#include <stdlib.h>
#include <string.h>
#include "matrix.h"

Matrix createMatrix(unsigned int rows, unsigned int cols)
{
    Matrix matrix = {NULL, 0, 0}; //Initialwerte, da unsicher ob allocierung funktioniert

    if(rows > 0 && cols > 0)
    {
        MatrixType *buffer = (MatrixType *)calloc(rows * cols, sizeof(MatrixType));
        if(buffer != NULL) 
        {
            matrix.buffer = buffer;
            matrix.rows = rows;
            matrix.cols = cols;
        }
    }

    return matrix;
}

void clearMatrix(Matrix *matrix)
{
    if(matrix != NULL)
    {
        free(matrix->buffer);
        matrix->buffer = NULL;
        matrix->rows = 0;
        matrix->cols = 0;
    }
}

void setMatrixAt(MatrixType value, Matrix matrix, unsigned int rowIdx, unsigned int colIdx)
{
    if(rowIdx < matrix.rows && colIdx < matrix.cols)
    {
        matrix.buffer[rowIdx * matrix.cols + colIdx] = value;
    }
}

MatrixType getMatrixAt(const Matrix matrix, unsigned int rowIdx, unsigned int colIdx)
{
    MatrixType value = UNDEFINED_MATRIX_VALUE;

    if(rowIdx < matrix.rows && colIdx < matrix.cols)
    {
        value = matrix.buffer[rowIdx * matrix.cols + colIdx];
    }

    return value;
}

static int isValidMatrix(const Matrix matrix)
{
    return matrix.buffer != NULL && matrix.rows > 0 && matrix.cols > 0;
}

static int hasSameDimensions(const Matrix matrix1, const Matrix matrix2)
{
    return matrix1.rows == matrix2.rows && matrix1.cols == matrix2.cols;
}

static int isColumnVector(const Matrix matrix)
{
    return matrix.cols == 1;
}

static Matrix addElementWise(const Matrix matrix1, const Matrix matrix2)
{
    Matrix result = createMatrix(matrix1.rows, matrix1.cols);

    if(isValidMatrix(result))
    {
        for(unsigned int i = 0; i < matrix1.rows * matrix1.cols; i++)
        {
            result.buffer[i] = matrix1.buffer[i] + matrix2.buffer[i];
        }
    }

    return result;
}

static Matrix addBroadcast(const Matrix matrix, const Matrix vector)
{
    Matrix result = createMatrix(matrix.rows, matrix.cols);

    if(isValidMatrix(result))
    {
        for(unsigned int rowIdx = 0; rowIdx < matrix.rows; rowIdx++)
        {
            for(unsigned int colIdx = 0; colIdx < matrix.cols; colIdx++)
            {
                unsigned int index = rowIdx * matrix.cols + colIdx;
                result.buffer[index] = matrix.buffer[index] + getMatrixAt(vector, rowIdx, 0);
            }
        }
    }

    return result;
}

Matrix add(const Matrix matrix1, const Matrix matrix2)
{
    Matrix result = {NULL, 0, 0}; //leere Matrix als Fehlerfall

    if(isValidMatrix(matrix1) && isValidMatrix(matrix2))
    {
        //normal add
        if(hasSameDimensions(matrix1, matrix2))
        {
            result = addElementWise(matrix1, matrix2);
        }
        //add Broadcast matrix2 = vektor and matrix1 = matrix
        else if(isColumnVector(matrix2) && matrix1.rows == matrix2.rows)
        {
            result = addBroadcast(matrix1, matrix2);
        }
        //add Broadcast matrix1 = vektor and matrix2 = matrix
        else if(isColumnVector(matrix1) && matrix1.rows == matrix2.rows)
        {
            result = addBroadcast(matrix2, matrix1);
        }
    }

    return result;
}

/* (Bedingung: matrix1.cols == matrix2.rows)
 * | 1 2 3 |   | 7  8  |   | 1*7+2*9+3*11  1*8+2*10+3*12 |   |  58  64 |
 * | 4 5 6 | * | 9  10 | = | 4*7+5*9+6*11  4*8+5*10+6*12 | = | 139 154 |
 *             | 11 12 |
 */
Matrix multiply(const Matrix matrix1, const Matrix matrix2)
{
    Matrix result = {NULL, 0, 0}; //leere Matrix als Fehlerfall

    if(isValidMatrix(matrix1) && isValidMatrix(matrix2) && matrix1.cols == matrix2.rows)
    {
        result = createMatrix(matrix1.rows, matrix2.cols);

        if(isValidMatrix(result))
        {
            for(unsigned int rowIdx = 0; rowIdx < matrix1.rows; rowIdx++)
            {
                for(unsigned int colIdx = 0; colIdx < matrix2.cols; colIdx++)
                {
                    MatrixType sum = 0;

                    for(unsigned int k = 0; k < matrix1.cols; k++)
                    {
                        sum += getMatrixAt(matrix1, rowIdx, k) * getMatrixAt(matrix2, k, colIdx);
                    }

                    setMatrixAt(sum, result, rowIdx, colIdx);
                }
            }
        }
    }

    return result;
}