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

import { fetchAPI } from './api';

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

export interface CreditBalance {
  credits: number;  // Current balance
  plan_credits_per_month: number;  // Monthly allocation from plan
  credits_used_this_month: number;  // Used this billing period
  credits_remaining: number;  // Remaining credits
}

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;
}

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

export interface Payment {
  id: number;
  invoice_id: number;
  invoice_number?: string;
  amount: string;
  currency: string;
  status: 'pending' | 'processing' | 'succeeded' | 'failed' | 'refunded' | 'cancelled' | 'pending_approval' | 'completed';
  payment_method: 'stripe' | 'paypal' | 'bank_transfer' | 'local_wallet' | 'manual';
  created_at: string;
  processed_at?: string;
  failed_at?: string;
  refunded_at?: string;
  failure_reason?: string;
  manual_reference?: string;
  manual_notes?: string;
  transaction_reference?: string;
}

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 TeamMember {
  id: number;
  email: string;
  first_name: string;
  last_name: string;
  role: string;
  is_active: boolean;
  is_staff?: boolean;
  created_at: string;
  date_joined?: string;
  last_login?: string;
}

export interface PaymentMethod {
  id: string;
  type: 'stripe' | 'paypal' | 'bank_transfer' | 'local_wallet';
  display_name: string;
  name?: string;
  is_enabled: boolean;
  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 PendingPayment extends Payment {
  account_name: string;
  user_email: string;
  invoice_number?: string;
  admin_notes?: string;
}

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

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

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

export async function getAdminInvoices(params?: { status?: string; account_id?: number; search?: string }): Promise<{
  results: Invoice[];
  count: number;
}> {
  const queryParams = new URLSearchParams();
  if (params?.status) queryParams.append('status', params.status);
  if (params?.account_id) queryParams.append('account_id', String(params.account_id));
  if (params?.search) queryParams.append('search', params.search);

  const url = `/v1/billing/admin/invoices/${queryParams.toString() ? '?' + queryParams.toString() : ''}`;
  return fetchAPI(url);
}

export async function getAdminPayments(params?: { status?: string; account_id?: number; payment_method?: string }): Promise<{
  results: Payment[];
  count: number;
}> {
  const queryParams = new URLSearchParams();
  if (params?.status) queryParams.append('status', params.status);
  if (params?.account_id) queryParams.append('account_id', String(params.account_id));
  if (params?.payment_method) queryParams.append('payment_method', params.payment_method);

  const url = `/v1/billing/admin/payments/${queryParams.toString() ? '?' + queryParams.toString() : ''}`;
  return fetchAPI(url);
}

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 }),
  });
}

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

export async function getInvoices(params?: {
  status?: string;
}): Promise<{
  results: Invoice[];
  count: number;
}> {
  const queryParams = new URLSearchParams();
  if (params?.status) queryParams.append('status', params.status);
  
  const url = `/v1/billing/invoices/${queryParams.toString() ? '?' + queryParams.toString() : ''}`;
  return fetchAPI(url);
}

export async function getInvoiceDetail(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 PDF');
  }
  
  return response.blob();
}

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

export async function getPayments(params?: {
  status?: string;
  invoice_id?: number;
}): Promise<{
  results: Payment[];
  count: number;
}> {
  const queryParams = new URLSearchParams();
  if (params?.status) queryParams.append('status', params.status);
  if (params?.invoice_id) queryParams.append('invoice_id', String(params.invoice_id));
  
  const url = `/v1/billing/payments/${queryParams.toString() ? '?' + queryParams.toString() : ''}`;
  return fetchAPI(url);
}

export async function submitManualPayment(data: {
  invoice_id?: number;
  payment_method: 'bank_transfer' | 'local_wallet' | 'manual';
  amount: string;
  currency?: string;
  reference?: string;
  notes?: string;
  proof_file?: File;
}): Promise<{
  id: number;
  status: string;
  message: string;
}> {
  return fetchAPI('/v1/billing/payments/manual/', {
    method: 'POST',
    body: JSON.stringify(data),
  });
}

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

export async function getCreditPackages(): Promise<{
  results: CreditPackage[];
  count: number;
}> {
  return fetchAPI('/v1/billing/credit-packages/');
}

export async function purchaseCreditPackage(data: {
  package_id: number;
  payment_method: 'stripe' | 'paypal' | 'bank_transfer' | 'local_wallet';
}): Promise<{
  invoice_id?: number;
  invoice_number?: string;
  total_amount?: string;
  status?: string;
  message?: string;
  next_action?: string;
  stripe_client_secret?: string;
  paypal_order_id?: string;
}> {
  return fetchAPI(`/v1/billing/credit-packages/${data.package_id}/purchase/`, {
    method: 'POST',
    body: JSON.stringify({ payment_method: data.payment_method }),
  });
}

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

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;
  role?: string;
}): Promise<{
  message: string;
  member?: TeamMember;
}> {
  return fetchAPI('/v1/account/team/invite/', {
    method: 'POST',
    body: JSON.stringify(data),
  });
}

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

// ============================================================================
// PAYMENT METHODS
// ============================================================================

export async function getAvailablePaymentMethods(): Promise<{
  results: PaymentMethod[];
  count: number;
}> {
  return fetchAPI('/v1/billing/payment-methods/');
}

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

// ============================================================================
// 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, data?: {
  notes?: string;
}): Promise<{
  message: string;
  payment: Payment;
}> {
  return fetchAPI(`/v1/billing/admin/${paymentId}/approve_payment/`, {
    method: 'POST',
    body: JSON.stringify(data || {}),
  });
}

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

// ============================================================================
// ACCOUNT MANAGEMENT
// ============================================================================

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/account/settings/');
}

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

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}`);
}