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

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

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

	if (node.internal.type === `UnicornsJson`) {
		const value = createFilePath({
			node,
			getNode
		});
		createNodeField({
			name: `slug`,
			node,
			value
		});
	}
};

exports.sourceNodes = ({ getNodesByType, actions: { createNodeField } }) => {
	const postNodes = getNodesByType(`MarkdownRemark`);
	const unicornNodes = getNodesByType(`UnicornsJson`);

	unicornNodes.forEach(unicornNode => {
		const isAuthor = postNodes
			// Ensure it's actually a post
			.filter(post => !!post.frontmatter.authors)
			.some(post => {
				return post.frontmatter.authors.includes(unicornNode.id);
			});

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

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

	const blogPost = path.resolve(`./src/templates/blog-post.js`);
	const blogProfile = path.resolve(`./src/templates/blog-profile.js`);
	const postList = path.resolve(`./src/templates/post-list.js`);
	return graphql(
		`
			{
				allMarkdownRemark(
					sort: { fields: [frontmatter___published], order: DESC }
					filter: { fileAbsolutePath: { regex: "/content/blog/" } }
					limit: 1000
				) {
					edges {
						node {
							fields {
								slug
							}
							frontmatter {
								title
								authors {
									id
								}
							}
						}
					}
				}
				allUnicornsJson(limit: 100) {
					edges {
						node {
							id
						}
					}
				}
			}
		`
	).then(result => {
		if (result.errors) {
			throw result.errors;
		}

		// Create blog posts pages.
		const posts = result.data.allMarkdownRemark.edges;
		const unicorns = result.data.allUnicornsJson.edges;

		posts.forEach((post, index, arr) => {
			const previous = index === arr.length - 1 ? null : arr[index + 1].node;
			const next = index === 0 ? null : arr[index - 1].node;

			const postInfo = post.node.frontmatter;
			if (postInfo.attached && postInfo.attached.length > 0) {
				postInfo.attached.forEach(({ file: fileStr }) => {
					const postPath = post.node.fields.slug;
					const relFilePath = path.join(
						__dirname,
						"static",
						"posts",
						postPath,
						fileStr
					);
					const fileExists = fs.existsSync(path.resolve(relFilePath));
					if (!fileExists) {
						console.error(
							`Could not find file to attach in the static folder: ${postPath}${fileStr}`
						);
						console.error(
							`To fix this problem, attach the file to the static folder's expected path above, or remove it from the post frontmatter definition`
						);
						process.exit(1);
					}
				});
			}

			createPage({
				path: `posts${post.node.fields.slug}`,
				component: blogPost,
				context: {
					slug: post.node.fields.slug,
					previous,
					next
				}
			});
		});

		const postsPerPage = 8;
		const numberOfPages = Math.ceil(posts.length / postsPerPage);

		createPage({
			path: `/`,
			component: postList,
			context: {
				limitNumber: postsPerPage,
				skipNumber: 0,
				pageIndex: 1,
				numberOfPages,
				relativePath: ""
			}
		});

		for (const i of Array(numberOfPages).keys()) {
			if (i === 0) continue;
			const pageNum = i + 1;
			const skipNumber = postsPerPage * i;
			createPage({
				path: `page/${pageNum}`,
				component: postList,
				context: {
					limitNumber: postsPerPage,
					skipNumber,
					pageIndex: pageNum,
					numberOfPages,
					relativePath: ""
				}
			});
		}

		unicorns.forEach(unicorn => {
			const uniId = unicorn.node.id;

			const uniPosts = posts.filter(({ node: { frontmatter } }) =>
				frontmatter.authors.find(uni => uni.id === uniId)
			);

			const numberOfUniPages = Math.ceil(uniPosts.length / postsPerPage);

			createPage({
				path: `unicorns/${unicorn.node.id}`,
				component: blogProfile,
				context: {
					slug: uniId,
					limitNumber: postsPerPage,
					skipNumber: 0,
					pageIndex: 1,
					numberOfPages: numberOfUniPages,
					relativePath: `unicorns/${uniId}`
				}
			});

			for (const i of Array(numberOfUniPages).keys()) {
				if (i === 0) continue;
				const pageNum = i + 1;
				const skipNumber = postsPerPage * i;
				createPage({
					path: `unicorns/${uniId}/page/${pageNum}`,
					component: blogProfile,
					context: {
						slug: uniId,
						limitNumber: postsPerPage,
						skipNumber,
						pageIndex: pageNum,
						numberOfPages: numberOfUniPages,
						relativePath: `unicorns/${uniId}`
					}
				});
			}
		});

		return null;
	});
};