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

// Matrix erstellen
Matrix createMatrix(unsigned int rows, unsigned int cols)
{
    Matrix matrix;

    matrix.rows = rows;
    matrix.cols = cols;

    matrix.buffer = calloc(rows * cols, sizeof(MatrixType));

    if (matrix.buffer == NULL)
    {
        matrix.rows = 0;
        matrix.cols = 0;
    }

    return matrix;
}

// Matrix-Speicher freigeben
void clearMatrix(Matrix* matrix)
{
    if (matrix != NULL)
    {
        free(matrix->buffer);

        matrix->buffer = NULL;
        matrix->rows = 0;
        matrix->cols = 0;
    }
}

// Wert an einer bestimmten Position setzen
void setMatrixAt(MatrixType value, Matrix matrix,
                 unsigned int rowIdx, unsigned int colIdx)
{
    if (matrix.buffer != NULL &&
        rowIdx < matrix.rows &&
        colIdx < matrix.cols)
    {
        matrix.buffer[rowIdx * matrix.cols + colIdx] = value;
    }
}

// Wert an einer bestimmten Position auslesen
MatrixType getMatrixAt(const Matrix matrix,
                       unsigned int rowIdx, unsigned int colIdx)
{
    if (matrix.buffer != NULL &&
        rowIdx < matrix.rows &&
        colIdx < matrix.cols)
    {
        return matrix.buffer[rowIdx * matrix.cols + colIdx];
    }

    return UNDEFINED_MATRIX_VALUE;
}

// Zwei Matrizen addieren
Matrix add(const Matrix matrix1, const Matrix matrix2)
{
    if (matrix1.rows != matrix2.rows ||
        matrix1.cols != matrix2.cols ||
        matrix1.buffer == NULL ||
        matrix2.buffer == NULL)
    {
        return createMatrix(0, 0);
    }

    Matrix result = createMatrix(matrix1.rows, matrix1.cols);

    if (result.buffer == NULL)
    {
        return result;
    }

    for (unsigned int i = 0; i < matrix1.rows; i++)
    {
        for (unsigned int j = 0; j < matrix1.cols; j++)
        {
            MatrixType value =
                getMatrixAt(matrix1, i, j) +
                getMatrixAt(matrix2, i, j);

            setMatrixAt(value, result, i, j);
        }
    }

    return result;
}

// Zwei Matrizen multiplizieren
Matrix multiply(const Matrix matrix1, const Matrix matrix2)
{
    if (matrix1.cols != matrix2.rows ||
        matrix1.buffer == NULL ||
        matrix2.buffer == NULL)
    {
        return createMatrix(0, 0);
    }

    Matrix result = createMatrix(matrix1.rows, matrix2.cols);

    if (result.buffer == NULL)
    {
        return result;
    }

    for (unsigned int i = 0; i < matrix1.rows; i++)  // nur < weil bei 0 angefangen zu zählen
    {
        for (unsigned int j = 0; j < matrix2.cols; j++)
        {
            MatrixType sum = 0;

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

            setMatrixAt(sum, result, i, j);
        }
    }

    return result;
}