Vulcan/lib/vote.js

  // returns how much "power" a user's votes have
  var getVotePower = function(user){
    // return isAdmin(user) ? 5 : 1;
    return 1; // for now, leave everybody at 1 including admins; 5 is too unbalanced
  };

  var modifyKarma = function(userId, karma){
    Meteor.users.update({_id: userId}, {$inc: {karma: karma}});
  };

  var hasUpvotedItem= function(item, user){
    return item.upvoters && item.upvoters.indexOf(user._id) != -1;
  };

  var hasDownvotedItem= function(item, user){
    return item.downvoters && item.downvoters.indexOf(user._id) != -1;
  };

  var addVote = function (userId, vote, collection, upOrDown) {
    var field = 'votes.' + upOrDown + 'voted' + collection;
    var add = {};
    add[field] = vote;
    var result = Meteor.users.update({_id: userId}, {
      $addToSet: add
    });
  };

  var removeVote = function (userId, itemId, collection, upOrDown) {
    var field = 'votes.' + upOrDown + 'voted' + collection;
    var remove = {};
    remove[field] = {itemId: itemId};
    Meteor.users.update({_id: userId}, {
      $pull: remove
    });
  };

  var upvoteItem = function(collection, item) {
    var user = Meteor.user(),
        votePower = getVotePower(user),
        collectionName = collection._name.slice(0,1).toUpperCase()+collection._name.slice(1);


    // make sure user has rights to upvote first
    if (!user || !canUpvote(user, collection, true) || hasUpvotedItem(item, user))
      return false;

    // in case user is upvoting a previously downvoted item, cancel downvote first
    cancelDownvote(collection, item, user);

    // Votes & Score
    var result = collection.update({_id: item && item._id, upvoters: {$not: {$in: [user._id]}}},{
      $addToSet: {upvoters: user._id},
      $inc: {upvotes: 1, baseScore: votePower},
      $set: {inactive: false}
    });

    if (result > 0) {
      // Add item to list of upvoted items
      var vote = {
        itemId: item._id,
        votedAt: new Date(),
        power: votePower
      };
      addVote(user._id, vote, collectionName, 'up');

      // extend item with baseScore to help calculate newScore
      item = _.extend(item, {baseScore: (item.baseScore + votePower)});
      updateScore({collection: collection, item: item, forceUpdate: true});

      // if the item is being upvoted by its own author, don't give karma
      if (item.userId != user._id){
        modifyKarma(item.userId, votePower);
      
        // if karma redistribution is enabled, give karma to all previous upvoters of the post 
        // (but not to the person doing the upvoting)
        if(getSetting('redistributeKarma', false)){
          _.each(item.upvoters, function(upvoterId){
            // share the karma equally among all upvoters, but cap the value at 0.1
            var karmaIncrease = Math.min(0.1, votePower/item.upvoters.length);
            modifyKarma(upvoterId, 0.1);
          });
        }
      }
    }
    // console.log(collection.findOne(item._id));
    return true;
  };

  var downvoteItem = function(collection, item) {
    var user = Meteor.user(),
        votePower = getVotePower(user),
        collectionName = collection._name.slice(0,1).toUpperCase()+collection._name.slice(1);

    // make sure user has rights to downvote first
    if (!user || !canDownvote(user, collection, true)  || hasDownvotedItem(item, user))
      return false;

    // in case user is downvoting a previously upvoted item, cancel upvote first
    cancelUpvote(collection, item, user);

    // Votes & Score
    var result = collection.update({_id: item && item._id, downvoters: {$not: {$in: [user._id]}}},{
      $addToSet: {downvoters: user._id},
      $inc: {downvotes: 1, baseScore: -votePower},
      $set: {inactive: false}
    });

    if (result > 0) {
      // Add item to list of downvoted items
      var vote = {
        itemId: item._id,
        votedAt: new Date(),
        power: votePower
      };
      addVote(user._id, vote, collectionName, 'down');

      // extend item with baseScore to help calculate newScore
      item = _.extend(item, {baseScore: (item.baseScore + votePower)});
      updateScore({collection: collection, item: item, forceUpdate: true});

      // if the item is being upvoted by its own author, don't give karma
      if (item.userId != user._id)
        modifyKarma(item.userId, votePower);
    }
    // console.log(collection.findOne(item._id));
    return true;
  };

  var cancelUpvote = function(collection, item) {
    var user = Meteor.user();
        votePower = getVotePower(user),
        collectionName = collection._name.slice(0,1).toUpperCase()+collection._name.slice(1);

    // if user isn't among the upvoters, abort
    if(!hasUpvotedItem(item, user))
      return false;

    // Votes & Score
    var result = collection.update({_id: item && item._id, upvoters: { $in: [user._id]}},{
      $pull: {upvoters: user._id},
      $inc: {upvotes: -1, baseScore: -votePower},
      $set: {inactive: false}
    });

    if (result > 0) {
      // Remove item from list of upvoted items
      removeVote(user._id, item._id, collectionName, 'up');

      // extend item with baseScore to help calculate newScore
      item = _.extend(item, {baseScore: (item.baseScore + votePower)});
      updateScore({collection: collection, item: item, forceUpdate: true});

      // if the item is being upvoted by its own author, don't give karma
      if (item.userId != user._id)
        modifyKarma(item.userId, votePower);
    }
    // console.log(collection.findOne(item._id));
    return true;
  };

  var cancelDownvote = function(collection, item) {
    var user = Meteor.user(),
        votePower = getVotePower(user),
        collectionName = collection._name.slice(0,1).toUpperCase()+collection._name.slice(1);

    // if user isn't among the downvoters, abort
    if(!hasDownvotedItem(item, user))
      return false;
    
    // Votes & Score
    var result = collection.update({_id: item && item._id, downvoters: {$in: [user._id]}},{
      $pull: {downvoters: user._id},
      $inc: {downvotes: 1, baseScore: votePower},
      $set: {inactive: false}
    });
    
    if (result > 0) {
      // Remove item from list of downvoted items
      removeVote(user._id, item._id, collectionName, 'down');

      // extend item with baseScore to help calculate newScore
      item = _.extend(item, {baseScore: (item.baseScore + votePower)});
      updateScore({collection: collection, item: item, forceUpdate: true});

      // if the item is being upvoted by its own author, don't give karma
      if (item.userId != user._id)
        modifyKarma(item.userId, votePower);
    }
    // console.log(collection.findOne(item._id));
    return true;
  };

  // note: doesn't actually seem very useful to enable admins to vote for other users. Remove this?
  var getUser = function(user){
    // only let admins specify different users for voting
    // if no user is specified, use current user by default
    return (isAdmin(Meteor.user()) && typeof user !== 'undefined') ? user : Meteor.user();
  };
  
  Meteor.methods({
    upvotePost: function(post, user){
      return upvoteItem.call(this, Posts, post);
    },
    downvotePost: function(post, user){
      return downvoteItem.call(this, Posts, post);
    },
    cancelUpvotePost: function(post, user){
      return cancelUpvote.call(this, Posts, post);
    },
    cancelDownvotePost: function(post, user){
      return cancelDownvote.call(this, Posts, post);
    },
    upvoteComment: function(comment, user){
      return upvoteItem.call(this, Comments, comment);
    },
    downvoteComment: function(comment, user){
      return downvoteItem.call(this, Comments, comment);
    },
    cancelUpvoteComment: function(comment, user){
      return cancelUpvote.call(this, Comments, comment);
    },
    cancelDownvoteComment: function(comment, user){
      return cancelDownvote.call(this, Comments, comment);
    }
  });