/*****************************************************************************

 * webvtt.c: WEBVTT shared code

 *****************************************************************************

 * Copyright (C) 2017 VideoLabs, VLC authors and VideoLAN

 *

 * 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 <vlc_common.h>

#include <vlc_charset.h>

#include <vlc_plugin.h>

#include "webvtt.h"

#include <ctype.h>

#include <assert.h>

/*****************************************************************************

 * Modules descriptor.

 *****************************************************************************/

vlc_module_begin ()

    set_capability( "spu decoder", 10 )

    set_shortname( N_("WEBVTT decoder"))

    set_description( N_("WEBVTT subtitles decoder") )

    set_callbacks( webvtt_OpenDecoder, webvtt_CloseDecoder )

    set_subcategory( SUBCAT_INPUT_SCODEC )

    add_submodule()

        set_shortname( "WEBVTT" )

        set_description( N_("WEBVTT subtitles parser") )

        set_capability( "demux", 11 )

        set_subcategory( SUBCAT_INPUT_DEMUX )

        set_callbacks( webvtt_OpenDemux, webvtt_CloseDemux )

        add_shortcut( "webvtt" )

    add_submodule()

        set_shortname( "WEBVTT" )

        set_description( N_("WEBVTT subtitles parser") )

        set_capability( "demux", 0 )

        set_subcategory( SUBCAT_INPUT_DEMUX )

        set_callbacks( webvtt_OpenDemuxStream, webvtt_CloseDemux )

        add_shortcut( "webvttstream" )

#ifdef ENABLE_SOUT

    add_submodule()

        set_description( "WEBVTT text encoder" )

        set_capability( "spu encoder", 101 )

        set_subcategory( SUBCAT_INPUT_SCODEC )

        set_callback( webvtt_OpenEncoder )

    add_submodule()

        set_description( N_("Raw WebVTT muxer") )

        set_capability( "sout mux", 0 )

        set_subcategory( SUBCAT_SOUT_MUX )

        add_shortcut( "webvtt", "rawvtt" )

        set_callbacks( webvtt_OpenMuxer, webvtt_CloseMuxer )

#endif

vlc_module_end ()

struct webvtt_text_parser_t

{

    enum

    {

        WEBVTT_SECTION_UNDEFINED = WEBVTT_HEADER_STYLE - 1,

        WEBVTT_SECTION_STYLE = WEBVTT_HEADER_STYLE,

        WEBVTT_SECTION_REGION = WEBVTT_HEADER_REGION,

        WEBVTT_SECTION_NOTE,

        WEBVTT_SECTION_CUES,

    } section;

    char * reads[3];

    void * priv;

    webvtt_cue_t *(*pf_get_cue)( void * );

    void (*pf_cue_done)( void *, webvtt_cue_t * );

    void (*pf_header)( void *, enum webvtt_header_line_e, bool, const char * );

    webvtt_cue_t *p_cue;

};

static vlc_tick_t MakeTime( unsigned t[4] )

{

    return vlc_tick_from_sec( t[0] * 3600 + t[1] * 60 + t[2] ) +

           VLC_TICK_FROM_MS(t[3]);

}

bool webvtt_scan_time( const char *psz, vlc_tick_t *p_time )

{

    unsigned t[4];

    if( sscanf( psz, "%2u:%2u.%3u",

                      &t[1], &t[2], &t[3] ) == 3 )

    {

        t[0] = 0;

        *p_time = MakeTime( t );

        return true;

    }

    else if( sscanf( psz, "%u:%2u:%2u.%3u",

                          &t[0], &t[1], &t[2], &t[3] ) == 4 )

    {

        *p_time = MakeTime( t );

        return true;

    }

    else return false;

}

static bool KeywordMatch( const char *psz, const char *keyword )

{

    const size_t i_len = strlen(keyword);

    return( !strncmp( keyword, psz, i_len ) && (!psz[i_len] || isspace(psz[i_len])) );

}

/*

*/

webvtt_text_parser_t * webvtt_text_parser_New( void *priv,

                    webvtt_cue_t *(*pf_get_cue)( void * ),

                    void (*pf_cue_done)( void *, webvtt_cue_t * ),

                    void (*pf_header)( void *, enum webvtt_header_line_e, bool, const char * ) )

{

    webvtt_text_parser_t *p = malloc(sizeof(*p));

    if( p )

    {

        p->section = WEBVTT_SECTION_UNDEFINED;

        for( int i=0; i<3; i++ )

            p->reads[i] = NULL;

        p->p_cue = NULL;

        p->priv = priv;

        p->pf_cue_done = pf_cue_done;

        p->pf_get_cue = pf_get_cue;

        p->pf_header = pf_header;

    }

    return p;

}

void webvtt_text_parser_Delete( webvtt_text_parser_t *p )

{

    for( int i=0; i<3; i++ )

        free( p->reads[i] );

    free( p );

}

static void forward_line( webvtt_text_parser_t *p, const char *psz_line, bool b_new )

{

    if( p->pf_header )

        p->pf_header( p->priv, (enum webvtt_header_line_e)p->section,

                      b_new, psz_line );

}

void webvtt_text_parser_Feed( webvtt_text_parser_t *p, char *psz_line )

{

    if( psz_line == NULL )

    {

        if( p->p_cue )

        {

            if( p->pf_cue_done )

                p->pf_cue_done( p->priv, p->p_cue );

            p->p_cue = NULL;

        }

        return;

    }

    free(p->reads[0]);

    p->reads[0] = p->reads[1];

    p->reads[1] = p->reads[2];

    p->reads[2] = psz_line;

    /* Lookup keywords */

    if( unlikely(p->section == WEBVTT_SECTION_UNDEFINED) )

    {

        if( KeywordMatch( psz_line, "\xEF\xBB\xBFWEBVTT" ) ||

            KeywordMatch( psz_line, "WEBVTT" )  )

        {

            p->section = WEBVTT_SECTION_UNDEFINED;

            if( p->p_cue )

            {

                if( p->pf_cue_done )

                    p->pf_cue_done( p->priv, p->p_cue );

                p->p_cue = NULL;

            }

            return;

        }

        else if( KeywordMatch( psz_line, "STYLE" ) )

        {

            p->section = WEBVTT_SECTION_STYLE;

            forward_line( p, psz_line, true );

            return;

        }

        else if( KeywordMatch( psz_line, "REGION" ) )

        {

            p->section = WEBVTT_SECTION_REGION;

            forward_line( p, psz_line, true );

            return;

        }

        else if( KeywordMatch( psz_line, "NOTE" ) )

        {

            p->section = WEBVTT_SECTION_NOTE;

            return;

        }

        else if( psz_line[0] != 0 )

        {

            p->section = WEBVTT_SECTION_CUES;

        }

    }

    if( likely(p->section == WEBVTT_SECTION_CUES) )

    {

        if( p->p_cue )

        {

            if( psz_line[0] == 0 )

            {

                if( p->p_cue )

                {

                    if( p->pf_cue_done )

                        p->pf_cue_done( p->priv, p->p_cue );

                    p->p_cue = NULL;

                }

            }

            else

            {

                char *psz_merged;

                if( -1 < asprintf( &psz_merged, "%s\n%s", p->p_cue->psz_text, psz_line ) )

                {

                    free( p->p_cue->psz_text );

                    p->p_cue->psz_text = psz_merged;

                }

                return;

            }

        }

        if( p->reads[1] == NULL )

            return;

        const char *psz_split = strstr( p->reads[1], " --> " );

        if( psz_split )

        {

            vlc_tick_t i_start, i_stop;

            if( webvtt_scan_time( p->reads[1], &i_start ) &&

                webvtt_scan_time( psz_split + 5,  &i_stop ) && i_start <= i_stop )

            {

                const char *psz_attrs = strchr( psz_split + 5 + 5, ' ' );

                p->p_cue = ( p->pf_get_cue ) ? p->pf_get_cue( p->priv ) : NULL;

                if( p->p_cue )

                {

                    p->p_cue->psz_attrs = ( psz_attrs ) ? strdup( psz_attrs ) : NULL;

                    p->p_cue->psz_id = p->reads[0];

                    p->reads[0] = NULL;

                    p->p_cue->psz_text = p->reads[2];

                    p->reads[2] = NULL;

                    p->p_cue->i_start = i_start;

                    p->p_cue->i_stop = i_stop;

                }

            }

        }

    }

    else if( p->section == WEBVTT_SECTION_STYLE )

    {

        forward_line( p, psz_line, false );

        if( psz_line[0] == 0 )

            p->section = WEBVTT_SECTION_UNDEFINED;

    }

    else if( p->section == WEBVTT_SECTION_REGION )

    {

        forward_line( p, psz_line, false );

        if( psz_line[0] == 0 ) /* End of region declaration */

            p->section = WEBVTT_SECTION_UNDEFINED;

    }

    else if( p->section == WEBVTT_SECTION_NOTE )

    {

        if( psz_line[0] == 0 )

            p->section = WEBVTT_SECTION_UNDEFINED;

    }

}