[site,#572][l]: merge in data literate material.

* Nav bar and layout
* Main catch all route that loads material from content
* Data Literate: demo plus all associated components
  * content/data-literate/demo.mdx
  * components/* (pretty much all are related to demo)
  * lib/markdown.js, lib/mdxUtils.js
  * api/proxy.js to proxy remote urls (to handle CORs)
  * content/data-literate.md (DL home page - old data literate home page converted to markdown)
* excel-viewer.js: excel viewer demo from data literate
* package.json / yarn.lock
  * Nav: @headlessui/react @heroicons/react/outline @heroicons/react
  * CSV support for table: papaparse
  * Excel support for tables etc: xlsx
  * Vega: react-vega vega vega-lite
  * MDX: next-mdx-remote (yarn rm @next/mdx)

site/pages/[...slug].js

@@ -0,0 +1,48 @@
+import fs from 'fs'
+import path from 'path'
+
+import parse from '../lib/markdown.js'
+
+import DataLiterate from '../components/DataLiterate'
+
+import { postFilePaths, POSTS_PATH } from '../lib/mdxUtils'
+
+
+export default function PostPage({ source, frontMatter }) {
+  return (
+    <DataLiterate source={source} frontMatter={frontMatter} />
+  )
+}
+
+export const getStaticProps = async ({ params }) => {
+  const mdxPath = path.join(POSTS_PATH, `${params.slug.join('/')}.mdx`)
+  const postFilePath = fs.existsSync(mdxPath) ? mdxPath : mdxPath.slice(0, -1)
+  const source = fs.readFileSync(postFilePath)
+
+  const { mdxSource, frontMatter } = await parse(source)
+
+  return {
+    props: {
+      source: mdxSource,
+      frontMatter: frontMatter,
+    },
+  }
+}
+
+export const getStaticPaths = async () => {
+  var paths = postFilePaths
+    // Remove file extensions for page paths
+    .map((path) => path.replace(/\.mdx?$/, ''))
+
+  // Map the path into the static paths object required by Next.js
+  paths = paths.map((slug) => {
+    // /demo => [demo]
+    const parts = slug.slice(1).split('/')
+    return { params: { slug: parts } }
+  })
+
+  return {
+    paths,
+    fallback: false,
+  }
+}

site/pages/api/hello.js

@@ -1,5 +0,0 @@
-// Next.js API route support: https://nextjs.org/docs/api-routes/introduction
-
-export default (req, res) => {
-  res.status(200).json({ name: 'John Doe' })
-}

site/pages/api/proxy.js

@@ -0,0 +1,26 @@
+import axios from 'axios'
+
+export default function handler(req, res) {
+  if (!req.query.url) {
+    res.status(200).send({
+      error: true,
+      info: 'No url to proxy in query string i.e. ?url=...'
+    })
+    return
+  }
+  axios({
+    method: 'get',
+    url: req.query.url,
+     responseType:'stream'
+    })
+  .then(resp => {
+    resp.data.pipe(res)
+  })
+  .catch(err => {
+    res.status(400).send({
+      error: true,
+      info: err.message,
+      detailed: err
+    })
+  })
+}

site/pages/excel-viewer.js

@@ -0,0 +1,12 @@
+import Head from 'next/head'
+import SheetJSApp from '../components/ExcelViewerApp.js'
+import Layout from '../components/Layout'
+
+export default function Index() {
+  return (
+    <Layout title='Excel Viewer'>
+      <h1>Excel Viewer</h1>
+      <SheetJSApp />
+    </Layout>
+  )
+}