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

#define BUFFER_SIZE 100
#define FILE_HEADER_STRING "__info2_image_file_format__"


/// @brief Gets the next char value from specified and opened file in the moment that is only ONE short int.
/// @param openedFile stream FILE, from which to read 
static int getCharValueFromFile(FILE* openedFile) {
    int addToFile = 0;

    if (openedFile == NULL) return 0;

    addToFile = fgetc(openedFile);
    addToFile += fgetc(openedFile) * 256;
    return addToFile;
}

GrayScaleImageSeries* readImages(const char *path)
{
    GrayScaleImageSeries *series = NULL;
    // uint16_t 
    FILE* openFile;

    openFile = fopen(path, "rb");

    // file Could not be opened/does not exist
    if (openFile != NULL) {

         char* actualFileTag = malloc(strlen(FILE_HEADER_STRING)+1 * sizeof(char));
         int numberOfImages = 0;
         int width = 0;
         int height = 0;

        for (int i = 0; i < strlen(FILE_HEADER_STRING); i++) {
            char tmpFileChar  = fgetc(openFile);

            if (tmpFileChar == EOF) {
                fclose(openFile);
                return NULL;
            }
            actualFileTag[i] = tmpFileChar;
        }
        actualFileTag[strlen(FILE_HEADER_STRING)] =  '\0';

        // checks if the files are equal
        int fileTagEqual = strcmp(actualFileTag, FILE_HEADER_STRING);

        //we only need the fileTag to verify its an image for our series.
        free(actualFileTag);
        actualFileTag = NULL;


        //only if equal, the method continues
        if (fileTagEqual == 0) {
            numberOfImages = getCharValueFromFile(openFile);

            // no Images in series -> No image-series
            if (numberOfImages == 0) {
                fclose(openFile);
                return NULL;
            }

            width  = getCharValueFromFile(openFile);
            height = getCharValueFromFile(openFile);

            // no height/width --> impossible file 
            if(height == 0 || width == 0) {
                fclose(openFile);
                return NULL;
            }

            //all the starting parameters are set --> the images can be read and stored
            series = malloc(sizeof(GrayScaleImageSeries));

            series->count = 0;
            series->images = malloc(numberOfImages * sizeof(GrayScaleImage));
            series->labels = malloc(numberOfImages * sizeof(unsigned char));

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

                for (int j = 0; j < (width * height); j++) {
                    // allocating the actual matrix image for image
                    series->images[i].buffer[j] = fgetc(openFile);
                }
                //rest of the values that only affect the image itself
                series->labels[i] = fgetc(openFile);
                series->count++;
            }
        }

        // the fclose happens here, since every other path closes the file beforehand
        fclose (openFile);
    }

    return series;
}

void clearSeries(GrayScaleImageSeries *series)
{
    if (series == NULL) return;

    for (int i = 0; i < series->count; i++) {
        free(series->images[i].buffer);
        series->images[i].buffer = NULL;
    }

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