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

#define BUFFER_SIZE 100
#define FILE_HEADER_STRING "__info2_image_file_format__"

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

    if (fread(buffer, sizeof(char), headerLen, file) != headerLen)
        return 0;

    return (strncmp(buffer, FILE_HEADER_STRING, headerLen) == 0);
}

// -----------------------------------------------------
// Funktion: Liest die Bilder aus einer Datei
// -----------------------------------------------------
GrayScaleImageSeries *readImages(const char *path)
{
    FILE *file = fopen(path, "rb");
    if (!file) return NULL;

    if (!checkFileHeader(file))
    {
        fclose(file);
        return NULL;
    }

    unsigned short numberOfImages = 0, width = 0, height = 0;

    // Đọc metadata: numberOfImages, height, width (theo cách test ghi)
    if (fread(&numberOfImages, sizeof(unsigned short), 1, file) != 1 ||
        fread(&height, sizeof(unsigned short), 1, file) != 1 ||
        fread(&width, sizeof(unsigned short), 1, file) != 1)
    {
        fclose(file);
        return NULL;
    }

    GrayScaleImageSeries *series = malloc(sizeof(GrayScaleImageSeries));
    if (!series)
    {
        fclose(file);
        return NULL;
    }

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

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

    for (unsigned short i = 0; i < numberOfImages; i++)
    {
        series->images[i].width = width;
        series->images[i].height = height;
        unsigned int pixelCount = width * height;

        series->images[i].buffer = malloc(pixelCount * sizeof(GrayScalePixelType));
        if (!series->images[i].buffer)
        {
            clearSeries(series);
            fclose(file);
            return NULL;
        }

        if (fread(series->images[i].buffer, sizeof(GrayScalePixelType), pixelCount, file) != pixelCount ||
            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);
            series->images[i].buffer = NULL;
        }
        free(series->images);
        series->images = NULL;
    }

    if (series->labels)
    {
        free(series->labels);
        series->labels = NULL;
    }

    free(series);
}