'use strict'

import * as utils from './../utils'

function encode(val) {
  return encodeURIComponent(val).replace(/%40/gi, '@').replace(/%3A/gi, ':').replace(/%24/g, '$').replace(/%2C/gi, ',').replace(/%20/g, '+').replace(/%5B/gi, '[').replace(/%5D/gi, ']')
}

/**
 * Build a URL by appending params to the end
 *
 * @param {string} url The base of the url (e.g., http://www.google.com)
 * @param {object} [params] The params to be appended
 * @returns {string} The formatted url
 */
export default function buildURL(url, params, paramsSerializer) {
  /*eslint no-param-reassign:0*/
  if (!params) {
    return url
  }

  var serializedParams
  if (paramsSerializer) {
    serializedParams = paramsSerializer(params)
  } else if (utils.isURLSearchParams(params)) {
    serializedParams = params.toString()
  } else {
    var parts = []

    utils.forEach(params, function serialize(val, key) {
      if (val === null || typeof val === 'undefined') {
        return
      }

      if (utils.isArray(val)) {
        key = key + '[]'
      } else {
        val = [val]
      }

      utils.forEach(val, function parseValue(v) {
        if (utils.isDate(v)) {
          v = v.toISOString()
        } else if (utils.isObject(v)) {
          v = JSON.stringify(v)
        }
        parts.push(encode(key) + '=' + encode(v))
      })
    })

    serializedParams = parts.join('&')
  }

  if (serializedParams) {
    var hashmarkIndex = url.indexOf('#')
    if (hashmarkIndex !== -1) {
      url = url.slice(0, hashmarkIndex)
    }

    url += (url.indexOf('?') === -1 ? '?' : '&') + serializedParams
  }

  return url
}
