// Copyright 2014 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.

package stack

import (
	"fmt"

	"github.com/holiman/uint256"
)

// Stack is an object for basic stack operations. Items popped to the stack are
// expected to be changed and modified. stack does not take care of adding newly
// initialised objects.
type Stack struct {
	Data []uint256.Int
}

func New(n ...int) *Stack {
	if len(n) > 0 {
		return &Stack{make([]uint256.Int, 0, n[0])}
	}
	return &Stack{}
}

// Data returns the underlying uint256.Int array.
func (st *Stack) GetData() []uint256.Int {
	return st.Data
}

func (st *Stack) Push(d *uint256.Int) {
	// NOTE push limit (1024) is checked in baseCheck
	st.Data = append(st.Data, *d)
}

func (st *Stack) Pop() uint256.Int {
	ret := st.Data[len(st.Data)-1]
	st.Data = st.Data[:len(st.Data)-1]
	return ret
}

func (st *Stack) Len() int {
	return len(st.Data)
}

func (st *Stack) Cap() int {
	return cap(st.Data)
}

func (st *Stack) Swap(n int) {
	st.Data[st.Len()-n], st.Data[st.Len()-1] = st.Data[st.Len()-1], st.Data[st.Len()-n]
}

func (st *Stack) Dup(n int) {
	st.Push(&st.Data[st.Len()-n])
}

func (st *Stack) Peek() *uint256.Int {
	return &st.Data[st.Len()-1]
}

// Back returns the n'th item in stack
func (st *Stack) Back(n int) *uint256.Int {
	return &st.Data[st.Len()-n-1]
}

func (st *Stack) Reset() {
	st.Data = st.Data[:0]
}

// Print dumps the content of the stack
func (st *Stack) Print() {
	fmt.Println("### stack ###")
	if len(st.Data) > 0 {
		for i, val := range st.Data {
			fmt.Printf("%-3d  %v\n", i, val)
		}
	} else {
		fmt.Println("-- empty --")
	}
	fmt.Println("#############")
}

// ReturnStack is an object for basic return stack operations.
type ReturnStack struct {
	data []uint64
}

func NewReturnStack() *ReturnStack {
	return &ReturnStack{data: make([]uint64, 0, 1024)}
}

func (st *ReturnStack) Push(d uint64) {
	st.data = append(st.data, d)
}

func (st *ReturnStack) Pop() (ret uint64) {
	ret = st.data[len(st.data)-1]
	st.data = st.data[:len(st.data)-1]
	return
}

func (st *ReturnStack) Data() []uint64 {
	return st.data
}