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

#define BUFFER_SIZE 100
#define FILE_HEADER_STRING "__info2_image_file_format__"
#define HEADER_LEN (sizeof(FILE_HEADER_STRING) - 1) //-1, um \0 Character rauszufiltern

// TODO Implementieren Sie geeignete Hilfsfunktionen für das Lesen der Bildserie aus einer Datei

static int checkDimensions(unsigned int width, unsigned int height){

    int ok = 0;
    
    if(width > 0 && height > 0)
        return ok = 1;
    
    else 
        return ok = 0;

}

static int checkHeader(const GrayScalePixelType *buffer){

    int ok = 0;
    char header[HEADER_LEN + 1]; //Array mit Platz für Header Länge + \0 Character -> String

    // Jeder Byte in String kopieren
    for(int i = 0; i < HEADER_LEN; i++){

        header[i] = buffer[i];

    }

    header[HEADER_LEN] = '\0'; // Nullterminator am Ende anhängen

    if(strcmp(header, FILE_HEADER_STRING) == 0) // wenn beide identische sind gibt cmp 0 zurück
        return ok = 1;

    else
        return ok = 0;

}

static FILE *openImageFile(const char *path)
{
    return fopen(path, "rb");
}

static int readHeaderFromFile(FILE *fp, GrayScalePixelType *headerBuffer)
{
    if (fread(headerBuffer, sizeof(GrayScalePixelType),HEADER_LEN, fp) != HEADER_LEN)
    {
        return 0;
    }
    return 1;
}

static int readMetaData(FILE *fp, unsigned int *numImages, unsigned int *width, unsigned int *height)
{
    if (fread(numImages, sizeof(unsigned int), 1, fp) != 1 || fread(width, sizeof(unsigned int), 1, fp) != 1 || fread(height, sizeof(unsigned int), 1, fp) != 1)

    {
    return 0;
    }
    return 1;
}

static GrayScaleImageSeries *allocateSeriesStruct(void)
{
    GrayScaleImageSeries *series = malloc(sizeof(GrayScaleImageSeries));
    return series;
}

static int allocateImageAndLabelArrays(GrayScaleImageSeries *series, unsigned int numImages, FILE *fp)
{
    series->count = numImages;
    //Speicher für die Pointer an sich belegen
    series->images = malloc(numImages * sizeof(GrayScaleImage));
    series->labels = malloc(numImages * sizeof(unsigned char));

    if (!series->images || !series->labels)
    {
        free(series->images); //wenn trotzdem was reingeschrieben wurde, dann freigeben
        free(series->labels);
        free(series);

        fclose(fp);
        return 0;
    }

    return 1;
}

static int allocateBufferForImages(GrayScaleImageSeries *series, unsigned int numImages, unsigned int width, unsigned int height, FILE *fp)
{
    for (unsigned int i = 0; i < numImages; i++)
    {
        series ->images[i].buffer = malloc(width * height);
        if (series ->images[i].buffer == NULL) 
        {
            for (unsigned int j = 0; j < i; j++)
            {
                free(series->images[j].buffer);
            }

            free(series->images);
            free(series->labels);
            free(series);

            fclose(fp);
            return 0;
        }
    }
    return 1;
}

static int readImagesAndLabels(FILE *fp, GrayScaleImageSeries *series, unsigned int numImages, unsigned int width, unsigned int height)
{
    for (unsigned int i = 0; i < numImages; i++)
    {
        series->images[i].width = width;
        series->images[i].height = height;

        if (fread(series->images[i].buffer, 1, width *height, fp) != (width * height))
        {
            clearSeries(series);
            fclose(fp);
            return 0;
        }

        fread(&series->labels[i], 1, 1, fp);
    }

    return 1;
}


// TODO Vervollständigen Sie die Funktion readImages unter Benutzung Ihrer Hilfsfunktionen
GrayScaleImageSeries *readImages(const char *path)
{
    GrayScaleImageSeries *series = NULL;

    FILE *fp = openImageFile(path);
    if (!fp)
    return NULL;

    GrayScalePixelType header[HEADER_LEN];

    if (!readHeaderFromFile(fp, header))
    {
        fclose(fp);
        return NULL;
    }

    if (!checkHeader(header))
    {
        fclose(fp);
        return NULL;
    }

    unsigned int numImages, width, height;
    if (!readMetaData(fp, &numImages, &width, &height))
    {
        fclos(fp);
        return NULL;
    }

    if (!checkDimensions(width, height))
    {
        fclose(fp);
        return NULL;
    }

    series = allocateSeriesStruct();
    if (!series)
    {
        free(series);
        fclose(fp);
        return NULL;
    }

    if (!allocateImageAndLabelArrays(series, numImages, fp))
    {
        return NULL;
    }

    if (!allocateImageAndLabelImages(series, numImages, width, height, fp))
    {
        return NULL;
    }

    if (!readImagesAndLabels(fp, series, numImages, width, height))
    {
        return NULL;
    }

    return series;

}   


// TODO Vervollständigen Sie die Funktion clearSeries, welche eine Bildserie vollständig aus dem Speicher freigibt
void clearSeries(GrayScaleImageSeries *series)
{

}