// Server-side helpers for the Areeba payment gateway (MPGS-style API).
//
// Areeba issues merchant credentials after onboarding:
//   AREEBA_API_BASE_URL  e.g. https://<your-gateway-host>.areeba.com
//   AREEBA_MERCHANT_ID   your merchant id
//   AREEBA_API_PASSWORD  API password for the merchant
//   AREEBA_API_VERSION   gateway REST API version (default: 100)
//
// NOTE: verify the exact field names against the integration docs Areeba
// sends you — the gateway is Mastercard Payment Gateway (MPGS) based, and
// the payloads below follow that convention.

export const areebaConfig = () => {
  const baseUrl = process.env.AREEBA_API_BASE_URL?.replace(/\/$/, "");
  const merchantId = process.env.AREEBA_MERCHANT_ID;
  const apiPassword = process.env.AREEBA_API_PASSWORD;
  const apiVersion = process.env.AREEBA_API_VERSION || "100";

  if (!baseUrl || !merchantId || !apiPassword) {
    throw new Error(
      "Missing Areeba configuration. Set AREEBA_API_BASE_URL, AREEBA_MERCHANT_ID and AREEBA_API_PASSWORD in .env",
    );
  }

  return { baseUrl, merchantId, apiPassword, apiVersion };
};

const authHeader = (merchantId: string, apiPassword: string) =>
  `Basic ${Buffer.from(`merchant.${merchantId}:${apiPassword}`).toString("base64")}`;

// Creates a checkout session and returns the hosted payment page URL.
export const createCheckoutSession = async ({
  orderId,
  amount,
  currency,
  description,
  returnUrl,
}: {
  orderId: string;
  amount: number; // major units, e.g. 25.5 USD
  currency: string;
  description: string;
  returnUrl: string;
}) => {
  const { baseUrl, merchantId, apiPassword, apiVersion } = areebaConfig();

  const res = await fetch(
    `${baseUrl}/api/rest/version/${apiVersion}/merchant/${merchantId}/session`,
    {
      method: "POST",
      headers: {
        "Content-Type": "application/json",
        Authorization: authHeader(merchantId, apiPassword),
      },
      body: JSON.stringify({
        apiOperation: "INITIATE_CHECKOUT",
        order: {
          id: orderId,
          amount: amount.toFixed(2),
          currency,
          description,
        },
        interaction: {
          operation: "PURCHASE",
          merchant: { name: "Waseel" },
          returnUrl,
        },
      }),
    },
  );

  const data = await res.json();

  if (!res.ok || !data?.session?.id) {
    console.log("[AREEBA_CREATE_SESSION]: ", data);
    throw new Error(
      data?.error?.explanation || "Failed to create Areeba checkout session",
    );
  }

  return {
    sessionId: data.session.id as string,
    // Used to verify the redirect result (compare with resultIndicator).
    successIndicator: data.successIndicator as string | undefined,
    checkoutUrl: `${baseUrl}/checkout/pay/${data.session.id}?checkoutVersion=1.0.0`,
  };
};

// Retrieves an order and reports whether it was paid.
export const retrieveOrder = async (orderId: string) => {
  const { baseUrl, merchantId, apiPassword, apiVersion } = areebaConfig();

  const res = await fetch(
    `${baseUrl}/api/rest/version/${apiVersion}/merchant/${merchantId}/order/${orderId}`,
    { headers: { Authorization: authHeader(merchantId, apiPassword) } },
  );

  const data = await res.json();

  if (!res.ok) {
    console.log("[AREEBA_RETRIEVE_ORDER]: ", data);
    throw new Error(
      data?.error?.explanation || "Failed to retrieve Areeba order",
    );
  }

  return {
    status: data.status as string | undefined,
    result: data.result as string | undefined,
    amount: data.amount as string | undefined,
    currency: data.currency as string | undefined,
    // PURCHASE auto-captures; CAPTURED means the money was taken.
    paid: data.result === "SUCCESS" && data.status === "CAPTURED",
  };
};