/////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// File:	StringBuilderExtNumeric.cs
// Date:	9th March 2010
// Author:	Gavin Pugh
// Details:	Extension methods for the 'StringBuilder' standard .NET class, to allow garbage-free concatenation of
//			a selection of simple numeric types.  
//
// Copyright (c) Gavin Pugh 2010 - Released under the zlib license: http://www.opensource.org/licenses/zlib-license.php
/////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Diagnostics;

namespace StringLeakTest
{
	public static partial class StringBuilderExtensions
	{
		// 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[]	ms_digits = new char[] { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F' };

		private static readonly uint	ms_default_decimal_places = 5; //< Matches standard .NET formatting dp's
		private static readonly char	ms_default_pad_char = '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 string_builder, uint uint_val, uint pad_amount, char pad_char, uint base_val )
		{
			Debug.Assert( pad_amount >= 0 );
			Debug.Assert( base_val > 0 && base_val <= 16 );

			// Calculate length of integer when written out
			uint length = 0;
			uint length_calc = uint_val;

			do
			{
				length_calc /= base_val;
				length++;
			}
			while ( length_calc > 0 );

			// Pad out space for writing.
			string_builder.Append( pad_char, (int)Math.Max( pad_amount, length ));

			int strpos = string_builder.Length;

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

				// Lookup from static char array, to cover hex values too
				string_builder[strpos] = ms_digits[uint_val % base_val];

				uint_val /= base_val;
				length--;
			}

			return string_builder;
		}

		//! 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 string_builder, uint uint_val )
		{
			string_builder.Concat( uint_val, 0, ms_default_pad_char, 10 );
			return string_builder;
		}

		//! Convert a given unsigned integer value to a string and concatenate onto the stringbuilder. Assume base ten.
		public static StringBuilder Concat( this StringBuilder string_builder, uint uint_val, uint pad_amount )
		{
			string_builder.Concat( uint_val, pad_amount, ms_default_pad_char, 10 );
			return string_builder;
		}

		//! Convert a given unsigned integer value to a string and concatenate onto the stringbuilder. Assume base ten.
		public static StringBuilder Concat( this StringBuilder string_builder, uint uint_val, uint pad_amount, char pad_char )
		{
			string_builder.Concat( uint_val, pad_amount, pad_char, 10 );
			return string_builder;
		}

		//! Convert a given signed integer value to a string and concatenate onto the stringbuilder. Any base value allowed.
		public static StringBuilder Concat( this StringBuilder string_builder, int int_val, uint pad_amount, char pad_char, uint base_val )
		{
			Debug.Assert( pad_amount >= 0 );
			Debug.Assert( base_val > 0 && base_val <= 16 );

			// Deal with negative numbers
			if (int_val < 0)
			{
				string_builder.Append( '-' );
				uint uint_val = uint.MaxValue - ((uint) int_val ) + 1; //< This is to deal with Int32.MinValue
				string_builder.Concat( uint_val, pad_amount, pad_char, base_val );
			}
			else
			{
				string_builder.Concat((uint)int_val, pad_amount, pad_char, base_val );
			}

			return string_builder;
		}

		//! 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 string_builder, int int_val )
		{
			string_builder.Concat( int_val, 0, ms_default_pad_char, 10 );
			return string_builder;
		}

		//! Convert a given signed integer value to a string and concatenate onto the stringbuilder. Assume base ten.
		public static StringBuilder Concat( this StringBuilder string_builder, int int_val, uint pad_amount )
		{
			string_builder.Concat( int_val, pad_amount, ms_default_pad_char, 10 );
			return string_builder;
		}

		//! Convert a given signed integer value to a string and concatenate onto the stringbuilder. Assume base ten.
		public static StringBuilder Concat( this StringBuilder string_builder, int int_val, uint pad_amount, char pad_char )
		{
			string_builder.Concat( int_val, pad_amount, pad_char, 10 );
			return string_builder;
		}

		//! Convert a given float value to a string and concatenate onto the stringbuilder
		public static StringBuilder Concat( this StringBuilder string_builder, float float_val, uint decimal_places, uint pad_amount, char pad_char )
		{
			Debug.Assert( pad_amount >= 0 );

			if ( decimal_places == 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 int_val;
				if ( float_val >= 0.0f )
				{
					// Round up
					int_val = (int)( float_val + 0.5f );
				}
				else
				{
					// Round down for negative numbers
					int_val = (int)( float_val - 0.5f );
				}

				string_builder.Concat( int_val, pad_amount, pad_char, 10 );
			}
			else
			{
				int int_part = (int)float_val;

				// First part is easy, just cast to an integer
				string_builder.Concat( int_part, pad_amount, pad_char, 10 );

				// Decimal point
				string_builder.Append( '.' );

				// Work out remainder we need to print after the d.p.
				float remainder = Math.Abs( float_val - int_part );

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

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

				// All done, print that as an int!
				string_builder.Concat( (uint)remainder, 0, '0', 10 );
			}
			return string_builder;
		}
		
		//! Convert a given float value to a string and concatenate onto the stringbuilder. Assumes five decimal places, and no padding.
		public static StringBuilder Concat(this StringBuilder string_builder, float float_val)
		{
			string_builder.Concat(float_val, ms_default_decimal_places, 0, ms_default_pad_char);
			return string_builder;
		}

		//! Convert a given float value to a string and concatenate onto the stringbuilder. Assumes no padding.
		public static StringBuilder Concat( this StringBuilder string_builder, float float_val, uint decimal_places )
		{
			string_builder.Concat (float_val, decimal_places, 0, ms_default_pad_char );
			return string_builder;
		}

		//! Convert a given float value to a string and concatenate onto the stringbuilder.
		public static StringBuilder Concat(this StringBuilder string_builder, float float_val, uint decimal_places, uint pad_amount)
		{
			string_builder.Concat(float_val, decimal_places, pad_amount, ms_default_pad_char);
			return string_builder;
		}
	}
}