/*      $OpenBSD: parser.c,v 1.2 2023/04/19 12:58:16 jsg Exp $  */

/*
 * Copyright (c) 2004 Esben Norby <norby@openbsd.org>
 * Copyright (c) 2003, 2004 Henning Brauer <henning@openbsd.org>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include <sys/types.h>
#include <sys/queue.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>

#include <net/if.h>
#include <netinet/if_ether.h>

#include <err.h>
#include <errno.h>
#include <event.h>
#include <imsg.h>
#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "slaacd.h"
#include "parser.h"

enum token_type {
        NOTOKEN,
        ENDTOKEN,
        INTERFACENAME,
        KEYWORD
};

struct token {
        enum token_type          type;
        const char              *keyword;
        int                      value;
        const struct token      *next;
};

static const struct token t_main[];
static const struct token t_log[];
static const struct token t_show[];
static const struct token t_show_interface[];
static const struct token t_send[];
static const struct token t_send_sol[];

static const struct token t_main[] = {
        {KEYWORD,       "show",         SHOW,           t_show},
        {KEYWORD,       "log",          NONE,           t_log},
        {KEYWORD,       "send",         NONE,           t_send},
        {ENDTOKEN,      "",             NONE,           NULL}
};

static const struct token t_log[] = {
        {KEYWORD,       "verbose",      LOG_VERBOSE,    NULL},
        {KEYWORD,       "brief",        LOG_BRIEF,      NULL},
        {ENDTOKEN,      "",             NONE,           NULL}
};

static const struct token t_show[] = {
        {KEYWORD,       "interface",    SHOW_INTERFACE,  t_show_interface},
        {ENDTOKEN,      "",             NONE,           NULL}
};

static const struct token t_send[] = {
        {KEYWORD,       "solicitation", SEND_SOLICITATION,      t_send_sol},
        {ENDTOKEN,      "",             NONE,                   NULL}
};
static const struct token t_send_sol[] = {
        {INTERFACENAME, "",             SEND_SOLICITATION,      NULL},
        {ENDTOKEN,      "",             NONE,                   NULL}
};

static const struct token t_show_interface[] = {
        {NOTOKEN,       "",             NONE,           NULL},
        {INTERFACENAME, "",             SHOW_INTERFACE, NULL},
        {ENDTOKEN,      "",             NONE,           NULL}
};

static const struct token *match_token(const char *, const struct token *,
    struct parse_result *);
static void show_valid_args(const struct token *);

struct parse_result *
parse(int argc, char *argv[])
{
        static struct parse_result      res;
        const struct token      *table = t_main;
        const struct token      *match;

        memset(&res, 0, sizeof(res));

        while (argc >= 0) {
                if ((match = match_token(argv[0], table, &res)) == NULL) {
                        fprintf(stderr, "valid commands/args:\n");
                        show_valid_args(table);
                        return (NULL);
                }

                argc--;
                argv++;

                if (match->type == NOTOKEN || match->next == NULL)
                        break;

                table = match->next;
        }

        if (argc > 0) {
                fprintf(stderr, "superfluous argument: %s\n", argv[0]);
                return (NULL);
        }

        return (&res);
}

static const struct token *
match_token(const char *word, const struct token *table,
    struct parse_result *res)
{
        u_int                    i, match;
        const struct token      *t = NULL;

        match = 0;

        for (i = 0; table[i].type != ENDTOKEN; i++) {
                switch (table[i].type) {
                case NOTOKEN:
                        if (word == NULL || strlen(word) == 0) {
                                match++;
                                t = &table[i];
                        }
                        break;
                case INTERFACENAME:
                        if (!match && word != NULL && strlen(word) > 0) {
                                if ((res->if_index = if_nametoindex(word)) == 0)
                                        errx(1, "unknown interface");
                                match++;
                                t = &table[i];
                                if (t->value)
                                        res->action = t->value;
                        }
                        break;
                case KEYWORD:
                        if (word != NULL && strncmp(word, table[i].keyword,
                            strlen(word)) == 0) {
                                match++;
                                t = &table[i];
                                if (t->value)
                                        res->action = t->value;
                        }
                        break;
                case ENDTOKEN:
                        break;
                }
        }

        if (match != 1) {
                if (word == NULL)
                        fprintf(stderr, "missing argument:\n");
                else if (match > 1)
                        fprintf(stderr, "ambiguous argument: %s\n", word);
                else if (match < 1)
                        fprintf(stderr, "unknown argument: %s\n", word);
                return (NULL);
        }

        return (t);
}

static void
show_valid_args(const struct token *table)
{
        int     i;

        for (i = 0; table[i].type != ENDTOKEN; i++) {
                switch (table[i].type) {
                case NOTOKEN:
                        fprintf(stderr, "  <cr>\n");
                        break;
                case INTERFACENAME:
                        fprintf(stderr, " <interface>\n");
                        break;
                case KEYWORD:
                        fprintf(stderr, "  %s\n", table[i].keyword);
                        break;
                case ENDTOKEN:
                        break;
                }
        }
}