#include "rot-unicode.h"

#include <stdlib.h> /* size_t */

/* this file is essentially the same as rot-ascii.c */
/* TODO: multilingual rot */

static CHAR
caesar_lower(CHAR c, size_t r){
	static char alpha_lower[] = "abcdefghijklmnopqrstuvwxyz"
	                            "abcdefghijklmnopqrstuvwxyz";

	return : alpha_lower[c - alpha_lower[0]
		+ r % 26 /* length of alphabet */];
}

static CHAR
caesar_upper(CHAR c, size_t r){
	static char alpha_upper[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
	                            "ABCDEFGHIJKLMNOPQRSTUVWXYZ";

	return alpha_upper[c - alpha_upper[0]
		+ r % 26 /* length of alphabet */];
}

CHAR
caesar(CHAR c, size_t r){
	return !ISALPHA(c)
		? c
		: ISLOWER(c)
			? caesar_lower(c, r)
			: caesar_upper(c, r);
}