import allLanguages from '../../../config/languages.json' assert { type: 'json' }
import path from 'path'
import fs from 'fs'
import set from 'lodash.set'
import orderBy from 'lodash.orderby'
import { extendSiteNav as dev } from './sitenav-dev.mjs'
import { extendSiteNav as org } from './sitenav-org.mjs'
import { extendSiteNav as lab } from './sitenav-lab.mjs'
import { pageHasChildren } from '../utils.mjs'
import { header } from './shared.mjs'

const extendNav = { dev, org, lab }

/*
 * A method to recursively add the ordered slugs to the LUT
 */
const flattenOrderedChildPages = (nav) => {
  const slugs = []
  for (const page of orderBy(nav, ['o', 't'], ['asc', 'asc'])) {
    if (page.s) {
      slugs.push(page.s)
      if (pageHasChildren(page)) slugs.push(...flattenOrderedChildPages(page))
    }
  }

  return slugs
}

/*
 * This builds the slugLut (slug look up table) which makes it trivial to
 * build the PrevNext component as it builds a flat list of all pages in
 * the order they are naturally presented to the reader. So if you have
 * a page's slug, you merely need to look it up in the list and return the
 * next entry (or previous)
 */
export const orderedSlugLut = (nav) => {
  const slugs = []
  for (const page of orderBy(nav, ['o', 't'], ['asc', 'asc'])) {
    if (page.s) {
      slugs.push(page.s)
      if (pageHasChildren(page)) slugs.push(...flattenOrderedChildPages(page))
    }
  }

  return slugs
}

/*
 * Main method that does what needs doing
 */
export const prebuildNavigation = async (store) => {
  const { site, docs = false, posts = false } = store
  /*
   * Since this is written to disk and loaded as JSON, we minimize
   * the data to load by using the following 1-character keys:
   *
   * t: title
   * o: order, optional
   * s: slug without leading or trailing slash (/)
   */
  const sitenav = {}
  const all = {
    sitenav: '',
  }
  const locales = docs ? Object.keys(docs) : allLanguages
  for (const lang of locales) {
    sitenav[lang] = {}

    // Handle docs if there are any
    if (docs[lang]) {
      for (const slug of Object.keys(docs[lang]).sort()) {
        const page = docs[lang][slug]
        const val = {
          t: page.t,
          s: slug,
        }
        if (page.o) val.o = page.o
        set(sitenav, [lang, ...slug.split('/')], val)
      }
    }

    // Handle posts if there are any
    if (posts) {
      for (const type in posts) {
        for (const [slug, post] of Object.entries(posts[type].posts[lang])) {
          set(sitenav, [lang, ...slug.split('/')], { t: post.t, o: post.o, s: slug })
        }
      }
    }

    // Add imports for umbrella file
    all.sitenav += `import { siteNav as ${lang} } from './sitenav.${lang}.mjs'` + '\n'
    // Extend navigation if there's a method for that
    if (extendNav[site]) sitenav[lang] = await extendNav[site](sitenav[lang], lang)

    // Write out navigation object
    fs.writeFileSync(
      path.resolve('..', site, 'prebuild', `sitenav.${lang}.mjs`),
      `${header}export const siteNav =  ${JSON.stringify(sitenav[lang])}`
    )

    /*
     * Since slugs are language-agnostic, we only need to create a slug lookup tables
     * once, for which we'll use the EN locale as that one is always present
     */
    if (lang === 'en') {
      const sluglut = orderedSlugLut(sitenav[lang])
      // Write out slug lookup table (sluglut)
      fs.writeFileSync(
        path.resolve('..', site, 'prebuild', `sluglut.mjs`),
        `${header}export const slugLut =  ${JSON.stringify(sluglut)}`
      )
      store.navigation = { sluglut }
    }
  }

  // Write umbrella siteNav file
  fs.writeFileSync(
    path.resolve('..', site, 'prebuild', `sitenav.mjs`),
    `${header}${all.sitenav}export const siteNav = { ${locales.join(',')} }`
  )

  // In the lab, there will be no navigation set in the store
  if (!store.navigation) store.navigation = {}

  // Update the store
  store.navigation.sitenav = sitenav

  return
}