// Copyright 2017 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef GARNET_BIN_UI_SKETCHY_BUFFER_MESH_BUFFER_H_
#define GARNET_BIN_UI_SKETCHY_BUFFER_MESH_BUFFER_H_

#include <zx/event.h>
#include <unordered_map>

#include "garnet/bin/ui/sketchy/buffer/shared_buffer.h"
#include "garnet/bin/ui/sketchy/frame.h"
#include "lib/escher/geometry/bounding_box.h"
#include "lib/escher/renderer/semaphore.h"
#include "lib/escher/scene/shape_modifier.h"
#include "lib/escher/vk/buffer.h"

namespace sketchy_service {

// Manages the buffers and semaphores of the mesh for multi-buffering.
class MeshBuffer final {
 public:
  // Prepare the current mesh buffer given the delta vertex/index counts. If
  // the current capacity is not enough, a new buffer will be grabbed from the
  // pool, and the original content will be copied to the new one. This is
  // MUST be called for multi-buffering purpose. Delta vertex/index count is
  // more of optimization; they won't affect correctness.
  void Prepare(Frame* frame, bool from_scratch, uint32_t delta_vertex_count = 0,
               uint32_t delta_index_count = 0);

  // Reserve appropriately-sized regions within the underlying vertex/index
  // buffers, each of which will be resized automatically if not enough free
  // space is available.
  std::pair<escher::impl::BufferRange, escher::impl::BufferRange> Reserve(
      Frame* frame, uint32_t vertex_count, uint32_t index_count,
      const escher::BoundingBox& bbox);

  // Provide all the necessary parameters to
  // fuchsia::ui::gfx::Mesh::BindBuffers().
  void ProvideBuffersToScenicMesh(scenic::Mesh* scenic_mesh);

  const SharedBufferPtr& vertex_buffer() const { return vertex_buffer_; }
  const SharedBufferPtr& index_buffer() const { return index_buffer_; }
  uint32_t vertex_count() const { return vertex_count_; }

 private:
  // Replace the buffer with one that is large enough for |capacity_req|. If
  // |keep_content| is true, the original content will be copied. A fence
  // listener will be implicitly setup to monitor the scenic release event.
  void ReplaceBuffer(Frame* frame, SharedBufferPtr& shared_buffer,
                     vk::DeviceSize capacity_req, bool keep_content);

  SharedBufferPtr vertex_buffer_;
  SharedBufferPtr index_buffer_;
  uint32_t vertex_count_ = 0;
  uint32_t index_count_ = 0;
  escher::BoundingBox bbox_;
};

}  // namespace sketchy_service

#endif  // GARNET_BIN_UI_SKETCHY_BUFFER_MESH_BUFFER_H_