/*
  * Copyright (c) 2011 Baptiste Coudurier
  * Copyright (c) 2011 Stefano Sabatini
  *
  * This file is part of FFmpeg.
  *
  * FFmpeg 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.
  *
  * FFmpeg 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 FFmpeg; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
 /**
  * @file
  * Libass subtitles burning filter.
  *
  * @see{http://www.matroska.org/technical/specs/subtitles/ssa.html}
  */
 
 #include <ass/ass.h>
 
 #include "libavutil/avstring.h"
 #include "libavutil/imgutils.h"

 #include "libavutil/opt.h"
 #include "libavutil/parseutils.h"

 #include "drawutils.h"
 #include "avfilter.h"
 
 typedef struct {

     const AVClass *class;

     ASS_Library  *library;
     ASS_Renderer *renderer;
     ASS_Track    *track;
     char *filename;
     uint8_t rgba_map[4];
     int     pix_step[4];       ///< steps per pixel for each plane of the main output

     int original_w, original_h;

     FFDrawContext draw;

 } AssContext;
 

 #define OFFSET(x) offsetof(AssContext, x)
 
 static const AVOption ass_options[] = {

     {"original_size",  "set the size of the original video (used to scale fonts)", OFFSET(original_w), AV_OPT_TYPE_IMAGE_SIZE, {.str = NULL},  CHAR_MIN, CHAR_MAX },

     {NULL},
 };
 
 static const char *ass_get_name(void *ctx)
 {
     return "ass";
 }
 
 static const AVClass ass_class = {
     "AssContext",
     ass_get_name,
     ass_options
 };
 

 /* libass supports a log level ranging from 0 to 7 */
 int ass_libav_log_level_map[] = {
     AV_LOG_QUIET,               /* 0 */
     AV_LOG_PANIC,               /* 1 */
     AV_LOG_FATAL,               /* 2 */
     AV_LOG_ERROR,               /* 3 */
     AV_LOG_WARNING,             /* 4 */
     AV_LOG_INFO,                /* 5 */
     AV_LOG_VERBOSE,             /* 6 */
     AV_LOG_DEBUG,               /* 7 */
 };
 
 static void ass_log(int ass_level, const char *fmt, va_list args, void *ctx)
 {
     int level = ass_libav_log_level_map[ass_level];
 
     av_vlog(ctx, level, fmt, args);
     av_log(ctx, level, "\n");
 }
 
 static av_cold int init(AVFilterContext *ctx, const char *args, void *opaque)
 {
     AssContext *ass = ctx->priv;

     int ret;
 
     ass->class = &ass_class;
     av_opt_set_defaults(ass);

 
     if (args)
         ass->filename = av_get_token(&args, ":");
     if (!ass->filename || !*ass->filename) {
         av_log(ctx, AV_LOG_ERROR, "No filename provided!\n");
         return AVERROR(EINVAL);
     }
 

     if (*args++ == ':' && (ret = av_set_options_string(ass, args, "=", ":")) < 0) {
         av_log(ctx, AV_LOG_ERROR, "Error parsing options string: '%s'\n", args);
         return ret;
     }
 

     ass->library = ass_library_init();
     if (!ass->library) {
         av_log(ctx, AV_LOG_ERROR, "Could not initialize libass.\n");
         return AVERROR(EINVAL);
     }
     ass_set_message_cb(ass->library, ass_log, ctx);
 
     ass->renderer = ass_renderer_init(ass->library);
     if (!ass->renderer) {
         av_log(ctx, AV_LOG_ERROR, "Could not initialize libass renderer.\n");
         return AVERROR(EINVAL);
     }
 
     ass->track = ass_read_file(ass->library, ass->filename, NULL);
     if (!ass->track) {
         av_log(ctx, AV_LOG_ERROR,
                "Could not create a libass track when reading file '%s'\n",
                ass->filename);
         return AVERROR(EINVAL);
     }
 
     ass_set_fonts(ass->renderer, NULL, NULL, 1, NULL, 1);
     return 0;
 }
 
 static av_cold void uninit(AVFilterContext *ctx)
 {
     AssContext *ass = ctx->priv;
 
     av_freep(&ass->filename);
     if (ass->track)
         ass_free_track(ass->track);
     if (ass->renderer)
         ass_renderer_done(ass->renderer);
     if (ass->library)
         ass_library_done(ass->library);
 }
 
 static int query_formats(AVFilterContext *ctx)
 {

     avfilter_set_common_pixel_formats(ctx, ff_draw_supported_pixel_formats(0));

     return 0;
 }
 
 static int config_input(AVFilterLink *inlink)
 {
     AssContext *ass = inlink->dst->priv;
 

     ff_draw_init(&ass->draw, inlink->format, 0);

 
     ass_set_frame_size  (ass->renderer, inlink->w, inlink->h);

     if (ass->original_w && ass->original_h)
         ass_set_aspect_ratio(ass->renderer, (double)inlink->w / inlink->h,
                              (double)ass->original_w / ass->original_h);

 
     return 0;
 }
 
 static void null_draw_slice(AVFilterLink *link, int y, int h, int slice_dir) { }
 
 /* libass stores an RGBA color in the format RRGGBBTT, where TT is the transparency level */
 #define AR(c)  ( (c)>>24)
 #define AG(c)  (((c)>>16)&0xFF)
 #define AB(c)  (((c)>>8) &0xFF)
 #define AA(c)  ((0xFF-c) &0xFF)
 

 static void overlay_ass_image(AssContext *ass, AVFilterBufferRef *picref,

                               const ASS_Image *image)
 {
     for (; image; image = image->next) {
         uint8_t rgba_color[] = {AR(image->color), AG(image->color), AB(image->color), AA(image->color)};

         FFDrawColor color;
         ff_draw_color(&ass->draw, &color, rgba_color);
         ff_blend_mask(&ass->draw, &color,
                       picref->data, picref->linesize,
                       picref->video->w, picref->video->h,
                       image->bitmap, image->stride, image->w, image->h,
                       3, 0, image->dst_x, image->dst_y);

     }
 }
 
 static void end_frame(AVFilterLink *inlink)
 {
     AVFilterContext *ctx = inlink->dst;
     AVFilterLink *outlink = ctx->outputs[0];
     AssContext *ass = ctx->priv;
     AVFilterBufferRef *picref = inlink->cur_buf;
     int detect_change = 0;
     double time_ms = picref->pts * av_q2d(inlink->time_base) * 1000;
     ASS_Image *image = ass_render_frame(ass->renderer, ass->track,
                                         time_ms, &detect_change);
 
     if (detect_change)
         av_log(ctx, AV_LOG_DEBUG, "Change happened at time ms:%f\n", time_ms);
 

     overlay_ass_image(ass, picref, image);

 
     avfilter_draw_slice(outlink, 0, picref->video->h, 1);
     avfilter_end_frame(outlink);
 }
 
 AVFilter avfilter_vf_ass = {
     .name          = "ass",
     .description   = NULL_IF_CONFIG_SMALL("Render subtitles onto input video using the libass library."),
     .priv_size     = sizeof(AssContext),
     .init          = init,
     .uninit        = uninit,
     .query_formats = query_formats,
 
     .inputs = (const AVFilterPad[]) {
         { .name             = "default",
           .type             = AVMEDIA_TYPE_VIDEO,
           .get_video_buffer = avfilter_null_get_video_buffer,
           .start_frame      = avfilter_null_start_frame,
           .draw_slice       = null_draw_slice,
           .end_frame        = end_frame,
           .config_props     = config_input,
           .min_perms        = AV_PERM_WRITE | AV_PERM_READ,
           .rej_perms        = AV_PERM_PRESERVE },
         { .name = NULL}
     },
     .outputs = (const AVFilterPad[]) {
         { .name             = "default",
           .type             = AVMEDIA_TYPE_VIDEO, },
         { .name = NULL}
     },
 };