import mkdirpModule from 'mkdirp'
import { promisify } from 'util'
import { extname, join, dirname, sep } from 'path'
import { renderToHTML } from '../next-server/server/render'
import { writeFile, access } from 'fs'
import AmpHtmlValidator from 'amphtml-validator'
import { loadComponents } from '../next-server/server/load-components'
import { isDynamicRoute } from '../next-server/lib/router/utils/is-dynamic'
import { getRouteMatcher } from '../next-server/lib/router/utils/route-matcher'
import { getRouteRegex } from '../next-server/lib/router/utils/route-regex'

const envConfig = require('../next-server/lib/runtime-config')
const writeFileP = promisify(writeFile)
const mkdirp = promisify(mkdirpModule)
const accessP = promisify(access)

global.__NEXT_DATA__ = {
  nextExport: true
}

export default async function ({
  path,
  pathMap,
  distDir,
  buildId,
  outDir,
  sprDataDir,
  renderOpts,
  buildExport,
  serverRuntimeConfig,
  subFolders,
  serverless
}) {
  let results = {
    ampValidations: []
  }

  try {
    let { query = {} } = pathMap
    const { page } = pathMap
    const filePath = path === '/' ? '/index' : path
    const ampPath = `${filePath}.amp`

    // Check if the page is a specified dynamic route
    if (isDynamicRoute(page) && page !== path) {
      const params = getRouteMatcher(getRouteRegex(page))(path)
      if (params) {
        query = {
          ...query,
          ...params
        }
      } else {
        throw new Error(
          `The provided export path '${path}' doesn't match the '${page}' page.\nRead more: https://err.sh/zeit/next.js/export-path-mismatch`
        )
      }
    }

    const headerMocks = {
      headers: {},
      getHeader: () => ({}),
      setHeader: () => {},
      hasHeader: () => false,
      removeHeader: () => {},
      getHeaderNames: () => []
    }

    const req = {
      url: path,
      ...headerMocks
    }
    const res = {
      ...headerMocks
    }

    envConfig.setConfig({
      serverRuntimeConfig,
      publicRuntimeConfig: renderOpts.runtimeConfig
    })

    let htmlFilename = `${filePath}${sep}index.html`
    if (!subFolders) htmlFilename = `${filePath}.html`

    const pageExt = extname(page)
    const pathExt = extname(path)
    // Make sure page isn't a folder with a dot in the name e.g. `v1.2`
    if (pageExt !== pathExt && pathExt !== '') {
      // If the path has an extension, use that as the filename instead
      htmlFilename = path
    } else if (path === '/') {
      // If the path is the root, just use index.html
      htmlFilename = 'index.html'
    }

    const baseDir = join(outDir, dirname(htmlFilename))
    const htmlFilepath = join(outDir, htmlFilename)

    await mkdirp(baseDir)
    let html
    let curRenderOpts = {}
    let renderMethod = renderToHTML

    // eslint-disable-next-line camelcase
    const renderedDuringBuild = unstable_getStaticProps => {
      // eslint-disable-next-line camelcase
      return !buildExport && unstable_getStaticProps && !isDynamicRoute(path)
    }

    if (serverless) {
      const mod = require(join(
        distDir,
        'serverless/pages',
        (page === '/' ? 'index' : page) + '.js'
      ))

      // for non-dynamic SPR pages we should have already
      // prerendered the file
      if (renderedDuringBuild(mod.unstable_getStaticProps)) return results

      renderMethod = mod.renderReqToHTML
      const result = await renderMethod(req, res, true)
      curRenderOpts = result.renderOpts || {}
      html = result.html

      if (!html) {
        throw new Error(`Failed to render serverless page`)
      }
    } else {
      const components = await loadComponents(
        distDir,
        buildId,
        page,
        serverless
      )

      // for non-dynamic SPR pages we should have already
      // prerendered the file
      if (renderedDuringBuild(components.unstable_getStaticProps)) {
        return results
      }

      if (typeof components.Component === 'string') {
        html = components.Component
      } else {
        curRenderOpts = { ...components, ...renderOpts, ampPath }
        html = await renderMethod(req, res, page, query, curRenderOpts)
      }
    }

    const validateAmp = async (html, page) => {
      const validator = await AmpHtmlValidator.getInstance()
      const result = validator.validateString(html)
      const errors = result.errors.filter(e => e.severity === 'ERROR')
      const warnings = result.errors.filter(e => e.severity !== 'ERROR')

      if (warnings.length || errors.length) {
        results.ampValidations.push({
          page,
          result: {
            errors,
            warnings
          }
        })
      }
    }

    if (curRenderOpts.inAmpMode) {
      await validateAmp(html, path)
    } else if (curRenderOpts.hybridAmp) {
      // we need to render the AMP version
      let ampHtmlFilename = `${ampPath}${sep}index.html`
      if (!subFolders) {
        ampHtmlFilename = `${ampPath}.html`
      }
      const ampBaseDir = join(outDir, dirname(ampHtmlFilename))
      const ampHtmlFilepath = join(outDir, ampHtmlFilename)

      try {
        await accessP(ampHtmlFilepath)
      } catch (_) {
        // make sure it doesn't exist from manual mapping
        let ampHtml
        if (serverless) {
          req.url += (req.url.includes('?') ? '&' : '?') + 'amp=1'
          ampHtml = (await renderMethod(req, res, true)).html
        } else {
          ampHtml = await renderMethod(
            req,
            res,
            page,
            { ...query, amp: 1 },
            curRenderOpts
          )
        }

        await validateAmp(ampHtml, page + '?amp=1')
        await mkdirp(ampBaseDir)
        await writeFileP(ampHtmlFilepath, ampHtml, 'utf8')
      }
    }

    if (curRenderOpts.sprData) {
      const dataFile = join(
        sprDataDir,
        htmlFilename.replace(/\.html$/, '.json')
      )

      await mkdirp(dirname(dataFile))
      await writeFileP(dataFile, JSON.stringify(curRenderOpts.sprData), 'utf8')
    }
    results.fromBuildExportRevalidate = curRenderOpts.revalidate

    await writeFileP(htmlFilepath, html, 'utf8')
    return results
  } catch (error) {
    console.error(`\nError occurred prerendering ${path}:`, error)
    return { ...results, error: true }
  }
}