/*****************************************************************************
 * modules.c : Builtin and plugin modules management functions
 *****************************************************************************
 * Copyright (C) 2001-2011 VLC authors and VideoLAN
 * $Id$
 *
 * Authors: Sam Hocevar <sam@zoy.org>
 *          Ethan C. Baldridge <BaldridgeE@cadmus.com>
 *          Hans-Peter Jansen <hpj@urpla.net>
 *          Gildas Bazin <gbazin@videolan.org>
 *          Rémi Denis-Courmont
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation; either version 2.1 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 Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser 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.
 *****************************************************************************/

#ifdef HAVE_CONFIG_H
# include "config.h"
#endif

#include <stdlib.h>
#include <string.h>
#ifdef ENABLE_NLS
# include <libintl.h>
#endif
#include <assert.h>

#include <vlc_common.h>
#include <vlc_modules.h>
#include "libvlc.h"
#include "config/configuration.h"
#include "vlc_arrays.h"
#include "modules/modules.h"

/**
 * Checks whether a module implements a capability.
 *
 * \param m the module
 * \param cap the capability to check
 * \return true if the module has the capability
 */
bool module_provides (const module_t *m, const char *cap)
{
    return !strcmp (module_get_capability (m), cap);
}

/**
 * Get the internal name of a module
 *
 * \param m the module
 * \return the module name
 */
const char *module_get_object( const module_t *m )
{
    if (unlikely(m->i_shortcuts == 0))
        return "unnamed";
    return m->pp_shortcuts[0];
}

/**
 * Get the human-friendly name of a module.
 *
 * \param m the module
 * \param long_name TRUE to have the long name of the module
 * \return the short or long name of the module
 */
const char *module_get_name( const module_t *m, bool long_name )
{
    if( long_name && ( m->psz_longname != NULL) )
        return m->psz_longname;

    if (m->psz_shortname != NULL)
        return m->psz_shortname;
    return module_get_object (m);
}

/**
 * Get the help for a module
 *
 * \param m the module
 * \return the help
 */
const char *module_get_help( const module_t *m )
{
    return m->psz_help;
}

/**
 * Gets the capability of a module
 *
 * \param m the module
 * \return the capability, or "none" if unspecified
 */
const char *module_get_capability (const module_t *m)
{
    return (m->psz_capability != NULL) ? m->psz_capability : "none";
}

/**
 * Get the score for a module
 *
 * \param m the module
 * return the score for the capability
 */
int module_get_score( const module_t *m )
{
    return m->i_score;
}

/**
 * Translate a string using the module's text domain
 *
 * \param m the module
 * \param str the American English ASCII string to localize
 * \return the gettext-translated string
 */
const char *module_gettext (const module_t *m, const char *str)
{
    if (unlikely(str == NULL || *str == '\0'))
        return "";
#ifdef ENABLE_NLS
    const char *domain = m->plugin->textdomain;
    return dgettext ((domain != NULL) ? domain : PACKAGE_NAME, str);
#else
    (void)m;
    return str;
#endif
}

#undef module_start
int module_start (vlc_object_t *obj, const module_t *m)
{
   int (*activate) (vlc_object_t *) = m->pf_activate;

   return (activate != NULL) ? activate (obj) : VLC_SUCCESS;
}

#undef module_stop
void module_stop (vlc_object_t *obj, const module_t *m)
{
   void (*deactivate) (vlc_object_t *) = m->pf_deactivate;

    if (deactivate != NULL)
        deactivate (obj);
}

static bool module_match_name (const module_t *m, const char *name)
{
     /* Plugins with zero score must be matched explicitly. */
     if (!strcasecmp ("any", name))
         return m->i_score > 0;

     for (unsigned i = 0; i < m->i_shortcuts; i++)
          if (!strcasecmp (m->pp_shortcuts[i], name))
              return true;
     return false;
}

static int module_load (vlc_object_t *obj, module_t *m,
                        vlc_activate_t init, va_list args)
{
    int ret = VLC_SUCCESS;

    if (module_Map(obj, m->plugin))
        return VLC_EGENERIC;

    if (m->pf_activate != NULL)
    {
        va_list ap;

        va_copy (ap, args);
        ret = init (m->pf_activate, ap);
        va_end (ap);
    }

    if (ret != VLC_SUCCESS)
        vlc_objres_clear(obj);

    return ret;
}

#undef vlc_module_load
/**
 * Finds and instantiates the best module of a certain type.
 * All candidates modules having the specified capability and name will be
 * sorted in decreasing order of priority. Then the probe callback will be
 * invoked for each module, until it succeeds (returns 0), or all candidate
 * module failed to initialize.
 *
 * The probe callback first parameter is the address of the module entry point.
 * Further parameters are passed as an argument list; it corresponds to the
 * variable arguments passed to this function. This scheme is meant to
 * support arbitrary prototypes for the module entry point.
 *
 * \param obj VLC object
 * \param capability capability, i.e. class of module
 * \param name name of the module asked, if any
 * \param strict if true, do not fallback to plugin with a different name
 *                 but the same capability
 * \param probe module probe callback
 * \return the module or NULL in case of a failure
 */
module_t *vlc_module_load(vlc_object_t *obj, const char *capability,
                          const char *name, bool strict,
                          vlc_activate_t probe, ...)
{
    char *var = NULL;

    if (name == NULL || name[0] == '\0')
        name = "any";

    /* Deal with variables */
    if (name[0] == '$')
    {
        var = var_InheritString (obj, name + 1);
        name = (var != NULL) ? var : "any";
    }

    /* Find matching modules */
    module_t **mods;
    ssize_t total = module_list_cap (&mods, capability);

    msg_Dbg (obj, "looking for %s module matching \"%s\": %zd candidates",
             capability, name, total);
    if (total <= 0)
    {
        free(var);
        module_list_free (mods);
        msg_Dbg (obj, "no %s modules", capability);
        return NULL;
    }

    module_t *module = NULL;
    const bool b_force_backup = obj->obj.force; /* FIXME: remove this */
    va_list args;

    va_start(args, probe);
    while (*name)
    {
        char buf[32];
        size_t slen = strcspn (name, ",");

        if (likely(slen < sizeof (buf)))
        {
            memcpy(buf, name, slen);
            buf[slen] = '\0';
        }
        name += slen;
        name += strspn (name, ",");
        if (unlikely(slen >= sizeof (buf)))
            continue;

        const char *shortcut = buf;
        assert (shortcut != NULL);

        if (!strcasecmp ("none", shortcut))
            goto done;

        obj->obj.force = strict && strcasecmp ("any", shortcut);
        for (ssize_t i = 0; i < total; i++)
        {
            module_t *cand = mods[i];
            if (cand == NULL)
                continue; // module failed in previous iteration
            if (!module_match_name (cand, shortcut))
                continue;
            mods[i] = NULL; // only try each module once at most...

            int ret = module_load (obj, cand, probe, args);
            switch (ret)
            {
                case VLC_SUCCESS:
                    module = cand;
                    /* fall through */
                case VLC_ETIMEOUT:
                    goto done;
            }
        }
    }

    /* None of the shortcuts matched, fall back to any module */
    if (!strict)
    {
        obj->obj.force = false;
        for (ssize_t i = 0; i < total; i++)
        {
            module_t *cand = mods[i];
            if (cand == NULL || module_get_score (cand) <= 0)
                continue;

            int ret = module_load (obj, cand, probe, args);
            switch (ret)
            {
                case VLC_SUCCESS:
                    module = cand;
                    /* fall through */
                case VLC_ETIMEOUT:
                    goto done;
            }
        }
    }
done:
    va_end (args);
    obj->obj.force = b_force_backup;
    module_list_free (mods);
    free (var);

    if (module != NULL)
    {
        msg_Dbg (obj, "using %s module \"%s\"", capability,
                 module_get_object (module));
        vlc_object_set_name (obj, module_get_object (module));
    }
    else
        msg_Dbg (obj, "no %s modules matched", capability);
    return module;
}

#undef vlc_module_unload
/**
 * Deinstantiates a module.
 * \param module the module pointer as returned by vlc_module_load()
 * \param deinit deactivation callback
 */
void vlc_module_unload(vlc_object_t *obj, module_t *module,
                       vlc_deactivate_t deinit, ...)
{
    if (module->pf_deactivate != NULL)
    {
        va_list ap;

        va_start(ap, deinit);
        deinit(module->pf_deactivate, ap);
        va_end(ap);
    }

    vlc_objres_clear(obj);
}


static int generic_start(void *func, va_list ap)
{
    vlc_object_t *obj = va_arg(ap, vlc_object_t *);
    int (*activate)(vlc_object_t *) = func;

    return activate(obj);
}

static void generic_stop(void *func, va_list ap)
{
    vlc_object_t *obj = va_arg(ap, vlc_object_t *);
    void (*deactivate)(vlc_object_t *) = func;

    deactivate(obj);
}

#undef module_need
module_t *module_need(vlc_object_t *obj, const char *cap, const char *name,
                      bool strict)
{
    return vlc_module_load(obj, cap, name, strict, generic_start, obj);
}

#undef module_unneed
void module_unneed(vlc_object_t *obj, module_t *module)
{
    msg_Dbg(obj, "removing module \"%s\"", module_get_object(module));
    vlc_module_unload(obj, module, generic_stop, obj);
}

/**
 * Get a pointer to a module_t given it's name.
 *
 * \param name the name of the module
 * \return a pointer to the module or NULL in case of a failure
 */
module_t *module_find (const char *name)
{
    size_t count;
    module_t **list = module_list_get (&count);

    assert (name != NULL);

    for (size_t i = 0; i < count; i++)
    {
        module_t *module = list[i];

        if (unlikely(module->i_shortcuts == 0))
            continue;
        if (!strcmp (module->pp_shortcuts[0], name))
        {
            module_list_free (list);
            return module;
        }
    }
    module_list_free (list);
    return NULL;
}

/**
 * Tell if a module exists
 *
 * \param psz_name th name of the module
 * \return TRUE if the module exists
 */
bool module_exists (const char * psz_name)
{
    return module_find (psz_name) != NULL;
}

/**
 * Get the configuration of a module
 *
 * \param module the module
 * \param psize the size of the configuration returned
 * \return the configuration as an array
 */
module_config_t *module_config_get( const module_t *module, unsigned *restrict psize )
{
    const vlc_plugin_t *plugin = module->plugin;

    if (plugin->module != module)
    {   /* For backward compatibility, pretend non-first modules have no
         * configuration items. */
        *psize = 0;
        return NULL;
    }

    unsigned i,j;
    size_t size = plugin->conf.size;
    module_config_t *config = vlc_alloc( size, sizeof( *config ) );

    assert( psize != NULL );
    *psize = 0;

    if( !config )
        return NULL;

    for( i = 0, j = 0; i < size; i++ )
    {
        const module_config_t *item = plugin->conf.items + i;
        if( item->b_internal /* internal option */
         || item->b_removed /* removed option */ )
            continue;

        memcpy( config + j, item, sizeof( *config ) );
        j++;
    }
    *psize = j;

    return config;
}

/**
 * Release the configuration
 *
 * \param the configuration
 * \return nothing
 */
void module_config_free( module_config_t *config )
{
    free( config );
}