#include <string.h>

#include "lauxlib.h"
#include "lua.h"
#include "nettle/sha2.h"

//#include "../qcommon/q3_lauxlib.h" FIXME? This doesn't seem to be hooked correctly into tremded.exe

#define SHA256_CTX "sha256_ctx*"

static int lsha256(lua_State *L)
{
	struct sha256_ctx *ctx;

	ctx = (struct sha256_ctx *)lua_newuserdata(L, sizeof(struct sha256_ctx));
	luaL_setmetatable(L, SHA256_CTX);
	sha256_init(ctx);
	return 1;
}

static int lsha256_digest(lua_State *L)
{
	struct sha256_ctx *ctx;
	char digest[SHA256_DIGEST_SIZE];

	ctx = luaL_checkudata(L, 1, SHA256_CTX);
	sha256_digest(ctx, sizeof(digest), digest);
	lua_pushlstring(L, digest, sizeof(digest));
	return 1;
}

static int lsha256_update(lua_State *L)
{
	struct sha256_ctx *ctx;
	const char *data;
	size_t len;

	ctx = luaL_checkudata(L, 1, SHA256_CTX);
	if (lua_isnil(L, 2)) {
		return 0;
	}
	data = luaL_tolstring(L, 2, &len);
	nettle_sha256_update(ctx, len, data);
	return 0;
}

static int lsha256_tostring(lua_State *L)
{
	struct sha256_ctx *ctx, ctx2;
	char digest[SHA256_DIGEST_SIZE];
	char hex[SHA256_DIGEST_SIZE*2+1];
	int i;

	ctx = luaL_checkudata(L, 1, SHA256_CTX);
	memcpy(&ctx2, ctx, sizeof(struct sha256_ctx));

	sha256_digest(&ctx2, sizeof(digest), digest);
	for (i = 0; i < sizeof(digest); i++) {
		sprintf(hex + 2 * i, "%02hhx", digest[i]);
	}

	lua_pushstring(L, hex);
	return 1;
}

/* functions for 'nettle' library */
static const luaL_Reg nettlelib[] = {
  {"sha256", lsha256},
  {NULL, NULL}
};

/* functions for sha256 objects */
static const luaL_Reg lsha256_methods[] = {
	{"digest", lsha256_digest},
	{"update", lsha256_update},
	{"__tostring", lsha256_tostring},
	{NULL, NULL}
};

static void createmeta (lua_State *L)
{
  luaL_newmetatable(L, SHA256_CTX);  /* create metatable for file handles */
  lua_pushvalue(L, -1);  /* push metatable */
  lua_setfield(L, -2, "__index");  /* metatable.__index = metatable */
  luaL_setfuncs(L, lsha256_methods, 0);  /* add file methods to new metatable */
  lua_pop(L, 1);  /* pop new metatable */
}

LUAMOD_API int luaopen_nettle (lua_State *L)
{
  luaL_newlib(L, nettlelib);
  createmeta(L);
  return 1;
}