module.exports = {
  siteMetadata: {
    title: 'Josh W Comeau',
    description:
      'Friendly tutorials for developers. Focus on React, Gatsby, CSS, and animation.',
    author: '@joshwcomeau',
    siteUrl: 'https://www.joshwcomeau.com',
  },
  plugins: [
    {
      resolve: `gatsby-plugin-sitemap`,
      options: {
        exclude: ['*/admin/*', '*/confirmed'],
        query: `
          {
            site {
              siteMetadata {
                siteUrl
              }
            }

            allSitePage {
              edges {
                node {
                  path
                  context {
                    isCanonical
                    isPublished
                  }
                }
              }
            }
          }
        `,
        serialize: ({ site, allSitePage, ...delegated }) => {
          return allSitePage.edges
            .map(edge => {
              if (edge.node.context.isCanonical === false) {
                return null;
              }
              
              return {
                url: site.siteMetadata.siteUrl + edge.node.path,
                changefreq: `daily`,
                priority: 0.7,
              };
            })
            .filter(edge => edge);
        },
      },
    },
  ],
};

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

  const { data } = await graphql(`
    query {
      allMdx(
        sort: { fields: [frontmatter___publishedOn], order: DESC }
        limit: 1000
      ) {
        edges {
          node {
            id
            fields {
              slug
            }
            frontmatter {
              title
              isPublished
              publishedOn
              type
              abstract
              level
              categories
              interactive
              alwaysShowDate
            }
          }
        }
      }
    }
  `);

  const content = data.allMdx.edges.map(edge => edge.node);

  content.forEach(item => {
    const { slug } = item.fields;
    const { categories } = item.frontmatter;

    // In this example, the first category listed is always
    // the canonical one.
    const firstCategory = categories[0];

    categories.forEach(category => {
      const pathname = getPathnameForMdxNode(category, slug);
      
      createPage({
        path: pathname,
        component: path.resolve('./src/components/TemplateTutorial/TemplateTutorial.js'),
        context: {
          isCanonical: category === firstCategory,
        },
      });
    });
  });
};

const getPathnameForMdxNode = (category, slug) => {
  return `${category}/${slug}`;
};