/**
 * @file React application middleware, supports server side rendering.
 * @see https://reactjs.org/docs/react-dom-server.html#rendertostaticmarkup
 */
import { isString } from 'uxui-modules/exotic'
import { oneRouter } from 'uxui-modules/router'
import { fromReqResToRespondFromCacheExistence } from '../middleware/cacheMiddleware'
import { renderUsingServerSideRendering } from './renderWithServerSide'
import { renderWithoutServerSide } from './renderWithoutServerSide'
import { Request, Response } from './typings'
import { respondError } from './responders'

/**
 * this is the critical first step so we can have a url on the server
 */
function setOneRouterUrl(req: Request) {
  oneRouter.oneUrl = req.oneUrl
  oneRouter.urlFromExpress = req.oneUrl || {
    full: 'webpack_hmr',
  }
}

function reactApplicationMiddleware(req: Request, res: Response) {
  setOneRouterUrl(req)

  /**
   * @todo - probably want to add a header
   */
  if (req.SHOULD_CACHE_SSR) {
    const success = fromReqResToRespondFromCacheExistence(req, res)
    if (success === true) {
      return
    }
  }

  /**
   * Ensure a nonce has been provided to us.
   * @see server/middleware/security.js for more info.
   */
  const nonce = res.locals.nonce
  if (!isString(nonce)) {
    console.warn('@todo - no nonce')
    // throw new Error('A "nonce" value has not been attached to the res')
  }

  /**
   * It's possible to disable SSR, which can be useful in development mode.
   * In this case traditional client side only rendering will occur.
   */
  if (process.env.DISABLE_SSR === 'true') {
    console.log('[ssr] DISABLED!!!', { requestUrl: oneRouter.urlFromExpress })
    renderWithoutServerSide(res, nonce)
  } else {
    console.debug('[ssr] ==> Handling react route __WITH__ SSR')
    console.info({ requestUrl: oneRouter.urlFromExpress })
    try {
      renderUsingServerSideRendering(req, res, nonce)
    } catch (renderingException) {
      console.error(
        '[EXCEPTION_ALERT] [ssr] renderingException: ',
        renderingException
      )
      respondError(res, renderingException)
    }
  }
}

export {
  reactApplicationMiddleware,
  reactApplicationMiddleware as reactApplication,
  renderUsingServerSideRendering as render,
}
export default reactApplicationMiddleware