/* GStreamer
 * Copyright (C) <2018-2019> Seungha Yang <seungha.yang@navercorp.com>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library 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
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public
 * License along with this library; if not, write to the
 * Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
 * Boston, MA 02110-1301, USA.
 */

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include "gstcudaloader.h"
#include "gstcudacontext.h"
#include "gstcudautils.h"

GST_DEBUG_CATEGORY_STATIC (gst_cuda_context_debug);
#define GST_CAT_DEFAULT gst_cuda_context_debug

/* store all context object with weak ref */
static GList *context_list = NULL;
G_LOCK_DEFINE_STATIC (list_lock);

enum
{
  PROP_0,
  PROP_DEVICE_ID
};

struct _GstCudaContextPrivate
{
  CUcontext context;
  CUdevice device;
  guint device_id;

  gint tex_align;

  GHashTable *accessible_peer;
};

#define gst_cuda_context_parent_class parent_class
G_DEFINE_TYPE_WITH_PRIVATE (GstCudaContext, gst_cuda_context, GST_TYPE_OBJECT);

static void gst_cuda_context_set_property (GObject * object, guint prop_id,
    const GValue * value, GParamSpec * pspec);
static void gst_cuda_context_get_property (GObject * object, guint prop_id,
    GValue * value, GParamSpec * pspec);
static void gst_cuda_context_constructed (GObject * object);
static void gst_cuda_context_finalize (GObject * object);
static void gst_cuda_context_weak_ref_notify (gpointer data,
    GstCudaContext * context);
static void gst_cuda_context_enable_peer_access (GstCudaContext * context,
    GstCudaContext * peer);

static void
gst_cuda_context_class_init (GstCudaContextClass * klass)
{
  GObjectClass *gobject_class = G_OBJECT_CLASS (klass);

  gobject_class->set_property = gst_cuda_context_set_property;
  gobject_class->get_property = gst_cuda_context_get_property;
  gobject_class->constructed = gst_cuda_context_constructed;
  gobject_class->finalize = gst_cuda_context_finalize;

  g_object_class_install_property (gobject_class, PROP_DEVICE_ID,
      g_param_spec_uint ("cuda-device-id", "Cuda Device ID",
          "Set the GPU device to use for operations",
          0, G_MAXUINT, 0,
          G_PARAM_CONSTRUCT_ONLY | G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS));

  GST_DEBUG_CATEGORY_INIT (gst_cuda_context_debug,
      "cudacontext", 0, "CUDA Context");
}

static void
gst_cuda_context_init (GstCudaContext * context)
{
  GstCudaContextPrivate *priv = gst_cuda_context_get_instance_private (context);

  priv->accessible_peer = g_hash_table_new (g_direct_hash, g_direct_equal);

  context->priv = priv;
}

static void
gst_cuda_context_set_property (GObject * object, guint prop_id,
    const GValue * value, GParamSpec * pspec)
{
  GstCudaContext *context = GST_CUDA_CONTEXT (object);
  GstCudaContextPrivate *priv = context->priv;

  switch (prop_id) {
    case PROP_DEVICE_ID:
      priv->device_id = g_value_get_uint (value);
      break;
    default:
      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
      break;
  }
}

static void
gst_cuda_context_get_property (GObject * object, guint prop_id,
    GValue * value, GParamSpec * pspec)
{
  GstCudaContext *context = GST_CUDA_CONTEXT (object);
  GstCudaContextPrivate *priv = context->priv;

  switch (prop_id) {
    case PROP_DEVICE_ID:
      g_value_set_uint (value, priv->device_id);
      break;
    default:
      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
      break;
  }
}

static void
gst_cuda_context_constructed (GObject * object)
{
  GstCudaContext *context = GST_CUDA_CONTEXT (object);
  GstCudaContextPrivate *priv = context->priv;
  CUcontext cuda_ctx, old_ctx;
  CUdevice cdev = 0;
  gint dev_count = 0;
  gint tex_align = 0;
  GList *iter;

  if (!gst_cuda_result (CuDeviceGetCount (&dev_count)) || dev_count == 0) {
    GST_WARNING ("No CUDA devices detected");
    return;
  }

  if (priv->device_id >= dev_count) {
    GST_WARNING ("Unavailable device id %d", priv->device_id);
    return;
  }

  if (!gst_cuda_result (CuDeviceGet (&cdev, priv->device_id))) {
    GST_WARNING ("Failed to get device for id %d", priv->device_id);
    return;
  }

  if (!gst_cuda_result (CuDeviceGetAttribute (&tex_align,
              CU_DEVICE_ATTRIBUTE_TEXTURE_ALIGNMENT, cdev))) {
    GST_WARNING ("Failed to query texture alignment");
    return;
  }

  priv->tex_align = tex_align;

  GST_DEBUG ("Creating cuda context for device index %d, Texture Alignment: %d",
      priv->device_id, priv->tex_align);

  if (!gst_cuda_result (CuCtxCreate (&cuda_ctx, 0, cdev))) {
    GST_WARNING ("Failed to create CUDA context for cuda device %d",
        priv->device_id);
    return;
  }

  if (!gst_cuda_result (CuCtxPopCurrent (&old_ctx))) {
    return;
  }

  GST_INFO ("Created CUDA context %p with device-id %d",
      cuda_ctx, priv->device_id);

  priv->context = cuda_ctx;
  priv->device = cdev;

  G_LOCK (list_lock);
  g_object_weak_ref (G_OBJECT (object),
      (GWeakNotify) gst_cuda_context_weak_ref_notify, NULL);
  for (iter = context_list; iter; iter = g_list_next (iter)) {
    GstCudaContext *peer = (GstCudaContext *) iter->data;

    /* EnablePeerAccess is unidirectional */
    gst_cuda_context_enable_peer_access (context, peer);
    gst_cuda_context_enable_peer_access (peer, context);
  }

  context_list = g_list_append (context_list, context);
  G_UNLOCK (list_lock);
}

/* must be called with list_lock taken */
static void
gst_cuda_context_enable_peer_access (GstCudaContext * context,
    GstCudaContext * peer)
{
  GstCudaContextPrivate *priv = context->priv;
  GstCudaContextPrivate *peer_priv = peer->priv;
  CUdevice device = priv->device;
  CUdevice other_dev = peer_priv->device;
  CUresult cuda_ret;
  gint can_access = 0;

  cuda_ret = CuDeviceCanAccessPeer (&can_access, device, other_dev);

  if (!gst_cuda_result (cuda_ret) || !can_access) {
    GST_DEBUG_OBJECT (context,
        "Peer access to %" GST_PTR_FORMAT " is not allowed", peer);
    return;
  }

  gst_cuda_context_push (context);
  if (gst_cuda_result (CuCtxEnablePeerAccess (peer_priv->context, 0))) {
    GST_DEBUG_OBJECT (context, "Enable peer access to %" GST_PTR_FORMAT, peer);
    g_hash_table_add (priv->accessible_peer, peer);
  }

  gst_cuda_context_pop (NULL);
}

static void
gst_cuda_context_weak_ref_notify (gpointer data, GstCudaContext * context)
{
  GList *iter;

  G_LOCK (list_lock);
  context_list = g_list_remove (context_list, context);

  /* disable self -> peer access */
  if (context->priv->accessible_peer) {
    GHashTableIter iter;
    gpointer key;
    g_hash_table_iter_init (&iter, context->priv->accessible_peer);
    if (gst_cuda_context_push (context)) {
      while (g_hash_table_iter_next (&iter, &key, NULL)) {
        GstCudaContext *peer = GST_CUDA_CONTEXT (key);
        CUcontext peer_handle = gst_cuda_context_get_handle (peer);
        GST_DEBUG_OBJECT (context,
            "Disable peer access to %" GST_PTR_FORMAT, peer);
        gst_cuda_result (CuCtxDisablePeerAccess (peer_handle));
      }
      gst_cuda_context_pop (NULL);
    }

    g_hash_table_destroy (context->priv->accessible_peer);
    context->priv->accessible_peer = NULL;
  }

  /* disable peer -> self access */
  for (iter = context_list; iter; iter = g_list_next (iter)) {
    GstCudaContext *other = (GstCudaContext *) iter->data;
    GstCudaContextPrivate *other_priv = other->priv;
    CUcontext self_handle;

    if (!other_priv->accessible_peer)
      continue;

    if (g_hash_table_lookup (other_priv->accessible_peer, context)) {
      if (gst_cuda_context_push (other)) {
        self_handle = gst_cuda_context_get_handle (context);
        GST_DEBUG_OBJECT (other,
            "Disable peer access to %" GST_PTR_FORMAT, context);
        gst_cuda_result (CuCtxDisablePeerAccess (self_handle));
        gst_cuda_context_pop (NULL);
      }

      g_hash_table_remove (other_priv->accessible_peer, context);
    }
  }
  G_UNLOCK (list_lock);
}

static void
gst_cuda_context_finalize (GObject * object)
{
  GstCudaContext *context = GST_CUDA_CONTEXT_CAST (object);
  GstCudaContextPrivate *priv = context->priv;

  if (priv->context) {
    GST_DEBUG_OBJECT (context, "Destroying CUDA context %p", priv->context);
    gst_cuda_result (CuCtxDestroy (priv->context));
  }

  G_OBJECT_CLASS (parent_class)->finalize (object);
}

/**
 * gst_cuda_context_new:
 * @device_id: device-id for creating #GstCudaContext
 *
 * Create #GstCudaContext with given device_id
 *
 * Returns: a new #GstCudaContext or %NULL on failure
 */
GstCudaContext *
gst_cuda_context_new (guint device_id)
{
  GstCudaContext *self =
      g_object_new (GST_TYPE_CUDA_CONTEXT, "cuda-device-id", device_id, NULL);

  gst_object_ref_sink (self);

  if (!self->priv->context) {
    GST_ERROR ("Failed to create CUDA context");
    gst_clear_object (&self);
  }

  return self;
}

/**
 * gst_cuda_context_push:
 * @ctx: a #GstCudaContext to push current thread
 *
 * Pushes the given @ctx onto the CPU thread's stack of current contexts.
 * The specified context becomes the CPU thread's current context,
 * so all CUDA functions that operate on the current context are affected.
 *
 * Returns: %TRUE if @ctx was pushed without error.
 */
gboolean
gst_cuda_context_push (GstCudaContext * ctx)
{
  g_return_val_if_fail (ctx, FALSE);
  g_return_val_if_fail (GST_IS_CUDA_CONTEXT (ctx), FALSE);

  return gst_cuda_result (CuCtxPushCurrent (ctx->priv->context));
}

/**
 * gst_cuda_context_pop:
 *
 * Pops the current CUDA context from CPU thread
 *
 * Returns: %TRUE if @ctx was pushed without error.
 */
gboolean
gst_cuda_context_pop (CUcontext * cuda_ctx)
{
  return gst_cuda_result (CuCtxPopCurrent (cuda_ctx));
}

/**
 * gst_cuda_context_get_handle:
 * @ctx: a #GstCudaContext
 *
 * Get CUDA device context. Caller must not modify and/or destroy
 * returned device context.
 *
 * Returns: the #CUcontext of @ctx
 */
gpointer
gst_cuda_context_get_handle (GstCudaContext * ctx)
{
  g_return_val_if_fail (ctx, NULL);
  g_return_val_if_fail (GST_IS_CUDA_CONTEXT (ctx), NULL);

  return ctx->priv->context;
}

/**
 * gst_cuda_context_get_texture_alignment:
 * @ctx: a #GstCudaContext
 *
 * Get required texture alignment by device
 *
 * Returns: the #CUcontext of @ctx
 */
gint
gst_cuda_context_get_texture_alignment (GstCudaContext * ctx)
{
  g_return_val_if_fail (ctx, 0);
  g_return_val_if_fail (GST_IS_CUDA_CONTEXT (ctx), 0);

  return ctx->priv->tex_align;
}

/**
 * gst_cuda_context_can_access_peer:
 * @ctx: a #GstCudaContext
 * @peer: a #GstCudaContext
 *
 * Query whether @ctx can access any memory which belongs to @peer directly.

 * Returns: %TRUE if @ctx can access @peer directly
 */
gboolean
gst_cuda_context_can_access_peer (GstCudaContext * ctx, GstCudaContext * peer)
{
  gboolean ret = FALSE;

  g_return_val_if_fail (GST_IS_CUDA_CONTEXT (ctx), FALSE);
  g_return_val_if_fail (GST_IS_CUDA_CONTEXT (peer), FALSE);

  G_LOCK (list_lock);
  if (ctx->priv->accessible_peer &&
      g_hash_table_lookup (ctx->priv->accessible_peer, peer)) {
    ret = TRUE;
  }
  G_UNLOCK (list_lock);

  return ret;
}