var _ = require('./utility');

function buildPayload(accessToken, data, jsonBackup) {
  if (!_.isType(data.context, 'string')) {
    var contextResult = _.stringify(data.context, jsonBackup);
    if (contextResult.error) {
      data.context = 'Error: could not serialize \'context\'';
    } else {
      data.context = contextResult.value || '';
    }
    if (data.context.length > 255) {
      data.context = data.context.substr(0, 255);
    }
  }
  return {
    access_token: accessToken,
    data: data
  };
}

function getTransportFromOptions(options, defaults, url) {
  var hostname = defaults.hostname;
  var protocol = defaults.protocol;
  var port = defaults.port;
  var path = defaults.path;
  var search = defaults.search;
  var timeout = options.timeout;
  var transport = detectTransport(options)

  var proxy = options.proxy;
  if (options.endpoint) {
    var opts = url.parse(options.endpoint);
    hostname = opts.hostname;
    protocol = opts.protocol;
    port = opts.port;
    path = opts.pathname;
    search = opts.search;
  }
  return {
    timeout: timeout,
    hostname: hostname,
    protocol: protocol,
    port: port,
    path: path,
    search: search,
    proxy: proxy,
    transport: transport
  };
}

function detectTransport(options) {
  var gWindow = ((typeof window != 'undefined') && window) || ((typeof self != 'undefined') && self);
  var transport = options.defaultTransport || 'xhr';
  if (typeof gWindow.fetch === 'undefined') transport = 'xhr';
  if (typeof gWindow.XMLHttpRequest === 'undefined') transport = 'fetch';
  return transport;
}

function transportOptions(transport, method) {
  var protocol = transport.protocol || 'https:';
  var port = transport.port || (protocol === 'http:' ? 80 : protocol === 'https:' ? 443 : undefined);
  var hostname = transport.hostname;
  var path = transport.path;
  var timeout = transport.timeout;
  var transportAPI = transport.transport;
  if (transport.search) {
    path = path + transport.search;
  }
  if (transport.proxy) {
    path = protocol + '//' + hostname + path;
    hostname = transport.proxy.host || transport.proxy.hostname;
    port = transport.proxy.port;
    protocol = transport.proxy.protocol || protocol;
  }
  return {
    timeout: timeout,
    protocol: protocol,
    hostname: hostname,
    path: path,
    port: port,
    method: method,
    transport: transportAPI
  };
}

function appendPathToPath(base, path) {
  var baseTrailingSlash = /\/$/.test(base);
  var pathBeginningSlash = /^\//.test(path);

  if (baseTrailingSlash && pathBeginningSlash) {
    path = path.substring(1);
  } else if (!baseTrailingSlash && !pathBeginningSlash) {
    path = '/' + path;
  }

  return base + path;
}

module.exports = {
  buildPayload: buildPayload,
  getTransportFromOptions: getTransportFromOptions,
  transportOptions: transportOptions,
  appendPathToPath: appendPathToPath
};