pub mod adjacency_list;
pub mod shortest_path;

pub trait WheightedGraph: Sized {
    type Node;
    fn num_edges(&self, node: &Self::Node) -> usize {
        self.edge_iter(node).count()
    }

    fn edge(&self, node: &Self::Node, num: usize) -> Option<(Self::Node, f64)>;

    fn edge_iter<'a, 'b>(&'a self, node: &'b Self::Node) -> WheightedGraphEdgeIter<'a, 'b, Self> {
        WheightedGraphEdgeIter::new(self, node)
    }
}

pub struct WheightedGraphEdgeIter<'a, 'b, G>
where
    G: WheightedGraph,
{
    graph: &'a G,
    node: &'b G::Node,
    count: usize,
}

impl<'a, 'b, G> WheightedGraphEdgeIter<'a, 'b, G>
where
    G: WheightedGraph,
{
    pub fn new(graph: &'a G, node: &'b G::Node) -> Self {
        Self {
            graph,
            node,
            count: 0,
        }
    }
}

impl<'a, 'b, G> Iterator for WheightedGraphEdgeIter<'a, 'b, G>
where
    G: WheightedGraph,
{
    type Item = (G::Node, f64);

    fn next(&mut self) -> Option<Self::Item> {
        self.count += 1;
        self.graph.edge(self.node, self.count - 1)
    }
}