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

#define FILE_HEADER_STRING "__info2_image_file_format__"

// --------------------------
// Hilfsfunktion: Prüft den Header der Datei
// --------------------------
static int checkFileHeader(FILE *file)
{
    char buffer[100] = {0};
    size_t headerLen = strlen(FILE_HEADER_STRING);

    // Lese Header aus Datei
    if (fread(buffer, sizeof(char), headerLen, file) != headerLen)
        return 0;

    // Prüfe, ob Header korrekt ist
    return strcmp(buffer, FILE_HEADER_STRING) == 0;
}

// --------------------------
// Hilfsfunktion: Liest ein einzelnes Bild
// --------------------------
static int readImage(FILE *file, GrayScaleImage *image, unsigned int width, unsigned int height)
{
    image->width = width;   // Breite setzen
    image->height = height; // Höhe setzen
    image->buffer = (GrayScalePixelType *)malloc(width * height * sizeof(GrayScalePixelType));

    if (!image->buffer)
        return 0; // Speicherfehler

    // Lese Pixelwerte
    if (fread(image->buffer, sizeof(GrayScalePixelType), width * height, file) != width * height)
    {
        free(image->buffer);
        image->buffer = NULL;
        return 0; // Lese Fehler
    }
    return 1; // Erfolg
}

// --------------------------
// Funktion: Liest eine Serie von Bildern aus einer Datei
// --------------------------
GrayScaleImageSeries *readImages(const char *path)
{
    FILE *file = fopen(path, "rb");
    if (!file)
        return NULL; // Datei existiert nicht

    // Prüfe Header
    if (!checkFileHeader(file))
    {
        fclose(file);
        return NULL; // Falsches Format
    }

    // Lese Anzahl der Bilder und deren Dimensionen
    unsigned int count = 0;
    unsigned short width = 0, height = 0;

    if (fread(&count, sizeof(unsigned int), 1, file) != 1 ||
        fread(&width, sizeof(unsigned short), 1, file) != 1 ||
        fread(&height, sizeof(unsigned short), 1, file) != 1)
    {
        fclose(file);
        return NULL;
    }

    // Speicher für Serie allozieren
    GrayScaleImageSeries *series = (GrayScaleImageSeries *)malloc(sizeof(GrayScaleImageSeries));
    if (!series)
    {
        fclose(file);
        return NULL;
    }

    series->count = count;
    series->images = (GrayScaleImage *)calloc(count, sizeof(GrayScaleImage));
    series->labels = (unsigned char *)calloc(count, sizeof(unsigned char));

    if (!series->images || !series->labels)
    {
        clearSeries(series);
        fclose(file);
        return NULL;
    }

    // Lese jedes Bild und Label
    for (unsigned int i = 0; i < count; i++)
    {
        if (!readImage(file, &series->images[i], width, height) ||
            fread(&series->labels[i], sizeof(unsigned char), 1, file) != 1)
        {
            clearSeries(series);
            fclose(file);
            return NULL;
        }
    }

    fclose(file);
    return series;
}

// --------------------------
// Funktion: Gibt eine Bildserie vollständig frei
// --------------------------
void clearSeries(GrayScaleImageSeries *series)
{
    if (!series)
        return;

    if (series->images)
    {
        for (unsigned int i = 0; i < series->count; i++)
        {
            free(series->images[i].buffer); // Speicher jedes Bildes freigeben
            series->images[i].buffer = NULL;
            series->images[i].width = 0;
            series->images[i].height = 0;
        }
        free(series->images); // Array der Bilder freigeben
    }

    if (series->labels)
        free(series->labels); // Labels freigeben

    free(series); // Serie selbst freigeben
}