namespace HeuristicLab.Problems.ProgramSynthesis {
  using System;
  using System.Diagnostics;
  using System.Globalization;
  using System.Text;

  public static class StringBuilderExtension {
    // These digits are here in a static array to support hex with simple, easily-understandable code.
    // Since A-Z don't sit next to 0-9 in the ascii table.
    private static readonly char[] MsDigits =
      {
        '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D',
        'E', 'F'
      };

    //private static readonly ulong MsDefaultDecimalPlaces = 5; //< Matches standard .NET formatting dp's

    private const char MsDefaultPadChar = '0';

    //! Convert a given unsigned integer value to a string and concatenate onto the stringbuilder. Any base value allowed.
    public static StringBuilder Concat(
      this StringBuilder stringBuilder,
      ulong ulongVal,
      ulong padAmount,
      char padChar,
      ulong baseVal) {
      Debug.Assert((baseVal > 0) && (baseVal <= 16));

      // Calculate length of integer when written out
      ulong length = 0;
      var lengthCalc = ulongVal;

      do {
        lengthCalc /= baseVal;
        length++;
      }
      while (lengthCalc > 0);

      // Pad out space for writing.
      stringBuilder.Append(padChar, (int)Math.Max(padAmount, length));

      var strpos = stringBuilder.Length;

      // We're writing backwards, one character at a time.
      while (length > 0) {
        strpos--;

        // Lookup from static char array, to cover hex values too
        stringBuilder[strpos] = MsDigits[ulongVal % baseVal];

        ulongVal /= baseVal;
        length--;
      }

      return stringBuilder;
    }

    //! Convert a given unsigned integer value to a string and concatenate onto the stringbuilder. Assume no padding and base ten.
    public static StringBuilder Concat(this StringBuilder stringBuilder, ulong ulongVal) {
      stringBuilder.Concat(ulongVal, 0, MsDefaultPadChar, 10);
      return stringBuilder;
    }

    //! Convert a given unsigned integer value to a string and concatenate onto the stringbuilder. Assume base ten.
    public static StringBuilder Concat(this StringBuilder stringBuilder, ulong ulongVal, ulong padAmount) {
      stringBuilder.Concat(ulongVal, padAmount, MsDefaultPadChar, 10);
      return stringBuilder;
    }

    //! Convert a given unsigned integer value to a string and concatenate onto the stringbuilder. Assume base ten.
    public static StringBuilder Concat(
      this StringBuilder stringBuilder,
      ulong ulongVal,
      ulong padAmount,
      char padChar) {
      stringBuilder.Concat(ulongVal, padAmount, padChar, 10);
      return stringBuilder;
    }

    //! Convert a given signed integer value to a string and concatenate onto the stringbuilder. Any base value allowed.
    public static StringBuilder Concat(
      this StringBuilder stringBuilder,
      long longVal,
      ulong padAmount,
      char padChar,
      ulong baseVal) {
      Debug.Assert((baseVal > 0) && (baseVal <= 16));

      // Deal with negative numbers
      if (longVal < 0) {
        stringBuilder.Append('-');
        var ulongVal = ulong.MaxValue - (ulong)longVal + 1; //< This is to deal with Int64.MinValue
        stringBuilder.Concat(ulongVal, padAmount, padChar, baseVal);
      } else {
        stringBuilder.Concat((ulong)longVal, padAmount, padChar, baseVal);
      }

      return stringBuilder;
    }

    //! Convert a given signed integer value to a string and concatenate onto the stringbuilder. Assume no padding and base ten.
    public static StringBuilder Concat(this StringBuilder stringBuilder, long longVal) {
      stringBuilder.Concat(longVal, 0, MsDefaultPadChar, 10);
      return stringBuilder;
    }

    //! Convert a given signed integer value to a string and concatenate onto the stringbuilder. Assume base ten.
    public static StringBuilder Concat(this StringBuilder stringBuilder, long longVal, ulong padAmount) {
      stringBuilder.Concat(longVal, padAmount, MsDefaultPadChar, 10);
      return stringBuilder;
    }

    //! Convert a given signed integer value to a string and concatenate onto the stringbuilder. Assume base ten.
    public static StringBuilder Concat(
      this StringBuilder stringBuilder,
      long longVal,
      ulong padAmount,
      char padChar) {
      stringBuilder.Concat(longVal, padAmount, padChar, 10);
      return stringBuilder;
    }

    //! Convert a given signed integer value to a string and concatenate onto the stringbuilder. Any base value allowed.
    public static StringBuilder Concat(
      this StringBuilder stringBuilder,
      int intVal,
      ulong padAmount,
      char padChar,
      ulong baseVal) {
      Debug.Assert((baseVal > 0) && (baseVal <= 16));

      // Deal with negative numbers
      if (intVal < 0) {
        stringBuilder.Append('-');
        var ulongVal = ulong.MaxValue - (ulong)intVal + 1; //< This is to deal with Int32.MinValue
        stringBuilder.Concat(ulongVal, padAmount, padChar, baseVal);
      } else {
        stringBuilder.Concat((ulong)intVal, padAmount, padChar, baseVal);
      }

      return stringBuilder;
    }

    //! Convert a given signed integer value to a string and concatenate onto the stringbuilder. Assume no padding and base ten.
    public static StringBuilder Concat(this StringBuilder stringBuilder, int intVal) {
      stringBuilder.Concat(intVal, 0, MsDefaultPadChar, 10);
      return stringBuilder;
    }

    //! Convert a given signed integer value to a string and concatenate onto the stringbuilder. Assume base ten.
    public static StringBuilder Concat(this StringBuilder stringBuilder, int intVal, ulong padAmount) {
      stringBuilder.Concat(intVal, padAmount, MsDefaultPadChar, 10);
      return stringBuilder;
    }

    //! Convert a given signed integer value to a string and concatenate onto the stringbuilder. Assume base ten.
    public static StringBuilder Concat(this StringBuilder stringBuilder, int intVal, ulong padAmount, char padChar) {
      stringBuilder.Concat(intVal, padAmount, padChar, 10);
      return stringBuilder;
    }

    //! Convert a given double value to a string and concatenate onto the stringbuilder
    public static StringBuilder Concat(
      this StringBuilder stringBuilder,
      double doubleVal,
      uint decimalPlaces,
      uint padAmount,
      char padChar,
      CultureInfo culturInfo = null) {
      culturInfo = culturInfo ?? CultureInfo.CurrentCulture;

      if (decimalPlaces == 0) {
        // No decimal places, just round up and print it as an int

        // Agh, Math.Floor() just works on doubles/decimals. Don't want to cast! Let's do this the old-fashioned way.
        int intVal;
        if (doubleVal >= 0.0d) intVal = (int)(doubleVal + 0.5d);
        else intVal = (int)(doubleVal - 0.5d);

        stringBuilder.Concat(intVal, padAmount, padChar, 10);
      } else {
        var intPart = (int)doubleVal;

        // First part is easy, just cast to an integer
        stringBuilder.Concat(intPart, padAmount, padChar, 10);

        // Decimal point
        var numberDecimalSeparator = Convert.ToChar(culturInfo.NumberFormat.NumberDecimalSeparator);
        stringBuilder.Append(numberDecimalSeparator);

        // Work out remainder we need to print after the d.p.
        var remainder = Math.Abs(doubleVal - intPart);

        // Multiply up to become an int that we can print
        do {
          remainder *= 10;
          decimalPlaces--;
        }
        while (remainder > (int)remainder && decimalPlaces > 0);

        // Round up. It's guaranteed to be a positive number, so no extra work required here.
        remainder += 0.5d;

        // All done, print that as an int!
        stringBuilder.Concat((ulong)remainder, 0, '0', 10);
      }
      return stringBuilder;
    }

    //! Convert a given double value to a string and concatenate onto the stringbuilder. Assumes five decimal places, and no padding.
    public static StringBuilder Concat(this StringBuilder stringBuilder, double doubleVal, CultureInfo culturInfo = null) {
      culturInfo = culturInfo ?? CultureInfo.CurrentCulture;

      stringBuilder.Concat(doubleVal, (uint)culturInfo.NumberFormat.NumberDecimalDigits, 0, MsDefaultPadChar, culturInfo);
      return stringBuilder;
    }

    //! Convert a given double value to a string and concatenate onto the stringbuilder. Assumes no padding.
    public static StringBuilder Concat(this StringBuilder stringBuilder, double doubleVal, uint decimalPlaces, CultureInfo culturInfo = null) {
      stringBuilder.Concat(doubleVal, decimalPlaces, 0, MsDefaultPadChar, culturInfo);
      return stringBuilder;
    }

    //! Convert a given double value to a string and concatenate onto the stringbuilder.
    public static StringBuilder Concat(
      this StringBuilder stringBuilder,
      double doubleVal,
      uint decimalPlaces,
      uint padAmount,
      CultureInfo culturInfo = null) {

      stringBuilder.Concat(doubleVal, decimalPlaces, padAmount, MsDefaultPadChar, culturInfo);
      return stringBuilder;
    }
  }
}