/*
 * Copyright (C) 2015 MediaTek Inc.
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 */

#include "ged_base.h"
#include "ged_hashtable.h"
#include <linux/hashtable.h>

typedef struct GED_HASHTABLE_TAG
{
    unsigned int        ui32Bits;
    unsigned int        ui32Length;
    unsigned int        ui32CurrentID;
    unsigned int        ui32Count;
    struct hlist_head*  psHashTable;
} GED_HASHTABLE;

typedef struct GED_HASHNODE_TAG
{
    unsigned int        ui32ID;
    void*               pvoid;
    struct hlist_node   sNode;
} GED_HASHNODE;

#define GED_HASHTABLE_INIT_ID 1234 // 0 = invalid

void* __ged_hashtable_find(struct hlist_head *head, unsigned int ui32ID)
{
    GED_HASHNODE* psHN;
    hlist_for_each_entry_rcu(psHN, head, sNode) 
    {
        if (psHN->ui32ID == ui32ID)
        {
            return psHN;
        }
    }
    return NULL;
}

static int ged_hash(GED_HASHTABLE_HANDLE hHashTable, unsigned int ui32ID)
{
    GED_HASHTABLE* psHT = (GED_HASHTABLE*)hHashTable;
    return hash_32(ui32ID, psHT->ui32Bits);
}

GED_HASHTABLE_HANDLE ged_hashtable_create(unsigned int ui32Bits)
{
    GED_HASHTABLE* psHT;
    unsigned int i;

    if (ui32Bits > 20)
    {
        // 1048576 slots !?
        // Need to check the necessary
        return NULL;
    }

    psHT = (GED_HASHTABLE*)ged_alloc(sizeof(GED_HASHTABLE));
    if (psHT)
    {
        psHT->ui32Bits = ui32Bits;
        psHT->ui32Length = 1 << ui32Bits;
        psHT->ui32CurrentID = GED_HASHTABLE_INIT_ID; // 0 = invalid
        psHT->psHashTable = (struct hlist_head*)ged_alloc(psHT->ui32Length * sizeof(struct hlist_head));
        if (psHT->psHashTable)
        {
            for (i = 0; i < psHT->ui32Length; i++)
            {
                INIT_HLIST_HEAD(&psHT->psHashTable[i]);
            }
            return (GED_HASHTABLE_HANDLE)psHT;
        }
    }

    ged_hashtable_destroy(psHT);
    return NULL;
}

void ged_hashtable_destroy(GED_HASHTABLE_HANDLE hHashTable)
{
    GED_HASHTABLE* psHT = (GED_HASHTABLE*)hHashTable;
    if (psHT)
    {
        int i = 0;
        while(psHT->ui32Count > 0)
        {
            unsigned int ui32ID = 0;
            GED_HASHNODE* psHN;
            // get one to be freed
            for (;i < psHT->ui32Length; i++)
            {
                struct hlist_head *head = &psHT->psHashTable[i];
                hlist_for_each_entry_rcu(psHN, head, sNode) 
                {
                    ui32ID = psHN->ui32ID;
                    break;
                }
                if (0 < ui32ID)
                {
                    break;
                }
            }

            if (i >= psHT->ui32Length)
            {
                break;
            }

            ged_hashtable_remove(psHT, ui32ID);
        }

        /* free the hash table */
        ged_free(psHT->psHashTable, psHT->ui32Length * sizeof(struct hlist_head));
        ged_free(psHT, sizeof(GED_HASHTABLE));
    }
}

GED_ERROR ged_hashtable_insert(GED_HASHTABLE_HANDLE hHashTable, void* pvoid, unsigned int* pui32ID)
{
    GED_HASHTABLE* psHT = (GED_HASHTABLE*)hHashTable;
    GED_HASHNODE* psHN = NULL;
    unsigned int ui32Hash, ui32ID;

    if ((!psHT) || (!pui32ID))
    {
        return GED_ERROR_INVALID_PARAMS;
    }

    ui32ID = psHT->ui32CurrentID + 1;
    while(1)
    {
        ui32Hash = ged_hash(psHT, ui32ID);
        psHN = __ged_hashtable_find(&psHT->psHashTable[ui32Hash], ui32ID);
        if (psHN != NULL)
        {
            ui32ID++;
            if (ui32ID == 0)//skip the value 0
            {
                ui32ID = 1;
            }
            if (ui32ID == psHT->ui32CurrentID)
            {
                return GED_ERROR_FAIL;
            }
        }
        else
        {
            break;
        }
    };

    psHN = (GED_HASHNODE*)ged_alloc(sizeof(GED_HASHNODE));
    if (psHN)
    {
        psHN->pvoid = pvoid;
        psHN->ui32ID = ui32ID;
        psHT->ui32CurrentID = ui32ID;
        *pui32ID = ui32ID;
        hlist_add_head_rcu(&psHN->sNode, &psHT->psHashTable[ui32Hash]);
        psHT->ui32Count += 1;
        return GED_OK;
    }

    return GED_ERROR_OOM;
}

void ged_hashtable_remove(GED_HASHTABLE_HANDLE hHashTable, unsigned int ui32ID)
{
    GED_HASHTABLE* psHT = (GED_HASHTABLE*)hHashTable;
    if (psHT)
    {
        unsigned int ui32Hash = ged_hash(psHT, ui32ID);
        GED_HASHNODE* psHN = __ged_hashtable_find(&psHT->psHashTable[ui32Hash], ui32ID);
        if (psHN)
        {
            hlist_del_rcu(&psHN->sNode);
            synchronize_rcu();
            ged_free(psHN, sizeof(GED_HASHNODE));
            psHT->ui32Count -= 1;
        }
    }
}

void* ged_hashtable_find(GED_HASHTABLE_HANDLE hHashTable, unsigned int ui32ID)
{
    GED_HASHTABLE* psHT = (GED_HASHTABLE*)hHashTable;
    if (psHT)
    {
        unsigned int ui32Hash = ged_hash(psHT, ui32ID);
        GED_HASHNODE* psHN = __ged_hashtable_find(&psHT->psHashTable[ui32Hash], ui32ID);
        if (psHN)
        {
            return psHN->pvoid;
        }
#ifdef GED_DEBUG
        if (ui32ID != 0)
        {
            GED_LOGE("ged_hashtable_find: ui32ID=%u ui32Hash=%u psHN=%p\n", ui32ID, ui32Hash, psHN);
        }
#endif
    }
    return NULL;
}

GED_ERROR ged_hashtable_set(GED_HASHTABLE_HANDLE hHashTable, unsigned int ui32ID, void* pvoid)
{
    GED_HASHTABLE* psHT = (GED_HASHTABLE*)hHashTable;
    if (psHT)
    {
        unsigned int ui32Hash = ged_hash(psHT, ui32ID);
        GED_HASHNODE* psHN = __ged_hashtable_find(&psHT->psHashTable[ui32Hash], ui32ID);
        if (psHN)
        {
            psHN->pvoid = pvoid;
            return GED_OK;
        }
    }

    return GED_ERROR_INVALID_PARAMS;
}