package main

import (
	"bufio"
	"fmt"
	"os"
	"strings"
)

func prompt(question string, options []string, defaultAnswer string, currentValue string, permitEmpty bool) (string, error) {
	r := bufio.NewReader(os.Stdin)
	if len(currentValue) == 0 {
		currentValue = "None"
	}
	if len(defaultAnswer) == 0 {
		defaultAnswer = "None"
	}
	if options == nil {
		fmt.Print("->", question, "( defaults to:", defaultAnswer, " current value:", currentValue, " )", ":")

	} else {
		fmt.Print("->", question, "( defaults to:", defaultAnswer, " current value:", currentValue, " )[ ", strings.Join(options, " | "), " ]", ":")
	}
	response, _ := r.ReadString('\n')
	response = strings.Trim(response, "\n")
	if len(response) == 0 && currentValue != "None" {
		response = currentValue
	}
	if len(response) == 0 && defaultAnswer != "None" {
		response = defaultAnswer
	}
	if options != nil {
		validOption := false
		for _, opt := range options {
			if strings.EqualFold(response, opt) {
				validOption = true
				response = opt
				break
			}
		}
		if !validOption {
			return response, fmt.Errorf("invalid option")
		}
	}
	if !permitEmpty && len(response) == 0 {
		return response, fmt.Errorf("empty response")
	}
	return response, nil
}