int32_t
ppb_video_decoder_decode(PP_Resource video_decoder,
                         const struct PP_VideoBitstreamBuffer_Dev *bitstream_buffer,
                         struct PP_CompletionCallback callback)
{
    struct pp_video_decoder_s *vd = pp_resource_acquire(video_decoder, PP_RESOURCE_VIDEO_DECODER);
    if (!vd) {
        trace_error("%s, bad resource\n", __func__);
        return PP_ERROR_BADRESOURCE;
    }

    if (vd->failed_state) {
        trace_warning("%s, there were errors before, giving up\n", __func__);
        pp_resource_release(video_decoder);
        return PP_ERROR_FAILED;
    }

    void *rawdata = ppb_buffer_map(bitstream_buffer->data);
    if (!rawdata) {
        trace_error("%s, bad bitstream buffer\n", __func__);
        pp_resource_release(video_decoder);
        return PP_ERROR_FAILED;
    }

    uint8_t *inbuf = rawdata;
    size_t   inbuf_sz = bitstream_buffer->size;

    while (inbuf_sz > 0) {
        uint8_t *outbuf = NULL;
        int      outbuf_sz = 0;
        int len = av_parser_parse2(vd->avparser, vd->avctx, &outbuf, &outbuf_sz,
                                   inbuf, inbuf_sz, 0, 0, AV_NOPTS_VALUE);
        if (outbuf_sz > 0)
            decode_frame(vd, outbuf, outbuf_sz, vd->last_consumed_bitstream_buffer_id);
        inbuf += len;
        inbuf_sz -= len;
    }

    vd->last_consumed_bitstream_buffer_id = bitstream_buffer->id;
    ppb_buffer_unmap(bitstream_buffer->data);

    pp_resource_release(video_decoder);
    ppb_core_call_on_main_thread(0, callback, PP_OK);
    return PP_OK_COMPLETIONPENDING;
}
int32_t
ppb_video_capture_open(PP_Resource video_capture, PP_Resource device_ref,
                       const struct PP_VideoCaptureDeviceInfo_Dev *requested_info,
                       uint32_t buffer_count, struct PP_CompletionCallback callback)
{
    int32_t result;
    struct pp_video_capture_s *vc = pp_resource_acquire(video_capture, PP_RESOURCE_VIDEO_CAPTURE);
    if (!vc) {
        trace_error("%s, bad resource\n", __func__);
        return PP_ERROR_BADRESOURCE;
    }

    const char *capture_device = default_capture_device;
    struct PP_Var longname = ppb_device_ref_get_longname(device_ref);

    if (longname.type == PP_VARTYPE_STRING)
        capture_device = ppb_var_var_to_utf8(longname, NULL);

    vc->fd = v4l2_open(capture_device, O_RDWR);

    ppb_var_release(longname);

    if (vc->fd < 0) {
        result = PP_ERROR_NOACCESS;
        goto point_1;
    }

    struct v4l2_capability caps;
    if (v4l2_ioctl(vc->fd, VIDIOC_QUERYCAP, &caps) != 0) {
        result = PP_ERROR_FAILED;
        goto point_2;
    }

#ifdef V4L2_CAP_DEVICE_CAPS
    const uint32_t device_caps = (caps.capabilities & V4L2_CAP_DEVICE_CAPS) ? caps.device_caps
                                                                            : caps.capabilities;
#else
    const uint32_t device_caps = caps.capabilities;
#endif // V4L2_CAP_DEVICE_CAPS

    if (!(device_caps & V4L2_CAP_VIDEO_CAPTURE)) {
        trace_error("%s, device can't capture\n", __func__);
        result = PP_ERROR_FAILED;
        goto point_2;
    }

    if (!(device_caps & V4L2_CAP_READWRITE)) {
        trace_error("%s, device doesn't support read/write interface\n", __func__);
        result = PP_ERROR_FAILED;
        goto point_2;
    }

    if (requested_info) {
        vc->width =  requested_info->width;
        vc->height = requested_info->height;
        vc->fps =    requested_info->frames_per_second;
    } else {
        vc->width =  640;
        vc->height = 480;
        vc->fps =    15;
    }

    struct v4l2_format fmt = {
        .type =                 V4L2_BUF_TYPE_VIDEO_CAPTURE,
        .fmt.pix.width =        vc->width,
        .fmt.pix.height =       vc->height,
        .fmt.pix.pixelformat =  V4L2_PIX_FMT_YUV420,    // PPAPI hardcodes format to YUV420
        .fmt.pix.field =        V4L2_FIELD_INTERLACED,
    };

    if (v4l2_ioctl(vc->fd, VIDIOC_S_FMT, &fmt) != 0) {
        trace_error("%s, failed to set resolution\n", __func__);
        result = PP_ERROR_FAILED;
        goto point_2;
    }

    vc->width =  fmt.fmt.pix.width;
    vc->height = fmt.fmt.pix.height;

    vc->buffer_size = fmt.fmt.pix.sizeimage;    // buffer size in bytes
    vc->buffer_count = MAX(buffer_count, 5);    // limit lowest number of buffers, just in case

    vc->buffers = calloc(sizeof(*vc->buffers), vc->buffer_count);
    if (!vc->buffers) {
        trace_error("%s, memory allocation failure (1)\n", __func__);
        result = PP_ERROR_FAILED;
        goto point_2;
    }

    vc->buffer_is_free = malloc(sizeof(*vc->buffer_is_free) * vc->buffer_count);
    if (!vc->buffer_is_free) {
        trace_error("%s, memory allocation failure (2)\n", __func__);
        result = PP_ERROR_FAILED;
        goto point_3;
    }

    for (unsigned int k = 0; k < vc->buffer_count; k ++) {
        vc->buffer_is_free[k] = 1;
        vc->buffers[k] = ppb_buffer_create(vc->instance->id, vc->buffer_size);
        if (vc->buffers[k] == 0)
            goto point_4;
    }

    struct PP_VideoCaptureDeviceInfo_Dev info = {
        .width =             vc->width,
        .height =            vc->height,
        .frames_per_second = vc->fps,
    };

    vc->ppp_video_capture_dev->OnDeviceInfo(vc->instance->id, video_capture, &info,
                                            vc->buffer_count, vc->buffers);

    result = PP_OK;
    goto point_1;

point_4:
    for (unsigned int k = 0; k < vc->buffer_count; k ++)
        ppb_core_release_resource(vc->buffers[k]);
    free_and_nullify(vc->buffer_is_free);
point_3:
    free_and_nullify(vc->buffers);
point_2:
    v4l2_close(vc->fd);
    vc->fd = -1;
point_1:
    pp_resource_release(video_capture);
    ppb_core_call_on_main_thread2(0, callback, result, __func__);
    return PP_OK_COMPLETIONPENDING;
}

struct on_buffer_ready_param_s {
    PP_Instance                            instance;
    PP_Resource                            video_capture;
    uint32_t                               buf_idx;
    const struct PPP_VideoCapture_Dev_0_1 *ppp_video_capture_dev;
};

static
void
on_buffer_ready_comt(void *user_data, int32_t result)
{
    struct on_buffer_ready_param_s *p = user_data;
    struct pp_instance_s *pp_i = tables_get_pp_instance(p->instance);
    if (!pp_i)
        return;

    p->ppp_video_capture_dev->OnBufferReady(p->instance, p->video_capture, p->buf_idx);
    g_slice_free1(sizeof(*p), p);
}

static
void *
video_capture_thread(void *param)
{
    struct pp_video_capture_s *vc = param;

    PP_Resource  video_capture = vc->self_id;
    PP_Instance  instance = vc->instance->id;
    const int    fd = vc->fd;
    const size_t buffer_size = vc->buffer_size;

    vc = pp_resource_acquire(video_capture, PP_RESOURCE_VIDEO_CAPTURE);
    if (!vc)
        goto gone;

    while (!vc->terminate_thread) {
        // find free buffer
        uint32_t buf_idx = (uint32_t)-1;
        for (uint32_t k = 0; k < vc->buffer_count; k ++) {
            if (vc->buffer_is_free[k]) {
                buf_idx = k;
                vc->buffer_is_free[k] = 0;
                break;
            }
        }

        if (buf_idx == (uint32_t)-1) {
            // all buffers are busy, wait for some to free, with resource unlocked
            pp_resource_release(video_capture);
            usleep(10);
            vc = pp_resource_acquire(video_capture, PP_RESOURCE_VIDEO_CAPTURE);
            if (!vc)
                goto gone;
            continue;
        }

        PP_Resource buffer = vc->buffers[buf_idx];
        pp_resource_release(video_capture);

        // wait on v4l2_read() with resource unlocked
        void *ptr = ppb_buffer_map(buffer);
        RETRY_ON_EINTR(v4l2_read(fd, ptr, buffer_size));
        ppb_buffer_unmap(buffer);

        vc = pp_resource_acquire(video_capture, PP_RESOURCE_VIDEO_CAPTURE);
        if (!vc)
            goto gone;

        struct on_buffer_ready_param_s *p = g_slice_alloc(sizeof(*p));
        p->instance =               instance;
        p->video_capture =          video_capture;
        p->buf_idx =                buf_idx;
        p->ppp_video_capture_dev =  vc->ppp_video_capture_dev;
        ppb_core_call_on_main_thread2(0, PP_MakeCCB(on_buffer_ready_comt, p), PP_OK, __func__);
    }

    pp_resource_release(video_capture);
    return NULL;

gone:
    trace_error("%s, resource gone\n", __func__);
    return NULL;
}

int32_t
ppb_video_capture_start_capture(PP_Resource video_capture)
{
    struct pp_video_capture_s *vc = pp_resource_acquire(video_capture, PP_RESOURCE_VIDEO_CAPTURE);
    if (!vc) {
        trace_error("%s, bad resource\n", __func__);
        return PP_ERROR_BADRESOURCE;
    }

    if (vc->thread_started)
        goto done;

    if (vc->fd < 0) {
        trace_error("%s, device is closed\n", __func__);
        pp_resource_release(video_capture);
        return PP_ERROR_FAILED;
    }

    vc->ppp_video_capture_dev->OnStatus(vc->instance->id, video_capture,
                                        PP_VIDEO_CAPTURE_STATUS_STARTING);

    pp_resource_ref(video_capture); // prevents freeing while thread is still running
    pthread_create(&vc->thread, NULL, video_capture_thread, vc);
    vc->thread_started = 1;

    vc->ppp_video_capture_dev->OnStatus(vc->instance->id, video_capture,
                                        PP_VIDEO_CAPTURE_STATUS_STARTED);

done:
    pp_resource_release(video_capture);
    return PP_OK;
}

int32_t
ppb_video_capture_reuse_buffer(PP_Resource video_capture, uint32_t buffer)
{
    struct pp_video_capture_s *vc = pp_resource_acquire(video_capture, PP_RESOURCE_VIDEO_CAPTURE);
    if (!vc) {
        trace_error("%s, bad resource\n", __func__);
        return PP_ERROR_BADRESOURCE;
    }

    if (buffer < vc->buffer_count)
        vc->buffer_is_free[buffer] = 1;

    pp_resource_release(video_capture);
    return PP_OK;
}

int32_t
ppb_video_capture_stop_capture(PP_Resource video_capture)
{
    struct pp_video_capture_s *vc = pp_resource_acquire(video_capture, PP_RESOURCE_VIDEO_CAPTURE);
    if (!vc) {
        trace_error("%s, bad resource\n", __func__);
        return PP_ERROR_BADRESOURCE;
    }

    if (!vc->thread_started)
        goto done;

    vc->ppp_video_capture_dev->OnStatus(vc->instance->id, video_capture,
                                        PP_VIDEO_CAPTURE_STATUS_STOPPING);

    vc->terminate_thread = 1;
    pthread_t thread = vc->thread;

    pp_resource_release(video_capture);

    pthread_join(thread, NULL);

    vc = pp_resource_acquire(video_capture, PP_RESOURCE_VIDEO_CAPTURE);
    if (!vc) {
        trace_error("%s, resource gone\n", __func__);
        return PP_ERROR_BADRESOURCE;
    }

    vc->thread_started = 0;
    vc->terminate_thread = 0;
    vc->ppp_video_capture_dev->OnStatus(vc->instance->id, video_capture,
                                        PP_VIDEO_CAPTURE_STATUS_STOPPED);

    pp_resource_unref(video_capture);   // remove reference made in start_capture()

done:
    pp_resource_release(video_capture);
    return PP_OK;
}

void
ppb_video_capture_close(PP_Resource video_capture)
{
    ppb_video_capture_stop_capture(video_capture);

    struct pp_video_capture_s *vc = pp_resource_acquire(video_capture, PP_RESOURCE_VIDEO_CAPTURE);
    if (!vc) {
        trace_error("%s, bad resource\n", __func__);
        return;
    }

    ppb_video_capture_destroy(vc);

    pp_resource_release(video_capture);
    return;
}


// trace wrappers
TRACE_WRAPPER
PP_Resource
trace_ppb_video_capture_create(PP_Instance instance)
{
    trace_info("[PPB] {full} %s instance=%d\n", __func__+6, instance);
    return ppb_video_capture_create(instance);
}