'use strict'

var fs = require('fs')
var isUrl = /^https?:/

function Redirect (request) {
  this.request = request
  this.followRedirect = true
  this.followRedirects = true
  this.followAllRedirects = false
  this.followOriginalHttpMethod = false
  this.followAuthorizationHeader = false
  this.allowRedirect = function () { return true }
  this.maxRedirects = 10
  this.redirects = []
  this.redirectsFollowed = 0
  this.removeRefererHeader = false
}

Redirect.prototype.onRequest = function (options) {
  var self = this

  if (options.maxRedirects !== undefined) {
    self.maxRedirects = options.maxRedirects
  }
  if (typeof options.followRedirect === 'function') {
    self.allowRedirect = options.followRedirect
  }
  if (options.followRedirect !== undefined) {
    self.followRedirects = !!options.followRedirect
  }
  if (options.followAllRedirects !== undefined) {
    self.followAllRedirects = options.followAllRedirects
  }
  if (self.followRedirects || self.followAllRedirects) {
    self.redirects = self.redirects || []
  }
  if (options.removeRefererHeader !== undefined) {
    self.removeRefererHeader = options.removeRefererHeader
  }
  if (options.followOriginalHttpMethod !== undefined) {
    self.followOriginalHttpMethod = options.followOriginalHttpMethod
  }
  if (options.followAuthorizationHeader !== undefined) {
    self.followAuthorizationHeader = options.followAuthorizationHeader
  }
}

Redirect.prototype.redirectTo = function (response) {
  var self = this
  var request = self.request

  var redirectTo = null
  if (response.statusCode >= 300 && response.statusCode < 400 && response.caseless.has('location')) {
    var location = response.caseless.get('location')
    request.debug('redirect', location)

    if (self.followAllRedirects) {
      redirectTo = location
    } else if (self.followRedirects) {
      switch (request.method) {
        case 'PATCH':
        case 'PUT':
        case 'POST':
        case 'DELETE':
          // Do not follow redirects
          break
        default:
          redirectTo = location
          break
      }
    }
  } else if (response.statusCode === 401) {
    // retry the request with the new Authorization header value using
    // WWW-Authenticate response header.
    // https://tools.ietf.org/html/rfc7235#section-3.1
    var authHeader = request._auth.onResponse(response)
    if (authHeader) {
      request.setHeader('Authorization', authHeader)
      redirectTo = request.uri
    }
  }
  return redirectTo
}

Redirect.prototype.onResponse = function (response) {
  var self = this
  var request = self.request
  var urlParser = request.urlParser
  var options = {}

  var redirectTo = self.redirectTo(response)
  if (!redirectTo || !self.allowRedirect.call(request, response)) {
    return false
  }

  request.debug('redirect to', redirectTo)

  // ignore any potential response body.  it cannot possibly be useful
  // to us at this point.
  // response.resume should be defined, but check anyway before calling. Workaround for browserify.
  if (response.resume) {
    response.resume()
  }

  if (self.redirectsFollowed >= self.maxRedirects) {
    request.emit('error', new Error('Exceeded maxRedirects. Probably stuck in a redirect loop ' + request.uri.href))
    return false
  }
  self.redirectsFollowed += 1

  if (!isUrl.test(redirectTo)) {
    redirectTo = urlParser.resolve(request.uri.href, redirectTo)
  }

  var uriPrev = request.uri
  request.uri = urlParser.parse(redirectTo)

  // handle the case where we change protocol from https to http or vice versa
  if (request.uri.protocol !== uriPrev.protocol) {
    delete request.agent
  }

  self.redirects.push({ statusCode: response.statusCode, redirectUri: redirectTo })

  // if the redirect hostname (not just port or protocol) is changed:
  //  1. remove host header, the new host will be populated on request.init
  //  2. remove authorization header, avoid authentication leak
  // @note: This is done because of security reasons, irrespective of the
  // status code or request method used.
  if (request.headers && uriPrev.hostname !== request.uri.hostname) {
    request.removeHeader('host')

    // use followAuthorizationHeader option to retain authorization header
    if (!self.followAuthorizationHeader) {
      request.removeHeader('authorization')
    }
  }

  delete request.src
  delete request.req
  delete request._started

  // if statusCode code is 401, 307 or 308:
  //  1. Switch request method to GET if followOriginalHttpMethod is not set
  //  2. Remove request body on redirect
  if (response.statusCode !== 401 && response.statusCode !== 307 && response.statusCode !== 308) {
    // force all redirects to use GET (due to legacy shenanigans)
    // use followOriginalHttpMethod option to avoid this
    // @todo: figure out why its only done for HEAD method and not for similar
    // request methods like OPTIONS or CONNECT.
    if (!self.followOriginalHttpMethod && request.method !== 'HEAD') {
      request.method = 'GET'
    }

    // Remove parameters from the previous response, unless this is the second request
    // for a server that requires digest authentication.
    delete request.body
    delete request._form
    if (request.headers) {
      request.removeHeader('host')
      request.removeHeader('content-type')
      request.removeHeader('content-length')
    }
  } else if (request.formData &&
      // make sure _form is released and there's no pending _streams left
      // which will be the case for 401 redirects. so, reuse _form on redirect
      // @note: multiple form-param / file-streams may cause following issue:
      // https://github.com/request/request/issues/887
      // @todo: expose stream errors as events
      request._form && request._form._released &&
      request._form._streams && !request._form._streams.length) {
    // reinitialize FormData stream for 307 or 308 redirects
    delete request._form
    // remove content-type header for new boundary
    request.removeHeader('content-type')
    // remove content-length header since FormValue may be dropped if its not a file stream
    request.removeHeader('content-length')

    var formData = []
    var resetFormData = function (key, value, paramOptions) {
      // if `value` is of type stream
      if (typeof (value && value.pipe) === 'function') {
        // bail out if not a file stream
        if (!(value.hasOwnProperty('fd') && value.path)) return
        // create new file stream
        value = fs.createReadStream(value.path)
      }

      formData.push({key: key, value: value, options: paramOptions})
    }
    for (var i = 0, ii = request.formData.length; i < ii; i++) {
      var formParam = request.formData[i]
      if (!formParam) { continue }
      resetFormData(formParam.key, formParam.value, formParam.options)
    }

    // setting `options.formData` will reinitialize FormData in `request.init`
    options.formData = formData
  }

  if (!self.removeRefererHeader) {
    request.setHeader('Referer', uriPrev.href)
  }

  request.emit('redirect')

  request.init(options)

  return true
}

exports.Redirect = Redirect
