package engine

import (
	"reflect"
	"testing"

	"gitlab.hive-brain.de/MDietermann/Archduino/internal/module"
)

func TestTopoSort(t *testing.T) {
	cases := []struct {
		name  string
		metas []module.Meta
		want  []string
		err   bool
	}{
		{
			name:  "linear chain",
			metas: []module.Meta{{ID: "a"}, {ID: "b", Deps: []string{"a"}}, {ID: "c", Deps: []string{"b"}}},
			want:  []string{"a", "b", "c"},
		},
		{
			name:  "independent modules sorted alphabetically",
			metas: []module.Meta{{ID: "c"}, {ID: "a"}, {ID: "b"}},
			want:  []string{"a", "b", "c"},
		},
		{
			name:  "diamond",
			metas: []module.Meta{{ID: "a"}, {ID: "b", Deps: []string{"a"}}, {ID: "c", Deps: []string{"a"}}, {ID: "d", Deps: []string{"b", "c"}}},
			want:  []string{"a", "b", "c", "d"},
		},
		{
			name:  "unknown dep",
			metas: []module.Meta{{ID: "a", Deps: []string{"missing"}}},
			err:   true,
		},
		{
			name:  "cycle",
			metas: []module.Meta{{ID: "a", Deps: []string{"b"}}, {ID: "b", Deps: []string{"a"}}},
			err:   true,
		},
	}
	for _, tc := range cases {
		t.Run(tc.name, func(t *testing.T) {
			got, err := TopoSort(tc.metas)
			if tc.err {
				if err == nil {
					t.Fatalf("want error, got nil (order=%v)", got)
				}
				return
			}
			if err != nil {
				t.Fatalf("unexpected error: %v", err)
			}
			if !reflect.DeepEqual(got, tc.want) {
				t.Fatalf("order = %v, want %v", got, tc.want)
			}
		})
	}
}

func TestDescendants(t *testing.T) {
	metas := []module.Meta{
		{ID: "a"},
		{ID: "b", Deps: []string{"a"}},
		{ID: "c", Deps: []string{"a"}},
		{ID: "d", Deps: []string{"b"}},
		{ID: "e"}, // independent
	}
	got := Descendants(metas, "a")
	want := map[string]bool{"b": true, "c": true, "d": true}
	if !reflect.DeepEqual(got, want) {
		t.Fatalf("descendants(a) = %v, want %v", got, want)
	}

	if len(Descendants(metas, "e")) != 0 {
		t.Fatalf("descendants(e) should be empty")
	}
}