import {
  InvalidRequest,
  UnsupportedResponseType,
  InvalidClient,
  UnauthorizedClient,
  InvalidScope,
  AccessDenied,
  InteractionRequired,
  InvalidGrant,
} from '../model/error';
import { OAuth2User } from '../model/model';
import { data as dataResponse } from '../utils/response';
import wrap from '../utils/wrap';

/**
 * Authorization and decision endpoint.
 */
export const authorization = wrap(async (req, res) => {
  let clientId: string | null = null;
  let redirectUri: string | null = null;
  let responseType: string | null = null;
  let grantTypes: string[] = [];
  let scope: string[] | null = null;
  let user: OAuth2User | null = null;

  const { oauth2 } = req;

  if (!req.query.redirect_uri) {
    throw new InvalidRequest(
      'redirect_uri field is mandatory for authorization endpoint'
    );
  }

  redirectUri = req.query.redirect_uri as string;
  req.oauth2.logger.debug('Parameter redirect uri is', redirectUri);

  if (!req.query.client_id) {
    throw new InvalidRequest(
      'client_id field is mandatory for authorization endpoint'
    );
  }

  // Check for client_secret (prevent passing it)
  if (req.query.client_secret) {
    throw new InvalidRequest(
      'client_secret field should not be passed to the authorization endpoint'
    );
  }

  clientId = req.query.client_id as string;
  req.oauth2.logger.debug('Parameter client_id is', clientId);

  if (!req.query.response_type) {
    throw new InvalidRequest(
      'response_type field is mandatory for authorization endpoint'
    );
  }

  responseType = req.query.response_type as string;
  req.oauth2.logger.debug('Parameter response_type is', responseType);

  // Support multiple types
  const responseTypes = responseType.split(' ');
  for (const i in responseTypes) {
    switch (responseTypes[i]) {
      case 'code':
        grantTypes.push('authorization_code');
        break;
      case 'token':
        grantTypes.push('implicit');
        break;
      case 'id_token':
        grantTypes.push('id_token');
        break;
      case 'none':
        grantTypes.push(responseTypes[i]);
        break;
      default:
        throw new UnsupportedResponseType(
          'Unknown response_type parameter passed'
        );
    }
  }

  // Filter out duplicates
  grantTypes = grantTypes.filter(
    (value, index, self) => self.indexOf(value) === index
  );

  // "None" type cannot be combined with others
  if (grantTypes.length > 1 && grantTypes.indexOf('none') !== -1) {
    throw new InvalidRequest(
      'Grant type "none" cannot be combined with other grant types'
    );
  }

  req.oauth2.logger.debug('Parameter grant_type is', grantTypes.join(' '));

  const client = await oauth2.model.client.fetchById(clientId);
  if (!client) {
    throw new InvalidClient('Client not found');
  }

  if (!(await oauth2.model.client.hasRedirectUri(client))) {
    throw new UnsupportedResponseType('The client has not set a redirect uri');
  } else if (
    !(await oauth2.model.client.checkRedirectUri(client, redirectUri))
  ) {
    throw new InvalidRequest('Wrong RedirectUri provided');
  }
  req.oauth2.logger.debug('redirect_uri check passed');

  // The client needs to support all grant types
  for (const grantType of grantTypes) {
    if (
      !oauth2.model.client.checkGrantType(client, grantType) &&
      grantType !== 'none'
    ) {
      throw new UnauthorizedClient(
        'This client does not support grant type ' + grantType
      );
    }
  }
  req.oauth2.logger.debug('Grant type check passed');

  scope = oauth2.model.client.transformScope(req.query.scope as string);
  if (!oauth2.model.client.checkScope(client, scope)) {
    throw new InvalidScope('Client does not allow access to this scope');
  }
  req.oauth2.logger.debug('Scope check passed');

  user = await oauth2.model.user.fetchFromRequest(req);
  if (!user) {
    throw new InvalidRequest('There is no currently logged in user');
  } else {
    if (!user.username) {
      throw new AccessDenied(user.username);
    }
    req.oauth2.logger.debug('User fetched from request');
  }

  const codeChallenge = req.query.code_challenge as string;
  const codeChallengeMethod = (req.query.code_challenge_method as 'plain' | 'S256') || 'plain';

  if (codeChallengeMethod && !['plain', 'S256'].includes(codeChallengeMethod)) {
    throw new InvalidGrant('Invalid code challenge method');
  }

  const prompt = ((req.query.prompt || '') as string).split(' ');
  let resObj: Record<string, string | number> = {};
  let consented = false;

  if (req.method === 'GET') {
    // Check if the user has already consented to this client with this scope
    consented = await oauth2.model.user.consented(
      oauth2.model.user.getId(user),
      oauth2.model.client.getId(client),
      scope
    );

    if (!consented && prompt.includes('none')) {
      throw new InteractionRequired('Interaction required!');
    }

    // Ask for consent
    if (!consented || (
        prompt.includes('login') ||
        prompt.includes('consent') ||
        prompt.includes('select_account')
    )) {
      return oauth2.decision(req, res, client, scope, user, redirectUri);
    }
  }

  // Save consent
  if (!consented) {
    if (!req.body || typeof req.body.decision === 'undefined') {
      throw new InvalidRequest('No decision parameter passed');
    } else if (req.body.decision === '0') {
      throw new AccessDenied('User denied access to the resource');
    }

    req.oauth2.logger.debug('Decision check passed');

    await oauth2.model.user.consent(
      oauth2.model.user.getId(user),
      oauth2.model.client.getId(client),
      scope
    );
  }

  for (const i in grantTypes) {
    let data = null;
    switch (grantTypes[i]) {
      case 'authorization_code':
        data = await oauth2.model.code.create(
          oauth2.model.user.getId(user),
          oauth2.model.client.getId(client),
          scope,
          oauth2.model.code.ttl,
          req.query.nonce as string,
          codeChallenge,
          codeChallengeMethod
        );

        resObj = { code: data, ...resObj };

        break;
      case 'implicit':
        data = await oauth2.model.accessToken.create(
          oauth2.model.user.getId(user),
          oauth2.model.client.getId(client),
          scope,
          oauth2.model.accessToken.ttl
        );

        resObj = {
          token_type: 'bearer',
          access_token: data,
          expires_in: oauth2.model.accessToken.ttl,
          ...resObj,
        };

        break;
      case 'id_token':
        if (!oauth2.model.jwt || !scope.includes('openid')) {
          break;
        }

        data = await oauth2.model.jwt.issueIdToken(
          user,
          client,
          scope,
          req.query.nonce as string | undefined
        );

        resObj = {
          id_token: data,
          ...resObj,
        };
      case 'none':
        resObj = {};
        break;
      default:
        throw new UnsupportedResponseType(
          'Unknown response_type parameter passed'
        );
    }
  }

  // Return non-code response types as fragment instead of query
  return dataResponse(req, res, resObj, redirectUri, responseType !== 'code');
}, true);