#include <stdio.h>
#include <stdlib.h>
#include "crc_util.h"

const long png_signature[8] = { 0x89, 0x50, 0x4e, 0x47, 0x0d, 0x0a, 0x1a, 0x0a };

unsigned long check_header_length(unsigned char *addr, long offset) {
        unsigned long res = 0;
        for( int i = 0; i < 4; i++ ) {
                res |= addr[offset+i];
                if (i < 3) {
                        res <<= 8;
                }
        }
        return res;
}

int check_file_header(char *addr) {
        int signature_match = 0;
        for( int i = 0; i < 8; i++ ) {
                if (addr[i] != png_signature[i]) {
                        signature_match = 1;
                }
        }
        printf("Sig Match: %d\n", signature_match);
        return signature_match;

}

void populate_idat_png(unsigned char *addr, struct PNG_IDAT_FILE_STRUCT *png_data, unsigned long offset) {
	unsigned long cur_idat_length = 0;
	for(int i = 0; i < 4; i++){
		png_data->idat_length[i] = addr[i+offset];
	}

	for(int i = 0; i < 4; i++){
		cur_idat_length += (png_data->idat_length[i] << (24-(8*i)));
	}

	for(int i = 0; i < 4; i++){
		png_data->idat_header[i] = addr[i+offset+4];
	}
}

void populate_start_png(unsigned char *addr, struct PNG_START_FILE_STRUCT *png_data) {
	union{
		unsigned char *data;
		struct PNG_START_FILE_STRUCT *png_data;
	}png;

	png.png_data = png_data;

	for(int i = 0; i < sizeof(struct PNG_START_FILE_STRUCT); i++) {
		png.data[i] = addr[i];
	}
}

int create_cc_file(unsigned char *addr, unsigned long file_length) {
        FILE *fp;
        fp = fopen("png2.png", "w");

        if(fp == NULL) {
                return EXIT_FAILURE;
        }

        for(int i = 0; i < file_length; i++){
                fputc(addr[i], fp);
        }
        fclose(fp);
	return 0;
}

unsigned char* file_to_char_array(FILE *in_file, size_t* size) {
        unsigned long c;
        unsigned long file_data_cap = 8;
        unsigned char* file_data = calloc(file_data_cap, sizeof(unsigned char));

        for(size_t i = 0;(c = fgetc(in_file)) != EOF; i++) {
                if(i == file_data_cap) {
                        file_data_cap *= 2;
                        file_data = reallocarray(file_data, file_data_cap, sizeof(unsigned char));
                        if(file_data == NULL) {
                                perror("FAILED ARRAY RESIZE");
                                return NULL;
                        }
                }
                file_data[i] = c;
                *size += 1;
        }
        return file_data;
}