using System;
/*
 * $Id: Matrix.cs 163 2010-04-20 13:58:20Z psoares33 $
 *
 * This file is part of the iText project.
 * Copyright (c) 1998-2012 1T3XT BVBA
 * Authors: Kevin Day, Bruno Lowagie, Paulo Soares, et al.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License version 3
 * as published by the Free Software Foundation with the addition of the
 * following permission added to Section 15 as permitted in Section 7(a):
 * FOR ANY PART OF THE COVERED WORK IN WHICH THE COPYRIGHT IS OWNED BY 1T3XT,
 * 1T3XT DISCLAIMS THE WARRANTY OF NON INFRINGEMENT OF THIRD PARTY RIGHTS.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 * or FITNESS FOR A PARTICULAR PURPOSE.
 * See the GNU Affero General Public License for more details.
 * You should have received a copy of the GNU Affero General Public License
 * along with this program; if not, see http://www.gnu.org/licenses or write to
 * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
 * Boston, MA, 02110-1301 USA, or download the license from the following URL:
 * http://itextpdf.com/terms-of-use/
 *
 * The interactive user interfaces in modified source and object code versions
 * of this program must display Appropriate Legal Notices, as required under
 * Section 5 of the GNU Affero General Public License.
 *
 * In accordance with Section 7(b) of the GNU Affero General Public License,
 * you must retain the producer line in every PDF that is created or manipulated
 * using iText.
 *
 * You can be released from the requirements of the license by purchasing
 * a commercial license. Buying such a license is mandatory as soon as you
 * develop commercial activities involving the iText software without
 * disclosing the source code of your own applications.
 * These activities include: offering paid services to customers as an ASP,
 * serving PDFs on the fly in a web application, shipping iText with a closed
 * source product.
 *
 * For more information, please contact iText Software Corp. at this
 * address: sales@itextpdf.com
 */

namespace iTextSharp.text.pdf.parser {

    /**
     * Keeps all the values of a 3 by 3 matrix
     * and allows you to do some math with matrices.
     * @since   2.1.4
     */
    public class Matrix {
        /** the row=1, col=1 position ('a') in the matrix. */
        public const int I11 = 0; 
        /** the row=1, col=2 position ('b') in the matrix. */
        public const int I12 = 1; 
        /** the row=1, col=3 position (always 0 for 2-D) in the matrix. */
        public const int I13 = 2;
        /** the row=2, col=1 position ('c') in the matrix. */
        public const int I21 = 3; 
        /** the row=2, col=2 position ('d') in the matrix. */
        public const int I22 = 4;  
        /** the row=2, col=3 position (always 0 for 2-D) in the matrix. */
        public const int I23 = 5;  
        /** the row=3, col=1 ('e', or X translation) position in the matrix. */
        public const int I31 = 6;  
        /** the row=3, col=2 ('f', or Y translation) position in the matrix. */
        public const int I32 = 7;  
        /** the row=3, col=3 position (always 1 for 2-D) in the matrix. */
        public const int I33 = 8;   
        
        /** the values inside the matrix (the identity matrix by default). */
        private float[] vals = new float[]{
                1,0,0,
                0,1,0,
                0,0,1
        };
        
        /**
         * constructs a new Matrix with identity.
         */
        public Matrix() {
        }

        /**
         * Constructs a matrix that represents translation
         * @param tx
         * @param ty
         */
        public Matrix(float tx, float ty){
            vals[I31] = tx;
            vals[I32] = ty;
        }
        
        /**
         * Creates a Matrix with 6 specified entries
         * @param a
         * @param b
         * @param c
         * @param d
         * @param e
         * @param f
         */
        public Matrix(float a, float b, float c, float d, float e, float f){
            vals[I11] = a;
            vals[I12] = b;
            vals[I13] = 0;
            vals[I21] = c;
            vals[I22] = d;
            vals[I23] = 0;
            vals[I31] = e;
            vals[I32] = f;
            vals[I33] = 1;
        }
        
        /**
         * Gets a specific value inside the matrix.
         * @param   index   an array index corresponding with a value inside the matrix
         * @return  the value at that specific position.
         */
        public float this[int index] {
            get {
                return vals[index];
            }
        }
        
        /**
         * multiplies this matrix by 'b' and returns the result
         * See http://en.wikipedia.org/wiki/Matrix_multiplication
         * @param by The matrix to multiply by
         * @return  the resulting matrix
         */
        public Matrix Multiply(Matrix by){
            Matrix rslt = new Matrix();
            
            float[] a = vals;
            float[] b = by.vals;
            float[] c = rslt.vals;
            
            c[I11] = a[I11]*b[I11] + a[I12]*b[I21] + a[I13]*b[I31];  
            c[I12] = a[I11]*b[I12] + a[I12]*b[I22] + a[I13]*b[I32]; 
            c[I13] = a[I11]*b[I13] + a[I12]*b[I23] + a[I13]*b[I33]; 
            c[I21] = a[I21]*b[I11] + a[I22]*b[I21] + a[I23]*b[I31];  
            c[I22] = a[I21]*b[I12] + a[I22]*b[I22] + a[I23]*b[I32]; 
            c[I23] = a[I21]*b[I13] + a[I22]*b[I23] + a[I23]*b[I33]; 
            c[I31] = a[I31]*b[I11] + a[I32]*b[I21] + a[I33]*b[I31];  
            c[I32] = a[I31]*b[I12] + a[I32]*b[I22] + a[I33]*b[I32]; 
            c[I33] = a[I31]*b[I13] + a[I32]*b[I23] + a[I33]*b[I33]; 
            
            return rslt;
        }

        /**
         * Subtracts a matrix from this matrix and returns the results
         * @param arg the matrix to subtract from this matrix
         * @return a Matrix object
         */
        public Matrix Subtract(Matrix arg){
            Matrix rslt = new Matrix();
            
            float[] a = vals;
            float[] b = arg.vals;
            float[] c = rslt.vals;
            
            c[I11] = a[I11]-b[I11];  
            c[I12] = a[I12]-b[I12]; 
            c[I13] = a[I13]-b[I13]; 
            c[I21] = a[I21]-b[I21];  
            c[I22] = a[I22]-b[I22]; 
            c[I23] = a[I23]-b[I23]; 
            c[I31] = a[I31]-b[I31];  
            c[I32] = a[I32]-b[I32]; 
            c[I33] = a[I33]-b[I33]; 

            return rslt;
        }
        
        /**
         * Computes the determinant of the matrix.
         * @return the determinant of the matrix
         */
        public float GetDeterminant(){
            // ref http://en.wikipedia.org/wiki/Determinant   
            // note that in PDF, I13 and I23 are always 0 and I33 is always 1
            // so this could be simplified/faster
            return    vals[I11] * vals[I22] * vals[I33] 
                    + vals[I12] * vals[I23] * vals[I31]
                    + vals[I13] * vals[I21] * vals[I32]
                    - vals[I11] * vals[I23] * vals[I32]
                    - vals[I12] * vals[I21] * vals[I33]
                    - vals[I13] * vals[I22] * vals[I31];
        }

        /**
         * Checks equality of matrices.
         * @param obj   the other Matrix that needs to be compared with this matrix.
         * @return  true if both matrices are equal
         * @see java.lang.Object#equals(java.lang.Object)
         */
        public override bool Equals(Object obj) {
            if (!(obj is Matrix))
                return false;
            Matrix other = (Matrix)obj;
            for (int i = 0; i < vals.Length; i++) {
                if (vals[i] != other.vals[i])
                    return false;
            }
            return true;
        }
        
        /**
         * Generates a hash code for this object.
         * @return  the hash code of this object
         * @see java.lang.Object#hashCode()
         */
        public override int GetHashCode() {            
            int result = 1;
            for (int i = 0; i < vals.Length; i++)
                result = 31 * result + vals[i].GetHashCode();
            return result;
        }
        
        /**
         * Generates a String representation of the matrix.
         * @return  the values, delimited with tabs and newlines.
         * @see java.lang.Object#toString()
         */
        public override String ToString() {
            return  vals[I11] + "\t" + vals[I12] + "\t" + vals[I13] + "\n" + 
                    vals[I21] + "\t" + vals[I22] + "\t" + vals[I13] + "\n" +
                    vals[I31] + "\t" + vals[I32] + "\t" + vals[I33];
        }
    }
}