const path = require(`path`);
const { createFilePath } = require(`gatsby-source-filesystem`);

exports.onCreateWebpackConfig = ({ actions }) => {
  actions.setWebpackConfig({
    resolve: {
      fallback: {
        crypto: require.resolve("crypto-browserify"),
        stream: require.resolve("stream-browserify"),
      },
    },
  });
};

exports.createPages = async ({ graphql, actions, reporter }) => {
  const { createPage } = actions;

  // Define a template for news post
  const PostTemplate = path.resolve(`./src/templates/news-post.js`);

  // Get all markdown news posts sorted by date and all possible authors
  const result = await graphql(
    `
      {
        allMarkdownRemark(
          sort: { fields: [frontmatter___date], order: ASC }
          filter: { frontmatter: { external: { eq: null } } }
        ) {
          nodes {
            id
            fields {
              slug
            }
          }
        }
      }
    `
  );

  if (result.errors) {
    reporter.panicOnBuild(`There was an error loading your news posts`, result.errors);
    return;
  }

  const posts = result.data.allMarkdownRemark.nodes;

  // Create news posts pages
  // But only if there's at least one markdown file found at "/data/news" (defined in gatsby-config.js)
  // `context` is available in the template as a prop and as a variable in GraphQL

  if (posts.length > 0) {
    posts.forEach((post, index) => {
      const previousPostId = index === 0 ? null : posts[index - 1].id;
      const nextPostId = index === posts.length - 1 ? null : posts[index + 1].id;

      createPage({
        path: post.fields.slug,
        component: PostTemplate,
        context: {
          id: post.id,
          previousPostId,
          nextPostId,
        },
      });
    });
  }
};

exports.onCreateNode = ({ node, actions, getNode }) => {
  const { createNodeField } = actions;

  if (node.internal.type === `MarkdownRemark`) {
    const value = createFilePath({ node, getNode });

    createNodeField({
      name: `slug`,
      node,
      value,
    });
  }
};

exports.createSchemaCustomization = ({ actions }) => {
  const { createTypes } = actions;

  // Explicitly define the siteMetadata {} object
  // This way those will always be defined even if removed from gatsby-config.js

  // Also explicitly define the Markdown frontmatter
  // This way the "MarkdownRemark" queries will return `null` even when no
  // news posts are stored inside "/data/news" instead of returning an error
  createTypes(`
    type SiteSiteMetadata {
      author: String
      siteUrl: String
      social: Social
    }
    type Author {
      name: String
      summary: String
    }
    type Social {
      twitter: String
    }
    type MarkdownRemark implements Node {
      frontmatter: Frontmatter
      fields: Fields
    }
    type Frontmatter {
      title: String
      description: String
      date: Date @dateformat
      author: String
      external: String
      hidden: Boolean
      categories: [String]
    }
    type Fields {
      slug: String
    }
  `);
};