prepare-destination.ts

import type { IncomingMessage } from 'http'
import type { Key } from 'next/dist/compiled/path-to-regexp'
import type { NextParsedUrlQuery } from '../../../../server/request-meta'
import type { Params } from '../../../../server/router'
import type { RouteHas } from '../../../../lib/load-custom-routes'
import type { BaseNextRequest } from '../../../../server/base-http'

import { compile, pathToRegexp } from 'next/dist/compiled/path-to-regexp'
import { escapeStringRegexp } from '../../escape-regexp'
import { parseUrl } from './parse-url'

export function matchHas(
  req: BaseNextRequest | 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 = Array.isArray(value)
        ? value.slice(-1)[0].match(matcher)
        : value.match(matcher)

      if (matches) {
        if (Array.isArray(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 compile(`/${value}`, { validate: false })(params).slice(1)
}

export function prepareDestination(args: {
  appendParamsToQuery: boolean
  destination: string
  params: Params
  query: NextParsedUrlQuery
}) {
  const query = Object.assign({}, args.query)
  delete query.__nextLocale
  delete query.__nextDefaultLocale

  let escapedDestination = args.destination

  for (const param of Object.keys({ ...args.params, ...query })) {
    escapedDestination = escapeSegment(escapedDestination, param)
  }

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

  const destParams: (string | number)[] = []

  destPathParamKeys.forEach((key) => destParams.push(key.name))
  destHostnameParamKeys.forEach((key) => destParams.push(key.name))

  const destPathCompiler = 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 }
  )

  const destHostnameCompiler = compile(destHostname, { validate: false })

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

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

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

  let newUrl

  try {
    newUrl = destPathCompiler(args.params)

    const [pathname, hash] = newUrl.split('#')
    parsedDestination.hostname = destHostnameCompiler(args.params)
    parsedDestination.pathname = pathname
    parsedDestination.hash = `${hash ? '#' : ''}${hash || ''}`
    delete (parsedDestination as any).search
  } catch (err: any) {
    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,
    destQuery,
    parsedDestination,
  }
}

/**
 * Ensure only a-zA-Z are used for param names for proper interpolating
 * with path-to-regexp
 */
function 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
}

function escapeSegment(str: string, segmentName: string) {
  return str.replace(
    new RegExp(`:${escapeStringRegexp(segmentName)}`, 'g'),
    `__ESC_COLON_${segmentName}`
  )
}

function unescapeSegments(str: string) {
  return str.replace(/__ESC_COLON_/gi, ':')
}