/*******************************************************************************
 * Copyright (c) 2014 Attila Kovacs <attila[AT]sigmyne.com>.
 * All rights reserved. 
 * 
 * This file is part of jnum.
 * 
 *     jnum is free software: you can redistribute it and/or modify
 *     it under the terms of the GNU General Public License as published by
 *     the Free Software Foundation, either version 3 of the License, or
 *     (at your option) any later version.
 * 
 *     jnum 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 General Public License for more details.
 * 
 *     You should have received a copy of the GNU General Public License
 *     along with jnum.  If not, see <http://www.gnu.org/licenses/>.
 * 
 * Contributors:
 *     Attila Kovacs <attila[AT]sigmyne.com> - initial API and implementation
 ******************************************************************************/


package jnum.math.matrix;

import java.util.Arrays;

import jnum.Copiable;
import jnum.Util;
import jnum.math.AbsoluteValue;
import jnum.math.AbstractAlgebra;
import jnum.math.LinearAlgebra;
import jnum.math.Metric;

import java.lang.reflect.*;


// [row][col] format. This way dot products are on middle indices....

/**
 * The Class GenericMatrix.
 *
 * @param <T> the generic type
 */
@SuppressWarnings("unchecked")
public class GenericMatrix<T extends Copiable<? super T> & LinearAlgebra<? super T> & AbstractAlgebra<? super T> & Metric<? super T> & AbsoluteValue> extends AbstractMatrix<T> {
	
	/** The Constant serialVersionUID. */
	private static final long serialVersionUID = -2705914561805806547L;

	/** The entry. */
	public T[][] entry; 
	
	/** The type. */
	protected Class<T> type;
	
	/**
	 * Instantiates a new generic matrix.
	 */
	protected GenericMatrix() {}
	
	/**
	 * Instantiates a new generic matrix.
	 *
	 * @param type the type
	 */
	public GenericMatrix(Class<T> type) { this.type = type; }

	// Check for rectangular shape
	/**
	 * Instantiates a new generic matrix.
	 *
	 * @param a the a
	 * @throws IllegalArgumentException the illegal argument exception
	 */
	public GenericMatrix(T[][] a) throws IllegalArgumentException { 
		this((Class<T>) a[0][0].getClass());
		entry = a; 
		validate();
	}

	/**
	 * Instantiates a new generic matrix.
	 *
	 * @param type the type
	 * @param rows the rows
	 * @param cols the cols
	 */
	public GenericMatrix(Class<T> type, int rows, int cols) { 
		super(type, rows, cols);
		this.type = type;
	}
	
	/* (non-Javadoc)
	 * @see kovacs.math.AbstractMatrix#getType()
	 */
	@Override
	public final Class<T> getType() { return type; }	
	
	/**
	 * New entry.
	 *
	 * @return the t
	 */
	public T newEntry() {
		try { return type.getConstructor().newInstance(); }
		catch(Exception e) { 
			Util.error(this, e);
			return null;
		}	
	}
	
	
	/* (non-Javadoc)
	 * @see kovacs.math.AbstractMatrix#noData()
	 */
	@Override
	public void noData() { entry = null; }
	
	/* (non-Javadoc)
	 * @see kovacs.math.AbstractMatrix#getData()
	 */
	@Override
	public Object getData() { return entry; }
	
	/* (non-Javadoc)
	 * @see kovacs.math.AbstractMatrix#getValue(int, int)
	 */
	@Override
	public final T getValue(int row, int col) { return entry[row][col]; }
	
	/* (non-Javadoc)
	 * @see kovacs.math.AbstractMatrix#setValue(int, int, java.lang.Object)
	 */
	@Override
	public final void setValue(int row, int col, T v) { entry[row][col] = v; }
	
	/* (non-Javadoc)
	 * @see kovacs.math.AbstractMatrix#validate()
	 */
	@Override
	public void validate() {
		super.validate();
		for(int i=rows(); --i >= 0; ) for(int j=cols(); --j >= 0; ) if(entry[i][j] == null) 
			throw new NullPointerException(getClass().getSimpleName() + " has null entries");
	}
	
	/* (non-Javadoc)
	 * @see kovacs.math.AbstractMatrix#checkShape()
	 */
	@Override
	protected void checkShape() throws IllegalStateException {
		if(getData() == null) return;
		if(rows() == 0) return;
		int m = cols();
		for(int i=rows(); --i > 0; ) if(entry[i].length != m) throw new IllegalStateException("Matrix has non-rectangular shape!");	
	}
	
	/* (non-Javadoc)
	 * @see kovacs.math.AbstractMatrix#calcProduct(kovacs.math.AbstractMatrix, kovacs.math.AbstractMatrix, boolean)
	 */
	@Override
	protected synchronized void calcProduct(AbstractMatrix<? extends T> A, AbstractMatrix<? extends T> B, boolean clearFirst) {		
		T term = newEntry();
		
		if(clearFirst) zero();
		
		for(int i=A.rows(); --i >= 0; ) for(int j=B.cols(); --j >= 0; ) for(int k=A.cols(); --k >= 0; ) {
			term.setProduct(A.getValue(i, k), B.getValue(k, j));
			entry[i][j].add(term);
		}
	}
	
	/**
	 * Dot.
	 *
	 * @param v the v
	 * @return the t[]
	 */
	public T[] dot(double[] v) {
		T[] result = (T[]) Array.newInstance(type, rows());
		dot(v, result);
		return result;
	}
	
	/**
	 * Dot.
	 *
	 * @param v the v
	 * @param result the result
	 */
	public void dot(double[] v, T[] result) {
		if(v.length != cols()) throw new IllegalArgumentException("Mismatched matrix/input-vector sizes.");
		if(result.length != rows()) throw new IllegalArgumentException("Mismatched matrix/output-vector sizes.");
		for(int i=rows(); --i >= 0; ) {
			result[i].zero();
			for(int j=cols(); --j >= 0; ) result[i].addScaled(entry[i][j], v[j]);
		}
	}
	
	/**
	 * Dot.
	 *
	 * @param v the v
	 * @return the t[]
	 */
	public T[] dot(float[] v) {
		T[] result = (T[]) Array.newInstance(type, rows());
		dot(v, result);
		return result;
	}
	
	/**
	 * Dot.
	 *
	 * @param v the v
	 * @param result the result
	 */
	public void dot(float[] v, T[] result) {
		if(v.length != cols()) throw new IllegalArgumentException("Mismatched matrix/input-vector sizes.");
		if(result.length != rows()) throw new IllegalArgumentException("Mismatched matrix/output-vector sizes.");
		for(int i=rows(); --i >= 0; ) {
			result[i].zero();
			for(int j=cols(); --j >= 0; ) result[i].addScaled(entry[i][j], v[j]);
		}
	}
	
	/**
	 * Dot.
	 *
	 * @param v the v
	 * @return the t[]
	 */
	public T[] dot(T[] v) {
		T[] result = (T[]) Array.newInstance(type, rows());
		dot(v, result);
		return result;
	}
	
	/**
	 * Dot.
	 *
	 * @param v the v
	 * @param result the result
	 */
	public synchronized void dot(T[] v, T[] result) {
		if(v.length != cols()) throw new IllegalArgumentException("Mismatched matrix/input-vector sizes.");
		if(result.length != rows()) throw new IllegalArgumentException("Mismatched matrix/output-vector sizes.");
		
		T term = newEntry();
		
		for(int i=rows(); --i >= 0; ) {
			result[i].zero();
			for(int j=cols(); --j >= 0; ) {
				term.setProduct(entry[i][j], v[j]);
				result[i].add(term);
			}
		}
	}
	
	
	/**
	 * Dot.
	 *
	 * @param v the v
	 * @return the generic vector
	 */
	public GenericVector<T> dot(RealVector v) {
		GenericVector<T> result = new GenericVector<T>(type, rows());
		dot(v, result);
		return result;
	}
	
	/**
	 * Dot.
	 *
	 * @param v the v
	 * @param result the result
	 */
	public void dot(RealVector v, GenericVector<T> result) {
		if(v.size() != cols()) throw new IllegalArgumentException("Mismatched matrix/input-vector sizes.");
		if(result.component == null) result.setSize(rows());
		else if(result.size() != rows()) result.setSize(rows());
		dot(v.component, result.component);
	}
	
	/**
	 * Dot.
	 *
	 * @param v the v
	 * @return the generic vector
	 */
	public GenericVector<T> dot(GenericVector<T> v) {
		GenericVector<T> result = new GenericVector<T>(type, rows());
		dot(v, result);
		return result;
	}
	
	/**
	 * Dot.
	 *
	 * @param v the v
	 * @param result the result
	 */
	public void dot(GenericVector<T> v, GenericVector<T> result) {
		if(v.size() != cols()) throw new IllegalArgumentException("Mismatched matrix/input-vector sizes.");
		if(result.component == null) result.setSize(rows());
		else if(result.size() != rows()) result.setSize(rows());
		dot(v.component, result.component);
	}
	
	
	/* (non-Javadoc)
	 * @see kovacs.math.AbstractMatrix#getTransposed()
	 */
	@Override
	public AbstractMatrix<T> getTransposed() {		
		GenericMatrix<T> M = new GenericMatrix<T>(type, cols(), rows());
		for(int i=rows(); --i >= 0; ) for(int j=cols(); --j >= 0; ) M.entry[j][i] = entry[i][j];
		return M;
	}
	
	/* (non-Javadoc)
	 * @see kovacs.math.LinearAlgebra#zero()
	 */
	@Override
	public void zero() {
		if(entry != null) for(int i=entry.length; --i >= 0; ) for(int j=entry[i].length; --j >= 0; ) {
			if(entry[i][j] == null) entry[i][j] = newEntry();
			entry[i][j].zero();
		}
	}
	

	// TODO Various decompositions.
	
	// TODO implement fast multiplication?

	/* (non-Javadoc)
	 * @see kovacs.math.LinearAlgebra#addMultipleOf(java.lang.Object, double)
	 */
	@Override
	public void addScaled(AbstractMatrix<? extends T> o, double factor) {
		for(int i=rows(); --i >= 0; ) for(int j=cols(); --j >= 0; ) entry[i][j].addScaled(o.getValue(i, j), factor);
	}

	/* (non-Javadoc)
	 * @see kovacs.math.Additive#subtract(java.lang.Object)
	 */
	@Override
	public void subtract(AbstractMatrix<? extends T> o) {
		for(int i=rows(); --i >= 0; ) for(int j=cols(); --j >= 0; ) entry[i][j].subtract(o.getValue(i, j));
	}

	/* (non-Javadoc)
	 * @see kovacs.math.Additive#add(java.lang.Object)
	 */
	@Override
	public void add(AbstractMatrix<? extends T> o) {
		for(int i=rows(); --i >= 0; ) for(int j=cols(); --j >= 0; ) entry[i][j].add(o.getValue(i, j));		
	}

	/* (non-Javadoc)
	 * @see kovacs.math.Scalable#scale(double)
	 */
	@Override
	public void scale(double factor) {
		for(int i=rows(); --i >= 0; ) for(int j=cols(); --j >= 0; ) entry[i][j].scale(factor);
	}

	/* (non-Javadoc)
	 * @see kovacs.math.Metric#distanceTo(java.lang.Object)
	 */
	@Override
	public double distanceTo(AbstractMatrix<? extends T> o) {
		double d2 = 0.0;
		for(int i=rows(); --i >= 0; ) for(int j=cols(); --j >= 0; ) {
			double d = entry[i][j].distanceTo(o.getValue(i, j));
			d2 += d*d;
		}
		return Math.sqrt(d2);
	}

	/* (non-Javadoc)
	 * @see kovacs.math.AbstractMatrix#cols()
	 */
	@Override
	public final int cols() { return entry[0].length; }

	/* (non-Javadoc)
	 * @see kovacs.math.AbstractMatrix#rows()
	 */
	@Override
	public final int rows() { return entry.length; }

	/* (non-Javadoc)
	 * @see kovacs.math.IdentityValue#setIdentity()
	 */
	@Override
	public void setIdentity() {		
		T value = newEntry();
		value.setIdentity();
		setScalar(value);
	}
	
	/* (non-Javadoc)
	 * @see kovacs.math.AbstractMatrix#setScalar(java.lang.Object)
	 */
	@Override
	public void setScalar(T value) {		
		entry = (T[][]) Array.newInstance(type, new int[] {1, 1});
		entry[0][0] = value;
	}
	 
	/* (non-Javadoc)
	 * @see kovacs.math.MatrixAlgebra#gaussJordan()
	 */
	@Override
	public void gaussJordan() {
		int rows = rows();
		int cols = cols();
			
		int[] indxc = new int[rows];
		int[] indxr = new int[rows];
		int[] ipiv = new int[rows];

		Arrays.fill(ipiv, -1);
		
		T temp = newEntry();
		T unused = newEntry();

		for(int i=rows; --i >= 0; ) {
			int icol=-1, irow=-1;
			double big=0.0;
			for(int j=rows; --j >= 0; ) if(ipiv[j] != 0) for(int k=rows; --k >= 0; ) {
				if(ipiv[k] == -1) {
					if(entry[j][k].abs() >= big) {
						big=entry[j][k].abs();
						irow=j;
						icol=k;
					}
				} 
				else if(ipiv[k] > 0) throw new IllegalArgumentException("Singular Matrix-1 during Gauss-Jordan elimination.");
			}
			++(ipiv[icol]);
			if(irow != icol) {
				for(int l=cols; --l >= 0; ) {
					temp = entry[irow][l];
					entry[irow][l] = entry[icol][l];
					entry[icol][l] = temp;
				}
			}
			indxr[i]=irow;
			indxc[i]=icol;
			if(entry[icol][icol].isNull()) throw new IllegalArgumentException("Singular Matrix-2 during Gauss-Jordan elimination.");
			
			temp = entry[icol][icol];
			temp.inverse();
			unused.setIdentity();
			entry[icol][icol] = unused;
			scaleRow(icol, temp);
			unused = temp;
			
			for(int ll=rows; --ll >= 0; ) if(ll != icol) {
				temp = entry[ll][icol];
				temp.scale(-1.0);
				unused.zero();
				entry[ll][icol] = unused;
				addMultipleOfRow(icol, ll, temp);
				unused = temp;
			}
		}
		for(int l=rows; -- l>= 0; ) if(indxr[l] != indxc[l]) for(int k=rows; --k >= 0; ) {
			temp = entry[k][indxr[l]];
			entry[k][indxr[l]] = entry[k][indxc[l]];
			entry[k][indxc[l]] = temp;
		}
	}
	
	

	/* (non-Javadoc)
	 * @see kovacs.math.AbstractMatrix#getColumn(int, java.lang.Object)
	 */
	@Override
	public void getColumn(int j, Object buffer) {
		T[] array = (T[]) buffer;
		for(int i=rows(); --i >= 0; ) array[i] = entry[i][j];
	}

	/* (non-Javadoc)
	 * @see kovacs.math.AbstractMatrix#getRow(int)
	 */
	@Override
	public T[] getRow(int i) {
		return entry[i];
	}
	
	/* (non-Javadoc)
	 * @see kovacs.math.AbstractMatrix#getRow(int, java.lang.Object)
	 */
	@Override
	public void getRow(int i, Object buffer) {
		T[] array = (T[]) buffer;
		for(int j=cols(); --j >= 0; ) array[j] = entry[i][j];
	}
	

	/* (non-Javadoc)
	 * @see kovacs.math.AbstractMatrix#setColumn(int, java.lang.Object)
	 */
	@Override
	public void setColumn(int j, Object value) throws IllegalArgumentException {
		T[] array = (T[]) value;
		if(array.length != rows()) throw new IllegalArgumentException("Cannot add mismatched " + getClass().getSimpleName() + " column.");
		for(int i=rows(); --i >= 0; ) entry[i][j] = array[i];
	}

	/* (non-Javadoc)
	 * @see kovacs.math.AbstractMatrix#setData(java.lang.Object)
	 */
	@Override
	public void setData(Object data) {
		entry = (T[][]) data;
	}

	/* (non-Javadoc)
	 * @see kovacs.math.AbstractMatrix#setRow(int, java.lang.Object)
	 */
	@Override
	public void setRow(int i, Object value) {
		T[] array = (T[]) value;
		if(array.length != cols()) throw new IllegalArgumentException("Cannot add mismatched " + getClass().getSimpleName() + " row.");
		entry[i] = array;
	}
	
	/* (non-Javadoc)
	 * @see kovacs.math.AbstractMatrix#switchRows(int, int)
	 */
	@Override
	public final void switchRows(int i, int j) {
		T[] temp = entry[i];
		entry[i] = entry[j];
		entry[j] = temp;	
	}
	
	/* (non-Javadoc)
	 * @see kovacs.math.AbstractMatrix#switchElements(int, int, int, int)
	 */
	@Override
	public final void switchElements(int i1, int j1, int i2, int j2) {
		T temp = entry[i1][j1];
		entry[i1][j1] = entry[i2][j2];
		entry[i2][j2] = temp;	
	}
	
	/* (non-Javadoc)
	 * @see kovacs.math.AbstractMatrix#addMultipleOfRow(int, int, double)
	 */
	@Override
	public void addMultipleOfRow(int row, int toRow, double scaling) {
		for(int j=cols(); --j >= 0; ) entry[toRow][j].addScaled(entry[row][j], scaling);
	}
	
	/* (non-Javadoc)
	 * @see kovacs.math.AbstractMatrix#addMultipleOfRow(int, int, java.lang.Object)
	 */
	@Override
	public synchronized void addMultipleOfRow(int row, int toRow, T scaling) {
		T term = newEntry();
		
		for(int j=cols(); --j >= 0; ) {
			term.setProduct(entry[row][j], scaling);
			entry[toRow][j].add(term);
		}
	}
	
	/* (non-Javadoc)
	 * @see kovacs.math.AbstractMatrix#addRow(int, int)
	 */
	@Override
	public void addRow(int row, int toRow) {
		for(int j=cols(); --j >= 0; ) entry[toRow][j].add(entry[row][j]);	
	}
	
	/* (non-Javadoc)
	 * @see kovacs.math.AbstractMatrix#subtractRow(int, int)
	 */
	@Override
	public void subtractRow(int row, int fromRow) {
		for(int j=cols(); --j >= 0; ) entry[fromRow][j].subtract(entry[row][j]);		
	}
	
	/* (non-Javadoc)
	 * @see kovacs.math.AbstractMatrix#zeroRow(int)
	 */
	@Override
	public void zeroRow(int i) {
		for(int j=cols(); --j >= 0; ) {
			if(entry[i][j] == null) entry[i][j] = newEntry();
			entry[i][j].zero();
		}
	}
	
	/* (non-Javadoc)
	 * @see kovacs.math.AbstractMatrix#scaleRow(int, double)
	 */
	@Override
	public void scaleRow(int i, double factor) {
		for(int j=0; j<cols(); j++) entry[i][j].scale(factor);
	}
	
	/* (non-Javadoc)
	 * @see kovacs.math.AbstractMatrix#scaleRow(int, java.lang.Object)
	 */
	@Override
	public void scaleRow(int i, T factor) {
		for(int j=cols(); --j >= 0; ) entry[i][j].multiplyBy(factor);
	}

	/**
	 * Offset.
	 *
	 * @param value the value
	 */
	public void offset(T value) {
		for(int i=rows(); --i >= 0; ) for(int j=cols(); --j >= 0; ) entry[i][j].add(value);			
	}

	/* (non-Javadoc)
	 * @see kovacs.math.AbstractMatrix#getRank()
	 */
	@Override
	public int getRank() {
		GenericMatrix<T> copy = (GenericMatrix<T>) copy();
		copy.gauss();
		int rank = 0;
		int col = 0;
		for(int i=0; i<rows(); i++) {
			T[] row = copy.entry[i];
			for(int j=col; j<cols(); j++) if(!row[j].isNull()) {
				col = j+1;
				break;
			}
		}
			
		return rank;
	}
	
	
	/* (non-Javadoc)
	 * @see kovacs.math.AbstractMatrix#getBasis()
	 */
	@Override
	public AbstractVectorBasis<T> getBasis() {
		GenericVectorBasis<T> basis = new GenericVectorBasis<T>();
		GenericMatrix<T> copy = (GenericMatrix<T>) copy();
		copy.gauss();

		int col = 0;
		for(int i=0; i<rows(); i++) {
			T[] row = copy.entry[i];
			for(int j=col; j<cols(); j++) {
				if(!row[j].isNull()) {
					GenericVector<T> v = new GenericVector<T>(type, cols());
					getColumn(j, v.component);
					basis.add(v);
					col = j+1;
					break;
				}
			}
		}
		
		return basis;
	}
	
	/* (non-Javadoc)
	 * @see kovacs.math.AbstractMatrix#isNullRow(int)
	 */
	@Override
	public boolean isNullRow(int i) {
		for(int j=0; j<cols(); j++) if(!entry[i][j].isNull()) return false;
		return true;
	}

	/* (non-Javadoc)
	 * @see kovacs.math.Additive#setSum(java.lang.Object, java.lang.Object)
	 */
	@Override
	public void setSum(AbstractMatrix<? extends T> a, AbstractMatrix<? extends T> b) {
		if(!a.isEqualSize(b))	throw new IllegalArgumentException("different size matrices.");
		
		for(int i=rows(); --i >= 0; ) for(int j=cols(); --j >= 0; ) {
			if(entry[i][j] == null) entry[i][j] = newEntry();
			entry[i][j].setSum(a.getValue(i, j), b.getValue(i,  j));
		}
	}

	/* (non-Javadoc)
	 * @see kovacs.math.Additive#setDifference(java.lang.Object, java.lang.Object)
	 */
	@Override
	public void setDifference(AbstractMatrix<? extends T> a, AbstractMatrix<? extends T> b) {
		if(!a.isEqualSize(b)) throw new IllegalArgumentException("different size matrices.");
		
		for(int i=rows(); --i >= 0; ) for(int j=cols(); --j >= 0; ) {
			if(entry[i][j] == null) entry[i][j] = newEntry();
			entry[i][j].setDifference(a.getValue(i, j), b.getValue(i,  j));
		}
	}
	
}
