// -*- Mode: C; tab-width: 8; indent-tabs-mode: t; c-basic-offset: 8 -*-
//
// System.Text.StringBuilder
//
// Author: Marcin Szczepanski (marcins@zipworld.com.au)
//
// TODO: Implement the AppendFormat methods.  Wasn't sure how
// best to do this at this early stage, might want to see
// how the String class and the IFormatProvider / IFormattable interfaces
// pan out first.
//  
// TODO: Make sure the coding complies to the ECMA draft, there's some
// variable names that probably don't (like sString)
//
namespace System.Text {
	public sealed class StringBuilder {

		private const int defaultCapacity = 16;

		private int sCapacity;
		private int sLength;
		private char[] sString;
		private int sMaxCapacity = Int32.MaxValue;

		public StringBuilder(string str, int startIndex, int length, int capacity) {
			// the capacity must be at least as big as the default capacity
			// LAMESPEC: what to do if capacity is too small to hold the substring?
			// For now, truncate the substring to "capacity" characters
			sCapacity = Math.Max(capacity, defaultCapacity);
			sString = new char[sCapacity];

			// LAMESPEC: what to do if startIndex is too big?  Throw an exception?  Which one?
			// For now, if the startIndex is beyond the end of the string, create an empty StringBuilder
			// Also, if str is null, then create an empty StringBuilder
			if (null == str || startIndex > str.Length - 1) 
			{
				sLength = 0;
			}
			else
			{
				// LAMESPEC: what if the length specified would take us past the end of the string?
				// For now, copy to the end of the string
				// First find out how many characters we can actually copy
				sLength = Math.Min(length, str.Length - startIndex);
				// Then limit the length to the capacity if necessary.  See LAMESPEC above.
				sLength = Math.Min(sLength, capacity);
			}

			// if the length is not going to be zero, then we have to copy some characters
			if (sLength > 0) {
				// Copy the correct number of characters into the internal array
				char[] tString = str.ToCharArray(startIndex, sLength);
				Array.Copy( tString, sString, sLength);
			}
		}

		public StringBuilder() : this(null, 0, 0, 0) {}

		public StringBuilder( int capacity ) : this(null, 0, 0, capacity) {}

		public StringBuilder( int capacity, int maxCapacity ) : this(null, 0, 0, capacity) {
			sMaxCapacity = maxCapacity;
		}

		public StringBuilder( string str ) : this(str, 0, str.Length, str.Length) {}
	
		public StringBuilder( string str, int capacity) : this(str, 0, str.Length, capacity) {}
	
		public int MaxCapacity 
		{
			get 
			{
				// TODO: Need to look at the memory of the system to return a useful value here
				return sMaxCapacity;
			}
		}

		public int Capacity {
			get {
				return sCapacity;
			}

			set {
				if( value < sLength ) {
					throw new ArgumentException( "Capacity must be > length" );
				} else {
					char[] tString = new char[value];	       
					Array.Copy( sString, tString, sLength );
					sString = tString;
					sCapacity = sString.Length;
				}
			}
		}


		public int Length {
			get {
				return sLength;
			}

			set {
				if( value < 0 || value > Int32.MaxValue) {
					throw new ArgumentOutOfRangeException();
				} else {
					if( value < sLength ) {
						// Truncate current string at value

						// LAMESPEC:  The spec is unclear as to what to do
						// with the capacity when truncating the string.
						//
						// Don't change the capacity, as this is what
						// the MS implementation does.

						sLength = value;
					} else {
						// Expand the capacity to the new length and
						// pad the string with spaces.
						
						// LAMESPEC: The spec says to put the spaces on the
						// left of the string however the MS implementation
						// puts them on the right.  We'll do that for 
						// compatibility (!)

						char[] tString = new char[ value ];
						int padLength = value - sLength;
						
						string padding = new String( ' ', padLength );
						Array.Copy( sString, tString, sLength );
						Array.Copy( padding.ToCharArray(), 0, tString, sLength, padLength );
						sString = tString;
						sLength = sString.Length;
						sCapacity = value;
					}
				}
			}
		}

		public char this[ int index ] {
			get {

				if( index >= sLength || index < 0 ) {
					throw new IndexOutOfRangeException();
				}
				return sString[ index ];
			} 

			set {
				if( index >= sLength || index < 0 ) {
					throw new IndexOutOfRangeException();
				}
				sString[ index ] = value;
			}
		}

		public override string ToString() {
			return ToString(0, sLength);
		}

		public string ToString( int startIndex, int length ) {
			if( startIndex < 0 || length < 0 || startIndex + length > sLength ) {
				throw new ArgumentOutOfRangeException();
			}
	
			return new String( sString, startIndex, length );
		}

		public int EnsureCapacity( int capacity ) {
			if( capacity < 0 ) {
				throw new ArgumentOutOfRangeException( 
									"Capacity must be greater than 0." );
			}

			if( capacity <= sCapacity ) {
				return sCapacity;
			} else {
				Capacity = capacity;
				return sCapacity;
			}
		}

		public bool Equals( StringBuilder sb ) {
			if( this.ToString() == sb.ToString() ) {
				return true;
			} else {
				return false;
			}
		}

		public StringBuilder Remove( int startIndex, int length ) {
			if( startIndex < 0 || length < 0 || startIndex + length > sLength ) {
				throw new ArgumentOutOfRangeException();
			}

			// Copy everything after the 'removed' part to the start 
						// of the removed part and truncate the sLength

			Array.Copy( sString, startIndex + length, sString, 
							startIndex, length );

			sLength -= length;
			return this;
		}			       

		public StringBuilder Replace( char oldChar, char newChar ) {
		
				return Replace( oldChar, newChar, 0, sLength);
		}

		public StringBuilder Replace( char oldChar, char newChar, int startIndex, int count ) {
			if( startIndex + count > sLength || startIndex < 0 || count < 0 ) {
				throw new ArgumentOutOfRangeException();
			}

			for( int replaceIterate = startIndex; replaceIterate < startIndex + count; replaceIterate++ ) {
				if( this[replaceIterate] == oldChar ) {
					this[replaceIterate] = newChar;
				}
			}

			return this;
		}

		public StringBuilder Replace( string oldValue, string newValue ) {
			return Replace( oldValue, newValue, 0, sLength );
		}

		public StringBuilder Replace( string oldValue, string newValue, int startIndex, int count ) {
			string startString = this.ToString();
			StringBuilder newStringB = new StringBuilder();
			string newString;

			if( oldValue == null ) { 
				throw new ArgumentNullException(
									"The old value cannot be null.");
			}

			if( startIndex < 0 || count < 0 || startIndex + count > sLength ) {
				throw new ArgumentOutOfRangeException();
			}

			if( oldValue.Length == 0 ) {
				throw new ArgumentException(
									"The old value cannot be zero length.");
			}

			int nextIndex = startIndex; // Where to start the next search
			int lastIndex = nextIndex;  // Where the last search finished

			while( nextIndex != -1 ) {
				nextIndex = startString.IndexOf( oldValue, lastIndex);				  
				if( nextIndex != -1 ) {
					// The MS implementation won't replace a substring 
										// if that substring goes over the "count"
										// boundary, so we'll make sure the behaviour 
										// here is the same.

					if( nextIndex + oldValue.Length <= startIndex + count ) {

						// Add everything to the left of the old 
												// string
						newStringB.Append( startString.Substring( lastIndex, nextIndex - lastIndex ) );
	
						// Add the replacement string
						newStringB.Append( newValue );
						
						// Set the next start point to the 
												// end of the last match
						lastIndex = nextIndex + oldValue.Length;
					} else {
						// We're past the "count" we're supposed to replace within
						nextIndex = -1;
						newStringB.Append( 
													startString.Substring( lastIndex ) );
					}

				} else {
					// Append everything left over
					newStringB.Append( startString.Substring( lastIndex ) );
				}
			} 

			newString = newStringB.ToString();

			EnsureCapacity( newString.Length );
			sString = newString.ToCharArray();
			sLength = newString.Length;
			return this;
		}

		      
		    /* The Append Methods */

		// TODO: Currently most of these methods convert the 
		// parameter to a CharArray (via a String) and then pass
		// it to Append( char[] ).  There might be a faster way
		// of doing this, but it's probably adequate and anything else
		// would make it too messy.
		//
		// As an example, a sample test run of appending a 100 character
		// string to the StringBuilder, and loooping this 50,000 times
		// results in an elapsed time of 2.4s using the MS StringBuilder
		// and 2.7s using this StringBuilder.  Note that this results
		// in a 5 million character string.  I believe MS uses a lot
		// of "native" DLLs for the "meat" of the base classes.


		public StringBuilder Append( char[] value ) {
			if( sLength + value.Length > sCapacity ) {
				// Need more capacity, double the capacity StringBuilder 
				// and make sure we have at least enough for the value 
				// if that's going to go over double. 
					 
				Capacity = value.Length + ( sCapacity + sCapacity);
			}

			Array.Copy( value, 0, sString, sLength, value.Length );
			sLength += value.Length;

			return this;
		} 
		
		public StringBuilder Append( string value ) {
			if( value != null ) {
				return Append( value.ToCharArray() );
			} else {
				return null;
			}
		}

		public StringBuilder Append( bool value ) {
			return Append( value.ToString().ToCharArray() );
		}
		
		public StringBuilder Append( byte value ) {
			return Append( value.ToString().ToCharArray() );
		}

		public StringBuilder Append( int index, char value) {
			char[] appendChar = new char[1];
			
			appendChar[0] = value;
			return Append( appendChar );
		}


		public StringBuilder Append( decimal value ) {
			return Append( value.ToString().ToCharArray() );
		}

		public StringBuilder Append( double value ) {
			return Append( value.ToString().ToCharArray() );
		}

		public StringBuilder Append( short value ) {
			return Append( value.ToString().ToCharArray() );
		}

		public StringBuilder Append( int value ) {
			return Append( value.ToString().ToCharArray() );
		}

		public StringBuilder Append( long value ) {
			return Append( value.ToString().ToCharArray() );
		}

		public StringBuilder Append( object value ) {
			return Append( value.ToString().ToCharArray() );
		}

		public StringBuilder Append( sbyte value ) {
			return Append( value.ToString().ToCharArray() );
		}

		public StringBuilder Append( float value ) {
			return Append( value.ToString().ToCharArray() );
		}

		public StringBuilder Append( ushort value ) {
			return Append( value.ToString().ToCharArray() );
		}	
		
		public StringBuilder Append( uint value ) {
			return Append( value.ToString().ToCharArray() );
		}

		public StringBuilder Append( ulong value ) {
			return Append( value.ToString().ToCharArray() );
		}

		public StringBuilder Append( char value ) {
			return Append (value, 1);
		}

		public StringBuilder Append( char value, int repeatCount ) {
			if( repeatCount < 0 ) {
				throw new ArgumentOutOfRangeException();
			}

			return Append( new String( value, repeatCount) );
		}

		public StringBuilder Append( char[] value, int startIndex, int charCount ) {

			if( (charCount < 0 || startIndex < 0) || 
					( charCount + startIndex > value.Length ) ) {
				throw new ArgumentOutOfRangeException();
			}
			
			if( value == null ) {
				if( !(startIndex == 0 && charCount == 0) ) {
					throw new ArgumentNullException();
				} else {
					return this;
				}
			} else {
				char[] appendChars = new char[ charCount ];
			
				Array.Copy( value, startIndex, appendChars, 0, charCount );
				return Append( appendChars );
			}
		}

		public StringBuilder Append( string value, int startIndex, int count ) {
			if( (count < 0 || startIndex < 0) || 
							( startIndex + count > value.Length ) ) { 
				throw new ArgumentOutOfRangeException();
			}

			return Append( value.Substring( startIndex, count ).ToCharArray() );
		}

		public StringBuilder AppendFormat( string format, object arg0 ) {
			// TODO: Implement
			return this;
		}

		public StringBuilder AppendFormat( string format, params object[] args ) {
			// TODO: Implement
			return this;
		}

		public StringBuilder AppendFormat( IFormatProvider provider, string format,
								params object[] args ) {
			// TODO: Implement
			return this;
		}

		public StringBuilder AppendFormat( string format, object arg0, object arg1 ) {
			// TODO: Implement;
			return this;
		}

		public StringBuilder AppendFormat( string format, object arg0, object arg1, object arg2 ) {
			// TODO Implement
			return this;
		}

		/*  The Insert Functions */
		
		// Similarly to the Append functions, get everything down to a CharArray 
		// and insert that.
		
		public StringBuilder Insert( int index, char[] value ) {
			if( index > sLength || index < 0) {
				throw new ArgumentOutOfRangeException();
			}

			if( value == null || value.Length == 0 ) {
				return this;
			} else {
				// Check we have the capacity to insert this array
				if( sCapacity < sLength + value.Length ) {
					Capacity = value.Length + ( sCapacity + sCapacity );
				}

				// Move everything to the right of the insert point across
				Array.Copy( sString, index, sString, index + value.Length, sLength - index);
				
				// Copy in stuff from the insert buffer
				Array.Copy( value, 0, sString, index, value.Length );
				
				sLength += value.Length;
				return this;
			}
		}
				
		public StringBuilder Insert( int index, string value ) {
			return Insert( index, value.ToCharArray() );
		}

		public StringBuilder Insert( int index, bool value ) {
			return Insert( index, value.ToString().ToCharArray() );
		}
		
		public StringBuilder Insert( int index, byte value ) {
			return Insert( index, value.ToString().ToCharArray() );
		}

		public StringBuilder Insert( int index, char value) {
			char[] insertChar = new char[1];
			
			insertChar[0] = value;
			return Insert( index, insertChar );
		}

		public StringBuilder Insert( int index, decimal value ) {
			return Insert( index, value.ToString().ToCharArray() );
		}

		public StringBuilder Insert( int index, double value ) {
			return Insert( index, value.ToString().ToCharArray() );
		}
		
		public StringBuilder Insert( int index, short value ) {
			return Insert( index, value.ToString().ToCharArray() );
		}

		public StringBuilder Insert( int index, int value ) {
			return Insert( index, value.ToString().ToCharArray() );
		}

		public StringBuilder Insert( int index, long value ) {
			return Insert( index, value.ToString().ToCharArray() );
		}
	
		public StringBuilder Insert( int index, object value ) {
			return Insert( index, value.ToString().ToCharArray() );
		}

		public StringBuilder Insert( int index, sbyte value ) {
			return Insert( index, value.ToString().ToCharArray() );
		}

		public StringBuilder Insert( int index, float value ) {
		return Insert( index, value.ToString().ToCharArray() );
		}

		public StringBuilder Insert( int index, ushort value ) {
			return Insert( index, value.ToString().ToCharArray() );
		}

		public StringBuilder Insert( int index, uint value ) {
			return Insert( index, value.ToString().ToCharArray() );
		}

		public StringBuilder Insert( int index, ulong value ) {
			return Insert( index, value.ToString().ToCharArray() );
		}

		public StringBuilder Insert( int index, string value, int count ) {
			if ( count < 0 ) {
				throw new ArgumentOutOfRangeException();
			}

			if( value != null ) {
				if( value != "" ) {
					for( int insertCount = 0; insertCount < count; 
											insertCount++ ) {
						Insert( index, value.ToCharArray() );	   
					}
				}
			}
			return this;
		}

		public StringBuilder Insert( int index, char[] value, int startIndex, 
					int charCount ) {

			if( value != null ) {
				if( charCount < 0 || startIndex < 0 || startIndex + charCount > value.Length ) {
					throw new ArgumentOutOfRangeException();
				}
					
				char[] insertChars = new char[ charCount  ];
				Array.Copy( value, startIndex, insertChars, 0, charCount );
				return Insert( index, insertChars );
			} else {
				return this;
			}
		}
	}
}