import { QueryCtx } from "../_generated/server";
import { Id, Doc } from "../_generated/dataModel";

export async function getOrderWithItems(
  ctx: QueryCtx,
  orderId: Id<"orders">,
) {
  const order = await ctx.db.get(orderId);
  if (!order) return null;

  const items = await ctx.db
    .query("orderItems")
    .withIndex("by_order", (q) => q.eq("orderId", orderId))
    .collect();

  return { ...order, items };
}

/**
 * Determines whether a customer is allowed to cancel a given order.
 *
 * NOTE: Cancellation only updates order status and restores stock.
 * Stripe refund processing is a separate concern handled via the admin
 * dashboard or a future automated flow. This helper does NOT trigger a refund.
 */
export function canCustomerCancel(order: Doc<"orders">): {
  allowed: boolean;
  reason?: string;
} {
  switch (order.status) {
    case "confirmed":
      return { allowed: true };
    case "pending":
      return {
        allowed: false,
        reason: "Order is still awaiting payment confirmation.",
      };
    case "cancelled":
      return { allowed: false, reason: "Order is already cancelled." };
    case "refunded":
      return { allowed: false, reason: "Order has already been refunded." };
    default:
      return {
        allowed: false,
        reason:
          "Order has progressed past the cancellation window. Please contact support.",
      };
  }
}

export interface OutOfStockItem {
  variantId: Id<"productVariants">;
  requested: number;
  available: number;
}

/**
 * Check each cart item for sufficient stock. Returns list of out-of-stock entries.
 */
export async function validateCartItems(
  ctx: Pick<QueryCtx, "db">,
  items: { variantId?: Id<"productVariants">; quantity: number }[]
): Promise<OutOfStockItem[]> {
  const outOfStock: OutOfStockItem[] = [];
  for (const item of items) {
    if (!item.variantId) continue;
    const variant = await ctx.db.get(item.variantId);
    if (!variant) {
      outOfStock.push({
        variantId: item.variantId,
        requested: item.quantity,
        available: 0,
      });
      continue;
    }
    if (variant.stockQuantity < item.quantity) {
      outOfStock.push({
        variantId: item.variantId,
        requested: item.quantity,
        available: variant.stockQuantity,
      });
    }
  }
  return outOfStock;
}