/*
 * Dynamic Lua binding to GObject using dynamic gobject-introspection.
 *
 * Copyright (c) 2010, 2011, 2012, 2013 Pavel Holejsovsky
 * Licensed under the MIT license:
 * http://www.opensource.org/licenses/mit-license.php
 *
 * Core C utility API.
 */

#include <string.h>
#include "lgi.h"

/* GLib 2.32 deprecated GStaticRecMutex in favor of GRecMutex.  For
   older GLib versions, use still older version. */
#if !GLIB_CHECK_VERSION(2, 32, 0)
#define GRecMutex GStaticRecMutex
#define G_REC_MUTEX_INIT  = G_STATIC_REC_MUTEX_INIT
#define g_rec_mutex_init g_static_rec_mutex_init
#define g_rec_mutex_lock g_static_rec_mutex_lock
#define g_rec_mutex_unlock g_static_rec_mutex_unlock
#define g_rec_mutex_clear g_static_rec_mutex_free
#else
#define G_REC_MUTEX_INIT
#endif

/* GLib 2.30 changed g_atomic_int_add() to return the new value. For
   older GLib versions, use g_atomic_int_exchange_and_add() which did. */
#if !GLIB_CHECK_VERSION(2, 30, 0)
#ifdef g_atomic_int_add
#undef g_atomic_int_add
#endif

#define g_atomic_int_add(atomic, val) \
  (g_atomic_int_exchange_and_add ((atomic), (val)))
#endif

volatile gint global_state_id = 0;

#ifndef NDEBUG
const char *lgi_sd (lua_State *L)
{
  int i;
  static gchar *msg = 0;
  g_free (msg);
  msg = g_strdup ("");
  int top = lua_gettop (L);
  for (i = 1; i <= top; i++)
    {
      int t = lua_type (L, i);
      gchar *item, *nmsg;
      switch (t)
	{
	case LUA_TSTRING:
	  item = g_strdup_printf ("`%s'", lua_tostring (L, i));
	  break;

	case LUA_TBOOLEAN:
	  item = g_strdup_printf (lua_toboolean (L, i) ? "true" : "false");
	  break;

	case LUA_TNUMBER:
	  item = g_strdup_printf ("%g", lua_tonumber (L, i));
	  break;

	default:
	  item = g_strdup_printf ("%s(%p)", lua_typename (L, t),
				  lua_topointer (L, i));
	  break;
	}
      nmsg = g_strconcat (msg, " ", item, NULL);
      g_free (msg);
      g_free (item);
      msg = nmsg;
    }
  return msg;
}
#endif

/* lightuserdata of this address is a key in LUA_REGISTRYINDEX table
   to repo table. */
static int repo;

/* lightuserdata of this address is a key in LUA_REGISTRYINDEX table
   to index table mapping lightuserdata-gtype -> repotable. */
static int repo_index;

void *
lgi_udata_test (lua_State *L, int narg, const char *name)
{
  void *udata = NULL;
  luaL_checkstack (L, 2, "");
  lgi_makeabs (L, narg);
  if (lua_getmetatable (L, narg))
    {
      luaL_getmetatable (L, name);
      if (lua_equal (L, -1, -2))
	udata = lua_touserdata (L, narg);
      lua_pop (L, 2);
    }
  return udata;
}

void
lgi_cache_create (lua_State *L, gpointer key, const char *mode)
{
  lua_pushlightuserdata (L, key);
  lua_newtable (L);
  if (mode)
    {
      lua_newtable (L);
      lua_pushstring (L, mode);
      lua_setfield (L, -2, "__mode");
      lua_setmetatable (L, -2);
    }
  lua_rawset (L, LUA_REGISTRYINDEX);
}

int
lgi_type_get_name (lua_State *L, GIBaseInfo *info)
{
  GSList *list = NULL, *i;
  int n = 1;
  lua_pushstring (L, g_base_info_get_namespace (info));

  if (g_base_info_get_type (info) == GI_INFO_TYPE_CALLBACK)
    /* Avoid duplicate name for callbacks. */
    info = g_base_info_get_container (info);

  /* Add names on the whole path, but in reverse order. */
  for (; info != NULL; info = g_base_info_get_container (info))
    if (!GI_IS_TYPE_INFO (info))
      list = g_slist_prepend (list, info);

  for (i = list; i != NULL; i = g_slist_next (i))
    {
      if (g_base_info_get_type (i->data) != GI_INFO_TYPE_TYPE)
	{
	  lua_pushstring (L, ".");
	  lua_pushstring (L, g_base_info_get_name (i->data));
	  n += 2;
	}
    }

  g_slist_free (list);
  return n;
}

void
lgi_type_get_repotype (lua_State *L, GType gtype, GIBaseInfo *info)
{
  luaL_checkstack (L, 4, "");

  /* Get repo-index table. */
  lua_pushlightuserdata (L, &repo_index);
  lua_rawget (L, LUA_REGISTRYINDEX);

  /* Prepare gtype, if not given directly. */
  if (gtype == G_TYPE_INVALID && info && GI_IS_REGISTERED_TYPE_INFO (info))
    {
      gtype = g_registered_type_info_get_g_type (info);
      if (gtype == G_TYPE_NONE)
	gtype = G_TYPE_INVALID;
    }

  /* First of all, check direct indexing of repo-index by gtype,
     should be fastest. */
  if (gtype != G_TYPE_INVALID)
    {
      lua_pushlightuserdata (L, (gpointer) gtype);
      lua_rawget (L, -2);
    }
  else
    lua_pushnil (L);

  if (lua_isnil (L, -1))
    {
      /* Not indexed yet.  Try to lookup by name - this works when
	 lazy-loaded repo tables are not loaded yet. */
      if (!info && gtype != G_TYPE_INVALID)
	{
	  info = g_irepository_find_by_gtype (NULL, gtype);
	  lgi_gi_info_new (L, info);
	}
      else
	/* Keep stack balanced as in the previous 'if' branch. */
	lua_pushnil (L);

      if (info)
	{
	  lua_pushlightuserdata (L, &repo);
	  lua_rawget (L, LUA_REGISTRYINDEX);
	  lua_getfield (L, -1, g_base_info_get_namespace (info));
	  lua_getfield (L, -1, g_base_info_get_name (info));
	  lua_replace (L, -5);
	  lua_pop (L, 3);
	}
      else
	lua_pop (L, 1);
    }
  lua_replace (L, -2);
}

GType
lgi_type_get_gtype (lua_State *L, int narg)
{
  /* Handle simple cases natively, forward to Lua implementation for
     the rest. */
  switch (lua_type (L, narg))
    {
    case LUA_TNIL:
    case LUA_TNONE:
      return G_TYPE_INVALID;

    case LUA_TNUMBER:
      return lua_tonumber (L, narg);

    case LUA_TLIGHTUSERDATA:
      return (GType) lua_touserdata (L, narg);

    case LUA_TSTRING:
      return g_type_from_name (lua_tostring (L, narg));

    case LUA_TTABLE:
      {
	GType gtype;
	lgi_makeabs (L, narg);
	lua_pushstring (L, "_gtype");
	lua_rawget (L, narg);
	gtype = lgi_type_get_gtype (L, -1);
	lua_pop (L, 1);
	return gtype;
      }

    default:
      return luaL_error (L, "GType expected, got %s",
			 lua_typename (L, lua_type (L, narg)));
    }
}

typedef struct _Guard
{
  gpointer data;
  GDestroyNotify destroy;
} Guard;
#define UD_GUARD "lgi.guard"

static int
guard_gc (lua_State *L)
{
  Guard *guard = lua_touserdata (L, 1);
  if (guard->data != NULL)
    guard->destroy (guard->data);
  return 0;
}

gpointer *
lgi_guard_create (lua_State *L, GDestroyNotify destroy)
{
  Guard *guard = lua_newuserdata (L, sizeof (Guard));
  g_assert (destroy != NULL);
  luaL_getmetatable (L, UD_GUARD);
  lua_setmetatable (L, -2);
  guard->data = NULL;
  guard->destroy = destroy;
  return &guard->data;
}

/* Converts any allowed GType kind to lightuserdata form. */
static int
core_gtype (lua_State *L)
{
  lua_pushlightuserdata (L, (gpointer) lgi_type_get_gtype (L, 1));
  return 1;
}

/* Converts either GType or gi.info into repotype table. */
static int
core_repotype (lua_State *L)
{
  GType gtype = G_TYPE_INVALID;
  GIBaseInfo **info = lgi_udata_test (L, 1, LGI_GI_INFO);
  if (!info)
    gtype = lgi_type_get_gtype (L, 1);
  lgi_type_get_repotype (L, gtype, info ? *info : NULL);
  return 1;
}

/* Instantiate constant from given gi_info. */
static int
core_constant (lua_State *L)
{
  /* Get typeinfo of the constant. */
  GIArgument val;
  GIConstantInfo *ci = *(GIConstantInfo **) luaL_checkudata (L, 1, LGI_GI_INFO);
  GITypeInfo *ti = g_constant_info_get_type (ci);
  lgi_gi_info_new (L, ti);
  g_constant_info_get_value (ci, &val);
  lgi_marshal_2lua (L, ti, NULL, GI_DIRECTION_IN, GI_TRANSFER_NOTHING, &val,
		    0, NULL, NULL);
  return 1;
}

typedef struct _LgiStateMutex
{
  /* Pointer to either local state lock (next member of this
     structure) or to global package lock. */
  GRecMutex *mutex;
  GRecMutex state_mutex;
} LgiStateMutex;

/* Global package lock (the one used for
   gdk_threads_enter/clutter_threads_enter) */
static GRecMutex package_mutex G_REC_MUTEX_INIT;

/* GC method for GRecMutex structure, which lives inside lua_State. */
static int
call_mutex_gc (lua_State* L)
{
  LgiStateMutex *mutex = lua_touserdata (L, 1);
  g_rec_mutex_unlock (mutex->mutex);
  g_rec_mutex_clear (&mutex->state_mutex);
  return 0;
}

/* MT for CallMutex. */
static int call_mutex_mt;

/* lightuserdata of address of this member is key to LUA_REGISTRYINDEX
   where CallMutex instance for this state resides. */
static int call_mutex;

gpointer
lgi_state_get_lock (lua_State *L)
{
  gpointer state_lock;
  lua_pushlightuserdata (L, &call_mutex);
  lua_gettable (L, LUA_REGISTRYINDEX);
  state_lock = lua_touserdata (L, -1);
  lua_pop (L, 1);
  return state_lock;
}

void
lgi_state_enter (gpointer state_lock)
{
  LgiStateMutex *mutex = state_lock;
  GRecMutex *wait_on;

  /* There is a complication with lock switching.  During the wait for
     the lock, someone could call core.registerlock() and thus change
     the lock protecting the state.  Accomodate for this situation. */
  for (;;)
    {
      wait_on = g_atomic_pointer_get (&mutex->mutex);
      g_rec_mutex_lock (wait_on);
      if (wait_on == mutex->mutex)
	break;

      /* The lock is changed, unlock this one and wait again. */
      g_rec_mutex_unlock (wait_on);
    }
}

void
lgi_state_leave (gpointer state_lock)
{
  /* Get pointer to the call mutex belonging to this state. */
  LgiStateMutex *mutex = state_lock;
  g_rec_mutex_unlock (mutex->mutex);
}

static const char* log_levels[] = {
  "ERROR", "CRITICAL", "WARNING", "MESSAGE", "INFO", "DEBUG", "???", NULL
};

static int
core_log (lua_State *L)
{
  const char *domain = luaL_checkstring (L, 1);
  int level = 1 << (luaL_checkoption (L, 2, log_levels[5], log_levels) + 2);
  const char *message = luaL_checkstring (L, 3);
  g_log (domain, level, "%s", message);
  return 0;
}

static int
core_yield (lua_State *L)
{
  /* Perform yield with unlocked mutex; this might force another
     threads waiting on the mutex to perform what they need to do
     (i.e. enter Lua with callbacks). */
  gpointer state_lock = lgi_state_get_lock (L);
  lgi_state_leave (state_lock);
  g_thread_yield ();
  lgi_state_enter (state_lock);
  return 0;
}

static void
package_lock_enter (void)
{
  g_rec_mutex_lock (&package_mutex);
}

static void
package_lock_leave (void)
{
  g_rec_mutex_unlock (&package_mutex);
}

static gpointer package_lock_register[8] = { NULL };

static int
core_registerlock (lua_State *L)
{
  void (*set_lock_functions)(GCallback, GCallback);
  LgiStateMutex *mutex;
  GRecMutex *wait_on;
  unsigned i;

  /* Get registration function. */
  luaL_checktype (L, 1, LUA_TLIGHTUSERDATA);
  set_lock_functions = lua_touserdata (L, 1);
  luaL_argcheck (L, set_lock_functions != NULL, 1, "NULL function");

  /* Check, whether this package was already registered. */
  for (i = 0; i < G_N_ELEMENTS (package_lock_register) &&
	 package_lock_register[i] != set_lock_functions; i++)
    {
      if (package_lock_register[i] == NULL)
	{
	  /* Register our package lock functions. */
	  package_lock_register[i] = set_lock_functions;
	  set_lock_functions (package_lock_enter, package_lock_leave);
	  break;
	}
    }

  /* Switch our statelock to actually use packagelock. */
  lua_pushlightuserdata (L, &call_mutex);
  lua_rawget (L, LUA_REGISTRYINDEX);
  mutex = lua_touserdata (L, -1);
  wait_on = g_atomic_pointer_get (&mutex->mutex);
  if (wait_on != &package_mutex)
    {
      g_rec_mutex_lock (&package_mutex);
      g_atomic_pointer_set (&mutex->mutex, &package_mutex);
      g_rec_mutex_unlock (wait_on);
    }
  return 0;
}

static int
core_band (lua_State *L)
{
  lua_pushnumber (L, (unsigned)luaL_checknumber (L, 1)
		  & (unsigned)luaL_checknumber (L, 2));
  return 1;
}

static int
core_bor (lua_State *L)
{
  lua_pushnumber (L, (unsigned)luaL_checknumber (L, 1)
		  | (unsigned)luaL_checknumber (L, 2));
  return 1;
}

#define UD_MODULE "lgi.core.module"

static int
module_gc (lua_State *L)
{
  GModule **module = luaL_checkudata (L, 1, UD_MODULE);
  g_module_close (*module);
  return 0;
}

static int
module_index (lua_State *L)
{
  GModule **module = luaL_checkudata (L, 1, UD_MODULE);
  gpointer address;
  if (g_module_symbol (*module, luaL_checkstring (L, 2), &address))
    {
      lua_pushlightuserdata (L, address);
      return 1;
    }

  lua_pushnil (L);
  lua_pushstring (L, g_module_error ());
  return 2;
}

static const struct luaL_Reg module_reg[] = {
  { "__gc", module_gc },
  { "__index", module_index },
  { NULL, NULL }
};

#if defined(G_WITH_CYGWIN)
#define MODULE_NAME_FORMAT_VERSION "cyg%s-%d.dll"
#define MODULE_NAME_FORMAT_PLAIN "cyg%s.dll"
#elif defined(G_OS_WIN32)
#define MODULE_NAME_FORMAT_VERSION "lib%s-%d.dll"
#define MODULE_NAME_FORMAT_PLAIN "lib%s.dll"
#elif defined(__APPLE__)
#define MODULE_NAME_FORMAT_VERSION "lib%s.%d.dylib"
#define MODULE_NAME_FORMAT_PLAIN "lib%s.dylib"
#else
#define MODULE_NAME_FORMAT_VERSION "lib%s.so.%d"
#define MODULE_NAME_FORMAT_PLAIN "lib%s.so"
#endif

/* Creates 'module' object which resolves symbol names to
   lightuserdata addresses.
   module, path = core.module(basename[, version]) */
static int
core_module (lua_State *L)
{
  char *name;

  /* If the version is present, combine it with basename.
     Except on OpenBSD, where libraries are versioned like libfoo.so.0.0
     and we will always load the shared object with the highest version
     number.
   */
#ifndef __OpenBSD__
  if (!lua_isnoneornil (L, 2))
    name = g_strdup_printf (MODULE_NAME_FORMAT_VERSION,
			    luaL_checkstring (L, 1),
			    (int) luaL_checkinteger (L, 2));
  else
#endif
    name = g_strdup_printf (MODULE_NAME_FORMAT_PLAIN,
			    luaL_checkstring (L, 1));

  /* Try to load the module. */
  GModule *module = g_module_open (name, 0);
  if (module == NULL)
    {
      lua_pushnil (L);
      goto end;
    }

  /* Embed the module in the userdata for the module. */
  *(GModule **) lua_newuserdata (L, sizeof (module)) = module;
  luaL_getmetatable (L, UD_MODULE);
  lua_setmetatable (L, -2);

 end:
  lua_pushstring (L, name);
  g_free (name);
  return 2;
}

static int core_upcase (lua_State *L)
{
  gchar *str = g_ascii_strup (luaL_checkstring (L, 1), -1);
  lua_pushstring (L, str);
  g_free (str);
  return 1;
}

static int core_downcase (lua_State *L)
{
  gchar *str = g_ascii_strdown (luaL_checkstring (L, 1), -1);
  lua_pushstring (L, str);
  g_free (str);
  return 1;
}

static const struct luaL_Reg lgi_reg[] = {
  { "log",  core_log },
  { "gtype", core_gtype },
  { "repotype", core_repotype },
  { "constant", core_constant },
  { "yield", core_yield },
  { "registerlock", core_registerlock },
  { "band", core_band },
  { "bor", core_bor },
  { "module", core_module },
  { "upcase", core_upcase },
  { "downcase", core_downcase },
  { NULL, NULL }
};

static void
create_repo_table (lua_State *L, const char *name, void *key)
{
  lua_newtable (L);
  lua_pushlightuserdata (L, key);
  lua_pushvalue (L, -2);
  lua_rawset (L, LUA_REGISTRYINDEX);
  lua_setfield (L, -2, name);
}

static void
set_resident (lua_State *L)
{
  /* Get '_CLIBS' table from the registry (Lua5.2). */
  lua_getfield (L, LUA_REGISTRYINDEX, "_CLIBS");
  if (!lua_isnil (L, -1))
    {
      /* Remove the very last item in they array part, which is handle
	 to our loaded module used by _CLIBS.gctm to clean modules
	 upon state cleanup. But before removing it, check, that it is
	 really the handle of our module.  Our module filename is
	 passed as arg 2. */
      lua_pushvalue (L, 2);
      lua_gettable (L, -2);
      lua_rawgeti (L, -2, lua_objlen (L, -2));
      if (lua_equal (L, -1, -2))
	{
	  lua_pushnil (L);
	  lua_rawseti (L, -4, lua_objlen (L, -4));
	}
      lua_pop (L, 3);
      return;
    }
  else
    {
      /* This hack tries to enumerate the whole registry table and
	 find 'LOADLIB: path' library.  When it detects itself, it
	 just removes pointer to the loaded library, disallowing Lua
	 to close it, thus leaving it resident even when the state is
	 closed. */

      /* Note: 'nil' is on the stack from lua_getfield() call above. */
      while (lua_next (L, LUA_REGISTRYINDEX))
	{
	  if (lua_type (L, -2) == LUA_TSTRING)
	    {
	      const char *str = lua_tostring (L, -2);
	      if (g_str_has_prefix (str, "LOADLIB: ") &&
		  strstr (str, "corelgilua5"))
		{
		  /* NULL the pointer to the loaded library. */
		  if (lua_type (L, -1) == LUA_TUSERDATA)
		    {
		      gpointer *lib = lua_touserdata (L, -1);
		      *lib = NULL;
		    }

		  /* Clean the stack and return. */
		  lua_pop (L, 2);
		  return;
		}
	    }

	  lua_pop (L, 1);
	}
    }
}

G_MODULE_EXPORT int
luaopen_lgi_corelgilua (lua_State* L)
{
  LgiStateMutex *mutex;
  gint state_id;

  /* Try to make itself resident.  This is needed because this dynamic
     module is 'statically' linked with glib/gobject, and these
     libraries are not designed to be unloaded.  Once they are
     unloaded, they cannot be safely loaded again into the same
     process.  To avoid problems when repeatedly opening and closing
     lua_States and loading lgi into them, we try to make the whole
     'core' module resident. */
  set_resident (L);

#if !GLIB_CHECK_VERSION(2, 36, 0)
  g_type_init ();
#endif

  /* Early GLib initializations. Make sure that following fundamental
     G_TYPEs are already initialized. */
  volatile GType unused;
  unused = G_TYPE_DATE;
  unused = G_TYPE_REGEX;
  unused = G_TYPE_DATE_TIME;
  unused = G_TYPE_VARIANT_TYPE;
  unused = G_TYPE_STRV;
  unused = unused;

  /* Register 'guard' metatable. */
  luaL_newmetatable (L, UD_GUARD);
  lua_pushcfunction (L, guard_gc);
  lua_setfield (L, -2, "__gc");
  lua_pop (L, 1);

  /* Register 'module' metatable. */
  luaL_newmetatable (L, UD_MODULE);
  luaL_register (L, NULL, module_reg);
  lua_pop (L, 1);

  /* Register 'call-mutex' metatable. */
  lua_pushlightuserdata (L, &call_mutex_mt);
  lua_newtable (L);
  lua_pushcfunction (L, call_mutex_gc);
  lua_setfield (L, -2, "__gc");
  lua_rawset (L, LUA_REGISTRYINDEX);

  /* Create call mutex guard, keep it locked initially (it is unlocked
     only when we are calling out to GObject-C code) and store it into
     the registry. */
  lua_pushlightuserdata (L, &call_mutex);
  mutex = lua_newuserdata (L, sizeof (*mutex));
  mutex->mutex = &mutex->state_mutex;
  g_rec_mutex_init (&mutex->state_mutex);
  g_rec_mutex_lock (&mutex->state_mutex);
  lua_pushlightuserdata (L, &call_mutex_mt);
  lua_rawget (L, LUA_REGISTRYINDEX);
  lua_setmetatable (L, -2);
  lua_rawset (L, LUA_REGISTRYINDEX);

  /* Register 'lgi.core' interface. */
  lua_newtable (L);
  luaL_register (L, NULL, lgi_reg);

  /* Add the state ID */
  state_id = g_atomic_int_add (&global_state_id, 1);
  if (state_id == 0)
    lua_pushliteral (L, "");
  else
    lua_pushfstring (L, "+L%d", state_id);
  lua_setfield (L, -2, "id");

  /* Add lock and enter/leave locking functions. */
  lua_pushlightuserdata (L, lgi_state_get_lock (L));
  lua_setfield (L, -2, "lock");
  lua_pushlightuserdata (L, lgi_state_enter);
  lua_setfield (L, -2, "enter");
  lua_pushlightuserdata (L, lgi_state_leave);
  lua_setfield (L, -2, "leave");

  /* Create repo and index table. */
  create_repo_table (L, "index", &repo_index);
  create_repo_table (L, "repo", &repo);

  /* Initialize modules. */
  lgi_buffer_init (L);
  lgi_gi_init (L);
  lgi_marshal_init (L);
  lgi_record_init (L);
  lgi_object_init (L);
  lgi_callable_init (L);

  /* Return registration table. */
  return 1;
}
