package dag

import (
	"reflect"
	"sync"
	"testing"
)

func TestAcyclicGraphRoot(t *testing.T) {
	var g AcyclicGraph
	g.Add(1)
	g.Add(2)
	g.Add(3)
	g.Connect(BasicEdge(3, 2))
	g.Connect(BasicEdge(3, 1))

	if root, err := g.Root(); err != nil {
		t.Fatalf("err: %s", err)
	} else if root != 3 {
		t.Fatalf("bad: %#v", root)
	}
}

func TestAcyclicGraphRoot_cycle(t *testing.T) {
	var g AcyclicGraph
	g.Add(1)
	g.Add(2)
	g.Add(3)
	g.Connect(BasicEdge(1, 2))
	g.Connect(BasicEdge(2, 3))
	g.Connect(BasicEdge(3, 1))

	if _, err := g.Root(); err == nil {
		t.Fatal("should error")
	}
}

func TestAcyclicGraphRoot_multiple(t *testing.T) {
	var g AcyclicGraph
	g.Add(1)
	g.Add(2)
	g.Add(3)
	g.Connect(BasicEdge(3, 2))

	if _, err := g.Root(); err == nil {
		t.Fatal("should error")
	}
}

func TestAcyclicGraphWalk(t *testing.T) {
	var g AcyclicGraph
	g.Add(1)
	g.Add(2)
	g.Add(3)
	g.Connect(BasicEdge(3, 2))
	g.Connect(BasicEdge(3, 1))

	var visits []Vertex
	var lock sync.Mutex
	err := g.Walk(func(v Vertex) {
		lock.Lock()
		defer lock.Unlock()
		visits = append(visits, v)
	})
	if err != nil {
		t.Fatalf("err: %s", err)
	}

	expected := [][]Vertex{
		{3, 1, 2},
		{3, 2, 1},
	}
	for _, e := range expected {
		if reflect.DeepEqual(visits, e) {
			return
		}
	}

	t.Fatalf("bad: %#v", visits)
}