#include "Matrix.h"

Matrix::Matrix() : n(0), m(0), entries(null)
{
}

Matrix::Matrix(size_t rows, size_t cols)
	: n(cols ? rows : 0)
	, m(rows ? cols : 0)
	, entries( rows && cols ? new double[rows * cols] : (double*)null )
{
	for ( size_t i = 0, size = rows * cols; i < size; ++i )
		entries[i] = 0.0;
}

Matrix::Matrix(const Matrix& other)
	: n(other.n)
	, m(other.m)
	, entries(null)
{
	if ( other.entries )
	{
		size_t size = n * m;
		entries = new double[size];
		for ( size_t i = 0; i < size; ++i)
			entries[i] = other.entries[i];
	}
}

const Matrix& Matrix::operator=(const Matrix& other)
{
	if ( this != &other )
	{
		n = other.n;
		m = other.m;
		size_t size = n * m;
		delete [] entries;
		entries = size ? new double[size] : (double*)null;
		for ( size_t i = 0; i < size; ++i )
			entries[i] = other.entries[i];
	}
	return *this;
}

Matrix::~Matrix()
{
	delete [] entries;
}

Matrix Matrix::operator+(const Matrix& other) const
{
	if ( n != other.n || m != other.m ) return Matrix();
	Matrix result(n, m);
	for ( size_t i = 0, size = n * m; i < size; ++i )
		result.entries[i] = entries[i] + other.entries[i];
	return result;
}

Matrix Matrix::operator-(const Matrix& other) const
{
	if ( n != other.n || m != other.m ) return Matrix();
	Matrix result(n, m);
	for ( size_t i = 0, size = n * m; i < size; ++i )
		result.entries[i] = entries[i] - other.entries[i];
	return result;
}

Matrix Matrix::operator*(double r) const
{
	Matrix result(n, m);
	for ( size_t i = 0, size = n * m; i < size; ++i )
		result.entries[i] = entries[i] * r;
	return result;
}

Matrix Matrix::operator*(const Matrix& other) const
{
	if ( m != other.n ) return Matrix();

	Matrix result(n, other.m);
	for ( size_t i = 0; i < n; ++i )
		for ( size_t j = 0; j < other.m; ++j )
			for ( size_t k = 0; k < m; ++k )
				result(i,j) += (*this)(i,k) * other(k, j);

	return result;
}

std::istream& operator>>(std::istream& input, Matrix& matrix)
{
	for ( size_t i = 0, size = matrix.n * matrix.m; i < size; ++i )
		input >> matrix.entries[i];

	return input;
}

std::ostream& operator<<(std::ostream& output, const Matrix& matrix)
{
	if ( ! matrix ) return output << "(null)\n";

	for ( size_t i = 0; i < matrix.rows(); ++i )
	{
		for ( size_t j = 0; j < matrix.cols(); ++j )
			output << matrix(i,j) << '\t';
		output << '\n';
	}

	return output;
}