const admin = require("firebase-admin");
const { FieldValue } = require("firebase-admin/firestore");

const ORDER_TYPES = {
  GIFT: "GIFT",
  SONG: "SONG",
  COINS: "COINS",
  SUBSCRIPTION: "SUBSCRIPTION",
};

const ORDER_STATUS = {
  PENDING: "PENDING",
  APPLIED: "APPLIED",
  REJECTED: "REJECTED",
};

const ORDERS_COLLECTION = "orders";

const isFiniteNumber = (value) => {
  if (typeof value === "number" && Number.isFinite(value)) {
    return true;
  }
  if (typeof value === "string") {
    const parsed = Number(value);
    return Number.isFinite(parsed);
  }
  return false;
};

const normalizeAmount = (amount) => {
  if (!isFiniteNumber(amount)) {
    return null;
  }
  return Number(amount);
};

const createOrderDocument = async ({
  userId,
  type,
  amount,
  songId = null,
  createdBy = "system",
  metadata = {},
  orderId = null,
}) => {
  if (!userId || typeof userId !== "string") {
    throw new Error("[orders] Missing userId when creating order");
  }

  if (!Object.values(ORDER_TYPES).includes(type)) {
    throw new Error(`[orders] Invalid order type "${type}"`);
  }

  const normalizedAmount = normalizeAmount(amount);

  if (normalizedAmount === null || normalizedAmount === 0) {
    throw new Error("[orders] Invalid order amount");
  }

  const payload = {
    userId,
    type,
    amount: normalizedAmount,
    songId: type === ORDER_TYPES.SONG ? songId || null : null,
    createdAt: FieldValue.serverTimestamp(),
    createdBy: createdBy || "system",
    status: ORDER_STATUS.PENDING,
    metadata: metadata || {},
  };

  const collectionRef = admin.firestore().collection(ORDERS_COLLECTION);
  const orderRef = orderId ? collectionRef.doc(orderId) : collectionRef.doc();

  if (orderId) {
    const existingSnapshot = await orderRef.get();
    if (existingSnapshot.exists) {
      return { orderRef, orderId: orderRef.id };
    }
  }

  await orderRef.set(payload);

  return { orderRef, orderId: orderRef.id };
};

module.exports = {
  ORDER_TYPES,
  ORDER_STATUS,
  ORDERS_COLLECTION,
  createOrderDocument,
  normalizeAmount,
};