blog/scripts/search/prepare-index.js

import path from 'path'
import { promises as fs } from 'fs'
import { globby } from 'globby'
import grayMatter from 'gray-matter'

(async function () {
    // prepare the dirs
    const srcDir = path.join(process.cwd(), 'src')
    const publicDir = path.join(process.cwd(), 'public')
    const contentBlogDir = path.join(srcDir, 'content', 'blog')
    const contentFilePattern = path.join(contentBlogDir, '*.md')
    const indexFile = path.join(publicDir, 'search-index.json')
    const getSlugFromPathname = (pathname) => path.basename(pathname, path.extname(pathname))

    const contentFilePaths = await globby([ contentFilePattern ])

    if(contentFilePaths.length) {
        const files = contentFilePaths.map(async(filePath) => await fs.readFile(filePath, 'utf8'))
        const index = []
        let i = 0
        for await (let file of files){
            const { data: { title, description, tags }, content } = grayMatter(file)
            index.push({
                slug: getSlugFromPathname(contentFilePaths[i]),
                category: 'blog',
                title,
                description,
                tags,
                body: content
            })
            i++
        }
        await fs.writeFile(indexFile, JSON.stringify(index))
        console.log(`Indexed ${index.length} documents from ${contentBlogDir} to ${indexFile}`)

        // This runs as `postbuild`, i.e. AFTER astro has already copied public/
        // into dist/ — so writing only to public/ leaves dist/ holding the
        // PREVIOUS run's index, and every deploy ships a search index one build
        // behind. Mirror it into dist/ when that exists.
        const distIndexFile = path.join(process.cwd(), 'dist', 'search-index.json')
        try {
            await fs.writeFile(distIndexFile, JSON.stringify(index))
            console.log(`Mirrored the index into ${distIndexFile}`)
        } catch (err) {
            if (err.code !== 'ENOENT') throw err   // no dist/ = a bare postbuild run
        }
    }

})();