package fifo

import "fmt"

type FIFO[T any] []T

func New[T any](items ...T) *FIFO[T] {
	f := FIFO[T](items)
	return &f
}

func (f *FIFO[T]) Push(item T) {
	*f = append(*f, item)
}

func (f *FIFO[T]) Empty() bool {
	return len(*f) == 0
}

func (f *FIFO[T]) MustPop() T {
	var item T

	*f, item = (*f)[:len(*f)-1], (*f)[len(*f)-1]
	return item
}

func (f *FIFO[T]) Pop() (T, error) {
	var item T

	if f.Empty() {
		return item, fmt.Errorf("stack is exhausted")
	}

	return f.MustPop(), nil
}