#include "ziputils.h"
#include <memory>
#include <zlib/zlib.h>

ZipUtils::ZipUtils()
{}

ZipUtils::~ZipUtils()
{}

#define CHUNK 16384

/* Compress from file source to file dest until EOF on source.
def() returns Z_OK on success, Z_MEM_ERROR if memory could not be
allocated for processing, Z_STREAM_ERROR if an invalid compression
level is supplied, Z_VERSION_ERROR if the version of zlib.h and the
version of the library linked do not match, or Z_ERRNO if there is
an error reading or writing the files. */
int ZipUtils::CompressString(const char* in_str, size_t in_len, std::string& out_str, int level)
{
    if (!in_str)
        return Z_DATA_ERROR;

    int ret, flush;
    unsigned have;
    z_stream strm;

    unsigned char out[CHUNK];

    /* allocate deflate state */
    strm.zalloc = Z_NULL;
    strm.zfree = Z_NULL;
    strm.opaque = Z_NULL;
    ret = deflateInit(&strm, level);
    if (ret != Z_OK)
        return ret;

    std::shared_ptr<z_stream> sp_strm(&strm, [](z_stream* strm)
    {
        (void)deflateEnd(strm);
    });

    const char* end = in_str + in_len;

    //size_t pos_index = 0;
    size_t distance = 0;
    /* compress until end of file */
    do
    {
        distance = end - in_str;
        strm.avail_in = (distance >= CHUNK) ? CHUNK : distance;
        strm.next_in = (Bytef*)in_str;

        // next pos
        in_str += strm.avail_in;
        flush = (in_str == end) ? Z_FINISH : Z_NO_FLUSH;

        /* run deflate() on input until output buffer not full, finish
        compression if all of source has been read in */
        do
        {
            strm.avail_out = CHUNK;
            strm.next_out = out;
            ret = deflate(&strm, flush);  /* no bad return value */
            if (ret == Z_STREAM_ERROR)
                break;
            have = CHUNK - strm.avail_out;
            out_str.append((const char*)out, have);
        }
        while (strm.avail_out == 0);

        if (strm.avail_in == 0)
            break;   /* all input will be used */

        /* done when last data in file processed */
    }
    while (flush != Z_FINISH);

    if (ret != Z_STREAM_END) /* stream will be complete */
        return Z_STREAM_ERROR;

    /* clean up and return */
    return Z_OK;
}

/* Decompress from file source to file dest until stream ends or EOF.
inf() returns Z_OK on success, Z_MEM_ERROR if memory could not be
allocated for processing, Z_DATA_ERROR if the deflate data is
invalid or incomplete, Z_VERSION_ERROR if the version of zlib.h and
the version of the library linked do not match, or Z_ERRNO if there
is an error reading or writing the files. */
int ZipUtils::DecompressString(const char* in_str, size_t in_len, std::string& out_str)
{
    if (!in_str)
        return Z_DATA_ERROR;

    int ret;
    unsigned have;
    z_stream strm;
    unsigned char out[CHUNK];

    /* allocate inflate state */
    strm.zalloc = Z_NULL;
    strm.zfree = Z_NULL;
    strm.opaque = Z_NULL;
    strm.avail_in = 0;
    strm.next_in = Z_NULL;
    ret = inflateInit(&strm);
    if (ret != Z_OK)
        return ret;

    std::shared_ptr<z_stream> sp_strm(&strm, [](z_stream* strm)
    {
        (void)inflateEnd(strm);
    });

    const char* end = in_str + in_len;

    //size_t pos_index = 0;
    size_t distance = 0;

    int flush = 0;
    /* decompress until deflate stream ends or end of file */
    do
    {
        distance = end - in_str;
        strm.avail_in = (distance >= CHUNK) ? CHUNK : distance;
        strm.next_in = (Bytef*)in_str;

        // next pos
        in_str += strm.avail_in;
        flush = (in_str == end) ? Z_FINISH : Z_NO_FLUSH;

        /* run inflate() on input until output buffer not full */
        do
        {
            strm.avail_out = CHUNK;
            strm.next_out = out;
            ret = inflate(&strm, Z_NO_FLUSH);

            if (ret == Z_STREAM_ERROR) /* state not clobbered */
                break;

            switch (ret)
            {
            case Z_NEED_DICT:
                ret = Z_DATA_ERROR;   /* and fall through */
            case Z_DATA_ERROR:
            case Z_MEM_ERROR:
                return ret;
            }
            have = CHUNK - strm.avail_out;
            out_str.append((const char*)out, have);
        }
        while (strm.avail_out == 0);

        /* done when inflate() says it's done */
    }
    while (flush != Z_FINISH);

    /* clean up and return */
    return ret == Z_STREAM_END ? Z_OK : Z_DATA_ERROR;
}