/**
 * XENDIT INDUSTRIAL BILLING ENGINE (X-IBE)
 * 
 * Engine pembayaran murni tanpa dependensi pihak ketiga.
 * Menggunakan standar REST API Xendit v2 untuk Invoice & Webhooks.
 */

const XENDIT_SECRET_KEY = process.env.XENDIT_SECRET_KEY || "";
const XENDIT_ENDPOINT = "https://api.xendit.co/v2/invoices";

export interface XenditInvoiceRequest {
  external_id: string;
  amount: number;
  payer_email: string;
  description: string;
  success_redirect_url: string;
  failure_redirect_url: string;
  currency: string;
  items?: Array<{
    name: string;
    quantity: number;
    price: number;
    category?: string;
  }>;
}

export class XenditEngine {
  private static getAuthHeader() {
    // Xendit requires Basic Auth with secret key as username and empty password
    const auth = Buffer.from(`${XENDIT_SECRET_KEY}:`).toString('base64');
    return `Basic ${auth}`;
  }

  static async createInvoice(req: XenditInvoiceRequest) {
    if (!XENDIT_SECRET_KEY) {
      console.warn("[XENDIT] Secret Key missing. Using Sandbox Mode (Simulated URL).");
      return { 
        id: "sim_inv_" + Date.now(),
        invoice_url: `${req.success_redirect_url}?sim_status=PAID&external_id=${req.external_id}` 
      };
    }

    try {
      const response = await fetch(XENDIT_ENDPOINT, {
        method: 'POST',
        headers: {
          'Authorization': this.getAuthHeader(),
          'Content-Type': 'application/json'
        },
        body: JSON.stringify({
          ...req,
          should_send_email: true,
          payment_methods: ["BNI", "BRI", "MANDIRI", "BCA", "PERMATA", "OVO", "DANA", "QRIS"]
        })
      });

      const data = await response.json();
      if (!response.ok) {
         throw new Error(data.message || "Xendit API Error");
      }

      return data; // returns { id, invoice_url, status, etc }
    } catch (error) {
      console.error("[XENDIT ERROR]", error);
      throw error;
    }
  }

  static async getInvoice(invoiceId: string) {
    try {
      const response = await fetch(`${XENDIT_ENDPOINT}/${invoiceId}`, {
        headers: { 'Authorization': this.getAuthHeader() }
      });
      return await response.json();
    } catch (error) {
       console.error("[XENDIT GET ERROR]", error);
       throw error;
    }
  }
}