/**
 * Copyright 2013, GitHub, Inc
 * Copyright 2009-2013, Daniel Lemire, Cliff Moon,
 *      David McIntosh, Robert Becho, Google Inc. and Veronika Zenz
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * 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.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, see <http://www.gnu.org/licenses/>.
 */
#include "git-compat-util.h"
#include "ewok.h"
#include "strbuf.h"

int ewah_serialize_native(struct ewah_bitmap *self, int fd)
{
        uint32_t write32;
        size_t to_write = self->buffer_size * 8;

        /* 32 bit -- bit size for the map */
        write32 = (uint32_t)self->bit_size;
        if (write(fd, &write32, 4) != 4)
                return -1;

        /** 32 bit -- number of compressed 64-bit words */
        write32 = (uint32_t)self->buffer_size;
        if (write(fd, &write32, 4) != 4)
                return -1;

        if (write(fd, self->buffer, to_write) != to_write)
                return -1;

        /** 32 bit -- position for the RLW */
        write32 = self->rlw - self->buffer;
        if (write(fd, &write32, 4) != 4)
                return -1;

        return (3 * 4) + to_write;
}

int ewah_serialize_to(struct ewah_bitmap *self,
                      int (*write_fun)(void *, const void *, size_t),
                      void *data)
{
        size_t i;
        eword_t dump[2048];
        const size_t words_per_dump = sizeof(dump) / sizeof(eword_t);
        uint32_t bitsize, word_count, rlw_pos;

        const eword_t *buffer;
        size_t words_left;

        /* 32 bit -- bit size for the map */
        bitsize =  htonl((uint32_t)self->bit_size);
        if (write_fun(data, &bitsize, 4) != 4)
                return -1;

        /** 32 bit -- number of compressed 64-bit words */
        word_count =  htonl((uint32_t)self->buffer_size);
        if (write_fun(data, &word_count, 4) != 4)
                return -1;

        /** 64 bit x N -- compressed words */
        buffer = self->buffer;
        words_left = self->buffer_size;

        while (words_left >= words_per_dump) {
                for (i = 0; i < words_per_dump; ++i, ++buffer)
                        dump[i] = htonll(*buffer);

                if (write_fun(data, dump, sizeof(dump)) != sizeof(dump))
                        return -1;

                words_left -= words_per_dump;
        }

        if (words_left) {
                for (i = 0; i < words_left; ++i, ++buffer)
                        dump[i] = htonll(*buffer);

                if (write_fun(data, dump, words_left * 8) != words_left * 8)
                        return -1;
        }

        /** 32 bit -- position for the RLW */
        rlw_pos = (uint8_t*)self->rlw - (uint8_t *)self->buffer;
        rlw_pos = htonl(rlw_pos / sizeof(eword_t));

        if (write_fun(data, &rlw_pos, 4) != 4)
                return -1;

        return (3 * 4) + (self->buffer_size * 8);
}

static int write_helper(void *fd, const void *buf, size_t len)
{
        return write((intptr_t)fd, buf, len);
}

int ewah_serialize(struct ewah_bitmap *self, int fd)
{
        return ewah_serialize_to(self, write_helper, (void *)(intptr_t)fd);
}

static int write_strbuf(void *user_data, const void *data, size_t len)
{
        struct strbuf *sb = user_data;
        strbuf_add(sb, data, len);
        return len;
}

int ewah_serialize_strbuf(struct ewah_bitmap *self, struct strbuf *sb)
{
        return ewah_serialize_to(self, write_strbuf, sb);
}

ssize_t ewah_read_mmap(struct ewah_bitmap *self, const void *map, size_t len)
{
        const uint8_t *ptr = map;
        size_t data_len;
        size_t i;

        if (len < sizeof(uint32_t))
                return error("corrupt ewah bitmap: eof before bit size");
        self->bit_size = get_be32(ptr);
        ptr += sizeof(uint32_t);
        len -= sizeof(uint32_t);

        if (len < sizeof(uint32_t))
                return error("corrupt ewah bitmap: eof before length");
        self->buffer_size = self->alloc_size = get_be32(ptr);
        ptr += sizeof(uint32_t);
        len -= sizeof(uint32_t);

        REALLOC_ARRAY(self->buffer, self->alloc_size);

        /*
         * Copy the raw data for the bitmap as a whole chunk;
         * if we're in a little-endian platform, we'll perform
         * the endianness conversion in a separate pass to ensure
         * we're loading 8-byte aligned words.
         */
        data_len = st_mult(self->buffer_size, sizeof(eword_t));
        if (len < data_len)
                return error("corrupt ewah bitmap: eof in data "
                             "(%"PRIuMAX" bytes short)",
                             (uintmax_t)(data_len - len));
        memcpy(self->buffer, ptr, data_len);
        ptr += data_len;
        len -= data_len;

        for (i = 0; i < self->buffer_size; ++i)
                self->buffer[i] = ntohll(self->buffer[i]);

        if (len < sizeof(uint32_t))
                return error("corrupt ewah bitmap: eof before rlw");
        self->rlw = self->buffer + get_be32(ptr);
        ptr += sizeof(uint32_t);
        len -= sizeof(uint32_t);

        return ptr - (const uint8_t *)map;
}

int ewah_deserialize(struct ewah_bitmap *self, int fd)
{
        size_t i;
        eword_t dump[2048];
        const size_t words_per_dump = sizeof(dump) / sizeof(eword_t);
        uint32_t bitsize, word_count, rlw_pos;

        eword_t *buffer = NULL;
        size_t words_left;

        ewah_clear(self);

        /* 32 bit -- bit size for the map */
        if (read(fd, &bitsize, 4) != 4)
                return -1;

        self->bit_size = (size_t)ntohl(bitsize);

        /** 32 bit -- number of compressed 64-bit words */
        if (read(fd, &word_count, 4) != 4)
                return -1;

        self->buffer_size = self->alloc_size = (size_t)ntohl(word_count);
        REALLOC_ARRAY(self->buffer, self->alloc_size);

        /** 64 bit x N -- compressed words */
        buffer = self->buffer;
        words_left = self->buffer_size;

        while (words_left >= words_per_dump) {
                if (read(fd, dump, sizeof(dump)) != sizeof(dump))
                        return -1;

                for (i = 0; i < words_per_dump; ++i, ++buffer)
                        *buffer = ntohll(dump[i]);

                words_left -= words_per_dump;
        }

        if (words_left) {
                if (read(fd, dump, words_left * 8) != words_left * 8)
                        return -1;

                for (i = 0; i < words_left; ++i, ++buffer)
                        *buffer = ntohll(dump[i]);
        }

        /** 32 bit -- position for the RLW */
        if (read(fd, &rlw_pos, 4) != 4)
                return -1;

        self->rlw = self->buffer + ntohl(rlw_pos);
        return 0;
}