/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 * 
 *  http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

#include <stddef.h>
#include <string.h>
#include <assert.h>
#include "nffs/nffs.h"
#include "nffs_priv.h"

struct nffs_hash_list *nffs_hash;

uint32_t nffs_hash_next_dir_id;
uint32_t nffs_hash_next_file_id;
uint32_t nffs_hash_next_block_id;

int
nffs_hash_id_is_dir(uint32_t id)
{
    return id >= NFFS_ID_DIR_MIN && id < NFFS_ID_DIR_MAX;
}

int
nffs_hash_id_is_file(uint32_t id)
{
    return id >= NFFS_ID_FILE_MIN && id < NFFS_ID_FILE_MAX;
}

int
nffs_hash_id_is_inode(uint32_t id)
{
    return nffs_hash_id_is_dir(id) || nffs_hash_id_is_file(id);
}

int
nffs_hash_id_is_block(uint32_t id)
{
    return id >= NFFS_ID_BLOCK_MIN && id < NFFS_ID_BLOCK_MAX;
}

static int
nffs_hash_fn(uint32_t id)
{
    return id % NFFS_HASH_SIZE;
}

static struct nffs_hash_entry *
nffs_hash_find_reorder(uint32_t id)
{
    struct nffs_hash_entry *entry;
    struct nffs_hash_entry *prev;
    struct nffs_hash_list *list;
    int idx;

    idx = nffs_hash_fn(id);
    list = nffs_hash + idx;

    prev = NULL;
    SLIST_FOREACH(entry, list, nhe_next) {
        if (entry->nhe_id == id) {
            /* Put entry at the front of the list. */
            if (prev != NULL) {
                SLIST_NEXT(prev, nhe_next) = SLIST_NEXT(entry, nhe_next);
                SLIST_INSERT_HEAD(list, entry, nhe_next);
            }
            return entry;
        }

        prev = entry;
    }

    return NULL;
}

struct nffs_hash_entry *
nffs_hash_find(uint32_t id)
{
    struct nffs_hash_entry *entry;
    struct nffs_hash_list *list;
    int idx;

    idx = nffs_hash_fn(id);
    list = nffs_hash + idx;

    SLIST_FOREACH(entry, list, nhe_next) {
        if (entry->nhe_id == id) {
            return entry;
        }
    }

    return NULL;
}

struct nffs_inode_entry *
nffs_hash_find_inode(uint32_t id)
{
    struct nffs_hash_entry *entry;

    assert(nffs_hash_id_is_inode(id));

    entry = nffs_hash_find_reorder(id);
    return (struct nffs_inode_entry *)entry;
}

struct nffs_hash_entry *
nffs_hash_find_block(uint32_t id)
{
    struct nffs_hash_entry *entry;

    assert(nffs_hash_id_is_block(id));

    entry = nffs_hash_find_reorder(id);
    return entry;
}

int
nffs_hash_entry_is_dummy(struct nffs_hash_entry *he)
{
        return(he->nhe_flash_loc == NFFS_FLASH_LOC_NONE);
}

int
nffs_hash_id_is_dummy(uint32_t id)
{
    struct nffs_hash_entry *he = nffs_hash_find(id);
    if (he != NULL) {
        return(he->nhe_flash_loc == NFFS_FLASH_LOC_NONE);
    }
    return 0;
}

void
nffs_hash_insert(struct nffs_hash_entry *entry)
{
    struct nffs_hash_list *list;
    struct nffs_inode_entry *nie;
    int idx;

    assert(nffs_hash_find(entry->nhe_id) == NULL);
    idx = nffs_hash_fn(entry->nhe_id);
    list = nffs_hash + idx;

    SLIST_INSERT_HEAD(list, entry, nhe_next);
    STATS_INC(nffs_stats, nffs_hashcnt_ins);

    if (nffs_hash_id_is_inode(entry->nhe_id)) {
        nie = nffs_hash_find_inode(entry->nhe_id);
        assert(nie);
        nffs_inode_setflags(nie, NFFS_INODE_FLAG_INHASH);
    } else {
        assert(nffs_hash_find(entry->nhe_id));
    }
}

void
nffs_hash_remove(struct nffs_hash_entry *entry)
{
    struct nffs_hash_list *list;
    struct nffs_inode_entry *nie = NULL;
    int idx;

    if (nffs_hash_id_is_inode(entry->nhe_id)) {
        nie = nffs_hash_find_inode(entry->nhe_id);
        assert(nie);
        assert(nffs_inode_getflags(nie, NFFS_INODE_FLAG_INHASH));
    } else {
        assert(nffs_hash_find(entry->nhe_id));
    }

    idx = nffs_hash_fn(entry->nhe_id);
    list = nffs_hash + idx;

    SLIST_REMOVE(list, entry, nffs_hash_entry, nhe_next);
    STATS_INC(nffs_stats, nffs_hashcnt_rm);

    if (nffs_hash_id_is_inode(entry->nhe_id) && nie) {
        nffs_inode_unsetflags(nie, NFFS_INODE_FLAG_INHASH);
    }
    assert(nffs_hash_find(entry->nhe_id) == NULL);
}

int
nffs_hash_init(void)
{
    int i;

    free(nffs_hash);

    nffs_hash = malloc(NFFS_HASH_SIZE * sizeof *nffs_hash);
    if (nffs_hash == NULL) {
        return FS_ENOMEM;
    }

    for (i = 0; i < NFFS_HASH_SIZE; i++) {
        SLIST_INIT(nffs_hash + i);
    }

    return 0;
}