web/middlewares/cmsContent.ts

import { type NextMiddleware, NextResponse } from "next/server"

import { notFound } from "@/server/errors/next"

import { findLang } from "@/utils/languages"
import { removeTrailingSlash } from "@/utils/url"

import { fetchAndCacheEntry, getDefaultRequestHeaders } from "./utils"

import type { MiddlewareMatcher } from "@/types/middleware"
import { PageContentTypeEnum } from "@/types/requests/contentType"

export const middleware: NextMiddleware = async (request) => {
  const { nextUrl } = request
  const lang = findLang(nextUrl.pathname)!

  const pathWithoutTrailingSlash = removeTrailingSlash(nextUrl.pathname)

  const contentTypePathName = pathWithoutTrailingSlash.replace(`/${lang}`, "")
  const isPreview = request.nextUrl.pathname.includes("/preview")
  const searchParams = new URLSearchParams(request.nextUrl.searchParams)

  let { contentType, uid } = await fetchAndCacheEntry(
    isPreview
      ? contentTypePathName.replace("/preview", "")
      : contentTypePathName,
    lang
  )

  if (!contentType || !uid) {
    // Routes to subpages we need to check if the parent of the incomingPathName exists.
    // Then we considered the incomingPathName to be a subpage. These subpages do not live in the CMS.
    const incomingPathName = isPreview
      ? contentTypePathName.replace("/preview", "")
      : contentTypePathName
    const incomingPathNameParts = incomingPathName.split("/")

    // If the incomingPathName has 2 or more parts, it could possibly be a subpage.
    if (incomingPathNameParts.length >= 2) {
      const subpage = incomingPathNameParts.pop()
      if (subpage) {
        const parentPageResult = await fetchAndCacheEntry(
          incomingPathNameParts.join("/"),
          lang
        )

        if (parentPageResult.uid) {
          switch (parentPageResult.contentType) {
            case PageContentTypeEnum.hotelPage:
              // E.g. Dedicated pages for restaurant, parking etc.
              contentType = parentPageResult.contentType
              uid = parentPageResult.uid
              searchParams.set("subpage", subpage)
              break
          }
        }
      }
    }
  }

  if (!contentType || !uid) {
    throw notFound(
      `Unable to resolve CMS entry for locale "${lang}": ${contentTypePathName}`
    )
  }
  const headers = getDefaultRequestHeaders(request)
  headers.set("x-uid", uid)
  headers.set("x-contenttype", contentType)

  const isCurrent = contentType ? contentType.indexOf("current") >= 0 : false

  if (isPreview) {
    searchParams.set("isPreview", "true")
    return NextResponse.rewrite(
      new URL(
        `/${lang}/${contentType}/${uid}?${searchParams.toString()}`,
        nextUrl
      ),
      {
        request: {
          headers,
        },
      }
    )
  }

  if (isCurrent) {
    searchParams.set("uid", uid)
    searchParams.set("uri", contentTypePathName)
    return NextResponse.rewrite(
      new URL(
        `/${lang}/current-content-page?${searchParams.toString()}`,
        nextUrl
      ),
      {
        request: {
          headers,
        },
      }
    )
  }

  return NextResponse.rewrite(
    new URL(
      `/${lang}/${contentType}/${uid}?${searchParams.toString()}`,
      nextUrl
    ),
    {
      request: {
        headers,
      },
    }
  )
}

export const matcher: MiddlewareMatcher = (request) => {
  // Do not process paths with file extension.
  // Only looking for dot might be too brute force/give false positives.
  // It works right now but adjust accordingly when new use cases/data emerges.
  const lastPathnameSegment = request.nextUrl.pathname.split("/").pop()
  return lastPathnameSegment?.indexOf(".") === -1
}