/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/***************************************************************************
 *            v4l.cc
 *
 *  Thu Sep 18 19:36:19 CEST 2014
 *  Copyright 2014 Bent Bisballe Nyeng
 *  deva@aasimon.org
 ****************************************************************************/

/*
 *  This file is part of SimpleRTP.
 *
 *  SimpleRTP is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  SimpleRTP 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 General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with SimpleRTP; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA.
 */

/*
 * This file is mostly taken from the v4l recording example in the v4l-util
 * package:
 * v4l-utils /v4l-utils-0.8.8/contrib/test/capture-example.c
 * Below is the original copyright notice:
 */

/*
 *  V4L2 video capture example
 *
 *  This program can be used and distributed without restrictions.
 *
 *      This program is provided with the V4L2 API
 * see http://linuxtv.org/docs.php for more information
 */

#include "v4l.h"

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>

#include <getopt.h>             /* getopt_long() */

#include <fcntl.h>              /* low-level i/o */
#include <unistd.h>
#include <errno.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/time.h>
#include <sys/mman.h>
#include <sys/ioctl.h>

#include <linux/videodev2.h>

#include <QMetaType>

extern "C" {
#include <jpeglib.h>
}

#include "mediaconfig.h"

#define JPEG_HEADER_PAD 500

static bool isYUYV = false;
static V4L *v4l = NULL;
static volatile bool running = true;

#define CLEAR(x) memset(&(x), 0, sizeof(x))

enum io_method {
  IO_METHOD_READ,
  IO_METHOD_MMAP,
  IO_METHOD_USERPTR,
};

struct buffer {
  void   *start;
  size_t  length;
};

static char            *dev_name;
static enum io_method   io = IO_METHOD_MMAP;
static int              fd = -1;
struct buffer          *buffers;
static unsigned int     n_buffers;
static int              out_buf;
static int              force_format;
static int              frame_count = 70;

static void errno_exit(const char *s)
{
  fprintf(stderr, "%s error %d, %s\n", s, errno, strerror(errno));
  exit(EXIT_FAILURE);
}

static int xioctl(int fh, int request, void *arg)
{
  int r;

  do {
    r = ioctl(fh, request, arg);
  } while (-1 == r && EINTR == errno);

  return r;
}

/*
 * In typical computer APIs, "YUV" actually means YCbCr, and "YUYV" means
 * "YCbCr 4:2:2" stored as Y0, Cb01, Y1, Cr01, Y2 ...
 * From: http://stackoverflow.com/questions/16390783/how-to-save-yuyv-raw-data-to-jpeg-using-libjpeg
 */
static void toJpeg(int quality, unsigned char *yuyv,
                   int image_width, int image_height,
                   char **out, size_t *size)
{
  JSAMPLE *image_buffer = (JSAMPLE*)yuyv;

  long unsigned int buffersize =
    (image_width * image_height * 3) + JPEG_HEADER_PAD;
  unsigned char *jpeg_output_buffer = (unsigned char *)malloc(buffersize);
  struct jpeg_compress_struct cinfo;
  struct jpeg_error_mgr jerr;
    
  JSAMPROW row_pointer[1];      // pointer to JSAMPLE row[s] 
  int row_stride;               // physical row width in image buffer 
    
  // Allocate and initialize JPEG compression object 
  cinfo.err = jpeg_std_error(&jerr);
  jpeg_create_compress(&cinfo);
    
  // Specify data destination (see jpeg_mem_dest)
  jpeg_mem_dest(&cinfo, &jpeg_output_buffer, &buffersize);
    
  // Set compression parameters
  cinfo.image_width = image_width;      // image width and height, in pixels 
  cinfo.image_height = image_height;
  cinfo.input_components = 3;           // # of color components per pixel 
  cinfo.in_color_space = JCS_YCbCr;       // colorspace of input image 
    
  jpeg_set_defaults(&cinfo);
    
  jpeg_set_quality(&cinfo, quality, TRUE); // limit to baseline-JPEG values
    
  // Start compressor 
  jpeg_start_compress(&cinfo, TRUE);
    
  // While (scan lines remain to be written) 
  row_stride = image_width * 3; // JSAMPLEs per row in image_buffer 

  unsigned char *yuv = new unsigned char[image_width * 3]; 
  while (cinfo.next_scanline < cinfo.image_height) {
     for (int i = 0; i < cinfo.image_width; i += 2) { 
        yuv[i*3]   = yuyv[i*2]; 
        yuv[i*3+1] = yuyv[i*2+1]; 
        yuv[i*3+2] = yuyv[i*2+3]; 
        yuv[i*3+3] = yuyv[i*2+2]; 
        yuv[i*3+4] = yuyv[i*2+1]; 
        yuv[i*3+5] = yuyv[i*2+3]; 
    } 
    row_pointer[0] = yuv; 
    yuyv += image_width * 2;
    jpeg_write_scanlines(&cinfo, row_pointer, 1);

    //    row_pointer[0] = & image_buffer[cinfo.next_scanline * row_stride];
    //    (void) jpeg_write_scanlines(&cinfo, row_pointer, 1);
  }
  delete[] yuv;

  // Finish compression 
  jpeg_finish_compress(&cinfo);

  // Release JPEG compression object 
  jpeg_destroy_compress(&cinfo);

  *size = buffersize;
  *out = (char*)jpeg_output_buffer;
}

static void process_image(const void *p, int size)
{
  const void *img = p;
  int img_size = size;

  if(isYUYV) {
    toJpeg(70, (unsigned char*)p, V4LWIDTH, V4LHEIGHT, (char**)&img, (size_t*)&img_size);
  }

  if(v4l) v4l->processImage(img, img_size);

  //TODO: if(img != p) free(img);
}

static int read_frame(void)
{
  struct v4l2_buffer buf;
  unsigned int i;

  switch (io) {
  case IO_METHOD_READ:
    if (-1 == read(fd, buffers[0].start, buffers[0].length)) {
      switch (errno) {
      case EAGAIN:
        return 0;

      case EIO:
        /* Could ignore EIO, see spec. */

        /* fall through */

      default:
        errno_exit("read");
      }
    }

    process_image(buffers[0].start, buffers[0].length);
    break;

  case IO_METHOD_MMAP:
    CLEAR(buf);

    buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
    buf.memory = V4L2_MEMORY_MMAP;

    if (-1 == xioctl(fd, VIDIOC_DQBUF, &buf)) {
      switch (errno) {
      case EAGAIN:
        return 0;

      case EIO:
        /* Could ignore EIO, see spec. */

        /* fall through */

      default:
        errno_exit("VIDIOC_DQBUF");
      }
    }

    assert(buf.index < n_buffers);

    process_image(buffers[buf.index].start, buf.bytesused);

    if (-1 == xioctl(fd, VIDIOC_QBUF, &buf))
      errno_exit("VIDIOC_QBUF");
    break;

  case IO_METHOD_USERPTR:
    CLEAR(buf);

    buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
    buf.memory = V4L2_MEMORY_USERPTR;

    if (-1 == xioctl(fd, VIDIOC_DQBUF, &buf)) {
      switch (errno) {
      case EAGAIN:
        return 0;

      case EIO:
        /* Could ignore EIO, see spec. */

        /* fall through */

      default:
        errno_exit("VIDIOC_DQBUF");
      }
    }

    for (i = 0; i < n_buffers; ++i)
      if (buf.m.userptr == (unsigned long)buffers[i].start
          && buf.length == buffers[i].length)
        break;

    assert(i < n_buffers);

    process_image((void *)buf.m.userptr, buf.bytesused);

    if (-1 == xioctl(fd, VIDIOC_QBUF, &buf))
      errno_exit("VIDIOC_QBUF");
    break;
  }

  return 1;
}

static void mainloop(void)
{
  unsigned int count;

  count = frame_count;

  while(running) {
    for (;;) {
      fd_set fds;
      struct timeval tv;
      int r;

      FD_ZERO(&fds);
      FD_SET(fd, &fds);

      /* Timeout. */
      tv.tv_sec = 2;
      tv.tv_usec = 0;

      r = select(fd + 1, &fds, NULL, NULL, &tv);

      if (-1 == r) {
        if (EINTR == errno)
          continue;
        errno_exit("select");
      }

      if (0 == r) {
        fprintf(stderr, "select timeout\n");
        //        exit(EXIT_FAILURE);
        continue;
      }

      if (read_frame())
        break;
      /* EAGAIN - continue select loop. */
    }
  }
}

static void stop_capturing(void)
{
  enum v4l2_buf_type type;

  switch (io) {
  case IO_METHOD_READ:
    /* Nothing to do. */
    break;

  case IO_METHOD_MMAP:
  case IO_METHOD_USERPTR:
    type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
    if (-1 == xioctl(fd, VIDIOC_STREAMOFF, &type))
      errno_exit("VIDIOC_STREAMOFF");
    break;
  }
}

static void start_capturing(void)
{
  unsigned int i;
  enum v4l2_buf_type type;

  switch (io) {
  case IO_METHOD_READ:
    /* Nothing to do. */
    break;

  case IO_METHOD_MMAP:
    for (i = 0; i < n_buffers; ++i) {
      struct v4l2_buffer buf;

      CLEAR(buf);
      buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
      buf.memory = V4L2_MEMORY_MMAP;
      buf.index = i;

      if (-1 == xioctl(fd, VIDIOC_QBUF, &buf))
        errno_exit("VIDIOC_QBUF");
    }
    type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
    if (-1 == xioctl(fd, VIDIOC_STREAMON, &type))
      errno_exit("VIDIOC_STREAMON");
    break;

  case IO_METHOD_USERPTR:
    for (i = 0; i < n_buffers; ++i) {
      struct v4l2_buffer buf;

      CLEAR(buf);
      buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
      buf.memory = V4L2_MEMORY_USERPTR;
      buf.index = i;
      buf.m.userptr = (unsigned long)buffers[i].start;
      buf.length = buffers[i].length;

      if (-1 == xioctl(fd, VIDIOC_QBUF, &buf))
        errno_exit("VIDIOC_QBUF");
    }
    type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
    if (-1 == xioctl(fd, VIDIOC_STREAMON, &type))
      errno_exit("VIDIOC_STREAMON");
    break;
  }
}

static void uninit_device(void)
{
  unsigned int i;

  switch (io) {
  case IO_METHOD_READ:
    free(buffers[0].start);
    break;

  case IO_METHOD_MMAP:
    for (i = 0; i < n_buffers; ++i)
      if (-1 == munmap(buffers[i].start, buffers[i].length))
        errno_exit("munmap");
    break;

  case IO_METHOD_USERPTR:
    for (i = 0; i < n_buffers; ++i)
      free(buffers[i].start);
    break;
  }

  free(buffers);
}

static void init_read(unsigned int buffer_size)
{
	buffers = (buffer*)calloc(1, sizeof(*buffers));

  if (!buffers) {
    fprintf(stderr, "Out of memory\n");
    exit(EXIT_FAILURE);
  }

  buffers[0].length = buffer_size;
  buffers[0].start = malloc(buffer_size);

  if (!buffers[0].start) {
    fprintf(stderr, "Out of memory\n");
    exit(EXIT_FAILURE);
  }
}

static void init_mmap(void)
{
  struct v4l2_requestbuffers req;

  CLEAR(req);

  req.count = 4;
  req.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
  req.memory = V4L2_MEMORY_MMAP;

  if (-1 == xioctl(fd, VIDIOC_REQBUFS, &req)) {
    if (EINVAL == errno) {
      fprintf(stderr, "%s does not support "
              "memory mapping\n", dev_name);
      exit(EXIT_FAILURE);
    } else {
      errno_exit("VIDIOC_REQBUFS");
    }
  }

  if (req.count < 2) {
    fprintf(stderr, "Insufficient buffer memory on %s\n",
            dev_name);
    exit(EXIT_FAILURE);
  }

  buffers = (buffer*)calloc(req.count, sizeof(*buffers));

  if (!buffers) {
    fprintf(stderr, "Out of memory\n");
    exit(EXIT_FAILURE);
  }

  for (n_buffers = 0; n_buffers < req.count; ++n_buffers) {
    struct v4l2_buffer buf;

    CLEAR(buf);

    buf.type        = V4L2_BUF_TYPE_VIDEO_CAPTURE;
    buf.memory      = V4L2_MEMORY_MMAP;
    buf.index       = n_buffers;

    if (-1 == xioctl(fd, VIDIOC_QUERYBUF, &buf))
      errno_exit("VIDIOC_QUERYBUF");

    buffers[n_buffers].length = buf.length;
    buffers[n_buffers].start =
      mmap(NULL /* start anywhere */,
           buf.length,
           PROT_READ | PROT_WRITE /* required */,
           MAP_SHARED /* recommended */,
           fd, buf.m.offset);

    if (MAP_FAILED == buffers[n_buffers].start)
      errno_exit("mmap");
  }
}

static void init_userp(unsigned int buffer_size)
{
  struct v4l2_requestbuffers req;

  CLEAR(req);

  req.count  = 4;
  req.type   = V4L2_BUF_TYPE_VIDEO_CAPTURE;
  req.memory = V4L2_MEMORY_USERPTR;

  if (-1 == xioctl(fd, VIDIOC_REQBUFS, &req)) {
    if (EINVAL == errno) {
      fprintf(stderr, "%s does not support "
              "user pointer i/o\n", dev_name);
      exit(EXIT_FAILURE);
    } else {
      errno_exit("VIDIOC_REQBUFS");
    }
  }

  buffers = (buffer*)calloc(4, sizeof(*buffers));

  if (!buffers) {
    fprintf(stderr, "Out of memory\n");
    exit(EXIT_FAILURE);
  }

  for (n_buffers = 0; n_buffers < 4; ++n_buffers) {
    buffers[n_buffers].length = buffer_size;
    buffers[n_buffers].start = malloc(buffer_size);

    if (!buffers[n_buffers].start) {
      fprintf(stderr, "Out of memory\n");
      exit(EXIT_FAILURE);
    }
  }
}

static void init_device(void)
{
  struct v4l2_capability cap;
  struct v4l2_cropcap cropcap;
  struct v4l2_crop crop;
  struct v4l2_format fmt;
  unsigned int min;

  if (-1 == xioctl(fd, VIDIOC_QUERYCAP, &cap)) {
    if (EINVAL == errno) {
      fprintf(stderr, "%s is no V4L2 device\n",
              dev_name);
      exit(EXIT_FAILURE);
    } else {
      errno_exit("VIDIOC_QUERYCAP");
    }
  }

  if (!(cap.capabilities & V4L2_CAP_VIDEO_CAPTURE)) {
    fprintf(stderr, "%s is no video capture device\n",
            dev_name);
    exit(EXIT_FAILURE);
  }
  
  switch (io) {
  case IO_METHOD_READ:
    if (!(cap.capabilities & V4L2_CAP_READWRITE)) {
      fprintf(stderr, "%s does not support read i/o\n",
              dev_name);
      exit(EXIT_FAILURE);
    }
    break;
    
  case IO_METHOD_MMAP:
  case IO_METHOD_USERPTR:
    if (!(cap.capabilities & V4L2_CAP_STREAMING)) {
      fprintf(stderr, "%s does not support streaming i/o\n",
              dev_name);
      exit(EXIT_FAILURE);
    }
    break;
  }
  
  
  /* Select video input, video standard and tune here. */
  
  
  CLEAR(cropcap);
  
  cropcap.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
  
  if (0 == xioctl(fd, VIDIOC_CROPCAP, &cropcap)) {
    crop.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
    crop.c = cropcap.defrect; /* reset to default */
    
    if (-1 == xioctl(fd, VIDIOC_S_CROP, &crop)) {
      switch (errno) {
      case EINVAL:
        /* Cropping not supported. */
        break;
      default:
        /* Errors ignored. */
        break;
      }
    }
  } else {
    /* Errors ignored. */
  }
  

  CLEAR(fmt);

  fmt.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
  if (true || force_format) {
    fmt.fmt.pix.width       = V4LWIDTH; 
    fmt.fmt.pix.height      = V4LHEIGHT;
    fmt.fmt.pix.pixelformat = V4L2_PIX_FMT_JPEG;
    // fmt.fmt.pix.field       = V4L2_FIELD_NONE;

    if (-1 == xioctl(fd, VIDIOC_S_FMT, &fmt))
      errno_exit("VIDIOC_S_FMT");

    printf("w: %d\n", fmt.fmt.pix.width);
    printf("h: %d\n", fmt.fmt.pix.height);

    char format[5];
    memcpy(format, &fmt.fmt.pix.pixelformat, 4);
    format[4] = '\0';
    printf("format: %s\n", format);
    if(strcmp(format, "JPEG")) {
      if(strcmp(format, "YUYV")) {
        printf("Webcam neither supports JPEG nor YUYV...!\n");
        exit(1);
      } else {
        isYUYV = true; // Activate libJPEG encoding on each frame.
      }
    }


    /* Note VIDIOC_S_FMT may change width and height. */
  } else {
    /* Preserve original settings as set by v4l2-ctl for example */
    if (-1 == xioctl(fd, VIDIOC_G_FMT, &fmt))
      errno_exit("VIDIOC_G_FMT");
  }
  
  /* Buggy driver paranoia. */
  min = fmt.fmt.pix.width * 2;
  if (fmt.fmt.pix.bytesperline < min)
    fmt.fmt.pix.bytesperline = min;
  min = fmt.fmt.pix.bytesperline * fmt.fmt.pix.height;
  if (fmt.fmt.pix.sizeimage < min)
    fmt.fmt.pix.sizeimage = min;
  
  switch (io) {
  case IO_METHOD_READ:
    init_read(fmt.fmt.pix.sizeimage);
    break;
    
  case IO_METHOD_MMAP:
    init_mmap();
    break;
    
  case IO_METHOD_USERPTR:
    init_userp(fmt.fmt.pix.sizeimage);
    break;
  }
}

static void close_device(void)
{
  if (-1 == close(fd))
    errno_exit("close");
  
  fd = -1;
}

static void open_device(void)
{
  struct stat st;

  if (-1 == stat(dev_name, &st)) {
    fprintf(stderr, "Cannot identify '%s': %d, %s\n",
            dev_name, errno, strerror(errno));
    exit(EXIT_FAILURE);
  }

  if (!S_ISCHR(st.st_mode)) {
    fprintf(stderr, "%s is no device\n", dev_name);
    exit(EXIT_FAILURE);
  }

  fd = open(dev_name, O_RDWR /* required */ | O_NONBLOCK, 0);

  if (-1 == fd) {
    fprintf(stderr, "Cannot open '%s': %d, %s\n",
            dev_name, errno, strerror(errno));
    exit(EXIT_FAILURE);
  }
}

V4L::V4L(QString device)
{
  qRegisterMetaType<Frame>("Frame");

  dev_name = strdup(device.toStdString().c_str());

  v4l = this; // Set global V4L object pointer.
  
  running = true;

  // Only start if we actually have a video interface.
  if(device != "") start();
}

V4L::~V4L()
{
  running = false;
  wait();

  free(dev_name);

  v4l = NULL; // Unset global V4L object pointer.
}

void V4L::run()
{
  force_format = true;

  open_device();
  init_device();
  start_capturing();
  mainloop();
  stop_capturing();
  uninit_device();
  close_device();
}


void V4L::processImage(const void *p, int size)
{
  Frame frame((const char *)p, size);
  emit newImage(frame);
}