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

#define BUFFER_SIZE 100
#define FILE_HEADER_STRING "__info2_image_file_format__"

// TODO Implementieren Sie geeignete Hilfsfunktionen für das Lesen der Bildserie aus einer Datei
int readHeader(FILE *file)
{
    char fileHeader[32];

    fread(fileHeader, sizeof(char), strlen(FILE_HEADER_STRING), file);

    if(strncmp(FILE_HEADER_STRING, fileHeader, strlen(FILE_HEADER_STRING))){
        return -1;
    } else{
        return 0;
    }
}

unsigned short readUnShortOfFile(FILE *file){
    unsigned short number = 0;

    if(fread(&number, sizeof(unsigned short), 1, file) != 1){
        return -1;
    }

    return number;
}

int readOneImage(GrayScaleImageSeries *series, FILE *file, unsigned short width, unsigned short height, unsigned short i){

    series->images[i].buffer = malloc(width * height * sizeof(GrayScalePixelType));
    fread(series->images[i].buffer, sizeof(GrayScalePixelType), width * height, file);
    fread(&series->labels[i], sizeof(unsigned char), 1, file);
    return 0;
    
}

// TODO Vervollständigen Sie die Funktion readImages unter Benutzung Ihrer Hilfsfunktionen
GrayScaleImageSeries *readImages(const char *path)
{
    GrayScaleImageSeries *series = NULL;
    FILE *file;
    unsigned short width, height;

    file = fopen(path, "rb");
    
    if(file == NULL || readHeader(file) == -1) {
        return NULL;
    }

    series = malloc(sizeof(GrayScaleImageSeries));

    series->count = readUnShortOfFile(file); 
    width = readUnShortOfFile(file);
    height = readUnShortOfFile(file);

    if(series->count == -1 || width == -1 || height == -1){
        return NULL;
    }

    series->images = malloc(series->count * sizeof(GrayScaleImage));
    series->labels = malloc(series->count * sizeof(unsigned char));
    
    for(int i = 0; i < series->count; i++){
        series->images[i].width = width;
        series->images[i].height = height;
        readOneImage(series, file, width, height, i);
    }
   
    return series;
}

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

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

    return;
}