Refactored and Included Tests for TopoSortFromBfsNodeMap

* Refactored the code for TopoSortFromBfsNodeMap for readability and time complexity purposes.
* Included tests for TopoSortFromBfsNodeMap

Signed-off-by: nathannaveen <42319948+nathannaveen@users.noreply.github.com>

pkg/guacanalytics/toposort.go

@@ -22,58 +22,65 @@ import (
 	"github.com/Khan/genqlient/graphql"
 )
 
-// TODO: add tests
-func ToposortFromBfsNodeMap(ctx context.Context, gqlClient graphql.Client, nodeMap map[string]BfsNode) (map[int][]string, []string, error) {
-	frontiers := make(map[int][]string)
-	parentsMap, infoNodes := copyParents(nodeMap)
-	frontierLevel := 0
+// TopoSortFromBfsNodeMap sorts the nodes such that it returns a map of level -> list of nodeIDs at that level
+func TopoSortFromBfsNodeMap(ctx context.Context, gqlClient graphql.Client, nodeMap map[string]BfsNode) (map[int][]string, []string, error) {
+	sortedNodes := make(map[int][]string) // map of level -> list of nodeIDs at that level
+	parentsMap, childrensMap, infoNodes := copyParents(nodeMap)
+	// parentsMap: map of nodeID (child) -> list of parents in the form of a map
+	// childrensMap: map of nodeID (parent) -> list of children in the form of a list
+	bfsLevel := 0
 	numNodes := 0
 	totalNodes := len(parentsMap)
 
 	for numNodes < totalNodes {
 		foundIDs := make(map[string]bool)
-		for id, parentsList := range parentsMap {
-			if len(parentsList) == 0 || (parentsList[0] == "" && len(parentsList) == 1) {
-				frontiers[frontierLevel] = append(frontiers[frontierLevel], id)
-				foundIDs[id] = true
+		for id, pMap := range parentsMap {
+			if pMap.parents != nil && len(pMap.parents) == 0 { // if this node has no parents, it is a root node
+				sortedNodes[bfsLevel] = append(sortedNodes[bfsLevel], id)
 				numNodes++
+				foundIDs[id] = true
+				delete(parentsMap, id)
 			}
 		}
 
-		if len(foundIDs) == 0 {
-			// TODO: print out offending cycle
-			return frontiers, infoNodes, fmt.Errorf("error: cycle detected")
-		}
-
 		for id := range foundIDs {
-			delete(parentsMap, id)
-		}
-
-		for id, parentsList := range parentsMap {
-			newParentsList := []string{}
-			for _, parentID := range parentsList {
-				if !foundIDs[parentID] {
-					newParentsList = append(newParentsList, parentID)
-				}
+			for _, childID := range childrensMap[id] { // loop through all the children of this node
+				delete(parentsMap[childID].parents, id) // remove this node from the map of parents of the child
 			}
+		}
 
-			parentsMap[id] = newParentsList
+		if len(foundIDs) == 0 {
+			return sortedNodes, infoNodes, fmt.Errorf("error: cycle detected")
 		}
-		frontierLevel++
+
+		bfsLevel++
 	}
 
-	return frontiers, infoNodes, nil
+	return sortedNodes, infoNodes, nil
 }
 
-func copyParents(inputMap map[string]BfsNode) (map[string][]string, []string) {
-	retMap := map[string][]string{}
+func copyParents(inputMap map[string]BfsNode) (map[string]parent, map[string][]string, []string) {
+	parentsMap := map[string]parent{}    // map of nodeID (child) -> map of the childs parents
+	childrenMap := map[string][]string{} // map of nodeID (parent) -> list of the parents children
 	var infoNodes []string
 	for key, value := range inputMap {
 		if !value.NotInBlastRadius {
-			retMap[key] = append(retMap[key], value.Parents...)
+			if _, ok := parentsMap[key]; !ok {
+				parentsMap[key] = parent{make(map[string]bool)}
+			}
+
+			for _, parent := range value.Parents {
+				parentsMap[key].parents[parent] = true
+				childrenMap[parent] = append(childrenMap[parent], key)
+			}
 		} else {
 			infoNodes = append(infoNodes, key)
 		}
 	}
-	return retMap, infoNodes
+
+	return parentsMap, childrenMap, infoNodes
+}
+
+type parent struct {
+	parents map[string]bool // Consider the map[string]bool as a set, the value doesn't matter just the key
 }

pkg/guacanalytics/toposort_test.go

@@ -0,0 +1,113 @@
+//
+// Copyright 2023 The GUAC Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package guacanalytics
+
+import (
+	"context"
+	"reflect"
+	"sort"
+	"testing"
+
+	"github.com/Khan/genqlient/graphql"
+)
+
+func TestTopoSortFromBfsNodeMap(t *testing.T) {
+	type args struct {
+		nodeMap map[string]BfsNode
+	}
+	tests := []struct {
+		name    string
+		args    args
+		want    map[int][]string
+		want1   []string
+		wantErr bool
+	}{
+		{
+			name: "default",
+			args: args{
+				/*
+						1
+					   / \
+					  2   3
+					 / \   \
+					4   5   6
+				*/
+				nodeMap: map[string]BfsNode{
+					"1": {Parents: []string{}},
+					"2": {Parents: []string{"1"}},
+					"3": {Parents: []string{"1"}},
+					"4": {Parents: []string{"2"}},
+					"5": {Parents: []string{"2"}},
+					"6": {Parents: []string{"3"}},
+				},
+			},
+			want: map[int][]string{
+				0: {"1"},
+				1: {"2", "3"},
+				2: {"4", "5", "6"},
+			},
+			want1: *new([]string),
+		},
+		{
+			name: "cycle error",
+			args: args{
+				/*
+						1
+					   / \
+					  2 - 3
+				*/
+				nodeMap: map[string]BfsNode{
+					"1": {Parents: []string{"3"}},
+					"2": {Parents: []string{"1"}},
+					"3": {Parents: []string{"2"}},
+				},
+			},
+			wantErr: true,
+		},
+		{
+			name: "infoNodes not empty",
+			args: args{
+				nodeMap: map[string]BfsNode{
+					"1": {NotInBlastRadius: true},
+				},
+			},
+			want:  map[int][]string{},
+			want1: []string{"1"},
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			ctx := context.Background()
+			gqlClient := graphql.NewClient("test", nil)
+			got, got1, err := TopoSortFromBfsNodeMap(ctx, gqlClient, tt.args.nodeMap)
+			if (err != nil) != tt.wantErr {
+				t.Errorf("TopoSortFromBfsNodeMap() error = %v, wantErr %v", err, tt.wantErr)
+				return
+			}
+			for k := range got {
+				sort.Strings(got[k])
+				sort.Strings(tt.want[k])
+				if !reflect.DeepEqual(got[k], tt.want[k]) {
+					t.Errorf("TopoSortFromBfsNodeMap() got = %v, want %v", got, tt.want)
+				}
+			}
+			if !reflect.DeepEqual(got1, tt.want1) {
+				t.Errorf("TopoSortFromBfsNodeMap() got1 = %v, want %v", got1, tt.want1)
+			}
+
+		})
+	}
+}