// Copyright 2017 clair 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 strutil

// CompareStringLists returns the strings that are present in X but not in Y.
func CompareStringLists(X, Y []string) []string {
	m := make(map[string]bool)

	for _, y := range Y {
		m[y] = true
	}

	diff := []string{}
	for _, x := range X {
		if m[x] {
			continue
		}

		diff = append(diff, x)
		m[x] = true
	}

	return diff
}

// CompareStringListsInBoth returns the strings that are present in both X and Y.
func CompareStringListsInBoth(X, Y []string) []string {
	m := make(map[string]struct{})

	for _, y := range Y {
		m[y] = struct{}{}
	}

	diff := []string{}
	for _, x := range X {
		if _, e := m[x]; e {
			diff = append(diff, x)
			delete(m, x)
		}
	}

	return diff
}