      discountAmount: (json['discount_amount'] as num?)?.toDouble(),
+      voucherType: json['voucher_type'] as String?,
+      priorityLevel: json['priority_level'] as int?,
+      usageCount: json['usage_count'] as int?,
+      maxUsage: json['max_usage'] as int?,
+      isUnlimited: json['is_unlimited'] as bool?,
+      remainingUses: json['remaining_uses'] as int?,
+      validFrom: json['valid_from'] as String?,
+      validUntil: json['valid_until'] as String?,
+      error: json['error'] as String?,
+    );
+  }
+}
+
+class VipRedemptionResult {
+  final int ticketId;
+  final String ticketNumber;
+  final String externalCustomerKey;
+  final String voucherCode;
+
+  VipRedemptionResult({
+    required this.ticketId,
+    required this.ticketNumber,
+    required this.externalCustomerKey,
+    required this.voucherCode,
+  });
+
+  factory VipRedemptionResult.fromJson(Map<String, dynamic> json) {
+    return VipRedemptionResult(
+      ticketId: json['ticket_id'] is int
+          ? json['ticket_id'] as int
+          : int.parse(json['ticket_id'].toString()),
+      ticketNumber: json['ticket_number'] as String,
+      externalCustomerKey: json['external_customer_key'] as String,
+      voucherCode: json['voucher_code'] as String,
+    );
+  }
+}
diff --git a/lib/services/shopinbit/src/models/webhook_event.dart b/lib/services/shopinbit/src/models/webhook_event.dart
new file mode 100644
index 0000000..7bf4169
--- /dev/null
+++ b/lib/services/shopinbit/src/models/webhook_event.dart
@@ -0,0 +1,28 @@
+enum WebhookEventType {
+  ticketStateChanged('ticket.state_changed'),
+  ticketMessageCreated('ticket.message_created');
+
+  final String value;
+  const WebhookEventType(this.value);
+
+  static WebhookEventType fromString(String s) {
+    return WebhookEventType.values.firstWhere(
+      (e) => e.value == s,
+      orElse: () => WebhookEventType.ticketStateChanged,
+    );
+  }
+}
+
+class WebhookEvent {
+  final WebhookEventType eventType;
+  final Map<String, dynamic> data;
+
+  WebhookEvent({required this.eventType, required this.data});
+
+  factory WebhookEvent.fromJson(Map<String, dynamic> json) {
+    return WebhookEvent(
+      eventType: WebhookEventType.fromString(json['event_type'] as String),
+      data: json['data'] as Map<String, dynamic>,
+    );
+  }
+}