groups.js

    // Seconds since call started, if a call is in progress
    call_time: Ember.computed('user.activeLiveCallAgents.[]', '[email protected]', '_call_time', function() {
        var self = this;

        // Basically, we want a way of having call_time update every second,
        // but only if a call is in progress.
        // We achieve that by having a timer update a property we are listening on,
        // which will start when the call time is requested, and stop when there
        // is no call in progress. We enforce that there is only ever one timer
        // running for an agent.
        // This code may be better suited on a user, and moved later.
        var timer = this.get('_timer') || {
            started: false,
            getCallTime() {
                if (!this.started) {
                    this.tick();
                }
                // TODO: Deal with case where there are multiple calls
                var agent = self.get('user.activeLiveCallAgents').find(agent => agent.state === CALL_STATE.IN_CALL);
                var callTime = agent && (new Date().getTime() - agent.group.jsAnswerTime)/1000;
                return callTime;
            },
            tick() {
                this.started = true;
                self.set('_call_time', this.getCallTime());
                if (self.get('_call_time') === undefined) {
                    this.started = false;
                } else {
                    setTimeout(() => this.tick(), 1000);
                }
            }
        };
        this.set('_timer', timer);
        return timer.getCallTime();
    })