/************************************************************************
* Author    : Tiago Dionizio ([email protected])                     *
* Library   : lzlib - Lua 5 interface to access zlib library functions  *
*                                                                       *
* Permission is hereby granted, free of charge, to any person obtaining *
* a copy of this software and associated documentation files (the       *
* "Software"), to deal in the Software without restriction, including   *
* without limitation the rights to use, copy, modify, merge, publish,   *
* distribute, sublicense, and/or sell copies of the Software, and to    *
* permit persons to whom the Software is furnished to do so, subject to *
* the following conditions:                                             *
*                                                                       *
* The above copyright notice and this permission notice shall be        *
* included in all copies or substantial portions of the Software.       *
*                                                                       *
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,       *
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF    *
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*
* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY  *
* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,  *
* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE     *
* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                *
************************************************************************/

/************************************************************************
$Id: lzlib.c,v 1.3 2004/07/22 19:10:47 tngd Exp $
Changes:
************************************************************************/
#include <stdlib.h>
#include <string.h>

#include "lua.h"
#include "lauxlib.h"

#include "zlib.h"


/*
** =========================================================================
** compile time options wich determine available functionality
** =========================================================================
*/


/*
** =========================================================================
** zlib stream metamethods
** =========================================================================
*/
#define ZSTREAMMETA "zlib:zstream"

#define LZANY     (void*)-1
#define LZNONE    (void*)0
#define LZDEFLATE (void*)1
#define LZINFLATE (void*)2

static z_stream *lzstream_new(lua_State *L)
{
   z_stream *s = (z_stream*)lua_newuserdata(L, sizeof(z_stream));

   luaL_getmetatable(L, ZSTREAMMETA);
   lua_setmetatable(L, -2);        /* set metatable */

   s->zalloc = Z_NULL;
   s->zfree = Z_NULL;

   s->next_out = Z_NULL;
   s->avail_out = 0;
   s->next_in = Z_NULL;
   s->avail_in = 0;

   s->opaque = LZNONE;

   return s;
}

static void lzstream_cleanup(lua_State *L, z_stream *s)
{
   if (s && s->opaque != LZNONE)
   {
       if (s->opaque == LZINFLATE)
           inflateEnd(s);
       if (s->opaque == LZDEFLATE)
           deflateEnd(s);
       s->opaque = LZNONE;
   }
}

/* ====================================================================== */

static z_stream *lzstream_get(lua_State *L, int index)
{
   z_stream *s = (z_stream*)luaL_checkudata(L, index, ZSTREAMMETA);
   if (s == NULL) luaL_argerror(L, index, "bad zlib stream");
   return s;
}

static z_stream *lzstream_check(lua_State *L, int index, void *state)
{
   z_stream *s = lzstream_get(L, index);
   if ((state != LZANY && s->opaque != state) || s->opaque == LZNONE)
       luaL_argerror(L, index, "attempt to use invalid zlib stream");
   return s;
}

/* ====================================================================== */

static int lzstream_tostring(lua_State *L)
{
   char buf[100];
   z_stream *s = (z_stream*)luaL_checkudata(L, 1, ZSTREAMMETA);
   if (s == NULL) luaL_argerror(L, 1, "bad zlib stream");

   if (s->opaque == LZNONE)
       strncpy(buf, "zlib stream (closed)", 100);
   else if (s->opaque == LZDEFLATE)
       snprintf(buf, 100, "zlib deflate stream (%p)", s);
   else if (s->opaque == LZINFLATE)
       snprintf(buf, 100, "zlib inflate stream (%p)", s);
   else
       snprintf(buf, 100, "%p", s);

   lua_pushstring(L, buf);
   return 1;
}

/* ====================================================================== */

static int lzstream_gc(lua_State *L)
{
   z_stream *s = lzstream_get(L, 1);
   lzstream_cleanup(L, s);
   return 0;
}

/* ====================================================================== */

static int lzstream_close(lua_State *L)
{
   z_stream *s = lzstream_check(L, 1, LZANY);
   lzstream_cleanup(L, s);
   return 0;
}

/* ====================================================================== */

static int lzstream_adler(lua_State *L)
{
   z_stream *s = lzstream_check(L, 1, LZANY);
   lua_pushnumber(L, s->adler);
   return 1;
}

/* ====================================================================== */

static int lzlib_deflate(lua_State *L)
{
   int level = luaL_optint(L, 1, Z_DEFAULT_COMPRESSION);
   int method = luaL_optint(L, 2, Z_DEFLATED);
   int windowBits = luaL_optint(L, 3, 15);
   int memLevel = luaL_optint(L, 4, 8);
   int strategy = luaL_optint(L, 5, Z_DEFAULT_STRATEGY);

   z_stream *s = lzstream_new(L);

   if (deflateInit2(s, level, method, windowBits, memLevel, strategy) != Z_OK)
   {
       lua_pushliteral(L, "failed to start decompressing");
       lua_error(L);
   }
   s->opaque = LZDEFLATE;
   return 1;
}

/* ====================================================================== */

static int lzlib_inflate(lua_State *L)
{
   int windowBits = luaL_optint(L, 1, 15);

   z_stream *s = lzstream_new(L);

   if (inflateInit2(s, windowBits) != Z_OK)
   {
       lua_pushliteral(L, "failed to start compressing");
       lua_error(L);
   }

   s->opaque = LZINFLATE;
   return 1;
}

/* ====================================================================== */

static int lzstream_decompress(lua_State *L)
{
   z_stream *s = lzstream_check(L, 1, LZINFLATE);
   s->next_in = (Bytef*)luaL_checkstring(L, 2);
   s->avail_in = lua_strlen(L, 2);

   {
       int r;
       luaL_Buffer b;
       luaL_buffinit(L, &b);

       do {
           s->next_out = (Bytef*)luaL_prepbuffer(&b);
           s->avail_out = LUAL_BUFFERSIZE;

           /* munch some more */
           r = inflate(s, Z_SYNC_FLUSH);
           if (r != Z_OK && r != Z_STREAM_END) {
               lua_pushfstring(L, "failed to decompress [%d]", r);
               lua_error(L);
           }

           /* push gathered data */
           luaL_addsize(&b, LUAL_BUFFERSIZE - s->avail_out);

           /* until we have free space in the output buffer - meaning we are done */
       } while (s->avail_in > 0 || s->avail_out == 0);

       /* send gathered data if any */
       luaL_pushresult(&b);
   }
   return 1;
}

/* ====================================================================== */

static int lzstream_compress(lua_State *L)
{
   z_stream *s = lzstream_check(L, 1, LZDEFLATE);
   s->next_in = (Bytef*)luaL_checkstring(L, 2);
   s->avail_in = lua_strlen(L, 2);

   {
       int r;
       luaL_Buffer b;
       luaL_buffinit(L, &b);

       do {
           s->next_out = (Bytef*)luaL_prepbuffer(&b);
           s->avail_out = LUAL_BUFFERSIZE;

           /* bake some more */
           if ((r = deflate(s, Z_NO_FLUSH)) != Z_OK)
           {
               lua_pushfstring(L, "failed to compress [%d]", r);
               lua_error(L);
           }

           /* push gathered data */
           luaL_addsize(&b, LUAL_BUFFERSIZE - s->avail_out);

           /* until we have free space in the output buffer - meaning we are done */
       } while (s->avail_out == 0);

       /* send gathered data if any */
       luaL_pushresult(&b);
   }
   return 1;
}

/* ====================================================================== */

static int lzstream_flush(lua_State *L)
{
   z_stream *s = lzstream_check(L, 1, LZANY);

   if (s->opaque == LZINFLATE) {
       lua_pushliteral(L, "");
       return 1;
   }

   s->next_in = (Bytef*)"";
   s->avail_in = 0;

   {
       int r = 0;
       luaL_Buffer b;
       luaL_buffinit(L, &b);

       do {
           s->next_out = (Bytef*)luaL_prepbuffer(&b);
           s->avail_out = LUAL_BUFFERSIZE;

           r = deflate(s, Z_FINISH);

           if (r != Z_OK && r != Z_STREAM_END) {
               lua_pushfstring(L, "failed to flush [%d]", r);
               lua_error(L);
           }

           /* push gathered data */
           luaL_addsize(&b, LUAL_BUFFERSIZE - s->avail_out);
       } while (r != Z_STREAM_END);

       /* send gathered data if any */
       luaL_pushresult(&b);
   }
   return 1;
}

/* ====================================================================== */

static int lzstream_reset(lua_State *L)
{
   z_stream *s = lzstream_check(L, 1, LZANY);

   if (s->state == LZDEFLATE)
       lua_pushnumber(L, deflateReset(s));
   else if (s->opaque == LZINFLATE)
       lua_pushnumber(L, inflateReset(s));
   else
   {
       lua_pushliteral(L, "invalid zlib stream state");
       lua_error(L);
   }

   return 1;
}


/*
** =========================================================================
** zlib functions
** =========================================================================
*/

static int lzlib_version(lua_State *L)
{
   lua_pushstring(L, zlibVersion());
   return 1;
}

/* ====================================================================== */
static int lzlib_adler32(lua_State *L)
{
   if (lua_gettop(L) == 0)
   {
       /* adler32 initial value */
       lua_pushnumber(L, adler32(0L, Z_NULL, 0));
   }
   else
   {
       /* update adler32 checksum */
       int adler = luaL_checkint(L, 1);
       const char* buf = luaL_checkstring(L, 2);
       int len = lua_strlen(L, 2);

       lua_pushnumber(L, adler32(adler, (const Bytef*)buf, len));
   }
   return 1;
}

/* ====================================================================== */
static int lzlib_crc32(lua_State *L)
{
   if (lua_gettop(L) == 0)
   {
       /* crc32 initial value */
       lua_pushnumber(L, crc32(0L, Z_NULL, 0));
   }
   else
   {
       /* update crc32 checksum */
       int crc = luaL_checkint(L, 1);
       const char* buf = luaL_checkstring(L, 2);
       int len = lua_strlen(L, 2);

       lua_pushnumber(L, crc32(crc, (const Bytef*)buf, len));
   }
   return 1;
}

/* ====================================================================== */


static int lzlib_compress(lua_State *L)
{
   const char *next_in = luaL_checkstring(L, 1);
   int avail_in = lua_strlen(L, 1);
   int level = luaL_optint(L, 2, Z_DEFAULT_COMPRESSION);
   int method = luaL_optint(L, 3, Z_DEFLATED);
   int windowBits = luaL_optint(L, 4, 15);
   int memLevel = luaL_optint(L, 5, 8);
   int strategy = luaL_optint(L, 6, Z_DEFAULT_STRATEGY);

   int ret;
   z_stream zs;
   luaL_Buffer b;
   luaL_buffinit(L, &b);

   zs.zalloc = Z_NULL;
   zs.zfree = Z_NULL;

   zs.next_out = Z_NULL;
   zs.avail_out = 0;
   zs.next_in = Z_NULL;
   zs.avail_in = 0;

   ret = deflateInit2(&zs, level, method, windowBits, memLevel, strategy);

   if (ret != Z_OK)
   {
       lua_pushnil(L);
       lua_pushnumber(L, ret);
       return 2;
   }

   zs.next_in = (Bytef*)next_in;
   zs.avail_in = avail_in;

   for(;;)
   {
       zs.next_out = (Bytef*)luaL_prepbuffer(&b);
       zs.avail_out = LUAL_BUFFERSIZE;

       /* munch some more */
       ret = deflate(&zs, Z_FINISH);

       /* push gathered data */
       luaL_addsize(&b, LUAL_BUFFERSIZE - zs.avail_out);

       /* done processing? */
       if (ret == Z_STREAM_END)
           break;

       /* error condition? */
       if (ret != Z_OK)
           break;
   }

   /* cleanup */
   deflateEnd(&zs);

   luaL_pushresult(&b);
   lua_pushnumber(L, ret);
   return 2;
}

/* ====================================================================== */

static int lzlib_decompress(lua_State *L)
{
   const char *next_in = luaL_checkstring(L, 1);
   int avail_in = lua_strlen(L, 1);
   int windowBits = luaL_optint(L, 2, 15);

   int ret;
   z_stream zs;
   luaL_Buffer b;
   luaL_buffinit(L, &b);


   zs.zalloc = Z_NULL;
   zs.zfree = Z_NULL;

   zs.next_out = Z_NULL;
   zs.avail_out = 0;
   zs.next_in = Z_NULL;
   zs.avail_in = 0;

   ret = inflateInit2(&zs, windowBits);

   if (ret != Z_OK)
   {
       lua_pushnil(L);
       lua_pushnumber(L, ret);
       return 2;
   }

   zs.next_in = (Bytef*)next_in;
   zs.avail_in = avail_in;

   for(;;)
   {
       zs.next_out = (Bytef*)luaL_prepbuffer(&b);
       zs.avail_out = LUAL_BUFFERSIZE;

       /* bake some more */
       ret = inflate(&zs, Z_FINISH);

       /* push gathered data */
       luaL_addsize(&b, LUAL_BUFFERSIZE - zs.avail_out);

       /* need dictionary? - no dictionary support here, so just quit */
       if (ret == Z_NEED_DICT)
           break;

       /* done processing? */
       if (ret == Z_STREAM_END)
           break;

       /* error condition? */
       if (ret != Z_BUF_ERROR)
           break;
   }

   /* cleanup */
   inflateEnd(&zs);

   luaL_pushresult(&b);
   lua_pushnumber(L, ret);
   return 2;
}


/*
** =========================================================================
** Register functions
** =========================================================================
*/


LUALIB_API int luaopen_zlib(lua_State *L)
{
   const luaL_reg zstreamm[] =
   {
       {"reset",           lzstream_reset      },

       {"compress",        lzstream_compress   },
       {"decompress",      lzstream_decompress },
       {"flush",           lzstream_flush      },
       {"close",           lzstream_close      },

       {"adler",           lzstream_adler      },

       {"__tostring",      lzstream_tostring   },
       {"__gc",            lzstream_gc         },
       {NULL, NULL}
   };

   const luaL_reg zlib[] =
   {
       {"version",         lzlib_version       },
       {"adler32",         lzlib_adler32       },
       {"crc32",           lzlib_crc32         },

       {"compressobj",     lzlib_deflate       },
       {"decompressobj",   lzlib_inflate       },

       {"compress",        lzlib_compress      },
       {"decompress",      lzlib_decompress    },

       {NULL, NULL}
   };

   /* ====================================================================== */

   /* make sure header and library version are consistent */
   const char* version = zlibVersion();
   if (strncmp(version, ZLIB_VERSION, 5))
   {
       lua_pushfstring(L, "zlib library version does not match - header: %s, library: %s", ZLIB_VERSION, version);
       lua_error(L);
   }

   /* create new metatable for zlib compression structures */
   luaL_newmetatable(L, ZSTREAMMETA);
   lua_pushliteral(L, "__index");
   lua_pushvalue(L, -2);               /* push metatable */
   lua_rawset(L, -3);                  /* metatable.__index = metatable */

   /*
   ** Stack: metatable
   */
   luaL_openlib(L, NULL, zstreamm, 0);

   lua_pop(L, 1);                      /* remove metatable from stack */

   /*
   ** Stack:
   */
   lua_newtable(L);
   luaL_openlib(L, NULL, zlib, 0);

   /*
   ** Stack: zlib table
   */
   return 1;
}

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