// Copyright 2019 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 SRC_UI_LIB_ESCHER_RENDERER_RENDER_FUNCS_H_
#define SRC_UI_LIB_ESCHER_RENDERER_RENDER_FUNCS_H_

#include "src/ui/lib/escher/forward_declarations.h"
#include "src/ui/lib/escher/renderer/frame.h"
#include "src/ui/lib/escher/renderer/uniform_binding.h"
#include "src/ui/lib/escher/vk/command_buffer.h"

#include <vulkan/vulkan.hpp>

namespace escher {

struct RenderQueueContext;
struct RenderQueueItem;

class RenderFuncs {
 public:
  // Struct to hold vertex index data.  Typically allocated as per-frame RenderQueue data.
  struct IndexBinding {
    vk::Buffer index_buffer;
    vk::IndexType index_type;
    uint64_t index_buffer_offset;

    void Bind(CommandBuffer* cb) const {
      cb->BindIndices(index_buffer, index_buffer_offset, index_type);
    }
  };

  // Struct to hold vertex buffer data.  Typically allocated as per-frame RenderQueue data.
  struct VertexBinding {
    uint32_t binding_index;
    vk::Buffer buffer;
    uint64_t offset;
    uint32_t stride;

    void Bind(CommandBuffer* cb) const { cb->BindVertices(binding_index, buffer, offset, stride); }
  };

  // Struct to hold vertex attribute data.  Typically allocated as per-frame RenderQueue data.
  struct VertexAttributeBinding {
    uint32_t binding_index;
    uint32_t attribute_index;
    vk::Format format;
    uint32_t offset;

    void Bind(CommandBuffer* cb) const {
      cb->SetVertexAttributes(binding_index, attribute_index, format, offset);
    }

    void Bind(CommandBufferPipelineState* cbps) const {
      cbps->SetVertexAttributes(binding_index, attribute_index, format, offset);
    }
  };

  // Allocates and initializes a temporary array of VertexAttributeBindings, one for each attribute
  // defined by |mesh_spec|.  This array is valid until the next time that |allocator| is reset.
  //
  // The caller must ensure that |mesh_spec.total_attribute_count()| == |total_attribute_count|.
  // This is passed as an arg because:
  //   - it involves non-negligible bit-shifting to compute
  //   - high-frequency callers will already know the count, e.g. |PaperRenderFuncs::MeshData()|.
  static RenderFuncs::VertexAttributeBinding* NewVertexAttributeBindings(
      const MeshAttributeBindingLocations& attribute_binding_locations, BlockAllocator* allocator,
      const MeshSpec& mesh_spec, uint32_t total_attribute_count);

  // Called in PaperRenderer::BeginFrame() to obtain suitable render targets.
  static void ObtainDepthAndMsaaTextures(Escher* escher, const FramePtr& frame, uint32_t width,
                                         uint32_t height, uint32_t sample_count,
                                         bool use_transient_attachment,
                                         vk::Format depth_stencil_format, vk::Format msaa_format,
                                         TexturePtr& depth_texture_inout,
                                         TexturePtr& msaa_texture_inout);

  // Updates or replaces the passed in depth texture (depth_texture_in_out) based on the provided
  // ImageInfo and vk::Format. If the texture pointer is null, a new texture will be allocated.
  static void ObtainDepthTexture(Escher* escher, const bool use_protected_memory,
                                 const ImageInfo& info, vk::Format depth_stencil_format,
                                 TexturePtr& depth_texture_in_out);
};

}  // namespace escher

#endif  // SRC_UI_LIB_ESCHER_RENDERER_RENDER_FUNCS_H_