package input_parser

var commandsTab []string
var prevInput string
var tabIndex int

func AutoComplete(input string) string {

	inputLength := len(input)

	if inputLength == 0 {
		return input
	}

	if tabIndex+2 > len(commandsTab) {
		tabIndex = -1
	}

	if prevInput == input {
		tabIndex = tabIndex + 1

		prevInput = commandsTab[tabIndex]
		return commandsTab[tabIndex]
	}

	prevInput = input
	tabIndex = 0

	currentCommands := []string{
		"cat",
		"cd",
		"cp",
		"echo",
		"head",
		"help",
		"ls",
		"man",
		"mv",
		"pwd",
		"rm",
		"tail",
		"touch",
	}

	var commandsWorking []string

	for _, currentCommand := range currentCommands {

		if len(currentCommand) < inputLength {
			continue
		}

		currentCommandWithoutEnd := currentCommand[:inputLength]

		if currentCommandWithoutEnd != input {
			continue
		}

		commandsWorking = append(commandsWorking, currentCommand)
	}

	commandsTab = commandsWorking

	if len(commandsTab) == 0 {
		return input
	}

	prevInput = commandsTab[0]
	return commandsTab[0]
}