(function() {
  'use strict';
  window.Whisper = window.Whisper || {};
  Whisper.ReadReceipts = new (Backbone.Collection.extend({
    forMessage: function(conversation, message) {
      if (!message.isOutgoing()) {
        return [];
      }
      var ids = [];
      if (conversation.isPrivate()) {
        ids = [conversation.id];
      } else {
        ids = conversation.get('members');
      }
      var receipts = this.filter(function(receipt) {
        return (
          receipt.get('timestamp') === message.get('sent_at') &&
          _.contains(ids, receipt.get('reader'))
        );
      });
      if (receipts.length) {
        console.log('Found early read receipts for message');
        this.remove(receipts);
      }
      return receipts;
    },
    onReceipt: function(receipt) {
      var messages = new Whisper.MessageCollection();
      return messages
        .fetchSentAt(receipt.get('timestamp'))
        .then(function() {
          if (messages.length === 0) {
            return;
          }
          var message = messages.find(function(message) {
            return (
              message.isOutgoing() &&
              receipt.get('reader') === message.get('conversationId')
            );
          });
          if (message) {
            return message;
          }

          var groups = new Whisper.GroupCollection();
          return groups.fetchGroups(receipt.get('reader')).then(function() {
            var ids = groups.pluck('id');
            ids.push(receipt.get('reader'));
            return messages.find(function(message) {
              return (
                message.isOutgoing() &&
                _.contains(ids, message.get('conversationId'))
              );
            });
          });
        })
        .then(
          function(message) {
            if (message) {
              var read_by = message.get('read_by') || [];
              read_by.push(receipt.get('reader'));
              return new Promise(
                function(resolve, reject) {
                  message.save({ read_by: read_by }).then(
                    function() {
                      // notify frontend listeners
                      var conversation = ConversationController.get(
                        message.get('conversationId')
                      );
                      if (conversation) {
                        conversation.trigger('read', message);
                      }

                      this.remove(receipt);
                      resolve();
                    }.bind(this),
                    reject
                  );
                }.bind(this)
              );
            } else {
              console.log(
                'No message for read receipt',
                receipt.get('reader'),
                receipt.get('timestamp')
              );
            }
          }.bind(this)
        )
        .catch(function(error) {
          console.log(
            'ReadReceipts.onReceipt error:',
            error && error.stack ? error.stack : error
          );
        });
    },
  }))();
})();