/*
  * V4L2 mem2mem decoders
  *
  * Copyright (C) 2017 Alexis Ballier <aballier@gentoo.org>
  * Copyright (C) 2017 Jorge Ramirez <jorge.ramirez-ortiz@linaro.org>
  *
  * 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 <linux/videodev2.h>
 #include <sys/ioctl.h>
 #include "libavutil/pixfmt.h"
 #include "libavutil/pixdesc.h"
 #include "libavutil/opt.h"
 #include "libavcodec/avcodec.h"
 #include "libavcodec/decode.h"
 
 #include "v4l2_context.h"
 #include "v4l2_m2m.h"
 #include "v4l2_fmt.h"
 
 static int v4l2_try_start(AVCodecContext *avctx)
 {

     V4L2m2mContext *s = ((V4L2m2mPriv*)avctx->priv_data)->context;

     V4L2Context *const capture = &s->capture;
     V4L2Context *const output = &s->output;
     struct v4l2_selection selection;
     int ret;
 
     /* 1. start the output process */
     if (!output->streamon) {
         ret = ff_v4l2_context_set_status(output, VIDIOC_STREAMON);
         if (ret < 0) {
             av_log(avctx, AV_LOG_DEBUG, "VIDIOC_STREAMON on output context\n");
             return ret;
         }
     }
 
     if (capture->streamon)
         return 0;
 
     /* 2. get the capture format */
     capture->format.type = capture->type;
     ret = ioctl(s->fd, VIDIOC_G_FMT, &capture->format);
     if (ret) {
         av_log(avctx, AV_LOG_WARNING, "VIDIOC_G_FMT ioctl\n");
         return ret;
     }
 
     /* 2.1 update the AVCodecContext */
     avctx->pix_fmt = ff_v4l2_format_v4l2_to_avfmt(capture->format.fmt.pix_mp.pixelformat, AV_CODEC_ID_RAWVIDEO);
     capture->av_pix_fmt = avctx->pix_fmt;
 
     /* 3. set the crop parameters */
     selection.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
     selection.r.height = avctx->coded_height;
     selection.r.width = avctx->coded_width;
     ret = ioctl(s->fd, VIDIOC_S_SELECTION, &selection);
     if (!ret) {
         ret = ioctl(s->fd, VIDIOC_G_SELECTION, &selection);
         if (ret) {
             av_log(avctx, AV_LOG_WARNING, "VIDIOC_G_SELECTION ioctl\n");
         } else {
             av_log(avctx, AV_LOG_DEBUG, "crop output %dx%d\n", selection.r.width, selection.r.height);
             /* update the size of the resulting frame */
             capture->height = selection.r.height;
             capture->width  = selection.r.width;
         }
     }
 
     /* 4. init the capture context now that we have the capture format */
     if (!capture->buffers) {
         ret = ff_v4l2_context_init(capture);
         if (ret) {
             av_log(avctx, AV_LOG_DEBUG, "can't request output buffers\n");
             return ret;
         }
     }
 
     /* 5. start the capture process */
     ret = ff_v4l2_context_set_status(capture, VIDIOC_STREAMON);
     if (ret) {
         av_log(avctx, AV_LOG_DEBUG, "VIDIOC_STREAMON, on capture context\n");
         return ret;
     }
 
     return 0;
 }
 
 static int v4l2_prepare_decoder(V4L2m2mContext *s)
 {
     struct v4l2_event_subscription sub;
     V4L2Context *output = &s->output;
     int ret;
 
     /**
      * requirements
      */
     memset(&sub, 0, sizeof(sub));
     sub.type = V4L2_EVENT_SOURCE_CHANGE;
     ret = ioctl(s->fd, VIDIOC_SUBSCRIBE_EVENT, &sub);
     if ( ret < 0) {
         if (output->height == 0 || output->width == 0) {
             av_log(s->avctx, AV_LOG_ERROR,
                 "the v4l2 driver does not support VIDIOC_SUBSCRIBE_EVENT\n"
                 "you must provide codec_height and codec_width on input\n");
             return ret;
         }
     }
 
     return 0;
 }
 
 static int v4l2_receive_frame(AVCodecContext *avctx, AVFrame *frame)
 {

     V4L2m2mContext *s = ((V4L2m2mPriv*)avctx->priv_data)->context;

     V4L2Context *const capture = &s->capture;
     V4L2Context *const output = &s->output;
     AVPacket avpkt = {0};
     int ret;
 
     ret = ff_decode_get_packet(avctx, &avpkt);
     if (ret < 0 && ret != AVERROR_EOF)
         return ret;
 
     if (s->draining)
         goto dequeue;
 
     ret = ff_v4l2_context_enqueue_packet(output, &avpkt);
     if (ret < 0) {
         if (ret != AVERROR(ENOMEM))
            return ret;
         /* no input buffers available, continue dequeing */
     }
 
     if (avpkt.size) {
         ret = v4l2_try_start(avctx);
         if (ret)
             return 0;
     }
 
 dequeue:
     return ff_v4l2_context_dequeue_frame(capture, frame);
 }
 
 static av_cold int v4l2_decode_init(AVCodecContext *avctx)
 {

     V4L2Context *capture, *output;
     V4L2m2mContext *s;

     int ret;
 

     ret = ff_v4l2_m2m_create_context(avctx, &s);
     if (ret < 0)
         return ret;
 
     capture = &s->capture;
     output = &s->output;
 

     /* if these dimensions are invalid (ie, 0 or too small) an event will be raised
      * by the v4l2 driver; this event will trigger a full pipeline reconfig and
      * the proper values will be retrieved from the kernel driver.
      */
     output->height = capture->height = avctx->coded_height;
     output->width = capture->width = avctx->coded_width;
 
     output->av_codec_id = avctx->codec_id;
     output->av_pix_fmt  = AV_PIX_FMT_NONE;
 
     capture->av_codec_id = AV_CODEC_ID_RAWVIDEO;
     capture->av_pix_fmt = avctx->pix_fmt;
 
     ret = ff_v4l2_m2m_codec_init(avctx);
     if (ret) {
         av_log(avctx, AV_LOG_ERROR, "can't configure decoder\n");
         return ret;
     }
 
     return v4l2_prepare_decoder(s);
 }
 

 #define OFFSET(x) offsetof(V4L2m2mPriv, x)

 #define FLAGS AV_OPT_FLAG_VIDEO_PARAM | AV_OPT_FLAG_DECODING_PARAM
 
 static const AVOption options[] = {
     V4L_M2M_DEFAULT_OPTS,
     { "num_capture_buffers", "Number of buffers in the capture context",

         OFFSET(num_capture_buffers), AV_OPT_TYPE_INT, {.i64 = 20}, 20, INT_MAX, FLAGS },

     { NULL},
 };
 
 #define M2MDEC(NAME, LONGNAME, CODEC, bsf_name) \
 static const AVClass v4l2_m2m_ ## NAME ## _dec_class = {\
     .class_name = #NAME "_v4l2_m2m_decoder",\
     .item_name  = av_default_item_name,\
     .option     = options,\
     .version    = LIBAVUTIL_VERSION_INT,\
 };\
 \
 AVCodec ff_ ## NAME ## _v4l2m2m_decoder = { \
     .name           = #NAME "_v4l2m2m" ,\
     .long_name      = NULL_IF_CONFIG_SMALL("V4L2 mem2mem " LONGNAME " decoder wrapper"),\
     .type           = AVMEDIA_TYPE_VIDEO,\
     .id             = CODEC ,\

     .priv_data_size = sizeof(V4L2m2mPriv),\

     .priv_class     = &v4l2_m2m_ ## NAME ## _dec_class,\
     .init           = v4l2_decode_init,\
     .receive_frame  = v4l2_receive_frame,\
     .close          = ff_v4l2_m2m_codec_end,\
     .bsfs           = bsf_name, \

     .capabilities   = AV_CODEC_CAP_HARDWARE | AV_CODEC_CAP_DELAY, \

     .wrapper_name   = "v4l2m2m", \

 };
 
 M2MDEC(h264,  "H.264", AV_CODEC_ID_H264,       "h264_mp4toannexb");
 M2MDEC(hevc,  "HEVC",  AV_CODEC_ID_HEVC,       "hevc_mp4toannexb");
 M2MDEC(mpeg1, "MPEG1", AV_CODEC_ID_MPEG1VIDEO, NULL);
 M2MDEC(mpeg2, "MPEG2", AV_CODEC_ID_MPEG2VIDEO, NULL);
 M2MDEC(mpeg4, "MPEG4", AV_CODEC_ID_MPEG4,      NULL);
 M2MDEC(h263,  "H.263", AV_CODEC_ID_H263,       NULL);
 M2MDEC(vc1 ,  "VC1",   AV_CODEC_ID_VC1,        NULL);
 M2MDEC(vp8,   "VP8",   AV_CODEC_ID_VP8,        NULL);
 M2MDEC(vp9,   "VP9",   AV_CODEC_ID_VP9,        NULL);