/*
  * Screenpresso decoder
  * Copyright (C) 2015 Vittorio Giovara <vittorio.giovara@gmail.com>
  *

  * 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
  * Screenpresso decoder
  *
  * Fourcc: SPV1
  *
  * Screenpresso simply horizontally flips and then deflates frames,
  * alternating full pictures and deltas. Deltas are related to the currently
  * rebuilt frame (not the reference), and since there is no coordinate system
  * they contain exactly as many pixel as the keyframe.
  *

  * Supports: BGRA, BGR24, RGB555

  */
 
 #include <stdint.h>
 #include <string.h>
 #include <zlib.h>
 
 #include "libavutil/imgutils.h"
 #include "libavutil/internal.h"

 #include "libavutil/mem.h"

 
 #include "avcodec.h"
 #include "internal.h"
 
 typedef struct ScreenpressoContext {
     AVFrame *current;
 

     /* zlib interaction */

     uint8_t *inflated_buf;
     uLongf inflated_size;
 } ScreenpressoContext;
 
 static av_cold int screenpresso_close(AVCodecContext *avctx)
 {
     ScreenpressoContext *ctx = avctx->priv_data;
 
     av_frame_free(&ctx->current);
     av_freep(&ctx->inflated_buf);
 
     return 0;
 }
 
 static av_cold int screenpresso_init(AVCodecContext *avctx)
 {
     ScreenpressoContext *ctx = avctx->priv_data;
 
     /* These needs to be set to estimate uncompressed buffer */
     int ret = av_image_check_size(avctx->width, avctx->height, 0, avctx);
     if (ret < 0) {
         av_log(avctx, AV_LOG_ERROR, "Invalid image size %dx%d.\n",
                avctx->width, avctx->height);
         return ret;
     }
 
     /* Allocate current frame */
     ctx->current = av_frame_alloc();
     if (!ctx->current)
         return AVERROR(ENOMEM);
 

     /* Allocate maximum size possible, a full RGBA frame */
     ctx->inflated_size = avctx->width * avctx->height * 4;

     ctx->inflated_buf  = av_malloc(ctx->inflated_size);
     if (!ctx->inflated_buf)
         return AVERROR(ENOMEM);
 

     return 0;
 }
 
 static void sum_delta_flipped(uint8_t       *dst, int dst_linesize,
                               const uint8_t *src, int src_linesize,
                               int bytewidth, int height)
 {
     int i;
     for (; height > 0; height--) {
         for (i = 0; i < bytewidth; i++)
             dst[i] += src[(height - 1) * src_linesize + i];
         dst += dst_linesize;
     }
 }
 
 static int screenpresso_decode_frame(AVCodecContext *avctx, void *data,
                                      int *got_frame, AVPacket *avpkt)
 {
     ScreenpressoContext *ctx = avctx->priv_data;
     AVFrame *frame = data;

     uLongf length = ctx->inflated_size;

     int keyframe, component_size, src_linesize;

     int ret;
 
     /* Size check */
     if (avpkt->size < 3) {
         av_log(avctx, AV_LOG_ERROR, "Packet too small (%d)\n", avpkt->size);
         return AVERROR_INVALIDDATA;
     }
 

     /* Compression level (4 bits) and keyframe information (1 bit) */
     av_log(avctx, AV_LOG_DEBUG, "Compression level %d\n", avpkt->data[0] >> 4);
     keyframe = avpkt->data[0] & 1;

     /* Pixel size */
     component_size = ((avpkt->data[1] >> 2) & 0x03) + 1;
     switch (component_size) {
     case 2:
         avctx->pix_fmt = AV_PIX_FMT_RGB555LE;
         break;
     case 3:
         avctx->pix_fmt = AV_PIX_FMT_BGR24;
         break;
     case 4:
         avctx->pix_fmt = AV_PIX_FMT_BGRA;
         break;
     default:
         av_log(avctx, AV_LOG_ERROR, "Invalid bits per pixel value (%d)\n",
                component_size);
         return AVERROR_INVALIDDATA;
     }
 

     /* Inflate the frame after the 2 byte header */

     ret = uncompress(ctx->inflated_buf, &length,

                      avpkt->data + 2, avpkt->size - 2);
     if (ret) {
         av_log(avctx, AV_LOG_ERROR, "Deflate error %d.\n", ret);
         return AVERROR_UNKNOWN;
     }
 

     ret = ff_reget_buffer(avctx, ctx->current);
     if (ret < 0)
         return ret;
 

     /* Codec has aligned strides */
     src_linesize = FFALIGN(avctx->width * component_size, 4);
 

     /* When a keyframe is found, copy it (flipped) */
     if (keyframe)
         av_image_copy_plane(ctx->current->data[0] +
                             ctx->current->linesize[0] * (avctx->height - 1),
                             -1 * ctx->current->linesize[0],

                             ctx->inflated_buf, src_linesize,
                             avctx->width * component_size, avctx->height);

     /* Otherwise sum the delta on top of the current frame */
     else
         sum_delta_flipped(ctx->current->data[0], ctx->current->linesize[0],

                           ctx->inflated_buf, src_linesize,
                           avctx->width * component_size, avctx->height);

 
     /* Frame is ready to be output */
     ret = av_frame_ref(frame, ctx->current);
     if (ret < 0)
         return ret;
 
     /* Usual properties */
     if (keyframe) {
         frame->pict_type = AV_PICTURE_TYPE_I;
         frame->key_frame = 1;
     } else {
         frame->pict_type = AV_PICTURE_TYPE_P;
     }
     *got_frame = 1;
 
     return 0;
 }
 
 AVCodec ff_screenpresso_decoder = {
     .name           = "screenpresso",
     .long_name      = NULL_IF_CONFIG_SMALL("Screenpresso"),
     .type           = AVMEDIA_TYPE_VIDEO,
     .id             = AV_CODEC_ID_SCREENPRESSO,
     .init           = screenpresso_init,
     .decode         = screenpresso_decode_frame,
     .close          = screenpresso_close,
     .priv_data_size = sizeof(ScreenpressoContext),
     .capabilities   = AV_CODEC_CAP_DR1,
     .caps_internal  = FF_CODEC_CAP_INIT_THREADSAFE |
                       FF_CODEC_CAP_INIT_CLEANUP,
 };