/*
  * PGS subtitle decoder
  * Copyright (c) 2009 Stephen Backway
  *
  * 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

  * PGS subtitle decoder
  */
 
 #include "avcodec.h"
 #include "bytestream.h"

 #include "internal.h"

 #include "mathops.h"

 #include "libavutil/colorspace.h"

 #include "libavutil/imgutils.h"

 #include "libavutil/opt.h"

 #define RGBA(r,g,b,a) (((unsigned)(a) << 24) | ((r) << 16) | ((g) << 8) | (b))

 #define MAX_EPOCH_PALETTES 8   // Max 8 allowed per PGS epoch
 #define MAX_EPOCH_OBJECTS  64  // Max 64 allowed per PGS epoch
 #define MAX_OBJECT_REFS    2   // Max objects per display set

 
 enum SegmentType {
     PALETTE_SEGMENT      = 0x14,

     OBJECT_SEGMENT       = 0x15,

     PRESENTATION_SEGMENT = 0x16,
     WINDOW_SEGMENT       = 0x17,
     DISPLAY_SEGMENT      = 0x80,
 };
 

 typedef struct PGSSubObjectRef {
     int     id;
     int     window_id;
     uint8_t composition_flag;
     int     x;
     int     y;
     int     crop_x;
     int     crop_y;
     int     crop_w;
     int     crop_h;
 } PGSSubObjectRef;

 
 typedef struct PGSSubPresentation {

     int id_number;

     int palette_id;
     int object_count;
     PGSSubObjectRef objects[MAX_OBJECT_REFS];

     int64_t pts;

 } PGSSubPresentation;
 

 typedef struct PGSSubObject {
     int          id;

     int          w;
     int          h;
     uint8_t      *rle;
     unsigned int rle_buffer_size, rle_data_len;

     unsigned int rle_remaining_len;

 } PGSSubObject;
 
 typedef struct PGSSubObjects {
     int          count;
     PGSSubObject object[MAX_EPOCH_OBJECTS];
 } PGSSubObjects;
 
 typedef struct PGSSubPalette {
     int         id;
     uint32_t    clut[256];
 } PGSSubPalette;
 
 typedef struct PGSSubPalettes {
     int           count;
     PGSSubPalette palette[MAX_EPOCH_PALETTES];
 } PGSSubPalettes;

 
 typedef struct PGSSubContext {

     AVClass *class;

     PGSSubPresentation presentation;

     PGSSubPalettes     palettes;
     PGSSubObjects      objects;

     int forced_subs_only;

 } PGSSubContext;
 

 static void flush_cache(AVCodecContext *avctx)

 {
     PGSSubContext *ctx = avctx->priv_data;

     int i;

     for (i = 0; i < ctx->objects.count; i++) {
         av_freep(&ctx->objects.object[i].rle);
         ctx->objects.object[i].rle_buffer_size  = 0;
         ctx->objects.object[i].rle_remaining_len  = 0;
     }
     ctx->objects.count = 0;
     ctx->palettes.count = 0;
 }

 static PGSSubObject * find_object(int id, PGSSubObjects *objects)
 {
     int i;
 
     for (i = 0; i < objects->count; i++) {
         if (objects->object[i].id == id)
             return &objects->object[i];

     }

     return NULL;
 }
 
 static PGSSubPalette * find_palette(int id, PGSSubPalettes *palettes)
 {
     int i;
 
     for (i = 0; i < palettes->count; i++) {
         if (palettes->palette[i].id == id)
             return &palettes->palette[i];
     }
     return NULL;

 }
 
 static av_cold int init_decoder(AVCodecContext *avctx)
 {
     avctx->pix_fmt     = AV_PIX_FMT_PAL8;
 
     return 0;
 }
 
 static av_cold int close_decoder(AVCodecContext *avctx)
 {
     flush_cache(avctx);

 
     return 0;
 }
 
 /**

  * Decode the RLE data.

  *

  * The subtitle is stored as a Run Length Encoded image.

  *
  * @param avctx contains the current codec context
  * @param sub pointer to the processed subtitle data
  * @param buf pointer to the RLE data to process
  * @param buf_size size of the RLE data to process
  */

 static int decode_rle(AVCodecContext *avctx, AVSubtitleRect *rect,

                       const uint8_t *buf, unsigned int buf_size)
 {
     const uint8_t *rle_bitmap_end;
     int pixel_count, line_count;
 
     rle_bitmap_end = buf + buf_size;
 

     rect->data[0] = av_malloc_array(rect->w, rect->h);

     if (!rect->data[0])

         return AVERROR(ENOMEM);

 
     pixel_count = 0;
     line_count  = 0;
 

     while (buf < rle_bitmap_end && line_count < rect->h) {

         uint8_t flags, color;
         int run;
 
         color = bytestream_get_byte(&buf);
         run   = 1;
 
         if (color == 0x00) {
             flags = bytestream_get_byte(&buf);
             run   = flags & 0x3f;
             if (flags & 0x40)
                 run = (run << 8) + bytestream_get_byte(&buf);
             color = flags & 0x80 ? bytestream_get_byte(&buf) : 0;
         }
 

         if (run > 0 && pixel_count + run <= rect->w * rect->h) {

             memset(rect->data[0] + pixel_count, color, run);

             pixel_count += run;
         } else if (!run) {
             /*
              * New Line. Check if correct pixels decoded, if not display warning
              * and adjust bitmap pointer to correct new line position.
              */

             if (pixel_count % rect->w > 0) {

                 av_log(avctx, AV_LOG_ERROR, "Decoded %d pixels, when line should be %d pixels\n",

                        pixel_count % rect->w, rect->w);

                 if (avctx->err_recognition & AV_EF_EXPLODE) {
                     return AVERROR_INVALIDDATA;
                 }
             }

             line_count++;
         }
     }
 

     if (pixel_count < rect->w * rect->h) {

         av_log(avctx, AV_LOG_ERROR, "Insufficient RLE data for subtitle\n");

         return AVERROR_INVALIDDATA;

     }
 

     ff_dlog(avctx, "Pixel Count = %d, Area = %d\n", pixel_count, rect->w * rect->h);

 
     return 0;
 }
 
 /**

  * Parse the picture segment packet.

  *
  * The picture segment contains details on the sequence id,
  * width, height and Run Length Encoded (RLE) bitmap data.
  *
  * @param avctx contains the current codec context
  * @param buf pointer to the packet to process
  * @param buf_size size of packet to process
  */

 static int parse_object_segment(AVCodecContext *avctx,

                                   const uint8_t *buf, int buf_size)
 {
     PGSSubContext *ctx = avctx->priv_data;

     PGSSubObject *object;

 
     uint8_t sequence_desc;
     unsigned int rle_bitmap_len, width, height;

     int id;

     if (buf_size <= 4)

         return AVERROR_INVALIDDATA;

     buf_size -= 4;
 

     id = bytestream_get_be16(&buf);
     object = find_object(id, &ctx->objects);
     if (!object) {
         if (ctx->objects.count >= MAX_EPOCH_OBJECTS) {
             av_log(avctx, AV_LOG_ERROR, "Too many objects in epoch\n");
             return AVERROR_INVALIDDATA;
         }
         object = &ctx->objects.object[ctx->objects.count++];
         object->id = id;
     }

     /* skip object version number */
     buf += 1;

 
     /* Read the Sequence Description to determine if start of RLE data or appended to previous RLE */
     sequence_desc = bytestream_get_byte(&buf);
 
     if (!(sequence_desc & 0x80)) {

         /* Additional RLE data */

         if (buf_size > object->rle_remaining_len)

             return AVERROR_INVALIDDATA;

         memcpy(object->rle + object->rle_data_len, buf, buf_size);
         object->rle_data_len += buf_size;
         object->rle_remaining_len -= buf_size;

         return 0;

     }
 

     if (buf_size <= 7)

         return AVERROR_INVALIDDATA;

     buf_size -= 7;
 
     /* Decode rle bitmap length, stored size includes width/height data */
     rle_bitmap_len = bytestream_get_be24(&buf) - 2*2;

     if (buf_size > rle_bitmap_len) {
         av_log(avctx, AV_LOG_ERROR,
                "Buffer dimension %d larger than the expected RLE data %d\n",
                buf_size, rle_bitmap_len);
         return AVERROR_INVALIDDATA;
     }
 

     /* Get bitmap dimensions from data */
     width  = bytestream_get_be16(&buf);
     height = bytestream_get_be16(&buf);
 
     /* Make sure the bitmap is not too large */

     if (avctx->width < width || avctx->height < height || !width || !height) {
         av_log(avctx, AV_LOG_ERROR, "Bitmap dimensions (%dx%d) invalid.\n", width, height);

         return AVERROR_INVALIDDATA;

     }
 

     object->w = width;
     object->h = height;

     av_fast_padded_malloc(&object->rle, &object->rle_buffer_size, rle_bitmap_len);

     if (!object->rle) {
         object->rle_data_len = 0;
         object->rle_remaining_len = 0;

         return AVERROR(ENOMEM);

     }

     memcpy(object->rle, buf, buf_size);
     object->rle_data_len = buf_size;
     object->rle_remaining_len = rle_bitmap_len - buf_size;

 
     return 0;
 }
 
 /**

  * Parse the palette segment packet.

  *
  * The palette segment contains details of the palette,
  * a maximum of 256 colors can be defined.
  *
  * @param avctx contains the current codec context
  * @param buf pointer to the packet to process
  * @param buf_size size of packet to process
  */

 static int parse_palette_segment(AVCodecContext *avctx,

                                   const uint8_t *buf, int buf_size)
 {
     PGSSubContext *ctx = avctx->priv_data;

     PGSSubPalette *palette;

 
     const uint8_t *buf_end = buf + buf_size;

     const uint8_t *cm      = ff_crop_tab + MAX_NEG_CROP;

     int color_id;
     int y, cb, cr, alpha;
     int r, g, b, r_add, g_add, b_add;

     int id;
 
     id  = bytestream_get_byte(&buf);
     palette = find_palette(id, &ctx->palettes);
     if (!palette) {
         if (ctx->palettes.count >= MAX_EPOCH_PALETTES) {
             av_log(avctx, AV_LOG_ERROR, "Too many palettes in epoch\n");
             return AVERROR_INVALIDDATA;
         }
         palette = &ctx->palettes.palette[ctx->palettes.count++];
         palette->id  = id;
     }

     /* Skip palette version */
     buf += 1;

 
     while (buf < buf_end) {
         color_id  = bytestream_get_byte(&buf);
         y         = bytestream_get_byte(&buf);
         cr        = bytestream_get_byte(&buf);

         cb        = bytestream_get_byte(&buf);

         alpha     = bytestream_get_byte(&buf);
 

         /* Default to BT.709 colorspace. In case of <= 576 height use BT.601 */

         if (avctx->height <= 0 || avctx->height > 576) {
             YUV_TO_RGB1_CCIR_BT709(cb, cr);
         } else {
             YUV_TO_RGB1_CCIR(cb, cr);
         }
 
         YUV_TO_RGB2_CCIR(r, g, b, y);

         ff_dlog(avctx, "Color %d := (%d,%d,%d,%d)\n", color_id, r, g, b, alpha);

 
         /* Store color in palette */

         palette->clut[color_id] = RGBA(r,g,b,alpha);

     }

     return 0;

 }
 
 /**

  * Parse the presentation segment packet.

  *
  * The presentation segment contains details on the video
  * width, video height, x & y subtitle position.
  *
  * @param avctx contains the current codec context
  * @param buf pointer to the packet to process
  * @param buf_size size of packet to process
  * @todo TODO: Implement cropping
  */

 static int parse_presentation_segment(AVCodecContext *avctx,
                                       const uint8_t *buf, int buf_size,
                                       int64_t pts)

 {
     PGSSubContext *ctx = avctx->priv_data;

     int i, state, ret;

     const uint8_t *buf_end = buf + buf_size;

     // Video descriptor

     int w = bytestream_get_be16(&buf);
     int h = bytestream_get_be16(&buf);

     ctx->presentation.pts = pts;
 

     ff_dlog(avctx, "Video Dimensions %dx%d\n",

             w, h);

     ret = ff_set_dimensions(avctx, w, h);
     if (ret < 0)
         return ret;

     /* Skip 1 bytes of unknown, frame rate */

     buf++;
 

     // Composition descriptor

     ctx->presentation.id_number = bytestream_get_be16(&buf);

     /*

      * state is a 2 bit field that defines pgs epoch boundaries
      * 00 - Normal, previously defined objects and palettes are still valid
      * 01 - Acquisition point, previous objects and palettes can be released
      * 10 - Epoch start, previous objects and palettes can be released
      * 11 - Epoch continue, previous objects and palettes can be released
      *
      * reserved 6 bits discarded

      */

     state = bytestream_get_byte(&buf) >> 6;
     if (state != 0) {
         flush_cache(avctx);
     }

 
     /*

      * skip palette_update_flag (0x80),

      */

     buf += 1;
     ctx->presentation.palette_id = bytestream_get_byte(&buf);

     ctx->presentation.object_count = bytestream_get_byte(&buf);

     if (ctx->presentation.object_count > MAX_OBJECT_REFS) {
         av_log(avctx, AV_LOG_ERROR,
                "Invalid number of presentation objects %d\n",
                ctx->presentation.object_count);
         ctx->presentation.object_count = 2;
         if (avctx->err_recognition & AV_EF_EXPLODE) {
             return AVERROR_INVALIDDATA;
         }

     }

     for (i = 0; i < ctx->presentation.object_count; i++)
     {

 
         if (buf_end - buf < 8) {
             av_log(avctx, AV_LOG_ERROR, "Insufficent space for object\n");
             ctx->presentation.object_count = i;
             return AVERROR_INVALIDDATA;
         }
 

         ctx->presentation.objects[i].id = bytestream_get_be16(&buf);
         ctx->presentation.objects[i].window_id = bytestream_get_byte(&buf);
         ctx->presentation.objects[i].composition_flag = bytestream_get_byte(&buf);

         ctx->presentation.objects[i].x = bytestream_get_be16(&buf);
         ctx->presentation.objects[i].y = bytestream_get_be16(&buf);

         // If cropping
         if (ctx->presentation.objects[i].composition_flag & 0x80) {
             ctx->presentation.objects[i].crop_x = bytestream_get_be16(&buf);
             ctx->presentation.objects[i].crop_y = bytestream_get_be16(&buf);
             ctx->presentation.objects[i].crop_w = bytestream_get_be16(&buf);
             ctx->presentation.objects[i].crop_h = bytestream_get_be16(&buf);
         }

         ff_dlog(avctx, "Subtitle Placement x=%d, y=%d\n",

                 ctx->presentation.objects[i].x, ctx->presentation.objects[i].y);

         if (ctx->presentation.objects[i].x > avctx->width ||
             ctx->presentation.objects[i].y > avctx->height) {

             av_log(avctx, AV_LOG_ERROR, "Subtitle out of video bounds. x = %d, y = %d, video width = %d, video height = %d.\n",

                    ctx->presentation.objects[i].x,
                    ctx->presentation.objects[i].y,
                     avctx->width, avctx->height);
             ctx->presentation.objects[i].x = 0;
             ctx->presentation.objects[i].y = 0;
             if (avctx->err_recognition & AV_EF_EXPLODE) {
                 return AVERROR_INVALIDDATA;
             }

         }
     }

 
     return 0;

 }
 
 /**

  * Parse the display segment packet.

  *
  * The display segment controls the updating of the display.
  *
  * @param avctx contains the current codec context
  * @param data pointer to the data pertaining the subtitle to display
  * @param buf pointer to the packet to process
  * @param buf_size size of packet to process
  */
 static int display_end_segment(AVCodecContext *avctx, void *data,
                                const uint8_t *buf, int buf_size)
 {
     AVSubtitle    *sub = data;
     PGSSubContext *ctx = avctx->priv_data;

     int64_t pts;

     PGSSubPalette *palette;
     int i, ret;

     pts = ctx->presentation.pts != AV_NOPTS_VALUE ? ctx->presentation.pts : sub->pts;

     memset(sub, 0, sizeof(*sub));

     sub->pts = pts;

     ctx->presentation.pts = AV_NOPTS_VALUE;

     sub->start_display_time = 0;

     // There is no explicit end time for PGS subtitles.  The end time
     // is defined by the start of the next sub which may contain no
     // objects (i.e. clears the previous sub)
     sub->end_display_time   = UINT32_MAX;

     sub->format             = 0;
 

     // Blank if last object_count was 0.
     if (!ctx->presentation.object_count)
         return 1;

     sub->rects = av_mallocz_array(ctx->presentation.object_count, sizeof(*sub->rects));

     if (!sub->rects) {
         return AVERROR(ENOMEM);
     }
     palette = find_palette(ctx->presentation.palette_id, &ctx->palettes);
     if (!palette) {
         // Missing palette.  Should only happen with damaged streams.
         av_log(avctx, AV_LOG_ERROR, "Invalid palette id %d\n",
                ctx->presentation.palette_id);
         avsubtitle_free(sub);
         return AVERROR_INVALIDDATA;
     }
     for (i = 0; i < ctx->presentation.object_count; i++) {
         PGSSubObject *object;

         sub->rects[i]  = av_mallocz(sizeof(*sub->rects[0]));
         if (!sub->rects[i]) {
             avsubtitle_free(sub);
             return AVERROR(ENOMEM);
         }
         sub->num_rects++;
         sub->rects[i]->type = SUBTITLE_BITMAP;

 
         /* Process bitmap */

         object = find_object(ctx->presentation.objects[i].id, &ctx->objects);
         if (!object) {
             // Missing object.  Should only happen with damaged streams.
             av_log(avctx, AV_LOG_ERROR, "Invalid object id %d\n",
                    ctx->presentation.objects[i].id);
             if (avctx->err_recognition & AV_EF_EXPLODE) {
                 avsubtitle_free(sub);
                 return AVERROR_INVALIDDATA;
             }
             // Leaves rect empty with 0 width and height.
             continue;

         }

         if (ctx->presentation.objects[i].composition_flag & 0x40)
             sub->rects[i]->flags |= AV_SUBTITLE_FLAG_FORCED;

         sub->rects[i]->x    = ctx->presentation.objects[i].x;
         sub->rects[i]->y    = ctx->presentation.objects[i].y;
 
         if (object->rle) {

             sub->rects[i]->w    = object->w;
             sub->rects[i]->h    = object->h;
 
             sub->rects[i]->linesize[0] = object->w;
 

             if (object->rle_remaining_len) {
                 av_log(avctx, AV_LOG_ERROR, "RLE data length %u is %u bytes shorter than expected\n",
                        object->rle_data_len, object->rle_remaining_len);
                 if (avctx->err_recognition & AV_EF_EXPLODE) {
                     avsubtitle_free(sub);
                     return AVERROR_INVALIDDATA;
                 }
             }
             ret = decode_rle(avctx, sub->rects[i], object->rle, object->rle_data_len);
             if (ret < 0) {
                 if ((avctx->err_recognition & AV_EF_EXPLODE) ||
                     ret == AVERROR(ENOMEM)) {
                     avsubtitle_free(sub);
                     return ret;
                 }
                 sub->rects[i]->w = 0;
                 sub->rects[i]->h = 0;
                 continue;
             }
         }

         /* Allocate memory for colors */

         sub->rects[i]->nb_colors    = 256;

         sub->rects[i]->data[1] = av_mallocz(AVPALETTE_SIZE);
         if (!sub->rects[i]->data[1]) {

             avsubtitle_free(sub);
             return AVERROR(ENOMEM);
         }

         if (!ctx->forced_subs_only || ctx->presentation.objects[i].composition_flag & 0x40)

         memcpy(sub->rects[i]->data[1], palette->clut, sub->rects[i]->nb_colors * sizeof(uint32_t));

 #if FF_API_AVPICTURE
 FF_DISABLE_DEPRECATION_WARNINGS

 {
         AVSubtitleRect *rect;
         int j;

         rect = sub->rects[i];
         for (j = 0; j < 4; j++) {
             rect->pict.data[j] = rect->data[j];
             rect->pict.linesize[j] = rect->linesize[j];
         }

 }

 FF_ENABLE_DEPRECATION_WARNINGS
 #endif

     }

     return 1;
 }
 
 static int decode(AVCodecContext *avctx, void *data, int *data_size,
                   AVPacket *avpkt)
 {
     const uint8_t *buf = avpkt->data;
     int buf_size       = avpkt->size;
 
     const uint8_t *buf_end;
     uint8_t       segment_type;
     int           segment_length;

     int i, ret;

     ff_dlog(avctx, "PGS sub packet:\n");

 
     for (i = 0; i < buf_size; i++) {

         ff_dlog(avctx, "%02x ", buf[i]);

         if (i % 16 == 15)

             ff_dlog(avctx, "\n");

     }
 
     if (i & 15)

         ff_dlog(avctx, "\n");

 
     *data_size = 0;
 
     /* Ensure that we have received at a least a segment code and segment length */
     if (buf_size < 3)
         return -1;
 
     buf_end = buf + buf_size;
 
     /* Step through buffer to identify segments */
     while (buf < buf_end) {
         segment_type   = bytestream_get_byte(&buf);
         segment_length = bytestream_get_be16(&buf);
 

         ff_dlog(avctx, "Segment Length %d, Segment Type %x\n", segment_length, segment_type);

 
         if (segment_type != DISPLAY_SEGMENT && segment_length > buf_end - buf)
             break;
 

         ret = 0;

         switch (segment_type) {
         case PALETTE_SEGMENT:

             ret = parse_palette_segment(avctx, buf, segment_length);

             break;

         case OBJECT_SEGMENT:

             ret = parse_object_segment(avctx, buf, segment_length);

             break;
         case PRESENTATION_SEGMENT:

             ret = parse_presentation_segment(avctx, buf, segment_length, ((AVSubtitle*)(data))->pts);

             break;
         case WINDOW_SEGMENT:
             /*
              * Window Segment Structure (No new information provided):

              *     2 bytes: Unknown,

              *     2 bytes: X position of subtitle,
              *     2 bytes: Y position of subtitle,
              *     2 bytes: Width of subtitle,
              *     2 bytes: Height of subtitle.
              */
             break;
         case DISPLAY_SEGMENT:

             ret = display_end_segment(avctx, data, buf, segment_length);
             if (ret >= 0)
                 *data_size = ret;

             break;
         default:
             av_log(avctx, AV_LOG_ERROR, "Unknown subtitle segment type 0x%x, length %d\n",
                    segment_type, segment_length);

             ret = AVERROR_INVALIDDATA;

             break;
         }

         if (ret < 0 && (avctx->err_recognition & AV_EF_EXPLODE))
             return ret;

 
         buf += segment_length;
     }
 
     return buf_size;
 }
 

 #define OFFSET(x) offsetof(PGSSubContext, x)
 #define SD AV_OPT_FLAG_SUBTITLE_PARAM | AV_OPT_FLAG_DECODING_PARAM
 static const AVOption options[] = {

     {"forced_subs_only", "Only show forced subtitles", OFFSET(forced_subs_only), AV_OPT_TYPE_BOOL, {.i64 = 0}, 0, 1, SD},

     { NULL },
 };
 
 static const AVClass pgsdec_class = {
     .class_name = "PGS subtitle decoder",
     .item_name  = av_default_item_name,
     .option     = options,
     .version    = LIBAVUTIL_VERSION_INT,
 };
 

 AVCodec ff_pgssub_decoder = {

     .name           = "pgssub",

     .long_name      = NULL_IF_CONFIG_SMALL("HDMV Presentation Graphic Stream subtitles"),

     .type           = AVMEDIA_TYPE_SUBTITLE,

     .id             = AV_CODEC_ID_HDMV_PGS_SUBTITLE,

     .priv_data_size = sizeof(PGSSubContext),
     .init           = init_decoder,
     .close          = close_decoder,
     .decode         = decode,

     .priv_class     = &pgsdec_class,

 };