/*
 * Copyright 2011-2013 Blender Foundation
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include <sstream>
#include <stdlib.h>

#include "device/device.h"
#include "device/device_intern.h"
#include "device/device_network.h"

#include "render/buffers.h"

#include "util/util_foreach.h"
#include "util/util_list.h"
#include "util/util_logging.h"
#include "util/util_map.h"
#include "util/util_time.h"

CCL_NAMESPACE_BEGIN

class MultiDevice : public Device {
 public:
  struct SubDevice {
    Stats stats;
    Device *device;
    map<device_ptr, device_ptr> ptr_map;
    int peer_island_index = -1;
  };

  list<SubDevice> devices, denoising_devices;
  device_ptr unique_key;
  vector<vector<SubDevice *>> peer_islands;
  bool matching_rendering_and_denoising_devices;

  MultiDevice(DeviceInfo &info, Stats &stats, Profiler &profiler, bool background_)
      : Device(info, stats, profiler, background_), unique_key(1)
  {
    foreach (DeviceInfo &subinfo, info.multi_devices) {
      /* Always add CPU devices at the back since GPU devices can change
       * host memory pointers, which CPU uses as device pointer. */
      SubDevice *sub;
      if (subinfo.type == DEVICE_CPU) {
        devices.emplace_back();
        sub = &devices.back();
      }
      else {
        devices.emplace_front();
        sub = &devices.front();
      }

      /* The pointer to 'sub->stats' will stay valid even after new devices
       * are added, since 'devices' is a linked list. */
      sub->device = Device::create(subinfo, sub->stats, profiler, background);
    }

    foreach (DeviceInfo &subinfo, info.denoising_devices) {
      denoising_devices.emplace_front();
      SubDevice *sub = &denoising_devices.front();

      sub->device = Device::create(subinfo, sub->stats, profiler, background);
    }

    /* Build a list of peer islands for the available render devices */
    foreach (SubDevice &sub, devices) {
      /* First ensure that every device is in at least once peer island */
      if (sub.peer_island_index < 0) {
        peer_islands.emplace_back();
        sub.peer_island_index = (int)peer_islands.size() - 1;
        peer_islands[sub.peer_island_index].push_back(&sub);
      }

      if (!info.has_peer_memory) {
        continue;
      }

      /* Second check peer access between devices and fill up the islands accordingly */
      foreach (SubDevice &peer_sub, devices) {
        if (peer_sub.peer_island_index < 0 &&
            peer_sub.device->info.type == sub.device->info.type &&
            peer_sub.device->check_peer_access(sub.device)) {
          peer_sub.peer_island_index = sub.peer_island_index;
          peer_islands[sub.peer_island_index].push_back(&peer_sub);
        }
      }
    }

    /* Try to re-use memory when denoising and render devices use the same physical devices
     * (e.g. OptiX denoising and CUDA rendering device pointing to the same GPU).
     * Ordering has to match as well, so that 'DeviceTask::split' behaves consistent. */
    matching_rendering_and_denoising_devices = denoising_devices.empty() ||
                                               (devices.size() == denoising_devices.size());
    if (matching_rendering_and_denoising_devices) {
      for (list<SubDevice>::iterator device_it = devices.begin(),
                                     denoising_device_it = denoising_devices.begin();
           device_it != devices.end() && denoising_device_it != denoising_devices.end();
           ++device_it, ++denoising_device_it) {
        const DeviceInfo &info = device_it->device->info;
        const DeviceInfo &denoising_info = denoising_device_it->device->info;
        if ((info.type != DEVICE_CUDA && info.type != DEVICE_OPTIX) ||
            (denoising_info.type != DEVICE_CUDA && denoising_info.type != DEVICE_OPTIX) ||
            info.num != denoising_info.num) {
          matching_rendering_and_denoising_devices = false;
          break;
        }
      }
    }

#ifdef WITH_NETWORK
    /* try to add network devices */
    ServerDiscovery discovery(true);
    time_sleep(1.0);

    vector<string> servers = discovery.get_server_list();

    foreach (string &server, servers) {
      Device *device = device_network_create(info, stats, profiler, server.c_str());
      if (device)
        devices.push_back(SubDevice(device));
    }
#endif
  }

  ~MultiDevice()
  {
    foreach (SubDevice &sub, devices)
      delete sub.device;
    foreach (SubDevice &sub, denoising_devices)
      delete sub.device;
  }

  const string &error_message()
  {
    error_msg.clear();

    foreach (SubDevice &sub, devices)
      error_msg += sub.device->error_message();
    foreach (SubDevice &sub, denoising_devices)
      error_msg += sub.device->error_message();

    return error_msg;
  }

  virtual bool show_samples() const
  {
    if (devices.size() > 1) {
      return false;
    }
    return devices.front().device->show_samples();
  }

  virtual BVHLayoutMask get_bvh_layout_mask() const
  {
    BVHLayoutMask bvh_layout_mask = BVH_LAYOUT_ALL;
    foreach (const SubDevice &sub_device, devices) {
      bvh_layout_mask &= sub_device.device->get_bvh_layout_mask();
    }
    return bvh_layout_mask;
  }

  bool load_kernels(const DeviceRequestedFeatures &requested_features)
  {
    foreach (SubDevice &sub, devices)
      if (!sub.device->load_kernels(requested_features))
        return false;

    if (requested_features.use_denoising) {
      /* Only need denoising feature, everything else is unused. */
      DeviceRequestedFeatures denoising_features;
      denoising_features.use_denoising = true;
      foreach (SubDevice &sub, denoising_devices)
        if (!sub.device->load_kernels(denoising_features))
          return false;
    }

    return true;
  }

  bool wait_for_availability(const DeviceRequestedFeatures &requested_features)
  {
    foreach (SubDevice &sub, devices)
      if (!sub.device->wait_for_availability(requested_features))
        return false;

    if (requested_features.use_denoising) {
      foreach (SubDevice &sub, denoising_devices)
        if (!sub.device->wait_for_availability(requested_features))
          return false;
    }

    return true;
  }

  DeviceKernelStatus get_active_kernel_switch_state()
  {
    DeviceKernelStatus result = DEVICE_KERNEL_USING_FEATURE_KERNEL;

    foreach (SubDevice &sub, devices) {
      DeviceKernelStatus subresult = sub.device->get_active_kernel_switch_state();
      switch (subresult) {
        case DEVICE_KERNEL_WAITING_FOR_FEATURE_KERNEL:
          result = subresult;
          break;

        case DEVICE_KERNEL_FEATURE_KERNEL_INVALID:
        case DEVICE_KERNEL_FEATURE_KERNEL_AVAILABLE:
          return subresult;

        case DEVICE_KERNEL_USING_FEATURE_KERNEL:
        case DEVICE_KERNEL_UNKNOWN:
          break;
      }
    }

    return result;
  }

  bool build_optix_bvh(BVH *bvh)
  {
    /* Broadcast acceleration structure build to all render devices */
    foreach (SubDevice &sub, devices) {
      if (!sub.device->build_optix_bvh(bvh))
        return false;
    }
    return true;
  }

  virtual void *bvh_device() const
  {
    /* CPU devices will always be at the back, so simply choose the last one.
       There should only ever be one CPU device anyway and we need the Embree device for it. */
    return devices.back().device->bvh_device();
  }

  virtual void *osl_memory()
  {
    if (devices.size() > 1) {
      return NULL;
    }
    return devices.front().device->osl_memory();
  }

  bool is_resident(device_ptr key, Device *sub_device)
  {
    foreach (SubDevice &sub, devices) {
      if (sub.device == sub_device) {
        return find_matching_mem_device(key, sub)->device == sub_device;
      }
    }
    return false;
  }

  SubDevice *find_matching_mem_device(device_ptr key, SubDevice &sub)
  {
    assert(key != 0 && (sub.peer_island_index >= 0 || sub.ptr_map.find(key) != sub.ptr_map.end()));

    /* Get the memory owner of this key (first try current device, then peer devices) */
    SubDevice *owner_sub = &sub;
    if (owner_sub->ptr_map.find(key) == owner_sub->ptr_map.end()) {
      foreach (SubDevice *island_sub, peer_islands[sub.peer_island_index]) {
        if (island_sub != owner_sub &&
            island_sub->ptr_map.find(key) != island_sub->ptr_map.end()) {
          owner_sub = island_sub;
        }
      }
    }
    return owner_sub;
  }

  SubDevice *find_suitable_mem_device(device_ptr key, const vector<SubDevice *> &island)
  {
    assert(!island.empty());

    /* Get the memory owner of this key or the device with the lowest memory usage when new */
    SubDevice *owner_sub = island.front();
    foreach (SubDevice *island_sub, island) {
      if (key ? (island_sub->ptr_map.find(key) != island_sub->ptr_map.end()) :
                (island_sub->device->stats.mem_used < owner_sub->device->stats.mem_used)) {
        owner_sub = island_sub;
      }
    }
    return owner_sub;
  }

  inline device_ptr find_matching_mem(device_ptr key, SubDevice &sub)
  {
    return find_matching_mem_device(key, sub)->ptr_map[key];
  }

  void mem_alloc(device_memory &mem)
  {
    device_ptr key = unique_key++;

    if (mem.type == MEM_PIXELS) {
      /* Always allocate pixels memory on all devices
       * This is necessary to ensure PBOs are registered everywhere, which FILM_CONVERT uses */
      foreach (SubDevice &sub, devices) {
        mem.device = sub.device;
        mem.device_pointer = 0;
        mem.device_size = 0;

        sub.device->mem_alloc(mem);
        sub.ptr_map[key] = mem.device_pointer;
      }
    }
    else {
      assert(mem.type == MEM_READ_ONLY || mem.type == MEM_READ_WRITE ||
             mem.type == MEM_DEVICE_ONLY);
      /* The remaining memory types can be distributed across devices */
      foreach (const vector<SubDevice *> &island, peer_islands) {
        SubDevice *owner_sub = find_suitable_mem_device(key, island);
        mem.device = owner_sub->device;
        mem.device_pointer = 0;
        mem.device_size = 0;

        owner_sub->device->mem_alloc(mem);
        owner_sub->ptr_map[key] = mem.device_pointer;
      }
    }

    mem.device = this;
    mem.device_pointer = key;
    stats.mem_alloc(mem.device_size);
  }

  void mem_copy_to(device_memory &mem)
  {
    device_ptr existing_key = mem.device_pointer;
    device_ptr key = (existing_key) ? existing_key : unique_key++;
    size_t existing_size = mem.device_size;

    /* The tile buffers are allocated on each device (see below), so copy to all of them */
    if (strcmp(mem.name, "RenderBuffers") == 0) {
      foreach (SubDevice &sub, devices) {
        mem.device = sub.device;
        mem.device_pointer = (existing_key) ? sub.ptr_map[existing_key] : 0;
        mem.device_size = existing_size;

        sub.device->mem_copy_to(mem);
        sub.ptr_map[key] = mem.device_pointer;
      }
    }
    else {
      foreach (const vector<SubDevice *> &island, peer_islands) {
        SubDevice *owner_sub = find_suitable_mem_device(existing_key, island);
        mem.device = owner_sub->device;
        mem.device_pointer = (existing_key) ? owner_sub->ptr_map[existing_key] : 0;
        mem.device_size = existing_size;

        owner_sub->device->mem_copy_to(mem);
        owner_sub->ptr_map[key] = mem.device_pointer;

        if (mem.type == MEM_GLOBAL || mem.type == MEM_TEXTURE) {
          /* Need to create texture objects and update pointer in kernel globals on all devices */
          foreach (SubDevice *island_sub, island) {
            if (island_sub != owner_sub) {
              island_sub->device->mem_copy_to(mem);
            }
          }
        }
      }
    }

    mem.device = this;
    mem.device_pointer = key;
    stats.mem_alloc(mem.device_size - existing_size);
  }

  void mem_copy_from(device_memory &mem, int y, int w, int h, int elem)
  {
    device_ptr key = mem.device_pointer;
    int i = 0, sub_h = h / devices.size();

    foreach (SubDevice &sub, devices) {
      int sy = y + i * sub_h;
      int sh = (i == (int)devices.size() - 1) ? h - sub_h * i : sub_h;

      SubDevice *owner_sub = find_matching_mem_device(key, sub);
      mem.device = owner_sub->device;
      mem.device_pointer = owner_sub->ptr_map[key];

      owner_sub->device->mem_copy_from(mem, sy, w, sh, elem);
      i++;
    }

    mem.device = this;
    mem.device_pointer = key;
  }

  void mem_zero(device_memory &mem)
  {
    device_ptr existing_key = mem.device_pointer;
    device_ptr key = (existing_key) ? existing_key : unique_key++;
    size_t existing_size = mem.device_size;

    /* This is a hack to only allocate the tile buffers on denoising devices
     * Similarly the tile buffers also need to be allocated separately on all devices so any
     * overlap rendered for denoising does not interfere with each other */
    if (strcmp(mem.name, "RenderBuffers") == 0) {
      vector<device_ptr> device_pointers;
      device_pointers.reserve(devices.size());

      foreach (SubDevice &sub, devices) {
        mem.device = sub.device;
        mem.device_pointer = (existing_key) ? sub.ptr_map[existing_key] : 0;
        mem.device_size = existing_size;

        sub.device->mem_zero(mem);
        sub.ptr_map[key] = mem.device_pointer;

        device_pointers.push_back(mem.device_pointer);
      }
      foreach (SubDevice &sub, denoising_devices) {
        if (matching_rendering_and_denoising_devices) {
          sub.ptr_map[key] = device_pointers.front();
          device_pointers.erase(device_pointers.begin());
        }
        else {
          mem.device = sub.device;
          mem.device_pointer = (existing_key) ? sub.ptr_map[existing_key] : 0;
          mem.device_size = existing_size;

          sub.device->mem_zero(mem);
          sub.ptr_map[key] = mem.device_pointer;
        }
      }
    }
    else {
      foreach (const vector<SubDevice *> &island, peer_islands) {
        SubDevice *owner_sub = find_suitable_mem_device(existing_key, island);
        mem.device = owner_sub->device;
        mem.device_pointer = (existing_key) ? owner_sub->ptr_map[existing_key] : 0;
        mem.device_size = existing_size;

        owner_sub->device->mem_zero(mem);
        owner_sub->ptr_map[key] = mem.device_pointer;
      }
    }

    mem.device = this;
    mem.device_pointer = key;
    stats.mem_alloc(mem.device_size - existing_size);
  }

  void mem_free(device_memory &mem)
  {
    device_ptr key = mem.device_pointer;
    size_t existing_size = mem.device_size;

    /* Free memory that was allocated for all devices (see above) on each device */
    if (strcmp(mem.name, "RenderBuffers") == 0 || mem.type == MEM_PIXELS) {
      foreach (SubDevice &sub, devices) {
        mem.device = sub.device;
        mem.device_pointer = sub.ptr_map[key];
        mem.device_size = existing_size;

        sub.device->mem_free(mem);
        sub.ptr_map.erase(sub.ptr_map.find(key));
      }
      foreach (SubDevice &sub, denoising_devices) {
        if (matching_rendering_and_denoising_devices) {
          sub.ptr_map.erase(key);
        }
        else {
          mem.device = sub.device;
          mem.device_pointer = sub.ptr_map[key];
          mem.device_size = existing_size;

          sub.device->mem_free(mem);
          sub.ptr_map.erase(sub.ptr_map.find(key));
        }
      }
    }
    else {
      foreach (const vector<SubDevice *> &island, peer_islands) {
        SubDevice *owner_sub = find_matching_mem_device(key, *island.front());
        mem.device = owner_sub->device;
        mem.device_pointer = owner_sub->ptr_map[key];
        mem.device_size = existing_size;

        owner_sub->device->mem_free(mem);
        owner_sub->ptr_map.erase(owner_sub->ptr_map.find(key));

        if (mem.type == MEM_TEXTURE) {
          /* Free texture objects on all devices */
          foreach (SubDevice *island_sub, island) {
            if (island_sub != owner_sub) {
              island_sub->device->mem_free(mem);
            }
          }
        }
      }
    }

    mem.device = this;
    mem.device_pointer = 0;
    mem.device_size = 0;
    stats.mem_free(existing_size);
  }

  void const_copy_to(const char *name, void *host, size_t size)
  {
    foreach (SubDevice &sub, devices)
      sub.device->const_copy_to(name, host, size);
  }

  void draw_pixels(device_memory &rgba,
                   int y,
                   int w,
                   int h,
                   int width,
                   int height,
                   int dx,
                   int dy,
                   int dw,
                   int dh,
                   bool transparent,
                   const DeviceDrawParams &draw_params)
  {
    assert(rgba.type == MEM_PIXELS);

    device_ptr key = rgba.device_pointer;
    int i = 0, sub_h = h / devices.size();
    int sub_height = height / devices.size();

    foreach (SubDevice &sub, devices) {
      int sy = y + i * sub_h;
      int sh = (i == (int)devices.size() - 1) ? h - sub_h * i : sub_h;
      int sheight = (i == (int)devices.size() - 1) ? height - sub_height * i : sub_height;
      int sdy = dy + i * sub_height;
      /* adjust math for w/width */

      rgba.device_pointer = sub.ptr_map[key];
      sub.device->draw_pixels(
          rgba, sy, w, sh, width, sheight, dx, sdy, dw, dh, transparent, draw_params);
      i++;
    }

    rgba.device_pointer = key;
  }

  void map_tile(Device *sub_device, RenderTile &tile)
  {
    if (!tile.buffer) {
      return;
    }

    foreach (SubDevice &sub, devices) {
      if (sub.device == sub_device) {
        tile.buffer = find_matching_mem(tile.buffer, sub);
        return;
      }
    }

    foreach (SubDevice &sub, denoising_devices) {
      if (sub.device == sub_device) {
        tile.buffer = sub.ptr_map[tile.buffer];
        return;
      }
    }
  }

  int device_number(Device *sub_device)
  {
    int i = 0;

    foreach (SubDevice &sub, devices) {
      if (sub.device == sub_device)
        return i;
      i++;
    }

    foreach (SubDevice &sub, denoising_devices) {
      if (sub.device == sub_device)
        return i;
      i++;
    }

    return -1;
  }

  void map_neighbor_tiles(Device *sub_device, RenderTileNeighbors &neighbors)
  {
    for (int i = 0; i < RenderTileNeighbors::SIZE; i++) {
      RenderTile &tile = neighbors.tiles[i];

      if (!tile.buffers) {
        continue;
      }

      device_vector<float> &mem = tile.buffers->buffer;
      tile.buffer = mem.device_pointer;

      if (mem.device == this && matching_rendering_and_denoising_devices) {
        /* Skip unnecessary copies in viewport mode (buffer covers the
         * whole image), but still need to fix up the tile device pointer. */
        map_tile(sub_device, tile);
        continue;
      }

      /* If the tile was rendered on another device, copy its memory to
       * to the current device now, for the duration of the denoising task.
       * Note that this temporarily modifies the RenderBuffers and calls
       * the device, so this function is not thread safe. */
      if (mem.device != sub_device) {
        /* Only copy from device to host once. This is faster, but
         * also required for the case where a CPU thread is denoising
         * a tile rendered on the GPU. In that case we have to avoid
         * overwriting the buffer being de-noised by the CPU thread. */
        if (!tile.buffers->map_neighbor_copied) {
          tile.buffers->map_neighbor_copied = true;
          mem.copy_from_device();
        }

        if (mem.device == this) {
          /* Can re-use memory if tile is already allocated on the sub device. */
          map_tile(sub_device, tile);
          mem.swap_device(sub_device, mem.device_size, tile.buffer);
        }
        else {
          mem.swap_device(sub_device, 0, 0);
        }

        mem.copy_to_device();

        tile.buffer = mem.device_pointer;
        tile.device_size = mem.device_size;

        mem.restore_device();
      }
    }
  }

  void unmap_neighbor_tiles(Device *sub_device, RenderTileNeighbors &neighbors)
  {
    RenderTile &target_tile = neighbors.target;
    device_vector<float> &mem = target_tile.buffers->buffer;

    if (mem.device == this && matching_rendering_and_denoising_devices) {
      return;
    }

    /* Copy denoised result back to the host. */
    mem.swap_device(sub_device, target_tile.device_size, target_tile.buffer);
    mem.copy_from_device();
    mem.restore_device();

    /* Copy denoised result to the original device. */
    mem.copy_to_device();

    for (int i = 0; i < RenderTileNeighbors::SIZE; i++) {
      RenderTile &tile = neighbors.tiles[i];
      if (!tile.buffers) {
        continue;
      }

      device_vector<float> &mem = tile.buffers->buffer;

      if (mem.device != sub_device && mem.device != this) {
        /* Free up memory again if it was allocated for the copy above. */
        mem.swap_device(sub_device, tile.device_size, tile.buffer);
        sub_device->mem_free(mem);
        mem.restore_device();
      }
    }
  }

  int get_split_task_count(DeviceTask &task)
  {
    int total_tasks = 0;
    list<DeviceTask> tasks;
    task.split(tasks, devices.size());
    foreach (SubDevice &sub, devices) {
      if (!tasks.empty()) {
        DeviceTask subtask = tasks.front();
        tasks.pop_front();

        total_tasks += sub.device->get_split_task_count(subtask);
      }
    }
    return total_tasks;
  }

  void task_add(DeviceTask &task)
  {
    list<SubDevice> task_devices = devices;
    if (!denoising_devices.empty()) {
      if (task.type == DeviceTask::DENOISE_BUFFER) {
        /* Denoising tasks should be redirected to the denoising devices entirely. */
        task_devices = denoising_devices;
      }
      else if (task.type == DeviceTask::RENDER && (task.tile_types & RenderTile::DENOISE)) {
        const uint tile_types = task.tile_types;
        /* For normal rendering tasks only redirect the denoising part to the denoising devices.
         * Do not need to split the task here, since they all run through 'acquire_tile'. */
        task.tile_types = RenderTile::DENOISE;
        foreach (SubDevice &sub, denoising_devices) {
          sub.device->task_add(task);
        }
        /* Rendering itself should still be executed on the rendering devices. */
        task.tile_types = tile_types ^ RenderTile::DENOISE;
      }
    }

    list<DeviceTask> tasks;
    task.split(tasks, task_devices.size());

    foreach (SubDevice &sub, task_devices) {
      if (!tasks.empty()) {
        DeviceTask subtask = tasks.front();
        tasks.pop_front();

        if (task.buffer)
          subtask.buffer = find_matching_mem(task.buffer, sub);
        if (task.rgba_byte)
          subtask.rgba_byte = sub.ptr_map[task.rgba_byte];
        if (task.rgba_half)
          subtask.rgba_half = sub.ptr_map[task.rgba_half];
        if (task.shader_input)
          subtask.shader_input = find_matching_mem(task.shader_input, sub);
        if (task.shader_output)
          subtask.shader_output = find_matching_mem(task.shader_output, sub);

        sub.device->task_add(subtask);

        if (task.buffers && task.buffers->buffer.device == this) {
          /* Synchronize access to RenderBuffers, since 'map_neighbor_tiles' is not thread-safe. */
          sub.device->task_wait();
        }
      }
    }
  }

  void task_wait()
  {
    foreach (SubDevice &sub, devices)
      sub.device->task_wait();
    foreach (SubDevice &sub, denoising_devices)
      sub.device->task_wait();
  }

  void task_cancel()
  {
    foreach (SubDevice &sub, devices)
      sub.device->task_cancel();
    foreach (SubDevice &sub, denoising_devices)
      sub.device->task_cancel();
  }
};

Device *device_multi_create(DeviceInfo &info, Stats &stats, Profiler &profiler, bool background)
{
  return new MultiDevice(info, stats, profiler, background);
}

CCL_NAMESPACE_END