#[Copyright 2024 ITwrx.
This file is part of WattstoDollars.
WattstoDollars is released under the GNU General Public License 3.0.
See COPYING or <https://www.gnu.org/licenses/> for details.]#

import std/[strutils, math]
import termstyle
  
proc vInputInt(inputValue: string, inputPrompt: string, inputName: string): int =
  try:
    let intInputValue = parseInt(inputValue)
    return intInputValue
  except CatchableError:
    echo red "\N" & inputName & " must be a whole number.\N"
    echo inputPrompt
    return vInputInt(readLine(stdin), inputPrompt, inputName)
  
proc vInputFloat(inputValue: string, inputPrompt: string, inputName: string): float =
  try:
    let floatInputValue = parseFloat(inputValue)
    return floatInputValue
  except CatchableError:
    echo red "\N" & inputName & " must be a float/decimal number.\N"
    echo inputPrompt
    return vInputFloat(readLine(stdin), inputPrompt, inputName)

echo yellow "\N**** Whole numbers required for all inputs except electrical rate, which accepts a float/decimal number. ***\N"
var prompt: string
#get watts from user
prompt = "Watts?\N"
echo prompt
echo yellow "Hint: You can enter the total watts used by a device, or enter the difference in watts between two devices, to see how much more a second device will cost.\N"
var watts = vInputInt(readLine(stdin), prompt, "Watts")  
#get watt hrs from user.
prompt = "\NNumber of hours of usage per day?\N"
echo prompt
var hours = vInputInt(readLine(stdin), prompt, "Hours")
#get days from user.
prompt = "\NNumber of days of usage?\N"
echo prompt
var days = vInputInt(readLine(stdin), prompt, "Days")
#get energy rate from user.
prompt = "\NElectrical rate per kilowatt hour?\N"
echo prompt
var kwRate = vInputFloat(readLine(stdin), prompt, "Electrical Rate")
let watthrsPerDay: int = watts * hours
#convert watts to kw hrs
let kwh: float = watthrsPerDay / 1000
#get kwhr usage per # of days.
let kwhUsage: float = kwh * parseFloat($days)
#get $ usage.
let energyCost: float = kwhUsage * parseFloat($kwRate)
let roundedEnergyCost = round(energyCost, 2)
echo "\N" & $watts & " watts, used " & $hours & " hours a day, for " & $days & " days = $" & $roundedEnergyCost & "\N"