#define _GNU_SOURCE
#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <stdint.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <assert.h>


static char* readfile(const char *fname, size_t *length){
	int fd = open(fname, O_RDONLY);
	if (fd < 0) {
		perror("open");
		exit(1);
	}

	struct stat statbuf;
	if (fstat(fd, &statbuf) < 0) {
		perror("stat");
		exit(1);
	}

	*length = statbuf.st_size;

	FILE *f = fdopen(fd, "r");
	if (!f) {
		fprintf(stderr, "Cannot open file '%s'\n", fname);
		exit(1);
	}
	char *mem = malloc(*length + 1);
	assert(fread(mem, 1, *length, f) == *length);
	fclose(f);

	return mem;
}

static void dump(const uint8_t *mem, size_t memsize, size_t mp) {
	size_t low = 0, high = memsize - 1;
	while (low < mp && mem[low] == 0) low++;
	while (high > mp && mem[high] == 0) high--;
	for (size_t i = low; i <= high; i++) {
		if (i == mp) fprintf(stderr, "\x1B[4m");
		fprintf(stderr, "%3u ", mem[i]);
		if (i == mp) fprintf(stderr, "\x1B[0m");
	}
	fprintf(stderr, "\n");
}


int main(int argc, char **argv) {
	if (argc != 2) {
		fprintf(stderr, "Usage: %s <file.bf>\n", argv[0]);
		return 1;
	}

	size_t srclen;
	char *source = readfile(argv[1], &srclen);

	size_t *jm = malloc(srclen * sizeof(size_t));
	size_t *stk = malloc(srclen * sizeof(size_t));
	size_t stklen = 0;
	for (size_t i = 0; i < srclen; i++) {
		if (source[i] == '[') {
			stk[stklen++] = i;
		} else if (source[i] == ']') {
			if (stklen == 0) {
				fprintf(stderr, "Too many ']'\n");
				return 1;
			}
			jm[stk[stklen-1]] = i;
			jm[i] = stk[stklen-1];
			stklen--;
		}
	}
	if (stklen > 0) {
		fprintf(stderr, "Too many '['\n");
		return 1;
	}

	free(stk);

	const size_t memsize = 60000;
	uint8_t *mem = calloc(memsize, 1);
	size_t mp = memsize / 2;
	bool stop = false;
	for (size_t i = 0; i < srclen && !stop; i++) {
		switch (source[i]) {
			case '+': mem[mp]++; break;
			case '-': mem[mp]--; break;
			case '>': mp++; break;
			case '<': mp--; break;
			case ',': mem[mp] = getchar(); break;
			case '.': putchar(mem[mp]); break;
			case '[': if (!mem[mp]) i = jm[i]; break;
			case ']': if (mem[mp]) i = jm[i]; break;
			case '`': stop = true; break;
			case '$': fprintf(stderr, "CRASH\n"); stop = true; break;
			// case '*': usleep(5000000); break;
			case '*': fprintf(stderr, "CHANGE\n"); source[i] = '`'; break;
			default: continue;
		}

		// dump(mem, memsize, mp);
	}

	dump(mem, memsize, mp);

	free(mem);
	free(source);
	free(jm);
}