/*
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 sets

type Empty struct{}

// Set implements a generic implementation of k8s.io/apimachinery/pkg/util/sets
// TODO: Remove our local generic implementation when migrating to a later version of
// https://github.com/kubernetes/apimachinery/blob/master/pkg/util/sets/set.go
type Set[T comparable] map[T]Empty

func New[T comparable](items ...T) Set[T] {
	ss := make(Set[T], len(items))
	ss.Insert(items...)
	return ss
}

// Insert adds items to the set.
func (s Set[T]) Insert(items ...T) Set[T] {
	for _, item := range items {
		s[item] = Empty{}
	}
	return s
}

// Delete removes all items from the set.
func (s Set[T]) Delete(items ...T) Set[T] {
	for _, item := range items {
		delete(s, item)
	}
	return s
}

// Has returns true if and only if item is contained in the set.
func (s Set[T]) Has(item T) bool {
	_, contained := s[item]
	return contained
}

// HasAll returns true if and only if all items are contained in the set.
func (s Set[T]) HasAll(items ...T) bool {
	for _, item := range items {
		if !s.Has(item) {
			return false
		}
	}
	return true
}

// HasAny returns true if any items are contained in the set.
func (s Set[T]) HasAny(items ...T) bool {
	for _, item := range items {
		if s.Has(item) {
			return true
		}
	}
	return false
}

// Clone returns a new set which is a copy of the current set.
func (s Set[T]) Clone() Set[T] {
	result := make(Set[T], len(s))
	for key := range s {
		result.Insert(key)
	}
	return result
}

// Difference returns a set of objects that are not in s2
// For example:
// s1 = {a1, a2, a3}
// s2 = {a1, a2, a4, a5}
// s1.Difference(s2) = {a3}
// s2.Difference(s1) = {a4, a5}
func (s Set[T]) Difference(s2 Set[T]) Set[T] {
	result := New[T]()
	for key := range s {
		if !s2.Has(key) {
			result.Insert(key)
		}
	}
	return result
}

// Union returns a new set which includes items in either s1 or s2.
// For example:
// s1 = {a1, a2}
// s2 = {a3, a4}
// s1.Union(s2) = {a1, a2, a3, a4}
// s2.Union(s1) = {a1, a2, a3, a4}
func (s Set[T]) Union(s2 Set[T]) Set[T] {
	result := s.Clone()
	for key := range s2 {
		result.Insert(key)
	}
	return result
}

// Intersection returns a new set which includes the item in BOTH s1 and s2
// For example:
// s1 = {a1, a2}
// s2 = {a2, a3}
// s1.Intersection(s2) = {a2}
func (s Set[T]) Intersection(s2 Set[T]) Set[T] {
	var walk, other Set[T]
	result := New[T]()
	if s.Len() < s2.Len() {
		walk = s
		other = s2
	} else {
		walk = s2
		other = s
	}
	for key := range walk {
		if other.Has(key) {
			result.Insert(key)
		}
	}
	return result
}

// IsSuperset returns true if and only if s1 is a superset of s2.
func (s Set[T]) IsSuperset(s2 Set[T]) bool {
	for item := range s2 {
		if !s.Has(item) {
			return false
		}
	}
	return true
}

func (s Set[T]) Equal(s2 Set[T]) bool {
	if s.Len() != s2.Len() {
		return false
	}
	for item := range s2 {
		if !s.Has(item) {
			return false
		}
	}
	return true
}

// List returns the slice with contents in random order.
func (s Set[T]) List() []T {
	res := make([]T, 0, len(s))
	for key := range s {
		res = append(res, key)
	}
	return res
}

// PopAny returns a single element from the set.
func (s Set[T]) PopAny() (T, bool) {
	for key := range s {
		s.Delete(key)
		return key, true
	}
	var zeroValue T
	return zeroValue, false
}

// Len returns the size of the set.
func (s Set[T]) Len() int {
	return len(s)
}