/*
 * Copyright (C) 2002-2021 ProcessOne, SARL. All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 */

#include <stdio.h>
#include <string.h>
#include <erl_driver.h>
#include <zlib.h>

/*
 * R15B changed several driver callbacks to use ErlDrvSizeT and
 * ErlDrvSSizeT typedefs instead of int.
 * This provides missing typedefs on older OTP versions.
 */
#if ERL_DRV_EXTENDED_MAJOR_VERSION < 2
typedef int ErlDrvSizeT;
typedef int ErlDrvSSizeT;
#endif

#define BUF_SIZE 1024

typedef struct {
      ErlDrvPort port;
      z_stream *d_stream;
      z_stream *i_stream;
} ezlib_data;

static void* zlib_alloc(void* data, unsigned int items, unsigned int size)
{
    return (void*) driver_alloc(items*size);
}

static void zlib_free(void* data, void* addr)
{
    driver_free(addr);
}

static ErlDrvData ezlib_drv_start(ErlDrvPort port, char *buff)
{
   ezlib_data *d =
      (ezlib_data *)driver_alloc(sizeof(ezlib_data));
   d->port = port;

   d->d_stream = (z_stream *)driver_alloc(sizeof(z_stream));

   d->d_stream->zalloc = zlib_alloc;
   d->d_stream->zfree = zlib_free;
   d->d_stream->opaque = (voidpf)0;

   deflateInit(d->d_stream, Z_DEFAULT_COMPRESSION);

   d->i_stream = (z_stream *)driver_alloc(sizeof(z_stream));

   d->i_stream->zalloc = zlib_alloc;
   d->i_stream->zfree = zlib_free;
   d->i_stream->opaque = (voidpf)0;

   inflateInit(d->i_stream);

   set_port_control_flags(port, PORT_CONTROL_FLAG_BINARY);

   return (ErlDrvData)d;
}

static void ezlib_drv_stop(ErlDrvData handle)
{
   ezlib_data *d = (ezlib_data *)handle;

   deflateEnd(d->d_stream);
   driver_free(d->d_stream);

   inflateEnd(d->i_stream);
   driver_free(d->i_stream);

   driver_free((char *)handle);
}


#define DEFLATE 1
#define INFLATE 2

#define die_unless(cond, errstr)				\
	 if (!(cond))						\
	 {							\
	    rlen = strlen(errstr) + 1;				\
	    b = driver_realloc_binary(b, rlen);			\
	    b->orig_bytes[0] = 1;				\
	    strncpy(b->orig_bytes + 1, errstr, rlen - 1);	\
	    *rbuf = (char *)b;					\
	    return rlen;					\
	 }


static ErlDrvSSizeT ezlib_drv_control(ErlDrvData handle,
				     unsigned int command,
				     char *buf, ErlDrvSizeT len,
				     char **rbuf, ErlDrvSizeT rlen)
{
   ezlib_data *d = (ezlib_data *)handle;
   int err;
   int size;
   ErlDrvBinary *b;

   switch (command)
   {
      case DEFLATE:
	 size = BUF_SIZE + 1;
	 rlen = 1;
	 b = driver_alloc_binary(size);
	 b->orig_bytes[0] = 0;

	 d->d_stream->next_in = (unsigned char *)buf;
	 d->d_stream->avail_in = len;
	 d->d_stream->avail_out = 0;
	 err = Z_OK;

	 while (err == Z_OK && d->d_stream->avail_out == 0)
	 {
	    d->d_stream->next_out = (unsigned char *)b->orig_bytes + rlen;
	    d->d_stream->avail_out = BUF_SIZE;

	    err = deflate(d->d_stream, Z_SYNC_FLUSH);

             // Output buffer was completely consumed and we have no more data to process
             // http://www.zlib.net/zlib_faq.html#faq05
             if(err == Z_BUF_ERROR && d->d_stream->avail_out == BUF_SIZE) {
                break;
             }

	    die_unless((err == Z_OK) || (err == Z_STREAM_END),
		       "Deflate error");

	    rlen += (BUF_SIZE - d->d_stream->avail_out);
	    size += (BUF_SIZE - d->d_stream->avail_out);
	    b = driver_realloc_binary(b, size);
	 }
	 b = driver_realloc_binary(b, rlen);
	 *rbuf = (char *)b;
	 return rlen;
      case INFLATE:
	 size = BUF_SIZE + 1;
	 rlen = 1;
	 b = driver_alloc_binary(size);
	 b->orig_bytes[0] = 0;

	 if (len > 0) {
	    d->i_stream->next_in = (unsigned char *)buf;
	    d->i_stream->avail_in = len;
	    d->i_stream->avail_out = 0;
	    err = Z_OK;

	    while (err == Z_OK && d->i_stream->avail_out == 0)
	    {
	       d->i_stream->next_out = (unsigned char *)b->orig_bytes + rlen;
	       d->i_stream->avail_out = BUF_SIZE;

	       err = inflate(d->i_stream, Z_SYNC_FLUSH);

               // Output buffer was completely consumed and we have no more data to process
               // http://www.zlib.net/zlib_faq.html#faq05
               if(err == Z_BUF_ERROR && d->i_stream->avail_out == BUF_SIZE) {
                  break;
               }

	       die_unless((err == Z_OK) || (err == Z_STREAM_END),
			  "Inflate error");

	       rlen += (BUF_SIZE - d->i_stream->avail_out);
	       size += (BUF_SIZE - d->i_stream->avail_out);
	       b = driver_realloc_binary(b, size);
	    }
	 }
	 b = driver_realloc_binary(b, rlen);
	 *rbuf = (char *)b;
	 return rlen;
   }

   b = driver_alloc_binary(1);
   b->orig_bytes[0] = 0;
   *rbuf = (char *)b;
   return 1;
}


ErlDrvEntry ezlib_driver_entry = {
   NULL,			/* F_PTR init, N/A */
   ezlib_drv_start,	/* L_PTR start, called when port is opened */
   ezlib_drv_stop,	/* F_PTR stop, called when port is closed */
   NULL,			/* F_PTR output, called when erlang has sent */
   NULL,			/* F_PTR ready_input, called when input descriptor ready */
   NULL,			/* F_PTR ready_output, called when output descriptor ready */
   "ezlib_drv",		/* char *driver_name, the argument to open_port */
   NULL,			/* F_PTR finish, called when unloaded */
   NULL,			/* handle */
   ezlib_drv_control,   /* F_PTR control, port_command callback */
   NULL,			/* F_PTR timeout, reserved */
   NULL,			/* F_PTR outputv, reserved */
  /* Added in Erlang/OTP R15B: */
  NULL,                 /* ready_async */
  NULL,                 /* flush */
  NULL,                 /* call */
  NULL,                 /* event */
  ERL_DRV_EXTENDED_MARKER,        /* extended_marker */
  ERL_DRV_EXTENDED_MAJOR_VERSION, /* major_version */
  ERL_DRV_EXTENDED_MINOR_VERSION, /* minor_version */
  0,                    /* driver_flags */
  NULL,                 /* handle2 */
  NULL,                 /* process_exit */
  NULL                  /* stop_select */
};

DRIVER_INIT(ezlib_drv) /* must match name in driver_entry */
{
   return &ezlib_driver_entry;
}