/**
 * Billing API Service
 * Uses STANDARD existing billing endpoints from /v1/billing/ and /v1/system/
 */

import { fetchAPI } from './api';

// ============================================================================
// TYPES
// ============================================================================

export interface CreditBalance {
  balance: number;
  credits: number;
  plan_credits_per_month: number;
  credits_used_this_month: number;
  credits_remaining: number;
  subscription_plan?: string;
  monthly_credits?: number;
  subscription_status?: string;
}

export interface CreditTransaction {
  id: number;
  amount: number;
  transaction_type: 'purchase' | 'subscription' | 'refund' | 'deduction' | 'adjustment' | 'grant';
  description: string;
  created_at: string;
  reference_id?: string;
  metadata?: Record<string, any>;
  balance_after?: number;
}

export interface CreditUsageLog {
  id: number;
  operation_type: string;
  credits_used: number;
  cost_usd: string;
  model_used?: string;
  tokens_input?: number;
  tokens_output?: number;
  created_at: string;
  metadata?: Record<string, any>;
}

export interface AdminBillingStats {
  total_accounts: number;
  active_subscriptions: number;
  total_revenue: string;
  revenue_this_month?: string;
  new_accounts_this_month?: number;
  active_accounts?: number;
  credits_issued_30d?: number;
  credits_used_30d?: number;
  pending_approvals?: number;
  invoices_pending?: number;
  invoices_overdue?: number;
  system_health?: {
    status: string;
    last_check: string;
  };
  recent_activity?: Array<{
    id: number;
    type: string;
    account_name: string;
    amount: string;
    currency: string;
    timestamp: string;
    description: string;
  }>;
}

export interface CreditCostConfig {
  id: number;
  operation_type: string;
  credits_cost: number;
  unit: string;
  display_name: string;
  description: string;
  is_active: boolean;
  updated_at: string;
}

export interface AdminUser {
  id: number;
  email: string;
  account_name: string;
  account_id: number;
  role: string;
  is_active: boolean;
  credit_balance: number;
  plan_name?: string;
  created_at: string;
  last_login?: string;
}

// ============================================================================
// CREDIT BALANCE & TRANSACTIONS
// ============================================================================

export async function getCreditBalance(): Promise<CreditBalance> {
  return fetchAPI('/v1/billing/credits/balance/balance/');
}

export async function getCreditTransactions(): Promise<{
  results: CreditTransaction[];
  count: number;
  current_balance?: number;
}> {
  return fetchAPI('/v1/billing/credits/transactions/');
}

// ============================================================================
// CREDIT USAGE LOGS
// ============================================================================

export async function getCreditUsage(params?: {
  operation_type?: string;
  start_date?: string;
  end_date?: string;
}): Promise<{
  results: CreditUsageLog[];
  count: number;
}> {
  const queryParams = new URLSearchParams();
  if (params?.operation_type) queryParams.append('operation_type', params.operation_type);
  if (params?.start_date) queryParams.append('start_date', params.start_date);
  if (params?.end_date) queryParams.append('end_date', params.end_date);
  
  const url = `/v1/billing/credits/usage/${queryParams.toString() ? '?' + queryParams.toString() : ''}`;
  return fetchAPI(url);
}

export async function getCreditUsageSummary(params?: {
  start_date?: string;
  end_date?: string;
}): Promise<{
  total_credits_used: number;
  total_cost_usd: string;
  by_operation: Record<string, {
    credits: number;
    cost: number;
    count: number;
  }>;
  by_model: Record<string, {
    credits: number;
    cost: number;
    count: number;
  }>;
}> {
  const queryParams = new URLSearchParams();
  if (params?.start_date) queryParams.append('start_date', params.start_date);
  if (params?.end_date) queryParams.append('end_date', params.end_date);
  
  const url = `/v1/billing/credits/usage/summary/${queryParams.toString() ? '?' + queryParams.toString() : ''}`;
  return fetchAPI(url);
}

export async function getCreditUsageLimits(): Promise<{
  plan_name: string;
  plan_credits_per_month: number;
  credits_used_this_month: number;
  credits_remaining: number;
  percentage_used: number;
  approaching_limit: boolean;
}> {
  return fetchAPI('/v1/billing/credits/usage/limits/');
}

// ============================================================================
// ADMIN - BILLING STATS & MANAGEMENT
// ============================================================================

export async function getAdminBillingStats(): Promise<AdminBillingStats> {
  return fetchAPI('/v1/admin/billing/stats/');
}

export async function getAdminUsers(params?: {
  search?: string;
  role?: string;
  is_active?: boolean;
}): Promise<{
  results: AdminUser[];
  count: number;
}> {
  const queryParams = new URLSearchParams();
  if (params?.search) queryParams.append('search', params.search);
  if (params?.role) queryParams.append('role', params.role);
  if (params?.is_active !== undefined) queryParams.append('is_active', String(params.is_active));
  
  const url = `/v1/admin/users/${queryParams.toString() ? '?' + queryParams.toString() : ''}`;
  return fetchAPI(url);
}

export async function adjustUserCredits(
  userId: number,
  data: {
    amount: number;
    reason: string;
  }
): Promise<{
  message: string;
  new_balance: number;
}> {
  return fetchAPI(`/v1/admin/users/${userId}/adjust-credits/`, {
    method: 'POST',
    body: JSON.stringify(data),
  });
}

// ============================================================================
// ADMIN - CREDIT COSTS CONFIGURATION
// ============================================================================

export async function getCreditCosts(): Promise<{
  results: CreditCostConfig[];
  count: number;
}> {
  return fetchAPI('/v1/admin/credit-costs/');
}

export async function updateCreditCosts(
  costs: Array<{
    operation_type: string;
    credits_cost: number;
  }>
): Promise<{
  message: string;
  updated_count: number;
}> {
  return fetchAPI('/v1/admin/credit-costs/', {
    method: 'POST',
    body: JSON.stringify({ costs }),
  });
}

// ============================================================================
// ACCOUNT SETTINGS (from /v1/system/)
// ============================================================================

export interface AccountSettings {
  id: number;
  name: string;
  slug: string;
  billing_address_line1?: string;
  billing_address_line2?: string;
  billing_city?: string;
  billing_state?: string;
  billing_postal_code?: string;
  billing_country?: string;
  tax_id?: string;
  billing_email?: string;
  credit_balance: number;
  plan_name?: string;
  created_at: string;
  updated_at: string;
}

export async function getAccountSettings(): Promise<AccountSettings> {
  return fetchAPI('/v1/system/settings/account/');
}

export async function updateAccountSettings(
  settings: Partial<AccountSettings>
): Promise<{
  message: string;
  account: Partial<AccountSettings>;
}> {
  return fetchAPI('/v1/system/settings/account/', {
    method: 'PATCH',
    body: JSON.stringify(settings),
  });
}

// ============================================================================
// TYPES
// ============================================================================

export interface CreditPackage {
  id: number;
  name: string;
  slug: string;
  credits: number;
  price: string;
  discount_percentage: number;
  is_featured: boolean;
  description: string;
  display_order: number;
}

export interface Invoice {
  id: number;
  invoice_number: string;
  status: 'draft' | 'pending' | 'paid' | 'void';
  total_amount: string;
  subtotal: string;
  tax_amount: string;
  currency: string;
  created_at: string;
  paid_at: string | null;
  due_date: string | null;
  line_items: Array<{
    description: string;
    amount: string;
    quantity: number;
  }>;
  billing_period_start: string | null;
  billing_period_end: string | null;
}

export interface Payment {
  id: number;
  amount: string;
  currency: string;
  payment_method: 'stripe' | 'paypal' | 'bank_transfer' | 'local_wallet' | 'manual';
  status: 'pending' | 'completed' | 'failed' | 'pending_approval';
  created_at: string;
  processed_at: string | null;
  invoice_id: number;
  invoice_number: string | null;
  transaction_reference: string;
  failure_reason: string | null;
}

export interface PaymentMethod {
  type: string;
  name: string;
  instructions: string;
  bank_details?: {
    bank_name: string;
    account_number: string;
    routing_number: string;
    swift_code: string;
  };
  wallet_details?: {
    wallet_type: string;
    wallet_id: string;
  };
}

export interface CreditTransaction {
  id: number;
  amount: number;
  transaction_type: string;
  description: string;
  created_at: string;
  reference_id: string;
  metadata: Record<string, any>;
}

export interface CreditBalance {
  balance: number;
  subscription_plan: string;
  monthly_credits: number;
  subscription_status: string | null;
}

export interface PendingPayment {
  id: number;
  account_name: string;
  amount: string;
  currency: string;
  payment_method: string;
  transaction_reference: string;
  created_at: string;
  invoice_number: string | null;
  admin_notes: string;
}

// ============================================================================
// CREDIT PACKAGES
// ============================================================================

export async function getCreditPackages(): Promise<{ results: CreditPackage[]; count: number }> {
  return fetchAPI('/billing/v2/credit-packages/');
}

export async function purchaseCreditPackage(
  packageId: number,
  paymentMethod: string
): Promise<{
  invoice_id: number;
  invoice_number: string;
  total_amount: string;
  message: string;
  next_action: string;
}> {
  return fetchAPI(`/billing/v2/credit-packages/${packageId}/purchase/`, {
    method: 'POST',
    body: JSON.stringify({ payment_method: paymentMethod }),
  });
}

// ============================================================================
// INVOICES
// ============================================================================

export async function getInvoices(status?: string): Promise<{ results: Invoice[]; count: number }> {
  const params = status ? `?status=${status}` : '';
  return fetchAPI(`/billing/v2/invoices/${params}`);
}

export async function getInvoice(invoiceId: number): Promise<Invoice> {
  return fetchAPI(`/v1/billing/invoices/${invoiceId}/`);
}

export async function downloadInvoicePDF(invoiceId: number): Promise<Blob> {
  const response = await fetch(`/api/v1/billing/invoices/${invoiceId}/download_pdf/`, {
    headers: {
      Authorization: `Bearer ${localStorage.getItem('access_token')}`,
    },
  });

  if (!response.ok) {
    throw new Error('Failed to download invoice');
  }

  return response.blob();
}

// ============================================================================
// PAYMENTS
// ============================================================================

export async function getPayments(status?: string): Promise<{ results: Payment[]; count: number }> {
  const params = status ? `?status=${status}` : '';
  return fetchAPI(`/v1/billing/payments/${params}`);
}

export async function getAvailablePaymentMethods(): Promise<{
  methods: PaymentMethod[];
  stripe: boolean;
  paypal: boolean;
  bank_transfer: boolean;
  local_wallet: boolean;
}> {
  return fetchAPI('/v1/billing/payments/available_methods/');
}

export async function createManualPayment(data: {
  invoice_id: number;
  payment_method: 'bank_transfer' | 'local_wallet';
  transaction_reference: string;
  notes?: string;
}): Promise<{
  id: number;
  status: string;
  message: string;
}> {
  return fetchAPI('/v1/billing/payments/create_manual_payment/', {
    method: 'POST',
    body: JSON.stringify(data),
  });
}

// ============================================================================
// CREDIT TRANSACTIONS
// ============================================================================

export async function getCreditTransactions(): Promise<{
  results: CreditTransaction[];
  count: number;
  current_balance: number;
}> {
  return fetchAPI('/v1/billing/credits/transactions/');
}

export async function getCreditBalance(): Promise<CreditBalance> {
  return fetchAPI('/v1/billing/credits/balance/balance/');
}

// ============================================================================
// ADMIN - PAYMENT APPROVALS
// ============================================================================

export async function getPendingPayments(): Promise<{
  results: PendingPayment[];
  count: number;
}> {
  return fetchAPI('/v1/billing/admin/pending_payments/');
}

export async function approvePayment(
  paymentId: number,
  notes?: string
): Promise<{
  id: number;
  status: string;
  message: string;
}> {
  return fetchAPI(`/v1/billing/admin/${paymentId}/approve_payment/`, {
    method: 'POST',
    body: JSON.stringify({ notes }),
  });
}

export async function rejectPayment(
  paymentId: number,
  reason: string
): Promise<{
  id: number;
  status: string;
  message: string;
}> {
  return fetchAPI(`/v1/billing/admin/${paymentId}/reject_payment/`, {
    method: 'POST',
    body: JSON.stringify({ reason }),
  });
}

export async function getAdminBillingStats(): Promise<{
  total_accounts: number;
  active_subscriptions: number;
  total_revenue: string;
  pending_approvals: number;
  invoices_pending: number;
  invoices_paid: number;
}> {
  return fetchAPI('/v1/billing/v2/admin/stats/');
}

// ============================================================================
// ACCOUNT SETTINGS
// ============================================================================

export interface AccountSettings {
  id: number;
  name: string;
  slug: string;
  billing_address_line1: string;
  billing_address_line2: string;
  billing_city: string;
  billing_state: string;
  billing_postal_code: string;
  billing_country: string;
  tax_id: string;
  billing_email: string;
  credit_balance: number;
  created_at: string;
  updated_at: string;
}

export async function getAccountSettings(): Promise<AccountSettings> {
  return fetchAPI('/v1/system/settings/account/');
}

export async function updateAccountSettings(
  settings: Partial<AccountSettings>
): Promise<{
  message: string;
  account: Partial<AccountSettings>;
}> {
  return fetchAPI('/v1/account/settings/', {
    method: 'PATCH',
    body: JSON.stringify(settings),
  });
}

// ============================================================================
// TEAM MANAGEMENT
// ============================================================================

export interface TeamMember {
  id: number;
  email: string;
  first_name: string;
  last_name: string;
  is_active: boolean;
  is_staff: boolean;
  date_joined: string;
  last_login: string | null;
}

export async function getTeamMembers(): Promise<{
  results: TeamMember[];
  count: number;
}> {
  return fetchAPI('/v1/account/team/');
}

export async function inviteTeamMember(data: {
  email: string;
  first_name?: string;
  last_name?: string;
}): Promise<{
  message: string;
  user: Partial<TeamMember>;
}> {
  return fetchAPI('/v1/account/team/', {
    method: 'POST',
    body: JSON.stringify(data),
  });
}

export async function removeTeamMember(userId: number): Promise<{
  message: string;
}> {
  return fetchAPI(`/v1/account/team/${userId}/`, {
    method: 'DELETE',
  });
}

// ============================================================================
// USAGE ANALYTICS
// ============================================================================

export interface UsageAnalytics {
  period_days: number;
  start_date: string;
  end_date: string;
  current_balance: number;
  usage_by_type: Array<{
    transaction_type: string;
    total: number;
    count: number;
  }>;
  purchases_by_type: Array<{
    transaction_type: string;
    total: number;
    count: number;
  }>;
  daily_usage: Array<{
    date: string;
    usage: number;
    purchases: number;
    net: number;
  }>;
  total_usage: number;
  total_purchases: number;
}

export async function getUsageAnalytics(days: number = 30): Promise<UsageAnalytics> {
  return fetchAPI(`/v1/account/usage/analytics/?days=${days}`);
}