/*****************************************************************************
 * extension.c: Lua Extensions (meta data, web information, ...)
 *****************************************************************************
 * Copyright (C) 2009-2010 VideoLAN and authors
 * $Id: 7fa4ca2fc2b3f38d5871f84da2008973c3f74e29 $
 *
 * Authors: Jean-Philippe André < jpeg # videolan.org >
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
 *****************************************************************************/

#include "vlc.h"
#include "libs.h"
#include "extension.h"
#include "assert.h"

#include <vlc_input.h>
#include <vlc_events.h>

/* Functions to register */
static const luaL_Reg p_reg[] =
{
    { NULL, NULL }
};

/*
 * Extensions capabilities
 * Note: #define and ppsz_capabilities must be in sync
 */
#define EXT_HAS_MENU          (1 << 0)   ///< Hook: menu
#define EXT_TRIGGER_ONLY      (1 << 1)   ///< Hook: trigger. Not activable
#define EXT_INPUT_LISTENER    (1 << 2)   ///< Hook: input_changed
#define EXT_META_LISTENER     (1 << 3)   ///< Hook: meta_changed
#define EXT_PLAYING_LISTENER  (1 << 4)   ///< Hook: status_changed

const char* const ppsz_capabilities[] = {
    "menu",
    "trigger",
    "input-listener",
    "meta-listener",
    "playing-listener",
    NULL
};

static int ScanExtensions( extensions_manager_t *p_this );
static int ScanLuaCallback( vlc_object_t *p_this, const char *psz_script,
                            void *pb_continue );
static int Control( extensions_manager_t *, int, va_list );
static int GetMenuEntries( extensions_manager_t *p_mgr, extension_t *p_ext,
                    char ***pppsz_titles, uint16_t **ppi_ids );
static lua_State* GetLuaState( extensions_manager_t *p_mgr,
                               extension_t *p_ext );
static int TriggerMenu( extension_t *p_ext, int id );
static int TriggerExtension( extensions_manager_t *p_mgr,
                             extension_t *p_ext );

int vlclua_extension_deactivate( lua_State *L );

/* Interactions */
static int vlclua_extension_dialog_callback( vlc_object_t *p_this,
                                             char const *psz_var,
                                             vlc_value_t oldval,
                                             vlc_value_t newval,
                                             void *p_data );

/* Input item callback: vlc_InputItemMetaChanged */
static void inputItemMetaChanged( const vlc_event_t *p_event,
                                  void *data );


/**
 * Module entry-point
 **/
int Open_Extension( vlc_object_t *p_this )
{
    msg_Dbg( p_this, "Opening EXPERIMENTAL Lua Extension module" );

    extensions_manager_t *p_mgr = ( extensions_manager_t* ) p_this;

    p_mgr->pf_control = Control;

    extensions_manager_sys_t *p_sys = ( extensions_manager_sys_t* )
                    calloc( 1, sizeof( extensions_manager_sys_t ) );
    if( !p_sys ) return VLC_ENOMEM;

    p_mgr->p_sys = p_sys;
    ARRAY_INIT( p_sys->activated_extensions );
    ARRAY_INIT( p_mgr->extensions );
    vlc_mutex_init( &p_mgr->lock );
    vlc_mutex_init( &p_mgr->p_sys->lock );

    /* Scan available Lua Extensions */
    if( ScanExtensions( p_mgr ) != VLC_SUCCESS )
    {
        msg_Err( p_mgr, "Can't load extensions modules" );
        return VLC_EGENERIC;
    }

    // Create the dialog-event variable
    var_Create( p_this, "dialog-event", VLC_VAR_ADDRESS );
    var_AddCallback( p_this, "dialog-event",
                     vlclua_extension_dialog_callback, NULL );

    return VLC_SUCCESS;
}

/**
 * Module unload function
 **/
void Close_Extension( vlc_object_t *p_this )
{
    extensions_manager_t *p_mgr = ( extensions_manager_t* ) p_this;
    msg_Dbg( p_mgr, "Deactivating all loaded extensions" );

    vlc_mutex_lock( &p_mgr->lock );
    p_mgr->p_sys->b_killed = true;
    vlc_mutex_unlock( &p_mgr->lock );

    var_Destroy( p_mgr, "dialog-event" );

    extension_t *p_ext = NULL;
    FOREACH_ARRAY( p_ext, p_mgr->p_sys->activated_extensions )
    {
        if( !p_ext ) break;
        msg_Dbg( p_mgr, "Deactivating '%s'", p_ext->psz_title );
        Deactivate( p_mgr, p_ext );
        WaitForDeactivation( p_ext );
    }
    FOREACH_END()

    msg_Dbg( p_mgr, "All extensions are now deactivated" );
    ARRAY_RESET( p_mgr->p_sys->activated_extensions );

    vlc_mutex_destroy( &p_mgr->lock );
    vlc_mutex_destroy( &p_mgr->p_sys->lock );
    free( p_mgr->p_sys );
    p_mgr->p_sys = NULL;

    /* Free extensions' memory */
    FOREACH_ARRAY( p_ext, p_mgr->extensions )
    {
        if( !p_ext )
            break;
        if( p_ext->p_sys->L )
            lua_close( p_ext->p_sys->L );
        free( p_ext->psz_name );
        free( p_ext->psz_title );
        free( p_ext->psz_author );
        free( p_ext->psz_description );
        free( p_ext->psz_shortdescription );
        free( p_ext->psz_url );
        free( p_ext->psz_version );

        vlc_mutex_destroy( &p_ext->p_sys->running_lock );
        vlc_mutex_destroy( &p_ext->p_sys->command_lock );
        vlc_cond_destroy( &p_ext->p_sys->wait );

        free( p_ext->p_sys );
        free( p_ext );
    }
    FOREACH_END()

    ARRAY_RESET( p_mgr->extensions );
}

/**
 * Batch scan all Lua files in folder "extensions"
 * @param p_mgr This extensions_manager_t object
 **/
static int ScanExtensions( extensions_manager_t *p_mgr )
{
    bool b_true = true;
    int i_ret =
        vlclua_scripts_batch_execute( VLC_OBJECT( p_mgr ),
                                      "extensions",
                                      &ScanLuaCallback,
                                      &b_true );

    if( !i_ret )
        return VLC_EGENERIC;

    return VLC_SUCCESS;
}

/**
 * Dummy Lua function: does nothing
 * @note This function can be used to replace "require" while scanning for
 * extensions
 * Even the built-in libraries are not loaded when calling descriptor()
 **/
static int vlclua_dummy_require( lua_State *L )
{
    (void) L;
    return 0;
}

/**
 * Batch scan all Lua files in folder "extensions": callback
 * @param p_this This extensions_manager_t object
 * @param psz_script Name of the script to run
 * @param L Lua State, common to all scripts here
 * @param pb_continue bool* that indicates whether to continue batch or not
 **/
int ScanLuaCallback( vlc_object_t *p_this, const char *psz_script,
                     void *pb_continue )
{
    extensions_manager_t *p_mgr = ( extensions_manager_t* ) p_this;
    bool b_ok = false;

    msg_Dbg( p_mgr, "Scanning Lua script %s", psz_script );

    vlc_mutex_lock( &p_mgr->lock );

    /* Create new script descriptor */
    extension_t *p_ext = ( extension_t* ) calloc( 1, sizeof( extension_t ) );
    if( !p_ext )
    {
        vlc_mutex_unlock( &p_mgr->lock );
        return 0;
    }

    p_ext->psz_name = strdup( psz_script );
    p_ext->p_sys = (extension_sys_t*) calloc( 1, sizeof( extension_sys_t ) );
    if( !p_ext->p_sys || !p_ext->psz_name )
    {
        free( p_ext->psz_name );
        free( p_ext->p_sys );
        free( p_ext );
        vlc_mutex_unlock( &p_mgr->lock );
        return 0;
    }
    p_ext->p_sys->p_mgr = p_mgr;

    /* Mutexes and conditions */
    vlc_mutex_init( &p_ext->p_sys->command_lock );
    vlc_mutex_init( &p_ext->p_sys->running_lock );
    vlc_cond_init( &p_ext->p_sys->wait );

    /* Prepare Lua state */
    lua_State *L = luaL_newstate();
    lua_register( L, "require", &vlclua_dummy_require );

    /* Let's run it */
    if( luaL_dofile( L, psz_script ) )
    {
        msg_Warn( p_mgr, "Error loading script %s: %s", psz_script,
                  lua_tostring( L, lua_gettop( L ) ) );
        lua_pop( L, 1 );
        goto exit;
    }

    /* Scan script for capabilities */
    lua_getglobal( L, "descriptor" );

    if( !lua_isfunction( L, -1 ) )
    {
        msg_Warn( p_mgr, "Error while running script %s, "
                  "function descriptor() not found", psz_script );
        goto exit;
    }

    if( lua_pcall( L, 0, 1, 0 ) )
    {
        msg_Warn( p_mgr, "Error while running script %s, "
                  "function descriptor(): %s", psz_script,
                  lua_tostring( L, lua_gettop( L ) ) );
        goto exit;
    }

    if( lua_gettop( L ) )
    {
        if( lua_istable( L, -1 ) )
        {
            /* Get caps */
            lua_getfield( L, -1, "capabilities" );
            if( lua_istable( L, -1 ) )
            {
                lua_pushnil( L );
                while( lua_next( L, -2 ) != 0 )
                {
                    /* Key is at index -2 and value at index -1. Discard key */
                    const char *psz_cap = luaL_checkstring( L, -1 );
                    int i_cap = 0;
                    bool b_ok = false;
                    /* Find this capability's flag */
                    for( const char *iter = *ppsz_capabilities;
                         iter != NULL;
                         iter = ppsz_capabilities[ ++i_cap ])
                    {
                        if( !strcmp( iter, psz_cap ) )
                        {
                            /* Flag it! */
                            p_ext->p_sys->i_capabilities |= 1 << i_cap;
                            b_ok = true;
                            break;
                        }
                    }
                    if( !b_ok )
                    {
                        msg_Warn( p_mgr, "Extension capability '%s' unknown in"
                                  " script %s", psz_cap, psz_script );
                    }
                    /* Removes 'value'; keeps 'key' for next iteration */
                    lua_pop( L, 1 );
                }
            }
            else
            {
                msg_Warn( p_mgr, "In script %s, function descriptor() "
                              "did not return a table of capabilities.",
                              psz_script );
            }
            lua_pop( L, 1 );

            /* Get title */
            lua_getfield( L, -1, "title" );
            if( lua_isstring( L, -1 ) )
            {
                p_ext->psz_title = strdup( luaL_checkstring( L, -1 ) );
            }
            else
            {
                msg_Dbg( p_mgr, "In script %s, function descriptor() "
                                "did not return a string as title.",
                                psz_script );
                p_ext->psz_title = strdup( psz_script );
            }
            lua_pop( L, 1 );

            /* Get author */
            lua_getfield( L, -1, "author" );
            if( lua_isstring( L, -1 ) )
            {
                p_ext->psz_author = strdup( luaL_checkstring( L, -1 ) );
            }
            else
            {
                p_ext->psz_author = NULL;
            }
            lua_pop( L, 1 );

            /* Get description */
            lua_getfield( L, -1, "description" );
            if( lua_isstring( L, -1 ) )
            {
                p_ext->psz_description = strdup( luaL_checkstring( L, -1 ) );
            }
            else
            {
                p_ext->psz_description = NULL;
            }
            lua_pop( L, 1 );

            /* Get short description */
            lua_getfield( L, -1, "shortdesc" );
            if( lua_isstring( L, -1 ) )
            {
                p_ext->psz_shortdescription = strdup( luaL_checkstring( L, -1 ) );
            }
            else
            {
                p_ext->psz_shortdescription = NULL;
            }
            lua_pop( L, 1 );

            /* Get URL */
            lua_getfield( L, -1, "url" );
            if( lua_isstring( L, -1 ) )
            {
                p_ext->psz_url = strdup( luaL_checkstring( L, -1 ) );
            }
            else
            {
                p_ext->psz_url = NULL;
            }
            lua_pop( L, 1 );

            /* Get version */
            lua_getfield( L, -1, "version" );
            if( lua_isstring( L, -1 ) )
            {
                p_ext->psz_version = strdup( luaL_checkstring( L, -1 ) );
            }
            else
            {
                p_ext->psz_version = NULL;
            }
            lua_pop( L, 1 );
        }
        else
        {
            msg_Warn( p_mgr, "In script %s, function descriptor() "
                      "did not return a table!", psz_script );
            goto exit;
        }
    }
    else
    {
        msg_Err( p_mgr, "Script %s went completely foobar", psz_script );
        goto exit;
    }

    msg_Dbg( p_mgr, "Script %s has the following capability flags: 0x%x",
             psz_script, p_ext->p_sys->i_capabilities );

    b_ok = true;
exit:
    lua_close( L );
    if( !b_ok )
    {
        free( p_ext->psz_name );
        free( p_ext->psz_title );
        free( p_ext->psz_url );
        free( p_ext->psz_author );
        free( p_ext->psz_description );
        free( p_ext->psz_shortdescription );
        free( p_ext->psz_version );
        vlc_mutex_destroy( &p_ext->p_sys->command_lock );
        vlc_mutex_destroy( &p_ext->p_sys->running_lock );
        vlc_cond_destroy( &p_ext->p_sys->wait );
        free( p_ext->p_sys );
        free( p_ext );
    }
    else
    {
        /* Add the extension to the list of known extensions */
        ARRAY_APPEND( p_mgr->extensions, p_ext );
    }

    vlc_mutex_unlock( &p_mgr->lock );
    /* Continue batch execution */
    return pb_continue ? ( (* (bool*)pb_continue) ? -1 : 0 ) : -1;
}

static int Control( extensions_manager_t *p_mgr, int i_control, va_list args )
{
    extension_t *p_ext = NULL;
    bool *pb = NULL;
    uint16_t **ppus = NULL;
    char ***pppsz = NULL;
    int i = 0;

    switch( i_control )
    {
        case EXTENSION_ACTIVATE:
            p_ext = ( extension_t* ) va_arg( args, extension_t* );
            return Activate( p_mgr, p_ext );

        case EXTENSION_DEACTIVATE:
            p_ext = ( extension_t* ) va_arg( args, extension_t* );
            return Deactivate( p_mgr, p_ext );

        case EXTENSION_IS_ACTIVATED:
            p_ext = ( extension_t* ) va_arg( args, extension_t* );
            pb = ( bool* ) va_arg( args, bool* );
            *pb = IsActivated( p_mgr, p_ext );
            break;

        case EXTENSION_HAS_MENU:
            p_ext = ( extension_t* ) va_arg( args, extension_t* );
            pb = ( bool* ) va_arg( args, bool* );
            *pb = ( p_ext->p_sys->i_capabilities & EXT_HAS_MENU ) ? 1 : 0;
            break;

        case EXTENSION_GET_MENU:
            p_ext = ( extension_t* ) va_arg( args, extension_t* );
            pppsz = ( char*** ) va_arg( args, char*** );
            ppus = ( uint16_t** ) va_arg( args, uint16_t** );
            return GetMenuEntries( p_mgr, p_ext, pppsz, ppus );

        case EXTENSION_TRIGGER_ONLY:
            p_ext = ( extension_t* ) va_arg( args, extension_t* );
            pb = ( bool* ) va_arg( args, bool* );
            *pb = ( p_ext->p_sys->i_capabilities & EXT_TRIGGER_ONLY ) ? 1 : 0;
            break;

        case EXTENSION_TRIGGER:
            p_ext = ( extension_t* ) va_arg( args, extension_t* );
            return TriggerExtension( p_mgr, p_ext );

        case EXTENSION_TRIGGER_MENU:
            p_ext = ( extension_t* ) va_arg( args, extension_t* );
            // GCC: 'uint16_t' is promoted to 'int' when passed through '...'
            i = ( int ) va_arg( args, int );
            return TriggerMenu( p_ext, i );

        case EXTENSION_SET_INPUT:
        {
            p_ext = ( extension_t* ) va_arg( args, extension_t* );
            input_thread_t *p_input = va_arg( args, struct input_thread_t * );

            if( !LockExtension( p_ext ) )
                return VLC_EGENERIC;

            // Change input
            input_thread_t *old = p_ext->p_sys->p_input;
            input_item_t *p_item;
            if( old )
            {
                // Untrack meta fetched events
                if( p_ext->p_sys->i_capabilities & EXT_META_LISTENER )
                {
                    p_item = input_GetItem( old );
                    vlc_event_detach( &p_item->event_manager,
                                      vlc_InputItemMetaChanged,
                                      inputItemMetaChanged,
                                      p_ext );
                    vlc_gc_decref( p_item );
                }
                vlc_object_release( old );
            }

            p_ext->p_sys->p_input = p_input ? vlc_object_hold( p_input )
                                            : p_input;

            // Tell the script the input changed
            if( p_ext->p_sys->i_capabilities & EXT_INPUT_LISTENER )
            {
                PushCommandUnique( p_ext, CMD_SET_INPUT );
            }

            // Track meta fetched events
            if( p_ext->p_sys->p_input &&
                p_ext->p_sys->i_capabilities & EXT_META_LISTENER )
            {
                p_item = input_GetItem( p_ext->p_sys->p_input );
                vlc_gc_incref( p_item );
                vlc_event_attach( &p_item->event_manager,
                                  vlc_InputItemMetaChanged,
                                  inputItemMetaChanged,
                                  p_ext );
            }

            UnlockExtension( p_ext );
            break;
        }
        case EXTENSION_PLAYING_CHANGED:
        {
            extension_t *p_ext;
            p_ext = ( extension_t* ) va_arg( args, extension_t* );
            assert( p_ext->psz_name != NULL );
            i = ( int ) va_arg( args, int );
            if( p_ext->p_sys->i_capabilities & EXT_PLAYING_LISTENER )
            {
                PushCommand( p_ext, CMD_PLAYING_CHANGED, i );
            }
            break;
        }
        default:
            msg_Warn( p_mgr, "Control '%d' not yet implemented in Extension",
                      i_control );
            return VLC_EGENERIC;
    }

    return VLC_SUCCESS;
}

int lua_ExtensionActivate( extensions_manager_t *p_mgr, extension_t *p_ext )
{
    assert( p_mgr != NULL && p_ext != NULL );
    return lua_ExecuteFunction( p_mgr, p_ext, "activate", LUA_END );
}

int lua_ExtensionDeactivate( extensions_manager_t *p_mgr, extension_t *p_ext )
{
    assert( p_mgr != NULL && p_ext != NULL );

    if( !p_ext->p_sys->L )
        return VLC_SUCCESS;

    // Unset and release input objects
    if( p_ext->p_sys->p_input )
    {
        if( p_ext->p_sys->i_capabilities & EXT_META_LISTENER )
        {
            // Release item
            input_item_t *p_item = input_GetItem( p_ext->p_sys->p_input );
            vlc_gc_decref( p_item );
        }
        vlc_object_release( p_ext->p_sys->p_input );
    }

    int i_ret = lua_ExecuteFunction( p_mgr, p_ext, "deactivate", LUA_END );

    /* Clear Lua State */
    lua_close( p_ext->p_sys->L );
    p_ext->p_sys->L = NULL;

    return i_ret;
}

int lua_ExtensionWidgetClick( extensions_manager_t *p_mgr,
                              extension_t *p_ext,
                              extension_widget_t *p_widget )
{
    if( !p_ext->p_sys->L )
        return VLC_SUCCESS;

    lua_State *L = GetLuaState( p_mgr, p_ext );
    lua_pushlightuserdata( L, p_widget );
    lua_gettable( L, LUA_REGISTRYINDEX );
    return lua_ExecuteFunction( p_mgr, p_ext, NULL, LUA_END );
}


/**
 * Get the list of menu entries from an extension script
 * @param p_mgr
 * @param p_ext
 * @param pppsz_titles Pointer to NULL. All strings must be freed by the caller
 * @param ppi_ids Pointer to NULL. Must be freed by the caller.
 * @note This function is allowed to run in the UI thread. This means
 *       that it MUST respond very fast.
 * @todo Remove the menu() hook and provide a new function vlc.set_menu()
 **/
static int GetMenuEntries( extensions_manager_t *p_mgr, extension_t *p_ext,
                    char ***pppsz_titles, uint16_t **ppi_ids )
{
    assert( *pppsz_titles == NULL );
    assert( *ppi_ids == NULL );

    if( !IsActivated( p_mgr, p_ext ) )
    {
        msg_Dbg( p_mgr, "Can't get menu before activating the extension!" );
        return VLC_EGENERIC;
    }

    if( !LockExtension( p_ext ) )
    {
        /* Dying extension, fail. */
        return VLC_EGENERIC;
    }

    int i_ret = VLC_EGENERIC;
    lua_State *L = GetLuaState( p_mgr, p_ext );

    if( ( p_ext->p_sys->i_capabilities & EXT_HAS_MENU ) == 0 )
    {
        msg_Dbg( p_mgr, "can't get a menu from an extension without menu!" );
        goto exit;
    }

    lua_getglobal( L, "menu" );

    if( !lua_isfunction( L, -1 ) )
    {
        msg_Warn( p_mgr, "Error while running script %s, "
                  "function menu() not found", p_ext->psz_name );
        goto exit;
    }

    if( lua_pcall( L, 0, 1, 0 ) )
    {
        msg_Warn( p_mgr, "Error while running script %s, "
                  "function menu(): %s", p_ext->psz_name,
                  lua_tostring( L, lua_gettop( L ) ) );
        goto exit;
    }

    if( lua_gettop( L ) )
    {
        if( lua_istable( L, -1 ) )
        {
            /* Get table size */
            size_t i_size = lua_objlen( L, -1 );
            *pppsz_titles = ( char** ) calloc( i_size+1, sizeof( char* ) );
            *ppi_ids = ( uint16_t* ) calloc( i_size+1, sizeof( uint16_t ) );

            /* Walk table */
            size_t i_idx = 0;
            lua_pushnil( L );
            while( lua_next( L, -2 ) != 0 )
            {
                assert( i_idx < i_size );
                if( (!lua_isstring( L, -1 )) || (!lua_isnumber( L, -2 )) )
                {
                    msg_Warn( p_mgr, "In script %s, an entry in "
                              "the menu table is invalid!", p_ext->psz_name );
                    goto exit;
                }
                (*pppsz_titles)[ i_idx ] = strdup( luaL_checkstring( L, -1 ) );
                (*ppi_ids)[ i_idx ] = (uint16_t) ( luaL_checkinteger( L, -2 ) & 0xFFFF );
                i_idx++;
                lua_pop( L, 1 );
            }
        }
        else
        {
            msg_Warn( p_mgr, "Function menu() in script %s "
                      "did not return a table", p_ext->psz_name );
            goto exit;
        }
    }
    else
    {
        msg_Warn( p_mgr, "Script %s went completely foobar", p_ext->psz_name );
        goto exit;
    }

    i_ret = VLC_SUCCESS;

exit:
    UnlockExtension( p_ext );
    if( i_ret != VLC_SUCCESS )
    {
        msg_Dbg( p_mgr, "Something went wrong in %s (%s:%d)",
                 __func__, __FILE__, __LINE__ );
    }
    return i_ret;
}

/* Must be entered with the Lock on Extension */
static lua_State* GetLuaState( extensions_manager_t *p_mgr,
                               extension_t *p_ext )
{
    lua_State *L = NULL;
    if( p_ext )
        L = p_ext->p_sys->L;

    if( !L )
    {
        L = luaL_newstate();
        if( !L )
        {
            msg_Err( p_mgr, "Could not create new Lua State" );
            return NULL;
        }
        vlclua_set_this( L, p_mgr );
        vlclua_extension_set( L, p_ext );

        luaL_openlibs( L );
        luaL_register( L, "vlc", p_reg );
        luaopen_msg( L );

        if( p_ext )
        {
            /* Load more libraries */
            luaopen_acl( L );
            luaopen_config( L );
            luaopen_dialog( L, p_ext );
            luaopen_input( L );
            luaopen_md5( L );
            luaopen_msg( L );
            luaopen_misc( L );
            luaopen_net( L );
            luaopen_object( L );
            luaopen_osd( L );
            luaopen_playlist( L );
            luaopen_sd( L );
            luaopen_stream( L );
            luaopen_strings( L );
            luaopen_variables( L );
            luaopen_video( L );
            luaopen_vlm( L );
            luaopen_volume( L );
            luaopen_xml( L );

            /* Register extension specific functions */
            lua_getglobal( L, "vlc" );
            lua_pushcfunction( L, vlclua_extension_deactivate );
            lua_setfield( L, -2, "deactivate" );

            /* Setup the module search path */
            if( vlclua_add_modules_path( p_mgr, L, p_ext->psz_name ) )
            {
                msg_Warn( p_mgr, "Error while setting the module search path for %s", p_ext->psz_name );
                return NULL;
            }

            /* Load and run the script(s) */
            if( luaL_dofile( L, p_ext->psz_name ) != 0 )
            {
                msg_Warn( p_mgr, "Error loading script %s: %s", p_ext->psz_name,
                          lua_tostring( L, lua_gettop( L ) ) );
                lua_pop( L, 1 );
                return NULL;
            }

            p_ext->p_sys->L = L;
        }
    }

    return L;
}

int lua_ExecuteFunction( extensions_manager_t *p_mgr, extension_t *p_ext,
                            const char *psz_function, ... )
{
    va_list args;
    va_start( args, psz_function );
    int i_ret = lua_ExecuteFunctionVa( p_mgr, p_ext, psz_function, args );
    va_end( args );
    return i_ret;
}

/**
 * Execute a function in a Lua script
 * @param psz_function Name of global function to execute. If NULL, assume
 *                     that the function object is already on top of the
 *                     stack.
 * @return < 0 in case of failure, >= 0 in case of success
 * @note It's better to call this function from a dedicated thread
 * (see extension_thread.c)
 **/
int lua_ExecuteFunctionVa( extensions_manager_t *p_mgr, extension_t *p_ext,
                            const char *psz_function, va_list args )
{
    int i_ret = VLC_EGENERIC;
    int i_args = 0;
    assert( p_mgr != NULL );
    assert( p_ext != NULL );

    lua_State *L = GetLuaState( p_mgr, p_ext );
    if( psz_function )
        lua_getglobal( L, psz_function );

    if( !lua_isfunction( L, -1 ) )
    {
        msg_Warn( p_mgr, "Error while running script %s, "
                  "function %s() not found", p_ext->psz_name, psz_function );
        goto exit;
    }

    lua_datatype_e type = LUA_END;
    while( ( type = va_arg( args, int ) ) != LUA_END )
    {
        if( type == LUA_NUM )
        {
            lua_pushnumber( L , ( int ) va_arg( args, int ) );
        }
        else if( type == LUA_TEXT )
        {
            lua_pushstring( L , ( char * ) va_arg( args, char* ) );
        }
        else
        {
            msg_Warn( p_mgr, "Undefined argument type %d to lua function %s"
                   "from script %s", type, psz_function, p_ext->psz_name );
            goto exit;
        }
        i_args ++;
    }
    if( lua_pcall( L, i_args, 1, 0 ) )
    {
        msg_Warn( p_mgr, "Error while running script %s, "
                  "function %s(): %s", p_ext->psz_name, psz_function,
                  lua_tostring( L, lua_gettop( L ) ) );
        goto exit;
    }

    i_ret = lua_DialogFlush( L );
exit:
    return i_ret;

}

static inline int TriggerMenu( extension_t *p_ext, int i_id )
{
    return PushCommand( p_ext, CMD_TRIGGERMENU, i_id );
}

int lua_ExtensionTriggerMenu( extensions_manager_t *p_mgr,
                              extension_t *p_ext, int id )
{
    int i_ret = VLC_EGENERIC;
    lua_State *L = GetLuaState( p_mgr, p_ext );

    if( !L )
        return VLC_EGENERIC;

    luaopen_dialog( L, p_ext );

    lua_getglobal( L, "trigger_menu" );
    if( !lua_isfunction( L, -1 ) )
    {
        msg_Warn( p_mgr, "Error while running script %s, "
                  "function trigger_menu() not found", p_ext->psz_name );
        return VLC_EGENERIC;
    }

    /* Pass id as unique argument to the function */
    lua_pushinteger( L, id );

    if( lua_pcall( L, 1, 1, 0 ) != 0 )
    {
        msg_Warn( p_mgr, "Error while running script %s, "
                  "function trigger_menu(): %s", p_ext->psz_name,
                  lua_tostring( L, lua_gettop( L ) ) );
        return VLC_EGENERIC;
    }

    i_ret = lua_DialogFlush( L );
    if( i_ret < VLC_SUCCESS )
    {
        msg_Dbg( p_mgr, "Something went wrong in %s (%s:%d)",
                 __func__, __FILE__, __LINE__ );
    }
    return i_ret;
}

/** Directly trigger an extension, without activating it
 * This is NOT multithreaded, and this code runs in the UI thread
 * @param p_mgr
 * @param p_ext Extension to trigger
 * @return Value returned by the lua function "trigger"
 **/
static int TriggerExtension( extensions_manager_t *p_mgr,
                             extension_t *p_ext )
{
    int i_ret = lua_ExecuteFunction( p_mgr, p_ext, "trigger", LUA_END );

    /* Close lua state for trigger-only extensions */
    if( p_ext->p_sys->L )
        lua_close( p_ext->p_sys->L );
    p_ext->p_sys->L = NULL;

    return i_ret;
}

/** Set extension associated to the current script
 * @param L current lua_State
 * @param p_ext the extension
 */
void vlclua_extension_set( lua_State *L, extension_t *p_ext )
{
    lua_pushlightuserdata( L, vlclua_extension_set );
    lua_pushlightuserdata( L, p_ext );
    lua_rawset( L, LUA_REGISTRYINDEX );
}

/** Retrieve extension associated to the current script
 * @param L current lua_State
 * @return Extension pointer
 **/
extension_t *vlclua_extension_get( lua_State *L )
{
    lua_pushlightuserdata( L, vlclua_extension_set );
    lua_rawget( L, LUA_REGISTRYINDEX );
    extension_t *p_ext = (extension_t*) lua_topointer( L, -1 );
    lua_pop( L, 1 );
    return p_ext;
}

/** Deactivate an extension by order from the extension itself
 * @param L lua_State
 * @note This is an asynchronous call. A script calling vlc.deactivate() will
 * be executed to the end before the last call to deactivate() is done.
 **/
int vlclua_extension_deactivate( lua_State *L )
{
    extension_t *p_ext = vlclua_extension_get( L );
    int i_ret = Deactivate( p_ext->p_sys->p_mgr, p_ext );
    return ( i_ret == VLC_SUCCESS ) ? 1 : 0;
}

/** Callback for the variable "dialog-event"
 * @param p_this Current object owner of the extension and the dialog
 * @param psz_var "dialog-event"
 * @param oldval Unused
 * @param newval Address of the dialog
 * @param p_data Unused
 **/
static int vlclua_extension_dialog_callback( vlc_object_t *p_this,
                                             char const *psz_var,
                                             vlc_value_t oldval,
                                             vlc_value_t newval,
                                             void *p_data )
{
    /* psz_var == "dialog-event" */
    ( void ) psz_var;
    ( void ) oldval;
    ( void ) p_data;

    extension_dialog_command_t *command = newval.p_address;
    assert( command != NULL );
    assert( command->p_dlg != NULL);

    extension_t *p_ext = command->p_dlg->p_sys;
    assert( p_ext != NULL );

    extension_widget_t *p_widget = command->p_data;

    switch( command->event )
    {
        case EXTENSION_EVENT_CLICK:
            assert( p_widget != NULL );
            PushCommandUnique( p_ext, CMD_CLICK, p_widget );
            break;
        case EXTENSION_EVENT_CLOSE:
            PushCommandUnique( p_ext, CMD_CLOSE );
            break;
        default:
            msg_Dbg( p_this, "Received unknown UI event %d, discarded",
                     command->event );
            break;
    }

    return VLC_SUCCESS;
}

/** Callback on vlc_InputItemMetaChanged event
 **/
static void inputItemMetaChanged( const vlc_event_t *p_event,
                                  void *data )
{
    assert( p_event && p_event->type == vlc_InputItemMetaChanged );

    extension_t *p_ext = ( extension_t* ) data;
    assert( p_ext != NULL );

    PushCommandUnique( p_ext, CMD_UPDATE_META );
}

/* Lock this extension. Can fail. */
bool LockExtension( extension_t *p_ext )
{
    if( p_ext->p_sys->b_exiting )
        return false;

    vlc_mutex_lock( &p_ext->p_sys->running_lock );
    if( p_ext->p_sys->b_exiting )
    {
        vlc_mutex_unlock( &p_ext->p_sys->running_lock );
        return false;
    }

    return true;
}

void UnlockExtension( extension_t *p_ext )
{
    vlc_mutex_unlock( &p_ext->p_sys->running_lock );
}
