/*
 * Copyright 2020 Toomas Soome <tsoome@me.com>
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

/*
 * Big Theory Statement.
 *
 * nvstore is abstraction layer to implement data read/write to different
 * types of non-volatile storage.
 *
 * User interfaces:
 * Provide mapping via environment: setenv/unsetenv/putenv. Access via
 * environment functions/commands is available once nvstore has
 * attached the backend and stored textual data is mapped to environment.
 *
 * Provide command "nvstore" to create new data instances.
 *
 * API: TBD.
 * nvstore_init(): attach new backend and create the environment mapping.
 * nvstore_fini: detach backend and unmap the related environment.
 *
 * The disk based storage, such as UFS file or ZFS bootenv label area, is
 * only accessible after root file system is set. Root file system change
 * will switch the back end storage.
 */

#include <sys/cdefs.h>

#include <stdbool.h>
#include <sys/queue.h>
#include <bootstrap.h>
#include "stand.h"

typedef struct nvstore {
        char            *nvs_name;
        void            *nvs_data;
        nvs_callbacks_t *nvs_cb;
        STAILQ_ENTRY(nvstore) nvs_next;
} nvstore_t;

typedef STAILQ_HEAD(store_list, nvstore) nvstore_list_t;

nvstore_list_t stores = STAILQ_HEAD_INITIALIZER(stores);

void *
nvstore_get_store(const char *name)
{
        nvstore_t *st;

        st = NULL;

        STAILQ_FOREACH(st, &stores, nvs_next) {
                if (strcmp(name, st->nvs_name) == 0)
                        break;
        }

        return (st);
}

int
nvstore_init(const char *name, nvs_callbacks_t *cb, void *data)
{
        nvstore_t *st;

        st = nvstore_get_store(name);
        if (st != NULL)
                return (EEXIST);

        if ((st = malloc(sizeof (*st))) == NULL)
                return (ENOMEM);

        if ((st->nvs_name = strdup(name)) == NULL) {
                free(st);
                return (ENOMEM);
        }

        st->nvs_data = data;
        st->nvs_cb = cb;

        STAILQ_INSERT_TAIL(&stores, st, nvs_next);
        return (0);
}

int
nvstore_fini(const char *name)
{
        nvstore_t *st;

        st = nvstore_get_store(name);
        if (st == NULL)
                return (ENOENT);

        STAILQ_REMOVE(&stores, st, nvstore, nvs_next);

        free(st->nvs_name);
        free(st->nvs_data);
        free(st);
        return (0);
}

int
nvstore_print(void *ptr)
{
        nvstore_t *st = ptr;

        return (st->nvs_cb->nvs_iterate(st->nvs_data, st->nvs_cb->nvs_print));
}

int
nvstore_get_var(void *ptr, const char *name, void **data)
{
        nvstore_t *st = ptr;

        return (st->nvs_cb->nvs_getter(st->nvs_data, name, data));
}

int
nvstore_set_var(void *ptr, int type, const char *name,
    void *data, size_t size)
{
        nvstore_t *st = ptr;

        return (st->nvs_cb->nvs_setter(st->nvs_data, type, name, data, size));
}

int
nvstore_set_var_from_string(void *ptr, const char *type, const char *name,
    const char *data)
{
        nvstore_t *st = ptr;

        return (st->nvs_cb->nvs_setter_str(st->nvs_data, type, name, data));
}

int
nvstore_unset_var(void *ptr, const char *name)
{
        nvstore_t *st = ptr;

        return (st->nvs_cb->nvs_unset(st->nvs_data, name));
}

COMMAND_SET(nvstore, "nvstore", "manage non-volatile data", command_nvstore);

static void
nvstore_usage(const char *me)
{
        printf("Usage:\t%s -l\n", me);
        printf("\t%s store -l\n", me);
        printf("\t%s store [-t type] key value\n", me);
        printf("\t%s store -g key\n", me);
        printf("\t%s store -d key\n", me);
}

/*
 * Usage: nvstore -l            # list stores
 *      nvstore store -l        # list data in store
 *      nvstore store [-t type] key value
 *      nvstore store -g key    # get value
 *      nvstore store -d key    # delete key
 */
static int
command_nvstore(int argc, char *argv[])
{
        int c;
        bool list, get, delete;
        nvstore_t *st;
        char *me, *name, *type;

        me = argv[0];
        optind = 1;
        optreset = 1;

        list = false;
        while ((c = getopt(argc, argv, "l")) != -1) {
                switch (c) {
                case 'l':
                        list = true;
                        break;
                case '?':
                default:
                        return (CMD_ERROR);
                }
        }

        argc -= optind;
        argv += optind;

        if (argc == 0) {
                if (list) {
                        if (STAILQ_EMPTY(&stores)) {
                                printf("No configured nvstores\n");
                                return (CMD_OK);
                        }
                        printf("List of configured nvstores:\n");
                        STAILQ_FOREACH(st, &stores, nvs_next) {
                                printf("\t%s\n", st->nvs_name);
                        }
                        return (CMD_OK);
                }
                nvstore_usage(me);
                return (CMD_ERROR);
        }

        if (argc == 0 || (argc != 0 && list)) {
                nvstore_usage(me);
                return (CMD_ERROR);
        }

        st = nvstore_get_store(argv[0]);
        if (st == NULL) {
                nvstore_usage(me);
                return (CMD_ERROR);
        }

        optind = 1;
        optreset = 1;
        name = NULL;
        type = NULL;
        get = delete = false;

        while ((c = getopt(argc, argv, "d:g:lt:")) != -1) {
                switch (c) {
                case 'd':
                        if (list || get) {
                                nvstore_usage(me);
                                return (CMD_ERROR);
                        }
                        name = optarg;
                        delete = true;
                        break;
                case 'g':
                        if (delete || list) {
                                nvstore_usage(me);
                                return (CMD_ERROR);
                        }
                        name = optarg;
                        get = true;
                        break;
                case 'l':
                        if (delete || get) {
                                nvstore_usage(me);
                                return (CMD_ERROR);
                        }
                        list = true;
                        break;
                case 't':
                        type = optarg;
                        break;
                case '?':
                default:
                        return (CMD_ERROR);
                }
        }

        argc -= optind;
        argv += optind;

        if (list) {
                (void) nvstore_print(st);
                return (CMD_OK);
        }

        if (delete && name != NULL) {
                (void) nvstore_unset_var(st, name);
                return (CMD_OK);
        }

        if (get && name != NULL) {
                char *ptr = NULL;

                if (nvstore_get_var(st, name, (void **)&ptr) == 0)
                        printf("%s = %s\n", name, ptr);
                return (CMD_OK);
        }

        if (argc == 2) {
                c = nvstore_set_var_from_string(st, type, argv[0], argv[1]);
                if (c != 0) {
                        printf("error: %s\n", strerror(c));
                        return (CMD_ERROR);
                }
                return (CMD_OK);
        }

        nvstore_usage(me);
        return (CMD_OK);
}