#include <tgmath.h>
#include <cstring>
#include <stdint.h>

constexpr void compute_md5_table(uint32_t*, size_t);

class Block {
public:
	char* data;
	char* hash;
	char* previous_hash;

	Block(char*, char*);
	char* hmac(char*);
};

Block::Block(char* data, char* prev) {
	this->data = data;
	this->hash = this->hmac(data);
	this->previous_hash = prev;
}



char* Block::hmac(char* input) {
	const size_t _TABLE_SIZE = 64;
	uint32_t table[_TABLE_SIZE];
	compute_md5_table(table, _TABLE_SIZE);

	// values are taken straight from wikipedia
	size_t a0 = 0x67452301;   // A
	size_t b0 = 0xefcdab89;   // B
	size_t c0 = 0x98badcfe;   // C
	size_t d0 = 0x10325476;   // D

	// lots of reallocs  inc
	size_t msg_len = strlen(input) + 1;
	uint8_t* buf = (uint8_t*)malloc(msg_len /* for the '1' bit */);
	memcpy(buf, input, msg_len);
	buf[strlen(input)] = 0x80; // adding in the '1' bit along with 7 bits for padding

	// calculate length of final message content with all padding
	size_t message_len_bits = msg_len * 8;
	while((message_len_bits) % 512 != 64 ) {
		message_len_bits += 8;
	}

	// prepare out new hash buffer which has a mutaable state
	uint8_t* hash_buf = (uint8_t*)malloc(message_len_bits / 8);
	memcpy(hash_buf, buf, msg_len);

	size_t hunk_count = msg_len/8;
	for(size_t i =0; i < hunk_count; i+=8) {
		uint8_t* hunk = &hash_buf[i]; // length should always be 8(bytes)/512 bits
		// split the hunk into pieces
		uint32_t parts[16];
		for(size_t p = 0; p < 16; p+=32) {
			parts[p] = (uint32_t)hunk[p];
		}
		for(size_t z = 0;z<16;z++) {
			printf("%08X ", parts[z]);
		}
		printf("\n");

	}
	free(hash_buf);
	free(buf);
	return NULL;
}

int main(void) {
	Block* b = new Block("something", NULL);

	return 0;
}


constexpr void compute_md5_table(uint32_t* table, size_t size) {
	for(int i = 0; i < 64; i++) {
		table[i] = floor( pow(2,32) * abs( sin(i+1) ) );
	}
}