/**
 * Billing Store (Zustand)
 * Manages credit balance and usage tracking with graceful error state
 */
import { create } from 'zustand';
import {
  getCreditBalance,
  getCreditUsageLimits,
  getCreditUsageSummary,
  type CreditBalance,
} from '../services/billing.api';

interface BillingState {
  balance: CreditBalance | null;
  usageSummary: any | null;
  usageLimits: any | null;
  loading: boolean;
  error: string | null;
  lastUpdated?: string | null;
  
  // Actions
  loadBalance: () => Promise<void>;
  loadUsageSummary: (startDate?: string, endDate?: string) => Promise<void>;
  loadUsageLimits: () => Promise<void>;
  reset: () => void;
}

export const useBillingStore = create<BillingState>((set, get) => ({
  balance: null,
  usageSummary: null,
  usageLimits: null,
  loading: false,
  error: null,
  lastUpdated: null,
  
  loadBalance: async () => {
    // keep existing balance while retrying
    set({ loading: true, error: null });
    try {
      const balance = await getCreditBalance();
      set({ balance, loading: false, error: null, lastUpdated: new Date().toISOString() });
    } catch (error: any) {
      set({ error: error.message || 'Balance unavailable', loading: false, balance: null });
    }
  },
  
  loadUsageSummary: async (startDate?: string, endDate?: string) => {
    set({ loading: true, error: null });
    try {
      const summary = await getCreditUsageSummary({ start_date: startDate, end_date: endDate } as any);
      set({ usageSummary: summary, loading: false });
    } catch (error: any) {
      set({ error: error.message, loading: false });
    }
  },

  loadUsageLimits: async () => {
    set({ loading: true, error: null });
    try {
      const limits = await getCreditUsageLimits();
      set({ usageLimits: limits, loading: false });
    } catch (error: any) {
      // If limits endpoint is not available (404), keep going without hard error
      if (error?.status === 404) {
        set({ usageLimits: null, loading: false });
        return;
      }
      set({ error: error.message || 'Usage limits unavailable', loading: false });
    }
  },
  
  reset: () => {
    set({
      balance: null,
      usageSummary: null,
      usageLimits: null,
      loading: false,
      error: null,
    });
  },
}));