/*
Copyright © 2025 filifa

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
package graph

import (
	"gonum.org/v1/gonum/graph/multi"
	"gonum.org/v1/gonum/graph/simple"
	"gonum.org/v1/gonum/mat"
)

// DirectedGraph embeds a multi.WeightedDirectedGraph (as opposed to
// simple.WeightedDirectedGraph) to handle self loops.
type WeightedDirectedGraph struct {
	*multi.WeightedDirectedGraph
}

// NewDirectedGraph returns a graph with no nodes or edges.
func NewWeightedDirectedGraph() *WeightedDirectedGraph {
	return &WeightedDirectedGraph{WeightedDirectedGraph: multi.NewWeightedDirectedGraph()}
}

// AdjacencyMatrix returns the graph's adjacency matrix.
func (g *WeightedDirectedGraph) AdjacencyMatrix() *mat.Dense {
	adj := simple.NewDirectedMatrix(g.Nodes().Len(), 0, 0, 0)
	matrix := toAdjMatrix(g, adj)
	return matrix
}