import fs from 'fs'
import { JSDOM } from 'jsdom'
import { parseExternalContext } from './externalContext.js'

const ConfigFile = fs.readFileSync('./config.json')
const Config = JSON.parse(ConfigFile)

function generateToc(dom) {
    // Get all ToC anchors from the DOM
    const tocAnchors = dom.window.document.querySelectorAll(".toc-anchor")
    
    // Generate links to lead to those anvhors.
    let tocLinks = []
    tocAnchors.forEach(anchor => tocLinks.push(`<a href="#${anchor.id}" class="${anchor.classList[1].replace("-anchor", "")}">${anchor.getAttribute('data-orig-text')}</a>`))

    return tocLinks
}

export function generateContext(prerenderedNjk, externalContext = undefined) {
    // Create a 'virtual DOM' for analysis.
    const dom = new JSDOM(prerenderedNjk)

    // Generate respective parts of the context.
    return {
        serverName: Config.serverName,
        tocLinks: generateToc(dom),
        externalMeta: externalContext ? parseExternalContext(externalContext) : undefined
    }
}