ABE v1.0

using System;

public class ABE
{
    static void Main ()
    {
        //

        // ++++CONSTANTS++++

        //

        // 13.5% tax rate.
        const double TAX = 0.135;

        // Power is 13.61 per unit.
        const double POWER = 0.1361;

        // Daily standing charge (DSC) of 41.4 cents.
        const double DSC = 0.41442623;

        // PSO levy of 2.73 per month.
        const double PSOL = 2.73;

        // There's an average of 30.5 days in a given calendar month.
        const double PSOL_TIMER = 30.5;

        // Table format 00 is used at the top. 01 and 02 are for formatting output. 03 is date.
        const string TBL_00 = "{0,-35}{1,10}";
        const string TBL_01 = "{0,-30}{1,-15:#.##}";
        const string TBL_02 = "{0,-30}{1,-15:C}";
        const string TBL_03 = "{0,-30}{1,-15:dd/MM/yyyy}";

        // Today's date.
        DateTime todayDate = DateTime.Now;

        //

        // ++++MOTD++++

        //

        Console.Clear();

        Console.WriteLine("Welcome to Airtricity bill estimator (ABE) v1.0!");
        Console.WriteLine();
        Console.Write("Press any key to begin... ");
        Console.ReadLine();

        //

        // ++++USER INPUT++++

        //

        Console.Clear();

        // Meter readings.
        Console.WriteLine("Meter readings:");
        Console.WriteLine();

        Console.Write(String.Format(TBL_00, "Last billed meter reading:",""));
        double lastRead = Convert.ToDouble(Console.ReadLine());

        Console.Write(String.Format(TBL_00, "Current meter reading:",""));
        double currentRead = Convert.ToDouble(Console.ReadLine());

        // Date of last bill.
        DateTime lastBilled;
        Console.Write(String.Format(TBL_00, "Date of last bill (YYYY-MM-DD):",""));
        lastBilled = Convert.ToDateTime(Console.ReadLine());

        //

        // ++++PROCESSING++++

        //

        // How many days have elapsed since the last bill?
        TimeSpan daysElapsed = todayDate - lastBilled;

        // Convert lastBilled to a double for easy manipulation.
        double daysElapsedDouble = Convert.ToDouble(daysElapsed.TotalDays);

        // How many kilowatts have you used since the last bill?
        double powerUsed = currentRead - lastRead;

        // And how much is that going to cost in practice?
        double billPowerCost = powerUsed * POWER;

        // DSC fee of 0.41442623 a day.
        double billDSCCost = DSC * daysElapsedDouble;

        // PSO levy, charged once per 30 days.
        double billPSOLevy = 0;
        if  (daysElapsedDouble >= PSOL_TIMER)
        {
            billPSOLevy = PSOL;
        }
        else if (daysElapsedDouble >= (PSOL_TIMER *2))
        {
            billPSOLevy = PSOL * 2;
        }

        // Tally the subtotal.
        double billSubtotal = billPSOLevy + billDSCCost + billPowerCost;

        // Tax.
        double billTax = billSubtotal * TAX;

        // Total
        double billTotal = billTax + billSubtotal;

        //

        // ++++OUTPUT++++

        //

        Console.Clear();

        Console.WriteLine();
        Console.WriteLine(String.Format(TBL_03, "Date of last bill:", lastBilled));
        Console.WriteLine(String.Format(TBL_03, "Today's date:", todayDate));
        Console.WriteLine(String.Format(TBL_01, "Days since last bill:", daysElapsed.TotalDays));
        Console.WriteLine(String.Format(TBL_01, "------------------------", "-------"));
        Console.WriteLine(String.Format(TBL_01, "Units consumed:", powerUsed));
        Console.WriteLine(String.Format(TBL_02, "Cost per unit:", POWER));
        Console.WriteLine(String.Format(TBL_01, "------------------------", "-------"));
        Console.WriteLine(String.Format(TBL_02, "Power cost:", billPowerCost));
        Console.WriteLine(String.Format(TBL_02, "Daily standing charge:", billDSCCost));
        Console.WriteLine(String.Format(TBL_02, "PSO levy:", billPSOLevy));
        Console.WriteLine();
        Console.WriteLine(String.Format(TBL_02, "Subtotal:", billSubtotal));
        Console.WriteLine(String.Format(TBL_01, "------------------------", "-------"));
        Console.WriteLine(String.Format(TBL_02, "Tax:", billTax));
        Console.WriteLine(String.Format(TBL_02, "Total estimated bill:", billTotal));

        //

        // ++++EOF++++

        //

        Console.WriteLine();
        Console.Write("Press any key to exit... ");
        Console.ReadLine();
    }
}