/* hostname.c — 随机主机名生成模块
 *
 * 基于当前时间戳的纳秒部分，从 78 张塔罗牌中随机选取一张作为主机名。
 * 格式：<5位时间戳十六进制>-<塔罗牌名>
 * 例如：1204f86c-king-of-cups
 *
 * 78 张牌 = 22 张大阿卡纳 + 56 张小阿卡纳（4花色×14数字）
 */

#include <stdio.h>
#include <time.h>
#include "hostname.h"

int choose_hostname(char *buff, size_t len)
{
	/* 小阿卡纳四花色 */
	static const char *suits[] = { "swords", "wands", "pentacles", "cups" };
	/* 小阿卡纳 14 张数字牌 */
	static const char *minor[] = {
		"ace", "two", "three", "four", "five", "six", "seven", "eight",
		"nine", "ten", "page", "knight", "queen", "king"
	};
	/* 大阿卡纳 22 张 */
	static const char *major[] = {
		"fool", "magician", "high-priestess", "empress", "emperor",
		"hierophant", "lovers", "chariot", "strength", "hermit",
		"wheel", "justice", "hanged-man", "death", "temperance",
		"devil", "tower", "star", "moon", "sun", "judgment", "world"
	};

	/* 用单调时钟的纳秒部分做随机种子 */
	struct timespec now = {0};
	clock_gettime(CLOCK_MONOTONIC, &now);
	size_t ix = now.tv_nsec % 78;  /* 78 张牌 */

	if (ix < sizeof(major) / sizeof(*major)) {
		/* 0~21：大阿卡纳 */
		snprintf(buff, len, "%05lx-%s", now.tv_sec, major[ix]);
	} else {
		/* 22~77：小阿卡纳（数字 + 花色） */
		ix -= sizeof(major) / sizeof(*major);
		snprintf(buff, len,
			 "%05lxc-%s-of-%s",
			 now.tv_sec,
			 minor[ix % (sizeof(minor) / sizeof(*minor))],
			 suits[ix / (sizeof(minor) / sizeof(*minor))]);
	}
	return 0;
}