/* lib9p/9p.c - Base 9P protocol utilities for both clients and servers
 *
 * Copyright (C) 2024-2025  Luke T. Shumaker <lukeshu@lukeshu.com>
 * SPDX-License-Identifier: AGPL-3.0-or-later
 */

#include <inttypes.h> /* for PRIu{n} */
#include <stdarg.h>   /* for va_* */
#include <string.h>   /* for strncpy() */

#include <libfmt/fmt.h> /* for fmt_vsnprintf() */

#include <lib9p/9p.h>

/* strings ********************************************************************/

struct lib9p_s lib9p_str(char *s) {
	if (!s)
		return (struct lib9p_s){0};
	return (struct lib9p_s){
		.len = strlen(s),
		.utf8 = s,
	};
}
struct lib9p_s lib9p_strn(char *s, size_t maxlen) {
	if (maxlen == 0 || !s)
		return (struct lib9p_s){0};
	return (struct lib9p_s){
		.len = strnlen(s, maxlen),
		.utf8 = s,
	};
}
struct lib9p_s lib9p_str_slice(struct lib9p_s s, uint16_t beg, uint16_t end) {
	assert(s.len == 0 || s.utf8);
	assert(beg <= end && end <= s.len);
	return (struct lib9p_s){
		.len = end - beg,
		.utf8 = &s.utf8[beg],
	};
}
bool lib9p_str_eq(struct lib9p_s a, struct lib9p_s b) {
	return a.len == b.len &&
		(a.len == 0 || memcmp(a.utf8, b.utf8, a.len) == 0);
}

/* ctx ************************************************************************/

void lib9p_ctx_clear_error(struct lib9p_ctx *ctx) {
	assert(ctx);
#if CONFIG_9P_ENABLE_9P2000_u
	ctx->err_num = 0;
#endif
	ctx->err_msg[0] = '\0';
}

bool lib9p_ctx_has_error(struct lib9p_ctx *ctx) {
	assert(ctx);
	return ctx->err_msg[0];
}

int lib9p_error(struct lib9p_ctx *ctx, lib9p_errno_t linux_errno, char const *msg) {
	if (lib9p_ctx_has_error(ctx))
		return -1;
	strncpy(ctx->err_msg, msg, sizeof(ctx->err_msg));
	ctx->err_msg[sizeof(ctx->err_msg)-1] = '\0';

#if CONFIG_9P_ENABLE_9P2000_u
	ctx->err_num = linux_errno;
#else
	(void)(linux_errno);
#endif

	return -1;
}

int lib9p_errorf(struct lib9p_ctx *ctx, lib9p_errno_t linux_errno, char const *fmt, ...) {
	int n;
	va_list args;

	if (lib9p_ctx_has_error(ctx))
		return -1;
	va_start(args, fmt);
	n = fmt_vsnprintf(ctx->err_msg, sizeof(ctx->err_msg), fmt, args);
	va_end(args);
	if ((size_t)(n+1) < sizeof(ctx->err_msg))
		memset(&ctx->err_msg[n+1], 0, sizeof(ctx->err_msg)-(n+1));

#if CONFIG_9P_ENABLE_9P2000_u
	ctx->err_num = linux_errno;
#else
	(void)(linux_errno);
#endif

	return -1;
}