feat: Add comprehensive GraphQL schema for subscriber management and charging operations

- Add custom scalars (DateTime, JSON) for complex data types
- Define enums for subscriber status, profile status, usage types, session status, payment methods, invoice status, and alert types
- Add core types: Subscriber, SubscriberAccount, UsageEvent, RatingPlan, ChargingSession, PaymentMethod, Invoice, Alert
- Add system monitoring types: SystemStats, HealthStatus
- Implement Relay-style pagination with Connection

apps/api-server/internal/graphql/schema.graphql

@@ -0,0 +1,483 @@
+scalar DateTime
+scalar JSON
+
+enum SubscriberStatus {
+  ACTIVE
+  INACTIVE
+  SUSPENDED
+  TERMINATED
+  PROVISIONING
+}
+
+enum ProfileStatus {
+  ACTIVE
+  INACTIVE
+  DOWNLOADING
+  FAILED
+}
+
+enum UsageType {
+  DATA
+  VOICE
+  SMS
+}
+
+enum SessionStatus {
+  ACTIVE
+  COMPLETED
+  TERMINATED
+}
+
+enum PaymentMethodType {
+  CREDIT_CARD
+  BANK_ACCOUNT
+}
+
+enum InvoiceStatus {
+  DRAFT
+  PENDING
+  PAID
+  OVERDUE
+  CANCELLED
+}
+
+enum AlertType {
+  LOW_BALANCE
+  HIGH_USAGE
+  PAYMENT_FAILED
+  SYSTEM_ERROR
+}
+
+enum AlertSeverity {
+  LOW
+  MEDIUM
+  HIGH
+  CRITICAL
+}
+
+type Subscriber {
+  id: ID!
+  imsi: String!
+  msisdn: String!
+  firstName: String!
+  lastName: String!
+  email: String!
+  organizationId: String
+  planId: Int!
+  euiccId: String
+  profileId: String
+  profileStatus: ProfileStatus!
+  status: SubscriberStatus!
+  balance: Float!
+  dataLimit: Float!
+  dataUsed: Float!
+  voiceLimit: Float!
+  voiceUsed: Float!
+  smsLimit: Float!
+  smsUsed: Float!
+  createdAt: DateTime!
+  updatedAt: DateTime!
+  
+  account: SubscriberAccount!
+  usageEvents(first: Int, after: String, filter: UsageEventFilter): UsageEventConnection!
+  invoices(first: Int, after: String, status: InvoiceStatus): InvoiceConnection!
+  alerts(first: Int, after: String, severity: AlertSeverity): AlertConnection!
+  ratingPlan: RatingPlan!
+}
+
+type SubscriberAccount {
+  imsi: String!
+  balance: Float!
+  dataLimit: Float!
+  dataUsed: Float!
+  voiceLimit: Float!
+  voiceUsed: Float!
+  smsLimit: Float!
+  smsUsed: Float!
+  status: SubscriberStatus!
+  lastUpdated: DateTime!
+}
+
+type UsageEvent {
+  id: ID!
+  imsi: String!
+  sessionId: String!
+  usageType: UsageType!
+  volume: Float!
+  timestamp: DateTime!
+  rate: Float!
+  cost: Float!
+  
+  subscriber: Subscriber!
+}
+
+type RatingPlan {
+  planId: String!
+  name: String!
+  dataRate: Float!
+  voiceRate: Float!
+  smsRate: Float!
+  monthlyFee: Float!
+  dataLimit: Float!
+  voiceLimit: Float!
+  smsLimit: Float!
+  
+  subscribers(first: Int, after: String, status: SubscriberStatus): SubscriberConnection!
+}
+
+type ChargingSession {
+  sessionId: String!
+  imsi: String!
+  startTime: DateTime!
+  endTime: DateTime
+  dataBytes: Float!
+  voiceSeconds: Float!
+  smsCount: Float!
+  totalCost: Float!
+  status: SessionStatus!
+  
+  subscriber: Subscriber!
+  usageEvents(first: Int, after: String): UsageEventConnection!
+}
+
+type PaymentMethod {
+  id: String!
+  type: PaymentMethodType!
+  last4: String!
+  expiryMonth: Int!
+  expiryYear: Int!
+  brand: String!
+  isDefault: Boolean!
+}
+
+type Invoice {
+  id: String!
+  subscriberId: Int!
+  amount: Float!
+  currency: String!
+  status: InvoiceStatus!
+  dueDate: DateTime!
+  createdAt: DateTime!
+  lineItems: [InvoiceLineItem!]!
+  
+  subscriber: Subscriber!
+}
+
+type InvoiceLineItem {
+  description: String!
+  quantity: Int!
+  unitPrice: Float!
+  amount: Float!
+}
+
+type Alert {
+  id: String!
+  type: AlertType!
+  severity: AlertSeverity!
+  message: String!
+  subscriberId: Int
+  timestamp: DateTime!
+  resolved: Boolean!
+  
+  subscriber: Subscriber
+}
+
+type SystemStats {
+  activeSessions: Int!
+  totalAccounts: Int!
+  blockedUsers: Int!
+  lowBalanceAlerts: Int!
+  uptime: Float!
+}
+
+type HealthStatus {
+  redisConnected: Boolean!
+  activeSync: Boolean!
+  lastSync: DateTime!
+  memoryUsage: Float!
+}
+
+type SubscriberConnection {
+  edges: [SubscriberEdge!]!
+  pageInfo: PageInfo!
+  totalCount: Int!
+}
+
+type SubscriberEdge {
+  node: Subscriber!
+  cursor: String!
+}
+
+type UsageEventConnection {
+  edges: [UsageEventEdge!]!
+  pageInfo: PageInfo!
+  totalCount: Int!
+}
+
+type UsageEventEdge {
+  node: UsageEvent!
+  cursor: String!
+}
+
+type InvoiceConnection {
+  edges: [InvoiceEdge!]!
+  pageInfo: PageInfo!
+  totalCount: Int!
+}
+
+type InvoiceEdge {
+  node: Invoice!
+  cursor: String!
+}
+
+type AlertConnection {
+  edges: [AlertEdge!]!
+  pageInfo: PageInfo!
+  totalCount: Int!
+}
+
+type AlertEdge {
+  node: Alert!
+  cursor: String!
+}
+
+type PageInfo {
+  hasNextPage: Boolean!
+  hasPreviousPage: Boolean!
+  startCursor: String
+  endCursor: String
+}
+
+type SubscriberFilter {
+  status: SubscriberStatus
+  organizationId: String
+  planId: Int
+  search: String
+  balanceMin: Float
+  balanceMax: Float
+  dataUsageMin: Float
+  dataUsageMax: Float
+}
+
+type UsageEventFilter {
+  usageType: UsageType
+  timestampGte: DateTime
+  timestampLte: DateTime
+  costMin: Float
+  costMax: Float
+}
+
+type CreateSubscriberInput {
+  msisdn: String!
+  firstName: String!
+  lastName: String!
+  email: String!
+  organizationId: String
+  planId: Int!
+  euiccId: String
+}
+
+type UpdateSubscriberInput {
+  firstName: String
+  lastName: String
+  email: String
+  organizationId: String
+  planId: Int
+}
+
+type TopUpInput {
+  amount: Float!
+  paymentMethodId: String
+}
+
+type UsageStatsInput {
+  imsi: String!
+  period: UsagePeriod!
+}
+
+enum UsagePeriod {
+  DAILY
+  WEEKLY
+  MONTHLY
+  YEARLY
+}
+
+type Query {
+  subscriber(id: ID!): Subscriber
+  subscriberByImsi(imsi: String!): Subscriber
+  subscribers(
+    first: Int
+    after: String
+    filter: SubscriberFilter
+    sort: SubscriberSort
+  ): SubscriberConnection!
+  
+  subscriberAccount(imsi: String!): SubscriberAccount
+  
+  usageEvents(
+    first: Int
+    after: String
+    imsi: String
+    filter: UsageEventFilter
+  ): UsageEventConnection!
+  usageStats(input: UsageStatsInput!): UsageStats!
+  realtimeUsage(imsi: String!): RealTimeUsage!
+  
+  invoices(
+    first: Int
+    after: String
+    imsi: String
+    status: InvoiceStatus
+  ): InvoiceConnection!
+  invoice(id: String!): Invoice
+  
+  ratingPlans: [RatingPlan!]!
+  ratingPlan(planId: String!): RatingPlan
+  
+  chargingSessions(
+    first: Int
+    after: String
+    imsi: String
+    status: SessionStatus
+  ): ChargingSessionConnection!
+  chargingSession(sessionId: String!): ChargingSession
+  
+  alerts(
+    first: Int
+    after: String
+    subscriberId: Int
+    severity: AlertSeverity
+    resolved: Boolean
+  ): AlertConnection!
+  
+  systemStats: SystemStats!
+  healthStatus: HealthStatus!
+  
+  searchSubscribers(query: String!, limit: Int): [Subscriber!]!
+  searchUsageEvents(query: String!, limit: Int): [UsageEvent!]!
+}
+
+type Mutation {
+  createSubscriber(input: CreateSubscriberInput!): Subscriber!
+  updateSubscriber(id: ID!, input: UpdateSubscriberInput!): Subscriber!
+  deleteSubscriber(id: ID!): Boolean!
+  
+  topUpBalance(imsi: String!, input: TopUpInput!): SubscriberAccount!
+  
+  suspendSubscriber(id: ID!): Subscriber!
+  activateSubscriber(id: ID!): Subscriber!
+  terminateSubscriber(id: ID!): Subscriber!
+  
+  provisionESIM(imsi: String!): ESIMProvisionResult!
+  activateESIM(imsi: String!, profileId: String!): Boolean!
+  deactivateESIM(imsi: String!, profileId: String!): Boolean!
+  
+  addPaymentMethod(subscriberId: Int!, input: PaymentMethodInput!): PaymentMethod!
+  removePaymentMethod(paymentMethodId: String!): Boolean!
+  setDefaultPaymentMethod(paymentMethodId: String!): PaymentMethod!
+  addPaymentMethod(subscriberId: Int!, input: PaymentMethodInput!): PaymentMethod!
+  removePaymentMethod(paymentMethodId: String!): Boolean!
+  setDefaultPaymentMethod(paymentMethodId: String!): PaymentMethod!
+  
+  resolveAlert(alertId: String!): Alert!
+  createAlert(input: CreateAlertInput!): Alert!
+  
+  triggerSystemMaintenance: Boolean!
+}
+
+type Subscription {
+  # Real-time subscriptions
+  subscriberUpdates(subscriberId: ID!): Subscriber!
+  usageUpdates(imsi: String!): UsageEvent!
+  alertUpdates(severity: AlertSeverity): Alert!
+  systemStatsUpdates: SystemStats!
+}
+
+type UsageStats {
+  dataUsage: Float!
+  voiceUsage: Float!
+  smsUsage: Float!
+  cost: Float!
+  period: String!
+  trend: UsageTrend!
+}
+
+type UsageTrend {
+  direction: TrendDirection!
+  percentage: Float!
+  periodOverPeriod: Float!
+}
+
+enum TrendDirection {
+  UP
+  DOWN
+  STABLE
+}
+
+type RealTimeUsage {
+  currentSession: CurrentSession
+  todayUsage: TodayUsage!
+}
+
+type CurrentSession {
+  sessionId: String!
+  startTime: DateTime!
+  dataUsed: Float!
+  voiceUsed: Float!
+  smsUsed: Float!
+  cost: Float!
+}
+
+type TodayUsage {
+  dataUsed: Float!
+  voiceUsed: Float!
+  smsUsed: Float!
+  cost: Float!
+}
+
+type ESIMProvisionResult {
+  profileId: String!
+  activationCode: String!
+  qrCode: String!
+}
+
+type PaymentMethodInput {
+  type: PaymentMethodType!
+  token: String!
+  isDefault: Boolean
+}
+
+type CreateAlertInput {
+  type: AlertType!
+  severity: AlertSeverity!
+  message: String!
+  subscriberId: Int
+}
+
+type ChargingSessionConnection {
+  edges: [ChargingSessionEdge!]!
+  pageInfo: PageInfo!
+  totalCount: Int!
+}
+
+type ChargingSessionEdge {
+  node: ChargingSession!
+  cursor: String!
+}
+
+enum SubscriberSort {
+  CREATED_AT_ASC
+  CREATED_AT_DESC
+  UPDATED_AT_ASC
+  UPDATED_AT_DESC
+  FIRST_NAME_ASC
+  FIRST_NAME_DESC
+  LAST_NAME_ASC
+  LAST_NAME_DESC
+  EMAIL_ASC
+  EMAIL_DESC
+  BALANCE_ASC
+  BALANCE_DESC
+  DATA_USED_ASC
+  DATA_USED_DESC
+}