/**
 * recover.c
 *
 * Computer Science 50
 * Problem Set 4
 *
 * Recovers JPEGs from a forensic image.
 */

#include <cs50.h>
#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>

typedef uint8_t BYTE;

#define BLOCK 512;

int main(int argc, char* argv[])
{
    // TODO

    // open card.raw to read
    FILE* file = fopen("card.raw", "r");

    // check if file is NULL
    if (file == NULL)
    {
        printf("Could not open %s.\n", "card.raw");
        return 1;
    }

    // 512 byte block
    uint8_t block[512];

    int i = 0;
    int j = 0;
    FILE* img = NULL;

    // read from the file in a loop
    while (fread(block, sizeof(block), 1, file) == 1)
    {
        // if signature is found
        if (block[0] == 0xff && block[1] == 0xd8 && block[2] == 0xff && (block[3] == 0xe0 || block[3] == 0xe1))
        {
            // if this is the first jpg
            if (i == 0)
            {
                // malloc space for title of new jpgs
                char* title = malloc(sizeof(char));

                // print new title of jpgs
                sprintf(title, "%03d.jpg", i);

                // open newly titled jpg
                img = fopen(title, "w");

                if (img == NULL)
                {
                    fclose(file);
                    fprintf(stderr, "Could not create %s.\n", title);
                    return 2;
                }

                fwrite(&block, sizeof(block), 1, img);
                // iterate i so program knows first jpg has been found
                i++;
                j++;
                free(title);
            }

            // if not first jpg
            else
            {
                // close previous jpg
                fclose(img);

                // increment 'i' (keeps track of jpgs)
                // my (not so elegant) solution on how to not pre-increment after first jpg
                if (j == 1)
                {
                    j++;
                }

                else
                {
                    i++;
                }

                // malloc space for title of new jpgs
                char* title = malloc(sizeof(char));

                // print new title of jpgs
                sprintf(title, "%03d.jpg", i);

                // open newly titled jpg
                img = fopen(title, "w");

                if (img == NULL)
                {
                    fclose(file);
                    fprintf(stderr, "Could not create %s.\n", title);
                    return 2;
                }

                // write first block to new jpg
                fwrite(&block, sizeof(block), 1, img);
                free(title);
            }
        }

        // if new jpg signature not found, but i > 0 (meaning first jpg has already been hit)
        else if (i > 0)
        {
            fwrite(&block, sizeof(block), 1, img);
        }

        // if first jpg has not been found, do nothing
        else
        {
            i = i + 0;
        }
    }

fclose(file);

}