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use super::LoadBalancingStrategy;

pub struct SingleNode<N> {
    cluster: Vec<N>,
}

impl<N> SingleNode<N> {
    pub fn new() -> Self {
        SingleNode { cluster: vec![] }
    }
}

impl<N> From<Vec<N>> for SingleNode<N> {
    fn from(cluster: Vec<N>) -> SingleNode<N> {
        SingleNode { cluster: cluster }
    }
}

impl<N> LoadBalancingStrategy<N> for SingleNode<N> {
    fn init(&mut self, cluster: Vec<N>) {
        self.cluster = cluster;
    }

    /// Returns first node from a cluster
    fn next(&self) -> Option<&N> {
        self.cluster.get(0)
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn single_node() {
        let nodes = vec!["a"];
        let nodes_c = nodes.clone();
        let load_balancer = SingleNode::from(nodes);
        assert_eq!(&nodes_c[0], load_balancer.next().unwrap());
        // and one more time to check
        assert_eq!(&nodes_c[0], load_balancer.next().unwrap());
    }
}