/*
 * Bitshuffle HDF5 filter
 *
 * This file is part of Bitshuffle
 * Author: Kiyoshi Masui <kiyo@physics.ubc.ca>
 * Website: http://www.github.com/kiyo-masui/bitshuffle
 * Created: 2014
 *
 * See LICENSE file for details about copyright and rights to use.
 *
 */

#include "bitshuffle.h"
#include "bshuf_h5filter.h"


#define PUSH_ERR(func, minor, str)                                      \
    H5Epush1(__FILE__, func, __LINE__, H5E_PLINE, minor, str)


// Prototypes from bitshuffle.c
void bshuf_write_uint64_BE(void* buf, uint64_t num);
uint64_t bshuf_read_uint64_BE(void* buf);
void bshuf_write_uint32_BE(void* buf, uint32_t num);
uint32_t bshuf_read_uint32_BE(const void* buf);


// Only called on compresion, not on reverse.
herr_t bshuf_h5_set_local(hid_t dcpl, hid_t type, hid_t space){

    herr_t r;
    size_t ii;

    unsigned int elem_size;

    unsigned int flags;
    size_t nelements = 8;
    size_t nelem_max = 11;
    unsigned values[] = {0,0,0,0,0,0,0,0,0,0,0};
    unsigned tmp_values[] = {0,0,0,0,0,0,0,0};
    char msg[80];

    r = H5Pget_filter_by_id2(dcpl, BSHUF_H5FILTER, &flags, &nelements,
            tmp_values, 0, NULL, NULL);
    if(r<0) return -1;

    // First 3 slots reserved. Move any passed options to higher addresses.
    for (ii=0; ii < nelements && ii + 3 < nelem_max; ii++) {
        values[ii + 3] = tmp_values[ii];
    }

    nelements = 3 + nelements;

    values[0] = BSHUF_VERSION_MAJOR;
    values[1] = BSHUF_VERSION_MINOR;

    elem_size = H5Tget_size(type);
    if(elem_size <= 0) {
        PUSH_ERR("bshuf_h5_set_local", H5E_CALLBACK, 
                "Invalid element size.");
        return -1;
    }

    values[2] = elem_size;

    // Validate user supplied arguments.
    if (nelements > 3) {
        if (values[3] % 8 || values[3] < 0) {
            sprintf(msg, "Error in bitshuffle. Invalid block size: %d.",
                    values[3]);
            PUSH_ERR("bshuf_h5_set_local", H5E_CALLBACK, msg);
            return -1;
        }
    }
    if (nelements > 4) {
        switch (values[4]) {
            case 0:
                break;
            case BSHUF_H5_COMPRESS_LZ4:
                break;
            default:
                PUSH_ERR("bshuf_h5_set_local", H5E_CALLBACK, 
                         "Invalid bitshuffle compression.");
        }
    }

    r = H5Pmodify_filter(dcpl, BSHUF_H5FILTER, flags, nelements, values);
    if(r<0) return -1;

    return 1;
}


size_t bshuf_h5_filter(unsigned int flags, size_t cd_nelmts,
           const unsigned int cd_values[], size_t nbytes,
           size_t *buf_size, void **buf) {

    size_t size, elem_size;
    int err;
    char msg[80];
    size_t block_size = 0;
    size_t buf_size_out, nbytes_uncomp, nbytes_out;
    char* in_buf = *buf;
    void *out_buf;

    if (cd_nelmts < 3) {
        PUSH_ERR("bshuf_h5_filter", H5E_CALLBACK, 
                "Not enough parameters.");
        return 0;
    }
    elem_size = cd_values[2];

    // User specified block size.
    if (cd_nelmts > 3) block_size = cd_values[3];

    if (block_size == 0) block_size = bshuf_default_block_size(elem_size);

    // Compression in addition to bitshiffle.
    if (cd_nelmts > 4 && cd_values[4] == BSHUF_H5_COMPRESS_LZ4) {
        if (flags & H5Z_FLAG_REVERSE) {
            // First eight bytes is the number of bytes in the output buffer,
            // little endian.
            nbytes_uncomp = bshuf_read_uint64_BE(in_buf);
            // Override the block size with the one read from the header.
            block_size = bshuf_read_uint32_BE((const char*) in_buf + 8) / elem_size;
            // Skip over the header.
            in_buf += 12;
            buf_size_out = nbytes_uncomp;
        } else {
            nbytes_uncomp = nbytes;
            buf_size_out = bshuf_compress_lz4_bound(nbytes_uncomp / elem_size, 
                    elem_size, block_size) + 12;
        }
    } else {
        nbytes_uncomp = nbytes;
        buf_size_out = nbytes;
    }

    // TODO, remove this restriction by memcopying the extra.
    if (nbytes_uncomp % elem_size) {
        PUSH_ERR("bshuf_h5_filter", H5E_CALLBACK, 
                "Non integer number of elements.");
        return 0;
    }
    size = nbytes_uncomp / elem_size;

    out_buf = malloc(buf_size_out);
    if (out_buf == NULL) {
        PUSH_ERR("bshuf_h5_filter", H5E_CALLBACK, 
                "Could not allocate output buffer.");
        return 0;
    }

    if (cd_nelmts > 4 && cd_values[4] == BSHUF_H5_COMPRESS_LZ4) {
        if (flags & H5Z_FLAG_REVERSE) {
            // Bit unshuffle/decompress.
            err = bshuf_decompress_lz4(in_buf, out_buf, size, elem_size, block_size);
            nbytes_out = nbytes_uncomp;
        } else {
            // Bit shuffle/compress.
            // Write the header, described in
            // http://www.hdfgroup.org/services/filters/HDF5_LZ4.pdf.
            // Techincally we should be using signed integers instead of
            // unsigned ones, however for valid inputs (positive numbers) these
            // have the same representation.
            bshuf_write_uint64_BE(out_buf, nbytes_uncomp);
            bshuf_write_uint32_BE((char*) out_buf + 8, block_size * elem_size);
            err = bshuf_compress_lz4(in_buf, (char*) out_buf + 12, size,
                    elem_size, block_size); nbytes_out = err + 12; } } else {
                if (flags & H5Z_FLAG_REVERSE) {
            // Bit unshuffle.
            err = bshuf_bitunshuffle(in_buf, out_buf, size, elem_size,
                    block_size); } else {
            // Bit shuffle.
            err = bshuf_bitshuffle(in_buf, out_buf, size, elem_size,
                    block_size); } nbytes_out = nbytes; }
    //printf("nb_in %d, nb_uncomp %d, nb_out %d, buf_out %d, block %d\n",
    //nbytes, nbytes_uncomp, nbytes_out, buf_size_out, block_size);

    if (err < 0) {
        sprintf(msg, "Error in bitshuffle with error code %d.", err);
        PUSH_ERR("bshuf_h5_filter", H5E_CALLBACK, msg);
        free(out_buf);
        return 0;
    } else {
        free(*buf);
        *buf = out_buf;
        *buf_size = buf_size_out;

        return nbytes_out;
    }
}



H5Z_class_t bshuf_H5Filter[1] = {{
    H5Z_CLASS_T_VERS,
    (H5Z_filter_t)(BSHUF_H5FILTER),
    1, 1,
    "bitshuffle; see https://github.com/kiyo-masui/bitshuffle",
    NULL,
    (H5Z_set_local_func_t)(bshuf_h5_set_local),
    (H5Z_func_t)(bshuf_h5_filter)
}};


int bshuf_register_h5filter(void){

    int retval;

    retval = H5Zregister(bshuf_H5Filter);
    if(retval<0){
        PUSH_ERR("bshuf_register_h5filter",
                 H5E_CANTREGISTER, "Can't register bitshuffle filter");
    }
    return retval;
}

