package main

import "net/url"

type History struct {
	history []*url.URL
	position int
}

func (history *History) Add (location *url.URL) {
	if len(history.history) == 0 {
		history.history = append(history.history, location)
		history.position = 0
		return
	}

	history.position ++

	if len(history.history) > history.position + 1 {
		history.history = history.history[:history.position + 1]
		history.history[history.position] = location
	} else {
		history.history = append(history.history, location)
	}
}

func (history *History) Backward () (location *url.URL) {
	if history.position < 1 || len(history.history) < 1 { return }
	history.position --
	location = history.history[history.position]
	return
}

func (history *History) Forward () (location *url.URL) {
	if history.position + 1 >= len(history.history) { return }
	history.position ++
	location = history.history[history.position]
	return
}

func (history *History) Remove () {
	if len(history.history) <= 1 { return }
	history.history = append (
		history.history[:history.position],
		history.history[history.position + 1:]...)
	history.position --
}