/*
  * Gryphon's Anim Compressor decoder
  * Copyright (c) 2019 Paul B Mahol
  *
  * 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
  */
 
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 
 #include "libavutil/imgutils.h"
 #include "libavutil/internal.h"
 #include "libavutil/intreadwrite.h"
 #include "libavutil/mem.h"
 
 #include "avcodec.h"
 #include "bytestream.h"
 #include "internal.h"
 
 typedef struct ARBCContext {
     GetByteContext gb;
 
     AVFrame *prev_frame;
 } ARBCContext;
 

 static int fill_tile4(AVCodecContext *avctx, int color, AVFrame *frame)

 {
     ARBCContext *s = avctx->priv_data;
     GetByteContext *gb = &s->gb;
     int nb_tiles = bytestream2_get_le16(gb);
     int h = avctx->height - 1;

     int pixels_overwritten = 0;

     if ((avctx->width / 4 + 1) * (avctx->height / 4 + 1) < nb_tiles)

         return 0;

     for (int i = 0; i < nb_tiles; i++) {
         int y = bytestream2_get_byte(gb);
         int x = bytestream2_get_byte(gb);
         uint16_t mask = bytestream2_get_le16(gb);
         int start_y = y * 4, start_x = x * 4;
         int end_y = start_y + 4, end_x = start_x + 4;
 
         for (int j = start_y; j < end_y; j++) {
             for (int k = start_x; k < end_x; k++) {
                 if (mask & 0x8000) {
                     if (j >= avctx->height || k >= avctx->width) {
                         mask = mask << 1;
                         continue;
                     }

                     AV_WB24(&frame->data[0][frame->linesize[0] * (h - j) + 3 * k], color);

                     pixels_overwritten ++;

                 }
                 mask = mask << 1;
             }
         }
     }

     return pixels_overwritten;

 }
 

 static int fill_tileX(AVCodecContext *avctx, int tile_width, int tile_height,

                        int color, AVFrame *frame)

 {
     ARBCContext *s = avctx->priv_data;
     GetByteContext *gb = &s->gb;
     const int step_h = tile_height / 4;
     const int step_w = tile_width / 4;
     int nb_tiles = bytestream2_get_le16(gb);
     int h = avctx->height - 1;

     int pixels_overwritten = 0;

     if ((avctx->width / tile_width + 1) * (avctx->height / tile_height + 1) < nb_tiles)

         return 0;

     for (int i = 0; i < nb_tiles; i++) {
         int y = bytestream2_get_byte(gb);
         int x = bytestream2_get_byte(gb);
         uint16_t mask = bytestream2_get_le16(gb);
         int start_y = y * tile_height, start_x = x * tile_width;
         int end_y = start_y + tile_height, end_x = start_x + tile_width;
 

         if (start_x >= avctx->width || start_y >= avctx->height)
             continue;
 

         for (int j = start_y; j < end_y; j += step_h) {
             for (int k = start_x; k < end_x; k += step_w) {
                 if (mask & 0x8000U) {
                     for (int m = 0; m < step_h; m++) {
                         for (int n = 0; n < step_w; n++) {
                             if (j + m >= avctx->height || k + n >= avctx->width)
                                 continue;

                             AV_WB24(&frame->data[0][frame->linesize[0] * (h - (j + m)) + 3 * (k + n)], color);

                         }
                     }

                     pixels_overwritten += FFMIN(step_h, avctx->height - j) * FFMIN(step_w, avctx->width - k);

                 }
                 mask = mask << 1;
             }
         }
     }

     return pixels_overwritten;

 }
 
 static int decode_frame(AVCodecContext *avctx, void *data,
                         int *got_frame, AVPacket *avpkt)
 {
     ARBCContext *s = avctx->priv_data;
     AVFrame *frame = data;

     int ret, nb_segments;
     int prev_pixels = avctx->width * avctx->height;

 
     if (avpkt->size < 10)
         return AVERROR_INVALIDDATA;
 

     bytestream2_init(&s->gb, avpkt->data, avpkt->size);
     bytestream2_skip(&s->gb, 8);
     nb_segments = bytestream2_get_le16(&s->gb);
     if (nb_segments == 0)

         return avpkt->size;

 
     if (7 * nb_segments > bytestream2_get_bytes_left(&s->gb))
         return AVERROR_INVALIDDATA;
 

     if ((ret = ff_get_buffer(avctx, frame, AV_GET_BUFFER_FLAG_REF)) < 0)
         return ret;
 
     if (s->prev_frame->data[0]) {
         ret = av_frame_copy(frame, s->prev_frame);
         if (ret < 0)
             return ret;
     }
 
     for (int i = 0; i < nb_segments; i++) {
         int resolution_flag;

         int fill;

 
         if (bytestream2_get_bytes_left(&s->gb) <= 0)
             return AVERROR_INVALIDDATA;
 

         fill = bytestream2_get_byte(&s->gb) << 16;

         bytestream2_skip(&s->gb, 1);

         fill |= bytestream2_get_byte(&s->gb) << 8;

         bytestream2_skip(&s->gb, 1);

         fill |= bytestream2_get_byte(&s->gb) << 0;

         bytestream2_skip(&s->gb, 1);
         resolution_flag = bytestream2_get_byte(&s->gb);
 
         if (resolution_flag & 0x10)

             prev_pixels -= fill_tileX(avctx, 1024, 1024, fill, frame);

         if (resolution_flag & 0x08)

             prev_pixels -= fill_tileX(avctx, 256, 256, fill, frame);

         if (resolution_flag & 0x04)

             prev_pixels -= fill_tileX(avctx, 64, 64, fill, frame);

         if (resolution_flag & 0x02)

             prev_pixels -= fill_tileX(avctx, 16, 16, fill, frame);

         if (resolution_flag & 0x01)

             prev_pixels -= fill_tile4(avctx, fill, frame);

     }
 
     av_frame_unref(s->prev_frame);
     if ((ret = av_frame_ref(s->prev_frame, frame)) < 0)
         return ret;
 

     frame->pict_type = prev_pixels <= 0 ? AV_PICTURE_TYPE_I : AV_PICTURE_TYPE_P;
     frame->key_frame = prev_pixels <= 0;

     *got_frame = 1;
 
     return avpkt->size;
 }
 
 static av_cold int decode_init(AVCodecContext *avctx)
 {
     ARBCContext *s = avctx->priv_data;
 
     avctx->pix_fmt = AV_PIX_FMT_RGB24;
 
     s->prev_frame = av_frame_alloc();
     if (!s->prev_frame)
         return AVERROR(ENOMEM);
 
     return 0;
 }
 

 static void decode_flush(AVCodecContext *avctx)
 {
     ARBCContext *s = avctx->priv_data;
 
     av_frame_unref(s->prev_frame);
 }
 

 static av_cold int decode_close(AVCodecContext *avctx)
 {
     ARBCContext *s = avctx->priv_data;
 
     av_frame_free(&s->prev_frame);
 
     return 0;
 }
 
 AVCodec ff_arbc_decoder = {
     .name           = "arbc",
     .long_name      = NULL_IF_CONFIG_SMALL("Gryphon's Anim Compressor"),
     .type           = AVMEDIA_TYPE_VIDEO,
     .id             = AV_CODEC_ID_ARBC,
     .priv_data_size = sizeof(ARBCContext),
     .init           = decode_init,
     .decode         = decode_frame,

     .flush          = decode_flush,

     .close          = decode_close,
     .capabilities   = AV_CODEC_CAP_DR1,
     .caps_internal  = FF_CODEC_CAP_INIT_CLEANUP,
 };