import type { Metadata } from "next";
import type { ApiProduct, ApiStoreItem, ApiVariant } from "./api";

function sellingPrice(variant: ApiVariant): number {
  const value = variant.discountedPrice ?? variant.price;
  return typeof value === "number" && Number.isFinite(value) ? Math.trunc(value) : 0;
}

function inStock(variant: ApiVariant): boolean {
  return variant.stockQuantity === null || (typeof variant.stockQuantity === "number" && variant.stockQuantity > 0);
}

export function pickTorobVariant(variants: ApiVariant[]): ApiVariant | undefined {
  if (!variants.length) return undefined;
  const available = variants.filter(inStock);
  const pool = available.length ? available : variants;
  return pool.reduce((cheapest, variant) =>
    sellingPrice(variant) < sellingPrice(cheapest) ? variant : cheapest,
  );
}

function toHttpsUrl(url?: string | null): string | undefined {
  if (!url) return undefined;
  const trimmed = url.trim();
  if (trimmed.startsWith("https://")) return trimmed;
  if (trimmed.startsWith("http://")) return `https://${trimmed.slice("http://".length)}`;
  if (trimmed.startsWith("//")) return `https:${trimmed}`;
  return undefined;
}

export function torobMetadata(product: ApiProduct, storeItem: ApiStoreItem | null): Pick<Metadata, "other" | "openGraph"> {
  const variant = storeItem ? pickTorobVariant(storeItem.variants ?? []) : undefined;
  const price = storeItem && variant ? sellingPrice(variant) : 0;
  const available = Boolean(storeItem && variant && inStock(variant));
  const name = variant?.productNameFa || variant?.productTitle || product.nameFa || product.title;
  const image =
    toHttpsUrl(variant?.productImage) ||
    toHttpsUrl(product.thumbnailUrl) ||
    toHttpsUrl(product.image) ||
    toHttpsUrl(product.thumbnail) ||
    toHttpsUrl(product.images?.[0]?.url);

  const other: Record<string, string> = {
    product_id: product.id,
    product_name: name,
    product_price: String(price),
    availability: available ? "instock" : "outofstock",
  };

  if (variant && variant.discountedPrice != null) {
    other.product_old_price = String(typeof variant.price === "number" ? Math.trunc(variant.price) : 0);
  }

  return {
    other,
    ...(image ? { openGraph: { images: [{ url: image }] } } : {}),
  };
}