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

Matrix createMatrix(unsigned int rows, unsigned int cols)
{
    if (rows != 0 && cols != 0)
    {
        Matrix matrix;
        matrix.rows = rows;
        matrix.cols = cols;
        matrix.buffer = (MatrixType*) calloc((size_t)rows * cols, sizeof(MatrixType));
        return matrix;
    }
    else
    {
        Matrix matrix;
        matrix.rows = 0;
        matrix.cols = 0;
        matrix.buffer = NULL;
        return matrix;
    }
}

void clearMatrix(Matrix *matrix)
{
    if (matrix != NULL)
    {
        if (matrix->buffer != 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)        //Values in matrix schreiben
{
    matrix.buffer[(size_t)rowIdx * matrix.cols + colIdx] = value;
}

MatrixType getMatrixAt(const Matrix matrix, unsigned int rowIdx, unsigned int colIdx)        //aus matrix auslesen
{
    if(rowIdx < matrix.rows && colIdx < matrix.cols){
        return matrix.buffer[(size_t)rowIdx * matrix.cols + colIdx];
    }else{
        return 0;
    }
}

Matrix add(const Matrix matrix1, const Matrix matrix2)
{
    // Case A: same shape -> elementwise add
    if (matrix1.rows == matrix2.rows && matrix1.cols == matrix2.cols)
    {
        Matrix result = createMatrix(matrix1.rows, matrix1.cols);
        if (result.buffer == NULL) return result;

        size_t n = (size_t)result.rows * result.cols;
        for (size_t i = 0; i < n; i++)
        {
            result.buffer[i] = matrix1.buffer[i] + matrix2.buffer[i];
        }
        return result;
    }

    // Case B: matrix1 besteht aus (rows x cols) und matrix2 ist (rows x 1) -> einmal alle rows einzeln auf die andere Addieren
    if (matrix1.rows == matrix2.rows && matrix2.cols == 1 && matrix1.cols > 1)
    {
        Matrix result = createMatrix(matrix1.rows, matrix1.cols);
        if (result.buffer == NULL) return result;

        for (unsigned int r = 0; r < matrix1.rows; r++)
        {
            MatrixType b = matrix2.buffer[(size_t)r * matrix2.cols + 0];
            for (unsigned int c = 0; c < matrix1.cols; c++)
            {
                result.buffer[(size_t)r * result.cols + c] = matrix1.buffer[(size_t)r * matrix1.cols + c] + b;
            }
        }
        return result;
    }

    // Case C: matrix1 ist (rows x 1) und matrix2 ist (rows x cols) -> einmal alle cols einzeln auf die andere Addieren
    if (matrix2.rows == matrix1.rows && matrix1.cols == 1 && matrix2.cols > 1)
    {
        Matrix result = createMatrix(matrix2.rows, matrix2.cols);
        if (result.buffer == NULL) return result;

        for (unsigned int r = 0; r < matrix2.rows; r++)
        {
            MatrixType b = matrix1.buffer[(size_t)r * matrix1.cols + 0];
            for (unsigned int c = 0; c < matrix2.cols; c++)
            {
                result.buffer[(size_t)r * result.cols + c] = matrix2.buffer[(size_t)r * matrix2.cols + c] + b;
            }
        }
        return result;
    }

    // unsupported shapes -> return empty matrix
    Matrix result = {0};
    result.rows = 0;
    result.cols = 0;
    result.buffer = NULL;
    return result;
}

Matrix multiply(const Matrix matrix1, const Matrix matrix2)
{
    if (matrix1.cols != matrix2.rows)        //Spalten und Zeilen sind nicht gleich groß
    {
        Matrix result;
        result.rows = 0;
        result.cols = 0;
        result.buffer = NULL;
        return result;
    }
    else
    {
        Matrix result = createMatrix(matrix1.rows, matrix2.cols);
        if (result.buffer == NULL) return result;

        for (unsigned int i = 0; i < result.rows; i++)
        {
            for (unsigned int j = 0; j < result.cols; j++)
            {
                MatrixType summe = 0;
                for (unsigned int k = 0; k < matrix1.cols; k++)
                {
                    summe += getMatrixAt(matrix1, i, k) * getMatrixAt(matrix2, k, j);
                }
                setMatrixAt(summe, result, i, j);
            }
        }
        return result;
    }
}