#include <stdio.h>
#include <stddef.h>
#include <string.h>

void
indicate_file_area(FILE* fd, size_t line, size_t column, size_t span) {
	const char margin[] = "  ";

	char buf[1024] = { '\0' };
	char *s = buf;
	char *line_start = buf;

	rewind(fd);
	while (line && !feof(fd) && fgets(buf, sizeof(buf), fd)) {
		s = buf;
		while (*s) {
			if (*(s++) == '\n') {
				line--;
			}
		}
	}

	while (*line_start == '\t' || *line_start == ' ') {
		line_start++;
	}

	fputs(margin, stderr);
	fputs(line_start, stderr);

	/* corner case (still needed?) - buf was just return */
	if (strlen(buf) == 1 && buf[0] == '\n') {
		fputc('\n', stderr);
	}

	fputs(margin, stderr);
	for (column--; column; column--) {
		fputc(' ', stderr);
	}
	for (; span; span--) {
		fputc('^', stderr);
	}
	fputc('\n', stderr);
}