use fixedbitset::FixedBitSet;

use super::EdgeType;

use super::graph::{Graph, IndexType, NodeIndex};

#[cfg(feature = "stable_graph")]

use crate::stable_graph::StableGraph;

use crate::visit::EdgeRef;

#[cfg(feature = "stable_graph")]

use crate::visit::{IntoEdgeReferences, NodeIndexable};

use super::visit::GetAdjacencyMatrix;

/// The adjacency matrix for **Graph** is a bitmap that's computed by

/// `.adjacency_matrix()`.

impl<N, E, Ty, Ix> GetAdjacencyMatrix for Graph<N, E, Ty, Ix>

where

    Ty: EdgeType,

    Ix: IndexType,

{

    type AdjMatrix = FixedBitSet;

    fn adjacency_matrix(&self) -> FixedBitSet {

        let n = self.node_count();

        let mut matrix = FixedBitSet::with_capacity(n * n);

        for edge in self.edge_references() {

            let i = edge.source().index() * n + edge.target().index();

            matrix.put(i);

            if !self.is_directed() {

                let j = edge.source().index() + n * edge.target().index();

                matrix.put(j);

            }

        }

        matrix

    }

    fn is_adjacent(&self, matrix: &FixedBitSet, a: NodeIndex<Ix>, b: NodeIndex<Ix>) -> bool {

        let n = self.node_count();

        let index = n * a.index() + b.index();

        matrix.contains(index)

    }

}

#[cfg(feature = "stable_graph")]

/// The adjacency matrix for **Graph** is a bitmap that's computed by

/// `.adjacency_matrix()`.

impl<N, E, Ty, Ix> GetAdjacencyMatrix for StableGraph<N, E, Ty, Ix>

where

    Ty: EdgeType,

    Ix: IndexType,

{

    type AdjMatrix = FixedBitSet;

    fn adjacency_matrix(&self) -> FixedBitSet {

        let n = self.node_bound();

        let mut matrix = FixedBitSet::with_capacity(n * n);

        for edge in self.edge_references() {

            let i = edge.source().index() * n + edge.target().index();

            matrix.put(i);

            if !self.is_directed() {

                let j = edge.source().index() + n * edge.target().index();

                matrix.put(j);

            }

        }

        matrix

    }

    fn is_adjacent(&self, matrix: &FixedBitSet, a: NodeIndex<Ix>, b: NodeIndex<Ix>) -> bool {

        let n = self.node_count();

        let index = n * a.index() + b.index();

        matrix.contains(index)

    }

}