next.js/packages/next/src/shared/lib/page-path/absolute-path-to-page.ts

import { ensureLeadingSlash } from './ensure-leading-slash'
import { normalizePathSep } from './normalize-path-sep'
import path from '../isomorphic/path'
import { removePagePathTail } from './remove-page-path-tail'
import { normalizeMetadataRoute } from '../../../lib/metadata/get-metadata-route'
import type { PAGE_TYPES } from '../../../lib/page-types'

/**
 * Given the absolute path to the pages folder, an absolute file path for a
 * page and the page extensions, this function will return the page path
 * relative to the pages folder. It doesn't consider index tail. Example:
 *  - `/Users/rick/my-project/pages/foo/bar/baz.js` -> `/foo/bar/baz`
 *
 * It also handles special metadata routes mapping. Example:
 * - `/Users/rick/my-project/app/sitemap.js` -> `/sitemap/route`
 *
 * @param filepath Absolute path to the page.
 * @param opts.dir Absolute path to the pages/app folder.
 * @param opts.extensions Extensions allowed for the page.
 * @param opts.keepIndex When true the trailing `index` kept in the path.
 * @param opts.pagesType Whether the page is in the pages or app directory.
 */
export function absolutePathToPage(
  pagePath: string,
  options: {
    extensions: string[] | readonly string[]
    keepIndex: boolean
    dir: string
    pagesType: PAGE_TYPES
  }
) {
  const isAppDir = options.pagesType === 'app'
  const page = removePagePathTail(
    normalizePathSep(ensureLeadingSlash(path.relative(options.dir, pagePath))),
    {
      extensions: options.extensions,
      keepIndex: options.keepIndex,
    }
  )
  return isAppDir ? normalizeMetadataRoute(page) : page
}