Meteor.methods({

  inviteUser: function(invitation){

    // invite user returns the following hash
    // { newUser : true|false }
    // newUser is true if the person being invited is not on the site yet
    
    // invitation can either contain userId or an email address : 
    // { invitedUserEmail : 'bob@gmail.com' } or { userId : 'user-id' } 

    check(invitation, Match.OneOf(
      { invitedUserEmail : String },
      { userId : String }
    ));

    var user = invitation.invitedUserEmail ?
          Meteor.users.findOne({ emails : { $elemMatch: { address: invitation.invitedUserEmail } } }) :
          Meteor.users.findOne({ _id : invitation.userId }),
        userEmail = invitation.invitedUserEmail ? invitation.invitedUserEmail :
          getEmail(user),
        currentUser = Meteor.user(),
        currentUserCanInvite = currentUserIsAdmin || 
          (currentUser.inviteCount > 0 && canInvite(currentUser)),
        currentUserIsAdmin = isAdmin(currentUser);

    // check if the person is already invited
    if(user && (isInvited(user) || isAdmin(user))){
      throw new Meteor.Error(403, "This person is already invited.");
    } else {

      if(!currentUserCanInvite){
        throw new Meteor.Error(701, "You can't invite this user, sorry.");
      }

      // don't allow duplicate multpile invite for the same person
      var existingInvite = Invites.findOne({ invitedUserEmail : userEmail }); 

      if(existingInvite){
        throw new Meteor.Error(403, "Somebody has already invited this person.");
      }

      // create an invite
      // consider invite accepted if the invited person has an account already
      Invites.insert({
        invitingUserId: Meteor.userId(),
        invitedUserEmail: userEmail,
        accepted: typeof user !== "undefined"
      });
      
      // update invinting user
      Meteor.users.update(Meteor.userId(), {$inc:{inviteCount: -1}, $inc:{invitedCount: 1}});

      if(user){
        // update invited user
        Meteor.users.update(user._id, {$set: {
          isInvited: true,
          invitedBy: Meteor.userId(),
          invitedByName: getDisplayName(currentUser)
        }});
      } 

      var emailTemplate = getTemplate('emailInvite'),
          communityName = getSetting('title','Telescope'),
          emailSubject = 'You are invited to try '+communityName,
          emailProperties = {
            newUser : typeof user === 'undefined',
            communityName : communityName,
            actionLink : user ? getSigninUrl() : getSignupUrl(),
            invitedBy : getDisplayName(currentUser),
            profileUrl : getProfileUrl(currentUser)
          },
          notificationHtml = Handlebars.templates[emailTemplate](emailProperties),
          html = buildEmailTemplate(notificationHtml);

      Meteor.setTimeout(function () {
        sendEmail(userEmail, emailSubject, html);
      }, 1);
      
    }
    
    return {
      newUser : typeof user === 'undefined'
    };
  }
});