/*
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
 *
 * Copyright 2021 Mike Becker, Olaf Wintermann All rights reserved.
 *
 * 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 COPYRIGHT HOLDERS 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 COPYRIGHT HOLDER 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.
 */

#include "cx/basic_mempool.h"
#include "cx/utils.h"
#include <string.h>

#define of_chk_(n) if (SIZE_MAX - sizeof(cx_destructor_func) < (n)) return NULL

/** Internal structure for denoting pooled memory. */
typedef struct {
    /** The destructor. */
    cx_destructor_func destructor;
    /**
     * Access to the first byte of the polled memory.
     */
    char c;
} cx_basic_mempool_memory;

static int cx_basic_mempool_chcap(
        struct cx_basic_mempool_s *pool,
        size_t newcap
) {
    if (newcap < pool->ndata) {
        return 1;
    }

    size_t newcapsz;
    if (cx_szmul(newcap, sizeof(void *), &newcapsz)) {
        return 1;
    }

    void **data = realloc(pool->data, newcapsz);
    if (data) {
        pool->data = data;
        pool->size = newcap;
        return 0;
    } else {
        return 1;
    }
}

void *cx_malloc_basic_mempool(
        void *data,
        size_t n
) {
    of_chk_(n);
    struct cx_basic_mempool_s *pool = data;

    if (pool->ndata >= pool->size) {
        size_t newcap = pool->size * 2;
        if (newcap < pool->size || cx_basic_mempool_chcap(pool, newcap)) {
            return NULL;
        }
    }

    cx_basic_mempool_memory *mem = malloc(sizeof(cx_destructor_func) + n);
    if (mem == NULL) {
        return NULL;
    }

    mem->destructor = NULL;
    pool->data[pool->ndata] = mem;
    pool->ndata++;

    return &(mem->c);
}

void *cx_calloc_basic_mempool(
        void *data,
        size_t nelem,
        size_t elsize
) {
    size_t msz;
    if (cx_szmul(nelem, elsize, &msz)) {
        return NULL;
    }
    void *ptr = cx_malloc_basic_mempool(data, msz);
    if (ptr == NULL) {
        return NULL;
    }
    memset(ptr, 0, nelem * elsize);
    return ptr;
}

void *cx_realloc_basic_mempool(
        void *data,
        void *ptr,
        size_t n
) {
    of_chk_(n);
    struct cx_basic_mempool_s *pool = data;

    char *mem = ((char *) ptr) - sizeof(cx_destructor_func);
    char *newm = (char *) realloc(mem, n + sizeof(cx_destructor_func));
    if (newm == NULL) {
        return NULL;
    }
    if (mem != newm) {
        cx_for_n(i, pool->ndata) {
            if (pool->data[i] == mem) {
                pool->data[i] = newm;
                return newm + sizeof(cx_destructor_func);
            }
        }
        abort();
    } else {
        return newm + sizeof(cx_destructor_func);
    }
}

void cx_free_basic_mempool(
        void *data,
        void *ptr
) {
    struct cx_basic_mempool_s *pool = data;

    cx_basic_mempool_memory *mem = (cx_basic_mempool_memory *)
            ((char *) ptr - sizeof(cx_destructor_func));
    cx_for_n(i, pool->ndata) {
        if (mem == pool->data[i]) {
            if (mem->destructor != NULL) {
                mem->destructor(&(mem->c));
            }
            free(mem);
            size_t last_index = pool->ndata - 1;
            if (i != last_index) {
                pool->data[i] = pool->data[last_index];
                pool->data[last_index] = NULL;
            }
            pool->ndata--;
            return;
        }
    }
    abort();
}

void cx_basic_mempool_destroy(CxMempool *p) {
    struct cx_basic_mempool_s *pool = (struct cx_basic_mempool_s *) p;
    cx_basic_mempool_memory *mem;
    cx_for_n(i, pool->ndata) {
        mem = (cx_basic_mempool_memory *) pool->data[i];
        if (mem) {
            if (mem->destructor) {
                mem->destructor(&(mem->c));
            }
            free(mem);
        }
    }
    free(pool->data);
    free((void *) p->allocator);
    free(pool);
}

void cx_basic_mempool_set_destr(
        __attribute__((__unused__)) CxMempool *pool,
        void *ptr,
        cx_destructor_func func
) {
    *(cx_destructor_func *) ((char *) ptr - sizeof(cx_destructor_func)) = func;
}

static cx_allocator_class cx_basic_mempool_allocator_class = {
        cx_malloc_basic_mempool,
        cx_realloc_basic_mempool,
        cx_calloc_basic_mempool,
        cx_free_basic_mempool
};

static cx_mempool_class cx_basic_mempool_class = {
        cx_basic_mempool_destroy,
        cx_basic_mempool_set_destr,
};

CxMempool *cxBasicMempoolCreate(size_t capacity) {
    size_t poolsize;
    if (cx_szmul(capacity, sizeof(void *), &poolsize)) {
        return NULL;
    }

    struct cx_basic_mempool_s *pool =
            malloc(sizeof(struct cx_basic_mempool_s));
    if (pool == NULL) {
        return NULL;
    }


    CxAllocator *provided_allocator = malloc(sizeof(CxAllocator));
    if (!provided_allocator) {
        free(pool);
        return NULL;
    }
    provided_allocator->cl = &cx_basic_mempool_allocator_class;
    provided_allocator->data = pool;

    pool->base.cl = &cx_basic_mempool_class;
    pool->base.allocator = provided_allocator;

    pool->data = malloc(poolsize);
    if (pool->data == NULL) {
        free(provided_allocator);
        free(pool);
        return NULL;
    }

    pool->ndata = 0;
    pool->size = capacity;

    return (CxMempool *) pool;
}