import Medusa from "@medusajs/js-sdk";

const MEDUSA_URL =
  process.env.MEDUSA_URL ?? process.env.NEXT_PUBLIC_MEDUSA_URL ?? "http://localhost:9000";
const PUBLISHABLE_KEY =
  process.env.MEDUSA_PUBLISHABLE_KEY ?? process.env.NEXT_PUBLIC_MEDUSA_PUBLISHABLE_KEY ?? "";
const REGION_ID =
  process.env.MEDUSA_REGION_ID ?? process.env.NEXT_PUBLIC_MEDUSA_REGION_ID ?? "";

// Create a single SDK instance at module scope.
// auth type "session" is not needed for server-side usage; we pass tokens
// via the ClientHeaders parameter where necessary.
const medusa = new Medusa({
  baseUrl: MEDUSA_URL,
  publishableKey: PUBLISHABLE_KEY,
  auth: { type: "jwt", jwtTokenStorageMethod: "nostore" },
});

// ── Types ──────────────────────────────────────────────────────────

export type MedusaMoneyAmount = {
  amount: number;
  currency_code: string;
};

export type MedusaVariant = {
  id: string;
  title: string;
  sku: string | null;
  calculated_price?: {
    calculated_amount: number;
    currency_code: string;
  };
  prices?: MedusaMoneyAmount[];
};

export type MedusaProduct = {
  id: string;
  title: string;
  handle: string;
  metadata?: {
    ean?: string;
    catalogue_number?: string;
    [key: string]: unknown;
  };
  variants: MedusaVariant[];
};

export type MedusaLineItem = {
  id: string;
  title: string;
  variant_id: string;
  variant: MedusaVariant;
  quantity: number;
  unit_price: number;
  total: number;
  product_title: string;
  product_handle?: string;
  thumbnail: string | null;
};

export type MedusaCart = {
  id: string;
  items: MedusaLineItem[];
  total: number;
  subtotal: number;
  shipping_total?: number;
  tax_total?: number;
  discount_total?: number;
  currency_code: string;
  email?: string;
  shipping_address?: MedusaAddress | null;
  billing_address?: MedusaAddress | null;
  shipping_methods?: { id: string; name: string; amount: number; shipping_option_id: string }[];
  payment_collection?: MedusaPaymentCollection | null;
  promotions?: { id: string; code?: string }[];
};

export type MedusaAddress = {
  first_name: string;
  last_name: string;
  address_1: string;
  address_2?: string;
  city: string;
  province?: string;
  postal_code: string;
  country_code: string;
  phone?: string;
};

export type MedusaShippingOption = {
  id: string;
  name: string;
  amount: number;
  price_type: string;
};

export type MedusaPaymentSession = {
  id: string;
  provider_id: string;
  status: string;
  data?: Record<string, unknown>;
};

export type MedusaPaymentCollection = {
  id: string;
  status: string;
  payment_sessions?: MedusaPaymentSession[];
};

export type MedusaOrder = {
  id: string;
  display_id: number;
  email: string;
  items: MedusaLineItem[];
  total: number;
  subtotal: number;
  shipping_total: number;
  tax_total: number;
  currency_code: string;
  shipping_address?: MedusaAddress | null;
};

// ── Helpers ────────────────────────────────────────────────────────

/** Build an authorization header object when a JWT auth token is provided. */
function authHeaders(authToken?: string): Record<string, string> {
  return authToken ? { Authorization: `Bearer ${authToken}` } : {};
}

// ── Product queries ────────────────────────────────────────────────

const PRODUCT_FIELDS =
  "id,title,handle,metadata,*variants,*variants.calculated_price,variants.sku";

/**
 * Fetches all products from the Store API (paginated).
 * Medusa v2 Store API doesn't support metadata filtering, so we fetch
 * the full catalog and match server-side. The result is cached by
 * Next.js via `fetch` deduplication + ISR revalidation.
 */
export async function getAllProducts(): Promise<MedusaProduct[]> {
  const all: MedusaProduct[] = [];
  let offset = 0;
  const limit = 100;

  // eslint-disable-next-line no-constant-condition
  while (true) {
    const data = await medusa.store.product.list({
      fields: PRODUCT_FIELDS,
      region_id: REGION_ID,
      limit,
      offset,
    });
    all.push(...(data.products as unknown as MedusaProduct[]));
    if (all.length >= data.count) break;
    offset += limit;
  }

  return all;
}

export async function getProductByEan(ean: string): Promise<MedusaProduct | null> {
  try {
    const products = await getAllProducts();
    return products.find((p) => p.metadata?.ean === ean) ?? null;
  } catch {
    return null;
  }
}

export async function getProductByCatalogNo(catalogNo: string): Promise<MedusaProduct | null> {
  try {
    const products = await getAllProducts();
    return (
      products.find(
        (p) => p.metadata?.catalogue_number?.toUpperCase() === catalogNo.toUpperCase(),
      ) ?? null
    );
  } catch {
    return null;
  }
}

// ── Cart operations ────────────────────────────────────────────────

const CART_FIELDS = "id,items,items.*,items.variant.*,items.thumbnail,total,subtotal,discount_total,currency_code,+promotions,+promotions.code";

export async function createCart(authToken?: string): Promise<MedusaCart> {
  const data = await medusa.store.cart.create(
    { region_id: REGION_ID },
    {},
    authHeaders(authToken),
  );
  return data.cart as unknown as MedusaCart;
}

export async function getCart(cartId: string): Promise<MedusaCart | null> {
  try {
    const data = await medusa.store.cart.retrieve(cartId, {
      fields: CART_FIELDS,
    });
    return data.cart as unknown as MedusaCart;
  } catch {
    return null;
  }
}

export async function addToCart(
  cartId: string,
  variantId: string,
  quantity = 1,
): Promise<MedusaCart> {
  const data = await medusa.store.cart.createLineItem(
    cartId,
    { variant_id: variantId, quantity },
    { fields: CART_FIELDS },
  );
  return data.cart as unknown as MedusaCart;
}

export async function updateCartItem(
  cartId: string,
  lineItemId: string,
  quantity: number,
): Promise<MedusaCart> {
  const data = await medusa.store.cart.updateLineItem(
    cartId,
    lineItemId,
    { quantity },
    { fields: CART_FIELDS },
  );
  return data.cart as unknown as MedusaCart;
}

export async function removeFromCart(
  cartId: string,
  lineItemId: string,
): Promise<MedusaCart> {
  // The SDK's deleteLineItem returns { parent: cart }.
  await medusa.store.cart.deleteLineItem(cartId, lineItemId);
  const cart = await getCart(cartId);
  if (!cart) throw new Error("Cart not found after removing item");
  return cart;
}

// ── Promotion operations ────────────────────────────────────────────

export async function applyPromoCode(
  cartId: string,
  code: string,
): Promise<MedusaCart> {
  await medusa.client.fetch(
    `/store/carts/${cartId}/promotions`,
    {
      method: "POST",
      body: { promo_codes: [code] },
    },
  );
  // Re-fetch with our field selection so the shape is consistent
  const cart = await getCart(cartId);
  if (!cart) throw new Error("Cart not found after applying promo");
  return cart;
}

export async function removePromoCode(
  cartId: string,
  code: string,
): Promise<MedusaCart> {
  await medusa.client.fetch(
    `/store/carts/${cartId}/promotions`,
    {
      method: "DELETE",
      body: { promo_codes: [code] },
    },
  );
  const cart = await getCart(cartId);
  if (!cart) throw new Error("Cart not found after removing promo");
  return cart;
}

// ── Checkout operations ─────────────────────────────────────────────

export async function updateCart(
  cartId: string,
  data: {
    email?: string;
    shipping_address?: MedusaAddress;
    billing_address?: MedusaAddress;
  },
  authToken?: string,
): Promise<MedusaCart> {
  const res = await medusa.store.cart.update(
    cartId,
    data,
    {},
    authHeaders(authToken),
  );
  return res.cart as unknown as MedusaCart;
}

export async function getShippingOptions(
  cartId: string,
): Promise<MedusaShippingOption[]> {
  const data = await medusa.store.fulfillment.listCartOptions({
    cart_id: cartId,
  });
  return data.shipping_options as unknown as MedusaShippingOption[];
}

export async function addShippingMethod(
  cartId: string,
  optionId: string,
): Promise<MedusaCart> {
  const data = await medusa.store.cart.addShippingMethod(cartId, {
    option_id: optionId,
  });
  return data.cart as unknown as MedusaCart;
}

export async function createPaymentCollection(
  cartId: string,
): Promise<MedusaPaymentCollection> {
  // The SDK's store.payment.initiatePaymentSession handles this automatically,
  // but we need to keep the two-step flow for callers. Use client.fetch for
  // the explicit payment-collection creation endpoint.
  const data = await medusa.client.fetch<{ payment_collection: MedusaPaymentCollection }>(
    "/store/payment-collections",
    {
      method: "POST",
      body: { cart_id: cartId },
    },
  );
  return data.payment_collection;
}

export async function initPaymentSession(
  paymentCollectionId: string,
  providerId: string,
  sessionData?: Record<string, unknown>,
): Promise<MedusaPaymentCollection> {
  const data = await medusa.client.fetch<{ payment_collection: MedusaPaymentCollection }>(
    `/store/payment-collections/${paymentCollectionId}/payment-sessions`,
    {
      method: "POST",
      body: {
        provider_id: providerId,
        ...(sessionData ? { data: sessionData } : {}),
      },
    },
  );
  return data.payment_collection;
}

export async function completeCart(
  cartId: string,
  authToken?: string,
): Promise<{ type: string; order?: MedusaOrder; cart?: MedusaCart }> {
  const data = await medusa.store.cart.complete(
    cartId,
    {},
    authHeaders(authToken),
  );
  return data as unknown as { type: string; order?: MedusaOrder; cart?: MedusaCart };
}

export async function getOrder(orderId: string): Promise<MedusaOrder | null> {
  try {
    const data = await medusa.store.order.retrieve(orderId);
    return data.order as unknown as MedusaOrder;
  } catch {
    return null;
  }
}