import { HIDDEN_PRODUCT_TAG, SHOPIFY_GRAPHQL_API_ENDPOINT, TAGS } from "lib/constants";
import { isShopifyError } from "lib/type-guards";
import { ensureStartsWith } from "lib/utils";
import { revalidateTag } from "next/cache";
import { headers } from "next/headers";
import { NextRequest, NextResponse } from "next/server";
import {
  addToCartMutation,
  createCartMutation,
  editCartItemsMutation,
  removeFromCartMutation
} from "./mutations/cart";
import { getCartQuery } from "./queries/cart";
import {
  getCollectionProductsQuery,
  getCollectionQuery,
  getCollectionsQuery
} from "./queries/collection";
import { getMenuQuery } from "./queries/menu";
import { getPageQuery, getPagesQuery } from "./queries/page";
import {
  getProductQuery,
  getProductRecommendationsQuery,
  getProductsQuery
} from "./queries/product";
import {
  Cart,
  Collection,
  Connection,
  Image,
  Menu,
  Page,
  Product,
  ShopifyAddToCartOperation,
  ShopifyCart,
  ShopifyCartOperation,
  ShopifyCollection,
  ShopifyCollectionOperation,
  ShopifyCollectionProductsOperation,
  ShopifyCollectionsOperation,
  ShopifyCreateCartOperation,
  ShopifyMenuOperation,
  ShopifyPageOperation,
  ShopifyPagesOperation,
  ShopifyProduct,
  ShopifyProductOperation,
  ShopifyProductRecommendationsOperation,
  ShopifyProductsOperation,
  ShopifyRemoveFromCartOperation,
  ShopifyUpdateCartOperation
} from "./types";

const domain = process.env.SHOPIFY_STORE_DOMAIN
  ? ensureStartsWith(process.env.SHOPIFY_STORE_DOMAIN, "https://")
  : "";
const endpoint = `${domain}${SHOPIFY_GRAPHQL_API_ENDPOINT}`;
const key = process.env.SHOPIFY_STOREFRONT_ACCESS_TOKEN!;

type ExtractVariables<T> = T extends { variables: object } ? T["variables"] : never;

export async function shopifyFetch<T>({
  cache = "force-cache",
  headers,
  query,
  tags,
  variables
}: {
  cache?: RequestCache;
  headers?: HeadersInit;
  query: string;
  tags?: string[];
  variables?: ExtractVariables<T>;
}): Promise<{ status: number; body: T } | never> {
  try {
    const result = await fetch(endpoint, {
      method: "POST",
      headers: {
        "Content-Type": "application/json",
        "X-Shopify-Storefront-Access-Token": key,
        ...headers
      },
      body: JSON.stringify({
        ...(query && { query }),
        ...(variables && { variables })
      }),
      cache,
      ...(tags && { next: { tags } })
    });

    const body = await result.json();

    if (body.errors) {
      throw body.errors[0];
    }

    return {
      status: result.status,
      body
    };
  } catch (e) {
    if (isShopifyError(e)) {
      throw {
        cause: e.cause?.toString() || "unknown",
        status: e.status || 500,
        message: e.message,
        query
      };
    }

    throw {
      error: e,
      query
    };
  }
}

const removeEdgesAndNodes = (array: Connection<any>) => {
  return array.edges.map((edge) => edge?.node);
};

const reshapeCart = (cart: ShopifyCart): Cart => {
  if (!cart.cost?.totalTaxAmount) {
    cart.cost.totalTaxAmount = {
      amount: "0.0",
      currencyCode: "USD"
    };
  }

  return {
    ...cart,
    lines: removeEdgesAndNodes(cart.lines)
  };
};

const reshapeCollection = (collection: ShopifyCollection): Collection | undefined => {
  if (!collection) {
    return undefined;
  }

  return {
    ...collection,
    path: `/search/${collection.handle}`
  };
};

const reshapeCollections = (collections: ShopifyCollection[]) => {
  const reshapedCollections = [];

  for (const collection of collections) {
    if (collection) {
      const reshapedCollection = reshapeCollection(collection);

      if (reshapedCollection) {
        reshapedCollections.push(reshapedCollection);
      }
    }
  }

  return reshapedCollections;
};

const reshapeImages = (images: Connection<Image>, productTitle: string) => {
  const flattened = removeEdgesAndNodes(images);

  return flattened.map((image) => {
    const filename = image.url.match(/.*\/(.*)\..*/)[1];
    return {
      ...image,
      altText: image.altText || `${productTitle} - ${filename}`
    };
  });
};

const reshapeProduct = (product: ShopifyProduct, filterHiddenProducts: boolean = true) => {
  if (!product || (filterHiddenProducts && product.tags.includes(HIDDEN_PRODUCT_TAG))) {
    return undefined;
  }

  const { images, variants, ...rest } = product;

  return {
    ...rest,
    images: reshapeImages(images, product.title),
    variants: removeEdgesAndNodes(variants)
  };
};

const reshapeProducts = (products: ShopifyProduct[]) => {
  const reshapedProducts = [];

  for (const product of products) {
    if (product) {
      const reshapedProduct = reshapeProduct(product);

      if (reshapedProduct) {
        reshapedProducts.push(reshapedProduct);
      }
    }
  }

  return reshapedProducts;
};

export async function createCart(): Promise<Cart> {
  const res = await shopifyFetch<ShopifyCreateCartOperation>({
    query: createCartMutation,
    cache: "no-store"
  });

  return reshapeCart(res.body.data.cartCreate.cart);
}

export async function addToCart(
  cartId: string,
  lines: { merchandiseId: string; quantity: number }[]
): Promise<Cart> {
  const res = await shopifyFetch<ShopifyAddToCartOperation>({
    query: addToCartMutation,
    variables: {
      cartId,
      lines
    },
    cache: "no-store"
  });
  return reshapeCart(res.body.data.cartLinesAdd.cart);
}

export async function removeFromCart(cartId: string, lineIds: string[]): Promise<Cart> {
  const res = await shopifyFetch<ShopifyRemoveFromCartOperation>({
    query: removeFromCartMutation,
    variables: {
      cartId,
      lineIds
    },
    cache: "no-store"
  });

  return reshapeCart(res.body.data.cartLinesRemove.cart);
}

export async function updateCart(
  cartId: string,
  lines: { id: string; merchandiseId: string; quantity: number }[]
): Promise<Cart> {
  const res = await shopifyFetch<ShopifyUpdateCartOperation>({
    query: editCartItemsMutation,
    variables: {
      cartId,
      lines
    },
    cache: "no-store"
  });

  return reshapeCart(res.body.data.cartLinesUpdate.cart);
}

export async function getCart(cartId: string): Promise<Cart | undefined> {
  const res = await shopifyFetch<ShopifyCartOperation>({
    query: getCartQuery,
    variables: { cartId },
    tags: [TAGS.cart],
    cache: "no-store"
  });

  // Old carts becomes `null` when you checkout.
  if (!res.body.data.cart) {
    return undefined;
  }

  return reshapeCart(res.body.data.cart);
}

export async function getCollection(handle: string): Promise<Collection | undefined> {
  const res = await shopifyFetch<ShopifyCollectionOperation>({
    query: getCollectionQuery,
    tags: [TAGS.collections],
    variables: {
      handle
    }
  });

  return reshapeCollection(res.body.data.collection);
}

export async function getCollectionProducts({
  collection,
  reverse,
  sortKey
}: {
  collection: string;
  reverse?: boolean;
  sortKey?: string;
}): Promise<Product[]> {
  const res = await shopifyFetch<ShopifyCollectionProductsOperation>({
    query: getCollectionProductsQuery,
    tags: [TAGS.collections, TAGS.products],
    variables: {
      handle: collection,
      reverse,
      sortKey: sortKey === "CREATED_AT" ? "CREATED" : sortKey
    }
  });

  if (!res.body.data.collection) {
    console.log(`No collection found for \`${collection}\``);
    return [];
  }

  return reshapeProducts(removeEdgesAndNodes(res.body.data.collection.products));
}

export async function getCollections(): Promise<Collection[]> {
  const res = await shopifyFetch<ShopifyCollectionsOperation>({
    query: getCollectionsQuery,
    tags: [TAGS.collections]
  });
  const shopifyCollections = removeEdgesAndNodes(res.body?.data?.collections);
  const collections = [
    {
      handle: "",
      title: "All",
      description: "All products",
      seo: {
        title: "All",
        description: "All products"
      },
      path: "/search",
      updatedAt: new Date().toISOString()
    },
    // Filter out the `hidden` collections.
    // Collections that start with `hidden-*` need to be hidden on the search page.
    ...reshapeCollections(shopifyCollections).filter(
      (collection) => !collection.handle.startsWith("hidden")
    )
  ];

  return collections;
}

export async function getMenu(handle: string): Promise<Menu[]> {
  const res = await shopifyFetch<ShopifyMenuOperation>({
    query: getMenuQuery,
    tags: [TAGS.collections],
    variables: {
      handle
    }
  });

  return (
    res.body?.data?.menu?.items.map((item: { title: string; url: string }) => ({
      title: item.title,
      path: item.url.replace(domain, "").replace("/collections", "/search").replace("/pages", "")
    })) || []
  );
}

export async function getPage(handle: string): Promise<Page> {
  const res = await shopifyFetch<ShopifyPageOperation>({
    query: getPageQuery,
    variables: { handle }
  });

  return res.body.data.pageByHandle;
}

export async function getPages(): Promise<Page[]> {
  const res = await shopifyFetch<ShopifyPagesOperation>({
    query: getPagesQuery
  });

  return removeEdgesAndNodes(res.body.data.pages);
}

export async function getProduct(handle: string): Promise<Product | undefined> {
  const res = await shopifyFetch<ShopifyProductOperation>({
    query: getProductQuery,
    tags: [TAGS.products],
    variables: {
      handle
    }
  });

  return reshapeProduct(res.body.data.product, false);
}

export async function getProductRecommendations(productId: string): Promise<Product[]> {
  const res = await shopifyFetch<ShopifyProductRecommendationsOperation>({
    query: getProductRecommendationsQuery,
    tags: [TAGS.products],
    variables: {
      productId
    }
  });

  return reshapeProducts(res.body.data.productRecommendations);
}

export async function getProducts({
  query,
  reverse,
  sortKey
}: {
  query?: string;
  reverse?: boolean;
  sortKey?: string;
}): Promise<Product[]> {
  const res = await shopifyFetch<ShopifyProductsOperation>({
    query: getProductsQuery,
    tags: [TAGS.products],
    variables: {
      query,
      reverse,
      sortKey
    }
  });

  return reshapeProducts(removeEdgesAndNodes(res.body.data.products));
}

// This is called from `app/api/revalidate.ts` so providers can control revalidation logic.
export async function revalidate(req: NextRequest): Promise<NextResponse> {
  // We always need to respond with a 200 status code to Shopify,
  // otherwise it will continue to retry the request.
  const collectionWebhooks = ["collections/create", "collections/delete", "collections/update"];
  const productWebhooks = ["products/create", "products/delete", "products/update"];
  const topic = headers().get("x-shopify-topic") || "unknown";
  const secret = req.nextUrl.searchParams.get("secret");
  const isCollectionUpdate = collectionWebhooks.includes(topic);
  const isProductUpdate = productWebhooks.includes(topic);

  if (!secret || secret !== process.env.SHOPIFY_REVALIDATION_SECRET) {
    console.error("Invalid revalidation secret.");
    return NextResponse.json({ status: 200 });
  }

  if (!isCollectionUpdate && !isProductUpdate) {
    // We don't need to revalidate anything for any other topics.
    return NextResponse.json({ status: 200 });
  }

  if (isCollectionUpdate) {
    revalidateTag(TAGS.collections);
  }

  if (isProductUpdate) {
    revalidateTag(TAGS.products);
  }

  return NextResponse.json({ status: 200, revalidated: true, now: Date.now() });
}