package heap

import (
	"cmp"
	"container/heap"
)

type Heap[T any] struct {
	Data     []T
	lessFunc func(a, b T) bool
}

func More[T cmp.Ordered](x, y T) bool {
	return !cmp.Less(x, y) && x != y
}

func NewBy[T any](lessFunc func(a, b T) bool, items ...T) *Heap[T] {
	h := &Heap[T]{items, lessFunc}
	heap.Init(h)
	return h
}

func New[T cmp.Ordered](items ...T) *Heap[T] {
	return NewBy[T](func(a, b T) bool { return a < b }, items...)
}

func (h Heap[T]) Len() int           { return len(h.Data) }
func (h Heap[T]) Less(i, j int) bool { return h.lessFunc(h.Data[i], h.Data[j]) }
func (h Heap[T]) Swap(i, j int)      { h.Data[i], h.Data[j] = h.Data[j], h.Data[i] }

func (h *Heap[T]) Push(x any) { h.Data = append(h.Data, x.(T)) }
func (h *Heap[T]) Pop() any {
	defer func() { h.Data = h.Data[:len(h.Data)-1] }()
	return h.Data[len(h.Data)-1]
}