/**
 * A helper for the GraphQL API.
 *
 * @param {String} query - The query to fetch for
 * @param {Object} param1.variables - The variables to pass to the query
 * @param {Object} param1.preview - Indicate if the query should be previewed
 * @returns {Promise} - A promise that resolves to the result of the query
 */
async function fetchAPI(query, { variables } = { variables: null }) {
  const res = await fetch(
    process.env.NEXT_PUBLIC_DOTCMS_HOST + "/api/v1/graphql",
    {
      method: "POST",
      headers: {
        "Content-Type": "application/json",
        Authorization: `Bearer ${process.env.DOTCMS_TOKEN}`,
      },
      body: JSON.stringify({
        query,
        variables,
      }),
    },
  );

  const json = await res.json();

  if (json.errors) {
    console.error(json.errors);
    throw new Error("Failed to fetch API");
  }

  return json.data;
}

/**
 * Get the correct type to filter post using preview flag
 *
 * @param preview
 * @returns {string}
 */
const showPreviewPosts = (preview) => {
  return preview === true
    ? "+working:true +deleted:false"
    : "+live:true +deleted:false";
};

/**
 * Fetch a single post and more posts
 *
 * @param {String} slug - The slug of the post to fetch
 * @param {boolean} preview - Whether or not to fetch the live post
 * @returns An object with a post and more posts array
 */
export async function getPostAndMorePosts(slug, preview) {
  const data = await fetchAPI(
    `
    query PostBySlug($query: String!, $morePostsQuery: String!) {
      post: BlogCollection(query: $query, limit: 1) {
        title
        urlTitle
        blogContent {
          json
        }
        postingDate
        image {
          idPath
        }
        author {
          firstName
          lastName
          profilePhoto {
            idPath
          }
        }
      }
      
      morePosts: BlogCollection(query: $morePostsQuery, limit: 2) {
        title
        urlTitle
        teaser
        postingDate
        image {
          idPath
        }
        author {
          firstName
          lastName
          profilePhoto {
            idPath
          }
        }
      }
    }
  `,
    {
      variables: {
        query: `+urlmap:/blog/post/${slug} ${showPreviewPosts(preview)}`,
        morePostsQuery: `-urlmap:/blog/post/${slug} ${showPreviewPosts(
          preview,
        )}`,
      },
    },
  );
  return {
    post: data?.post[0] ?? {},
    morePosts: data?.morePosts ?? [],
  };
}

/**
 * Fetch one post and more post with preview mode flag.
 *
 * @param slug
 * @param isPreview
 * @returns {Promise<{post, morePosts}>}
 */
export async function getPreviewPostBySlug(slug, isPreview) {
  return await getPostAndMorePosts(slug, isPreview);
}

/**
 * Fetch all posts with slug
 *
 * @returns An array of posts with the following shape:
 * {
 *  urlTitle: string
 * }
 */
export async function getAllPostsWithSlug() {
  const entries = await fetchAPI(`
    query getAllPostsWithSlug {
      BlogCollection(query: "+live:true +deleted:false") {
        urlTitle
      }
    }
  `);

  return entries?.BlogCollection ?? [];
}

/**
 * Fetch all posts
 *
 * @param {boolean} preview - If true, return a preview of the post
 * @returns An array of posts
 */
export async function getAllPostsForHome(preview) {
  const entries = await fetchAPI(
    `
    query getAllPostsForHome($query: String!) {
      BlogCollection(query: $query) {
        title
        teaser
        postingDate
        author {
          firstName
          lastName
          profilePhoto {
            idPath
          }
        }
        urlTitle
        image {
          idPath
        }
      }
    }
  `,
    {
      variables: {
        query: `${showPreviewPosts(preview)}`,
      },
    },
  );
  return entries?.BlogCollection ?? [];
}