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

#define BUFFER_SIZE 100
#define FILE_HEADER_STRING "__info2_image_file_format__"

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

static unsigned short readUShort(FILE *file) {
    unsigned short value = 0;
    if (fread(&value, sizeof(unsigned short), 1, file) != 1) {
        return 0;
    }
    return value;
}


GrayScaleImageSeries *readImages(const char *path)
{
    GrayScaleImageSeries *series = NULL;
    FILE *file = fopen(path, "rb"); // "rb" damit zeilenumbrüpche nicht korrigiert werden

    if (file == NULL) {
        return NULL;
    }

    // Header prüfen
    char headerBuffer[BUFFER_SIZE] = {0};
    size_t headerLen = strlen(FILE_HEADER_STRING);
    if (fread(headerBuffer, sizeof(char), headerLen, file) != headerLen ||
        strcmp(headerBuffer, FILE_HEADER_STRING) != 0) {
        fclose(file);
        return NULL;
    }

    // Metadaten lesen
    unsigned short count = readUShort(file);
    unsigned short width = readUShort(file);
    unsigned short height = readUShort(file);

    // Speicher für die Serie reservieren
    series = (GrayScaleImageSeries*)calloc(1, sizeof(GrayScaleImageSeries));
    if (series == NULL) { 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 == NULL || series->labels == NULL) {
        clearSeries(series);
        fclose(file);
        return NULL;
    }

    // Bilder und Labels lesen
    unsigned int pixelCount = width * height;
    for (unsigned int i = 0; i < count; i++) {
        series->images[i].width = width;
        series->images[i].height = height;
        series->images[i].buffer = (GrayScalePixelType*)malloc(pixelCount * sizeof(GrayScalePixelType));

        if (series->images[i].buffer != NULL) {
            fread(series->images[i].buffer, sizeof(GrayScalePixelType), pixelCount, file);
        }
        fread(&series->labels[i], sizeof(unsigned char), 1, file);
    }

    fclose(file);
    return series;
}

//  Vervollständigen die Funktion clearSeries, welche eine Bildserie vollständig aus dem Speicher freigibt
void clearSeries(GrayScaleImageSeries *series)
{
    if (series != NULL) {
        if (series->images != NULL) {
            for (unsigned int i = 0; i < series->count; i++) {
                if (series->images[i].buffer != NULL) {
                    free(series->images[i].buffer);
                }
            }
            free(series->images);
        }
        if (series->labels != NULL) {
            free(series->labels);
        }
        free(series);
    }
}