package common

import (
	"errors"
	"sync"
)

type Stack[T any] struct {
	items []T
	mutex sync.Mutex
}

func NewStack[T any]() *Stack[T] {
	return &Stack[T]{
		items: make([]T, 0),
		mutex: sync.Mutex{},
	}
}

func (s *Stack[T]) Push(item T) {
	s.mutex.Lock()
	defer s.mutex.Unlock()

	s.items = append(s.items, item)
}

func (s *Stack[T]) Pop() (T, error) {
	s.mutex.Lock()
	defer s.mutex.Unlock()

	if len(s.items) == 0 {
		var empty T
		return empty, errors.New("stack is empty")
	}

	item := s.items[len(s.items)-1]
	s.items = s.items[:len(s.items)-1]

	return item, nil
}