#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <stdint.h>
#include <ctype.h>

#pragma pack(1)

struct __attribute__((__packed__)) ft {
	double frequency;
	uint32_t duration;
	uint32_t padding;
};

int main(int argc, char **argv) {
	// arguments: freq samplerate samples/bit 
	
	if(argc < 4) {
		fprintf(stderr, "Error: set arguments: freq samplerate samples/bit\n");
		exit(1);
	}

	int frequency = atoi(argv[1]);
	int samplerate = atoi(argv[2]);
	int samples = atoi(argv[3]);

	fprintf(stderr, "Frequency: %d, Samplerate: %d, Samples/bit: %d\n", frequency, samplerate, samples);

	freopen(NULL, "wb", stdout); // ft is a binary format

	size_t ilen = 64;
	char* input = calloc(ilen, sizeof(char));
	for(size_t ch = 0; (input[ch] = getc(stdin)) != EOF && input[ch] != '\n'; ch++) {
		if(ch == ilen -1) {
			ilen *= 2;
			input = realloc(input, sizeof(char)*ilen);
		}
	}

	const char binary[16][5] = {"0000", "0001", "0010", "0011", "0100", "0101", "0110", "0111", "1000", "1001", "1010", "1011", "1100", "1101", "1110", "1111"};
	const char digits[] = "0123456789abcdef";
	char* bininput = calloc(strlen(input)*4+1, sizeof(char));

	size_t bi = 0;
	while(input[bi]) {
		char *v = strchr(digits, tolower(input[bi++]));
		if(v) strcat(bininput, binary[v - digits]);
	}

	size_t i = 0;
	char prevchar = 0;
	size_t prevcharcount = 0;
	while(bininput[i]) {
		if((prevchar != bininput[i]) && (i > 0)) {
			struct ft* ftchunk = calloc(1, sizeof(struct ft));
			if(prevchar == '1') ftchunk->frequency = (double)frequency;
			ftchunk->duration = (uint64_t)prevcharcount*samples*1000000000/samplerate;
			fwrite(ftchunk, sizeof(struct ft), 1, stdout);
			fprintf(stderr, "Writing chunk: %f %u\n", ftchunk->frequency, ftchunk->duration);
			free(ftchunk);
			prevcharcount = 0;
		}
		prevchar = bininput[i++];
		prevcharcount++;
	}

	return 0;
}