// @flow
import {parse as urlParse} from 'url';
import * as c from './constants';
import {buildQueryStringFromParams, joinUrlAndQueryString} from 'insomnia-url';
import {authorizeUserInWindow, responseToObject} from './misc';
import {escapeRegex} from '../../common/misc';
import * as models from '../../models/index';
import {sendWithSettings} from '../network';
import {getBasicAuthHeader} from '../basic-auth/get-header';

export default async function (
  requestId: string,
  authorizeUrl: string,
  accessTokenUrl: string,
  credentialsInBody: boolean,
  clientId: string,
  clientSecret: string,
  redirectUri: string = '',
  scope: string = '',
  state: string = ''
): Promise<Object> {
  if (!authorizeUrl) {
    throw new Error('Invalid authorization URL');
  }

  if (!accessTokenUrl) {
    throw new Error('Invalid access token URL');
  }

  const authorizeResults = await _authorize(
    authorizeUrl,
    clientId,
    redirectUri,
    scope,
    state
  );

  // Handle the error
  if (authorizeResults[c.P_ERROR]) {
    const code = authorizeResults[c.P_ERROR];
    const msg = authorizeResults[c.P_ERROR_DESCRIPTION];
    const uri = authorizeResults[c.P_ERROR_URI];
    throw new Error(`OAuth 2.0 Error ${code}\n\n${msg}\n\n${uri}`);
  }

  return _getToken(
    requestId,
    accessTokenUrl,
    credentialsInBody,
    clientId,
    clientSecret,
    authorizeResults[c.P_CODE],
    redirectUri,
    state
  );
}

async function _authorize (url, clientId, redirectUri = '', scope = '', state = '') {
  const params = [
    {name: c.P_RESPONSE_TYPE, value: c.RESPONSE_TYPE_CODE},
    {name: c.P_CLIENT_ID, value: clientId}
  ];

  // Add optional params
  redirectUri && params.push({name: c.P_REDIRECT_URI, value: redirectUri});
  scope && params.push({name: c.P_SCOPE, value: scope});
  state && params.push({name: c.P_STATE, value: state});

  // Add query params to URL
  const qs = buildQueryStringFromParams(params);
  const finalUrl = joinUrlAndQueryString(url, qs);
  const successRegex = new RegExp(`${escapeRegex(redirectUri)}.*(code=)`, 'i');
  const failureRegex = new RegExp(`${escapeRegex(redirectUri)}.*(error=)`, 'i');

  const redirectedTo = await authorizeUserInWindow(finalUrl, successRegex, failureRegex);

  console.log('[oauth2] Detected redirect ' + redirectedTo);

  const {query} = urlParse(redirectedTo);
  return responseToObject(query, [
    c.P_CODE,
    c.P_STATE,
    c.P_ERROR,
    c.P_ERROR_DESCRIPTION,
    c.P_ERROR_URI
  ]);
}

async function _getToken (
  requestId: string,
  url: string,
  credentialsInBody: boolean,
  clientId: string,
  clientSecret: string,
  code: string,
  redirectUri: string = '',
  state: string = ''
): Promise<Object> {
  const params = [
    {name: c.P_GRANT_TYPE, value: c.GRANT_TYPE_AUTHORIZATION_CODE},
    {name: c.P_CODE, value: code}
  ];

  // Add optional params
  redirectUri && params.push({name: c.P_REDIRECT_URI, value: redirectUri});
  state && params.push({name: c.P_STATE, value: state});

  const headers = [
    {name: 'Content-Type', value: 'application/x-www-form-urlencoded'},
    {name: 'Accept', value: 'application/x-www-form-urlencoded, application/json'}
  ];

  if (credentialsInBody) {
    params.push({name: c.P_CLIENT_ID, value: clientId});
    params.push({name: c.P_CLIENT_SECRET, value: clientSecret});
  } else {
    headers.push(getBasicAuthHeader(clientId, clientSecret));
  }

  const response = await sendWithSettings(requestId, {
    headers,
    url,
    method: 'POST',
    body: models.request.newBodyFormUrlEncoded(params)
  });

  const bodyBuffer = models.response.getBodyBuffer(response);
  if (!bodyBuffer) {
    throw new Error(`[oauth2] No body returned from ${url}`);
  }

  const statusCode = response.statusCode || 0;
  if (statusCode < 200 || statusCode >= 300) {
    throw new Error(
      `[oauth2] Failed to fetch token url=${url} status=${statusCode}\n` +
      bodyBuffer.toString('utf8')
    );
  }

  return responseToObject(bodyBuffer.toString('utf8'), [
    c.P_ACCESS_TOKEN,
    c.P_REFRESH_TOKEN,
    c.P_EXPIRES_IN,
    c.P_TOKEN_TYPE,
    c.P_SCOPE,
    c.P_ERROR,
    c.P_ERROR_URI,
    c.P_ERROR_DESCRIPTION
  ]);
}