rsnext/packages/next/next-server/lib/router/utils/prepare-destination.ts

import { IncomingMessage } from 'http'
import { ParsedUrlQuery } from 'querystring'
import { searchParamsToUrlQuery } from './querystring'
import { parseRelativeUrl } from './parse-relative-url'
import * as pathToRegexp from 'next/dist/compiled/path-to-regexp'
import { RouteHas } from '../../../../lib/load-custom-routes'

type Params = { [param: string]: any }

// ensure only a-zA-Z are used for param names for proper interpolating
// with path-to-regexp
export const getSafeParamName = (paramName: string) => {
  let newParamName = ''

  for (let i = 0; i < paramName.length; i++) {
    const charCode = paramName.charCodeAt(i)

    if (
      (charCode > 64 && charCode < 91) || // A-Z
      (charCode > 96 && charCode < 123) // a-z
    ) {
      newParamName += paramName[i]
    }
  }
  return newParamName
}

export function matchHas(
  req: IncomingMessage,
  has: RouteHas[],
  query: Params
): false | Params {
  const params: Params = {}
  const allMatch = has.every((hasItem) => {
    let value: undefined | string
    let key = hasItem.key

    switch (hasItem.type) {
      case 'header': {
        key = key!.toLowerCase()
        value = req.headers[key] as string
        break
      }
      case 'cookie': {
        value = (req as any).cookies[hasItem.key]
        break
      }
      case 'query': {
        value = query[key!]
        break
      }
      case 'host': {
        const { host } = req?.headers || {}
        // remove port from host if present
        const hostname = host?.split(':')[0].toLowerCase()
        value = hostname
        break
      }
      default: {
        break
      }
    }

    if (!hasItem.value && value) {
      params[getSafeParamName(key!)] = value
      return true
    } else if (value) {
      const matcher = new RegExp(`^${hasItem.value}$`)
      const matches = value.match(matcher)

      if (matches) {
        if (matches.groups) {
          Object.keys(matches.groups).forEach((groupKey) => {
            params[groupKey] = matches.groups![groupKey]
          })
        } else if (hasItem.type === 'host' && matches[0]) {
          params.host = matches[0]
        }
        return true
      }
    }
    return false
  })

  if (allMatch) {
    return params
  }
  return false
}

export function compileNonPath(value: string, params: Params): string {
  if (!value.includes(':')) {
    return value
  }

  for (const key of Object.keys(params)) {
    if (value.includes(`:${key}`)) {
      value = value
        .replace(
          new RegExp(`:${key}\\*`, 'g'),
          `:${key}--ESCAPED_PARAM_ASTERISKS`
        )
        .replace(
          new RegExp(`:${key}\\?`, 'g'),
          `:${key}--ESCAPED_PARAM_QUESTION`
        )
        .replace(new RegExp(`:${key}\\+`, 'g'), `:${key}--ESCAPED_PARAM_PLUS`)
        .replace(
          new RegExp(`:${key}(?!\\w)`, 'g'),
          `--ESCAPED_PARAM_COLON${key}`
        )
    }
  }
  value = value
    .replace(/(:|\*|\?|\+|\(|\)|\{|\})/g, '\\$1')
    .replace(/--ESCAPED_PARAM_PLUS/g, '+')
    .replace(/--ESCAPED_PARAM_COLON/g, ':')
    .replace(/--ESCAPED_PARAM_QUESTION/g, '?')
    .replace(/--ESCAPED_PARAM_ASTERISKS/g, '*')

  // the value needs to start with a forward-slash to be compiled
  // correctly
  return pathToRegexp
    .compile(`/${value}`, { validate: false })(params)
    .substr(1)
}

export default function prepareDestination(
  destination: string,
  params: Params,
  query: ParsedUrlQuery,
  appendParamsToQuery: boolean
) {
  let parsedDestination: {
    query?: ParsedUrlQuery
    protocol?: string
    hostname?: string
    port?: string
  } & ReturnType<typeof parseRelativeUrl> = {} as any

  // clone query so we don't modify the original
  query = Object.assign({}, query)
  const hadLocale = query.__nextLocale
  delete query.__nextLocale
  delete query.__nextDefaultLocale

  if (destination.startsWith('/')) {
    parsedDestination = parseRelativeUrl(destination)
  } else {
    const {
      pathname,
      searchParams,
      hash,
      hostname,
      port,
      protocol,
      search,
      href,
    } = new URL(destination)

    parsedDestination = {
      pathname,
      query: searchParamsToUrlQuery(searchParams),
      hash,
      protocol,
      hostname,
      port,
      search,
      href,
    }
  }

  const destQuery = parsedDestination.query
  const destPath = `${parsedDestination.pathname!}${
    parsedDestination.hash || ''
  }`
  const destPathParamKeys: pathToRegexp.Key[] = []
  pathToRegexp.pathToRegexp(destPath, destPathParamKeys)

  const destPathParams = destPathParamKeys.map((key) => key.name)

  let destinationCompiler = pathToRegexp.compile(
    destPath,
    // we don't validate while compiling the destination since we should
    // have already validated before we got to this point and validating
    // breaks compiling destinations with named pattern params from the source
    // e.g. /something:hello(.*) -> /another/:hello is broken with validation
    // since compile validation is meant for reversing and not for inserting
    // params from a separate path-regex into another
    { validate: false }
  )
  let newUrl

  // update any params in query values
  for (const [key, strOrArray] of Object.entries(destQuery)) {
    let value = Array.isArray(strOrArray) ? strOrArray[0] : strOrArray
    if (value) {
      // the value needs to start with a forward-slash to be compiled
      // correctly
      value = compileNonPath(value, params)
    }
    destQuery[key] = value
  }

  // add path params to query if it's not a redirect and not
  // already defined in destination query or path
  let paramKeys = Object.keys(params)

  // remove internal param for i18n
  if (hadLocale) {
    paramKeys = paramKeys.filter((name) => name !== 'nextInternalLocale')
  }

  if (
    appendParamsToQuery &&
    !paramKeys.some((key) => destPathParams.includes(key))
  ) {
    for (const key of paramKeys) {
      if (!(key in destQuery)) {
        destQuery[key] = params[key]
      }
    }
  }

  try {
    newUrl = destinationCompiler(params)

    const [pathname, hash] = newUrl.split('#')
    parsedDestination.pathname = pathname
    parsedDestination.hash = `${hash ? '#' : ''}${hash || ''}`
    delete (parsedDestination as any).search
  } catch (err) {
    if (err.message.match(/Expected .*? to not repeat, but got an array/)) {
      throw new Error(
        `To use a multi-match in the destination you must add \`*\` at the end of the param name to signify it should repeat. https://nextjs.org/docs/messages/invalid-multi-match`
      )
    }
    throw err
  }

  // Query merge order lowest priority to highest
  // 1. initial URL query values
  // 2. path segment values
  // 3. destination specified query values
  parsedDestination.query = {
    ...query,
    ...parsedDestination.query,
  }

  return {
    newUrl,
    parsedDestination,
  }
}