/* global JsonRoutes */
if (Meteor.isServer) {
  // todo XXX once we have a real API in place, move that route there
  // todo XXX also  share the route definition between the client and the server
  // so that we could use something like
  // `ApiRoutes.path('boards/export', boardId)``
  // on the client instead of copy/pasting the route path manually between the
  // client and the server.
  /*
   * This route is used to export the board FROM THE APPLICATION.
   * If user is already logged-in, pass loginToken as param "authToken":
   * '/api/boards/:boardId/export?authToken=:token'
   *
   * See https://blog.kayla.com.au/server-side-route-authentication-in-meteor/
   * for detailed explanations
   */
  JsonRoutes.add('get', '/api/boards/:boardId/export', function (req, res) {
    const boardId = req.params.boardId;
    let user = null;
    // todo XXX for real API, first look for token in Authentication: header
    // then fallback to parameter
    const loginToken = req.query.authToken;
    if (loginToken) {
      const hashToken = Accounts._hashLoginToken(loginToken);
      user = Meteor.users.findOne({
        'services.resume.loginTokens.hashedToken': hashToken,
      });
    }

    const exporter = new Exporter(boardId);
    if(exporter.canExport(user)) {
      JsonRoutes.sendResult(res, { code: 200, data: exporter.build() });
    } else {
      // we could send an explicit error message, but on the other hand the only
      // way to get there is by hacking the UI so let's keep it raw.
      JsonRoutes.sendResult(res, 403);
    }
  });
}

class Exporter {
  constructor(boardId) {
    this._boardId = boardId;
  }

  build() {
    const byBoard = { boardId: this._boardId };
    // we do not want to retrieve boardId in related elements
    const noBoardId = { fields: { boardId: 0 } };
    const result = {
      _format: 'wekan-board-1.0.0',
    };
    _.extend(result, Boards.findOne(this._boardId, { fields: { stars: 0 } }));
    result.lists = Lists.find(byBoard, noBoardId).fetch();
    result.cards = Cards.find(byBoard, noBoardId).fetch();
    result.swimlanes = Swimlanes.find(byBoard, noBoardId).fetch();
    result.comments = CardComments.find(byBoard, noBoardId).fetch();
    result.activities = Activities.find(byBoard, noBoardId).fetch();
    result.checklists = [];
    result.cards.forEach((card) => {
      result.checklists.push(...Checklists.find({ cardId: card._id }).fetch());
    });
    // [Old] for attachments we only export IDs and absolute url to original doc
    // [New] Encode attachment to base64
    const getBase64Data = function(doc, callback) {
      let buffer = new Buffer(0);
      // callback has the form function (err, res) {}
      const readStream = doc.createReadStream();
      readStream.on('data', function(chunk) {
        buffer = Buffer.concat([buffer, chunk]);
      });
      readStream.on('error', function(err) {
        callback(err, null);
      });
      readStream.on('end', function() {
        // done
        callback(null, buffer.toString('base64'));
      });
    };
    const getBase64DataSync = Meteor.wrapAsync(getBase64Data);
    result.attachments = Attachments.find(byBoard).fetch().map((attachment) => {
      return {
        _id: attachment._id,
        cardId: attachment.cardId,
        // url: FlowRouter.url(attachment.url()),
        file: getBase64DataSync(attachment),
        name: attachment.original.name,
        type: attachment.original.type,
      };
    });

    // we also have to export some user data - as the other elements only
    // include id but we have to be careful:
    // 1- only exports users that are linked somehow to that board
    // 2- do not export any sensitive information
    const users = {};
    result.members.forEach((member) => { users[member.userId] = true; });
    result.lists.forEach((list) => { users[list.userId] = true; });
    result.cards.forEach((card) => {
      users[card.userId] = true;
      if (card.members) {
        card.members.forEach((memberId) => { users[memberId] = true; });
      }
    });
    result.comments.forEach((comment) => { users[comment.userId] = true; });
    result.activities.forEach((activity) => { users[activity.userId] = true; });
    result.checklists.forEach((checklist) => { users[checklist.userId] = true; });
    const byUserIds = { _id: { $in: Object.getOwnPropertyNames(users) } };
    // we use whitelist to be sure we do not expose inadvertently
    // some secret fields that gets added to User later.
    const userFields = {
      fields: {
        _id: 1,
        username: 1,
        'profile.fullname': 1,
        'profile.initials': 1,
        'profile.avatarUrl': 1,
      },
    };
    result.users = Users.find(byUserIds, userFields).fetch().map((user) => {
      // user avatar is stored as a relative url, we export absolute
      if (user.profile.avatarUrl) {
        user.profile.avatarUrl = FlowRouter.url(user.profile.avatarUrl);
      }
      return user;
    });
    return result;
  }

  canExport(user) {
    const board = Boards.findOne(this._boardId);
    return board && board.isVisibleBy(user);
  }
}
