import { fileURLToPath } from 'url'
import path from 'path'
import languages from './languages.js'
import { allVersions } from './all-versions.js'
import createTree from './create-tree.js'
import renderContent from './render-content/index.js'
import loadSiteData from './site-data.js'
import nonEnterpriseDefaultVersion from './non-enterprise-default-version.js'
const __dirname = path.dirname(fileURLToPath(import.meta.url))
const versions = Object.keys(allVersions)
const enterpriseServerVersions = versions.filter((v) => v.startsWith('enterprise-server@'))
const renderOpts = { textOnly: true, encodeEntities: true }

/**
 * We only need to initialize pages _once per language_ since pages don't change per version. So we do that
 * first since it's the most expensive work. This gets us a nested object with pages attached that we can use
 * as the basis for the siteTree after we do some versioning. We can also use it to derive the pageList.
 */
export async function loadUnversionedTree() {
  const unversionedTree = {}

  await Promise.all(
    Object.values(languages).map(async (langObj) => {
      const localizedContentPath = path.posix.join(__dirname, '..', langObj.dir, 'content')
      unversionedTree[langObj.code] = await createTree(localizedContentPath, langObj)
    })
  )

  return unversionedTree
}

/**
 * The siteTree is a nested object with pages for every language and version, useful for nav because it
 * contains parent, child, and sibling relationships:
 *
 * siteTree[languageCode][version].childPages[<array of pages>].childPages[<array of pages>] (etc...)

* Given an unversioned tree of all pages per language, we can walk it for each version and do a couple operations:
 * 1. Add a versioned href to every item, where the href is the relevant permalink for the current version.
 * 2. Drop any child pages that are not available in the current version.
 *
 * Order of languages and versions doesn't matter, but order of child page arrays DOES matter (for navigation).
*/
export async function loadSiteTree(unversionedTree, siteData) {
  const site = siteData || loadSiteData()
  const rawTree = Object.assign({}, unversionedTree || (await loadUnversionedTree()))
  const siteTree = {}

  // For every language...
  await Promise.all(
    Object.keys(languages).map(async (langCode) => {
      const treePerVersion = {}
      // in every version...
      await Promise.all(
        versions.map(async (version) => {
          // "version" the pages.
          treePerVersion[version] = await versionPages(
            Object.assign({}, rawTree[langCode]),
            version,
            langCode,
            site
          )
        })
      )

      siteTree[langCode] = treePerVersion
    })
  )

  return siteTree
}

export async function versionPages(obj, version, langCode, site) {
  // Add a versioned href as a convenience for use in layouts.
  obj.href = obj.page.permalinks.find(
    (pl) =>
      pl.pageVersion === version ||
      (pl.pageVersion === 'homepage' && version === nonEnterpriseDefaultVersion)
  ).href

  const context = {
    currentLanguage: langCode,
    currentVersion: version,
    enterpriseServerVersions,
    site: site[langCode].site,
  }

  // The Liquid parseAndRender method is MUCH faster than renderContent or renderProp.
  // This only works for titles and short titles, which have no other Markdown that needs
  // to be converted to HTML, so we can get away with _only_ parsing Liquid.
  obj.renderedFullTitle = obj.page.title.includes('{')
    ? await renderContent.liquid.parseAndRender(obj.page.title, context, renderOpts)
    : obj.page.title

  if (obj.page.shortTitle) {
    obj.renderedShortTitle = obj.page.shortTitle.includes('{')
      ? await renderContent.liquid.parseAndRender(obj.page.shortTitle, context, renderOpts)
      : obj.page.shortTitle
  }

  if (!obj.childPages) return obj

  const versionedChildPages = await Promise.all(
    obj.childPages
      // Drop child pages that do not apply to the current version
      .filter((childPage) => childPage.page.applicableVersions.includes(version))
      // Version the child pages recursively.
      .map((childPage) => versionPages(Object.assign({}, childPage), version, langCode, site))
  )

  obj.childPages = [...versionedChildPages]

  return obj
}

// Derive a flat array of Page objects in all languages.
export async function loadPageList(unversionedTree) {
  const rawTree = unversionedTree || (await loadUnversionedTree())
  const pageList = []

  await Promise.all(
    Object.keys(languages).map(async (langCode) => {
      await addToCollection(rawTree[langCode], pageList)
    })
  )

  async function addToCollection(item, collection) {
    if (!item.page) return
    collection.push(item.page)

    if (!item.childPages) return
    await Promise.all(
      item.childPages.map(async (childPage) => await addToCollection(childPage, collection))
    )
  }

  return pageList
}

export const loadPages = loadPageList

// Create an object from the list of all pages with permalinks as keys for fast lookup.
export function createMapFromArray(pageList) {
  const pageMap = pageList.reduce((pageMap, page) => {
    for (const permalink of page.permalinks) {
      pageMap[permalink.href] = page
    }
    return pageMap
  }, {})

  return pageMap
}

export async function loadPageMap(pageList) {
  const pages = pageList || (await loadPageList())
  return createMapFromArray(pages)
}

export default {
  loadUnversionedTree,
  loadSiteTree,
  loadPages: loadPageList,
  loadPageMap,
}