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

#define BUFFER_SIZE 100
#define FILE_HEADER_STRING "__info2_image_file_format__"

//Datei öffnen, Header, Anzahl, Höhe und Breite lesen, geöffnete Datei zurückgeben
static FILE* openAndReadShort (const char *path, unsigned short *count, unsigned short *width, unsigned short *height) {
    FILE *file = fopen(path, "rb");
    if (!file) {
        return NULL;
    }
    size_t headerLength = strlen(FILE_HEADER_STRING);
    char *header = malloc (headerLength + 1);
    if(!header) {
        return NULL;
    }

    if (fread(header, sizeof(char), headerLength, file) != headerLength) {
        free (header);
        return NULL;
    }

    header[headerLength] = '\0';

    if (strcmp (header, FILE_HEADER_STRING) != 0) {
        free(header);
        return NULL;
    }
    
    free (header);

    fread(count, sizeof(unsigned short), 1, file);
    fread(width, sizeof(unsigned short), 1, file);
    fread(height, sizeof(unsigned short), 1, file);

    return file;
}

//Speicher anlegen und Pixel eines Bildes einlesen
static GrayScaleImage* readPixles (FILE *file, unsigned short *width, unsigned short *height) {
    GrayScaleImage *image = malloc (sizeof(GrayScaleImage));
    image->width = *width;
    image->height = *height;
    image->buffer = malloc ((*width) * (*height) * sizeof(GrayScalePixelType));
    if (!image->buffer) {
        free(image);
        return NULL;
    }

    for (unsigned int i = 0; i < (*width) * (*height); i++) {
        unsigned char pixel;
        if (fread(&pixel, sizeof(unsigned char), 1, file) != 1) {
            free(image->buffer);
            free(image);
            return NULL;
        }
    image->buffer[i] = pixel;
    }

    return image;
}

//Ausführen von openAndReadShort, Anlegen des Speichers für Bilderserie, readPixles wird für jedes Bild ausgeführt
//Nach jedem Bild wird das zugehörige Label gelesen, bei sämtlichen Fehlern wird NULL zurückgegeben und Speicher durch clearSeries bereinigt
GrayScaleImageSeries *readImages(const char *path)
{
    unsigned short count = 0, width = 0, height = 0;

    FILE *file = openAndReadShort(path, &count, &width, &height);
    if (file == 0) {
        return NULL;
    }
    GrayScaleImageSeries *series = malloc(sizeof(GrayScaleImageSeries));
    if (!series) {
        fclose(file);
        return NULL;
    }
    series->count = count;

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

    for (unsigned int i = 0; i < series->count; i++) {
       GrayScaleImage *image = readPixles(file, &width, &height);
       series->images[i] = *image;
       free(image);

       if (fread(&series->labels[i], sizeof(unsigned char), 1, file) != 1) {
            clearSeries(series); 
            fclose(file); 
            return NULL; 
        }
    }
    fclose(file);
    
    return series;
}

//Bereinigt den Speicher
void clearSeries(GrayScaleImageSeries *series)
{
    for (unsigned int i = 0; i < series->count; i++) {
        free(series->images[i].buffer);
    }

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