import Document, { Html, Head, Main, NextScript } from 'next/document'
import { ServerStyleSheets } from '@material-ui/core/styles'
import theme from '../components/theme'
import CleanCSS from "clean-css"
import { Children } from 'react'
const cleanCSS = new CleanCSS({
level: {
1: {},
2: {}
}
})
const minified_css_cache = new Map()
export default class MyDocument extends Document {
render() {
return (
{/* PWA primary color */}
)
}
}
// `getInitialProps` belongs to `_document` (instead of `_app`),
// it's compatible with server-side generation (SSG).
MyDocument.getInitialProps = async (ctx) => {
// Resolution order
//
// On the server:
// 1. app.getInitialProps
// 2. page.getInitialProps
// 3. document.getInitialProps
// 4. app.render
// 5. page.render
// 6. document.render
//
// On the server with error:
// 1. document.getInitialProps
// 2. app.render
// 3. page.render
// 4. document.render
//
// On the client
// 1. app.getInitialProps
// 2. page.getInitialProps
// 3. app.render
// 4. page.render
// Render app and page and get the context of the page with collected side effects.
const sheets = new ServerStyleSheets()
const originalRenderPage = ctx.renderPage
ctx.renderPage = () =>
originalRenderPage({
// eslint-disable-next-line react/display-name
enhanceApp: (App) => (props) => sheets.collect(),
})
const initialProps = await Document.getInitialProps(ctx)
let css = sheets.toString()
if (css && process.env.NODE_ENV === "production") {
const min_css = minified_css_cache.get(css)
if (min_css) {
css = min_css
} else {
const old_css = css
css = cleanCSS.minify(css).styles
minified_css_cache.set(old_css, css)
}
}
return {
...initialProps,
// Styles fragment is rendered after the app and page rendering finish.
styles: [...Children.toArray(initialProps.styles), ],
}
}