// Copyright 2021 The Tint Authors.
//
// 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 "src/val/val.h"

#include "src/ast/module.h"
#include "src/program.h"
#include "src/utils/io/command.h"
#include "src/utils/io/tmpfile.h"

#ifdef _WIN32
#include <Windows.h>
#include <d3dcommon.h>
#include <d3dcompiler.h>

#include <wrl.h>
using Microsoft::WRL::ComPtr;
#endif  // _WIN32

namespace tint {
namespace val {

Result HlslUsingDXC(const std::string& dxc_path,
                    const std::string& source,
                    Program* program) {
  Result result;

  auto dxc = utils::Command(dxc_path);
  if (!dxc.Found()) {
    result.output = "DXC not found at '" + std::string(dxc_path) + "'";
    result.failed = true;
    return result;
  }

  result.source = source;

  utils::TmpFile file;
  file << source;

  bool found_an_entrypoint = false;
  for (auto* func : program->AST().Functions()) {
    if (func->IsEntryPoint()) {
      found_an_entrypoint = true;

      const char* profile = "";

      switch (func->pipeline_stage()) {
        case ast::PipelineStage::kNone:
          result.output = "Invalid PipelineStage";
          result.failed = true;
          return result;
        case ast::PipelineStage::kVertex:
          profile = "-T vs_6_0";
          break;
        case ast::PipelineStage::kFragment:
          profile = "-T ps_6_0";
          break;
        case ast::PipelineStage::kCompute:
          profile = "-T cs_6_0";
          break;
      }

      auto name = program->Symbols().NameFor(func->symbol());
      auto res = dxc(profile, "-E " + name, file.Path());
      if (!res.out.empty()) {
        if (!result.output.empty()) {
          result.output += "\n";
        }
        result.output += res.out;
      }
      if (!res.err.empty()) {
        if (!result.output.empty()) {
          result.output += "\n";
        }
        result.output += res.err;
      }
      result.failed = (res.error_code != 0);
    }
  }

  if (!found_an_entrypoint) {
    result.output = "No entrypoint found";
    result.failed = true;
    return result;
  }

  return result;
}

#ifdef _WIN32
Result HlslUsingFXC(const std::string& source, Program* program) {
  Result result;

  // This library leaks if an error happens in this function, but it is ok
  // because it is loaded at most once, and the executables using HlslUsingFXC
  // are short-lived.
  HMODULE fxcLib = LoadLibraryA("d3dcompiler_47.dll");
  if (fxcLib == nullptr) {
    result.output = "Couldn't load FXC";
    result.failed = true;
    return result;
  }

  pD3DCompile d3dCompile =
      reinterpret_cast<pD3DCompile>(GetProcAddress(fxcLib, "D3DCompile"));
  if (d3dCompile == nullptr) {
    result.output = "Couldn't load D3DCompile from FXC";
    result.failed = true;
    return result;
  }

  result.source = source;

  bool found_an_entrypoint = false;
  for (auto* func : program->AST().Functions()) {
    if (func->IsEntryPoint()) {
      found_an_entrypoint = true;

      const char* profile = "";
      switch (func->pipeline_stage()) {
        case ast::PipelineStage::kNone:
          result.output = "Invalid PipelineStage";
          result.failed = true;
          return result;
        case ast::PipelineStage::kVertex:
          profile = "vs_5_1";
          break;
        case ast::PipelineStage::kFragment:
          profile = "ps_5_1";
          break;
        case ast::PipelineStage::kCompute:
          profile = "cs_5_1";
          break;
      }

      auto name = program->Symbols().NameFor(func->symbol());

      ComPtr<ID3DBlob> compiledShader;
      ComPtr<ID3DBlob> errors;
      if (FAILED(d3dCompile(source.c_str(), source.length(), nullptr, nullptr,
                            nullptr, name.c_str(), profile, 0, 0,
                            &compiledShader, &errors))) {
        result.output = static_cast<char*>(errors->GetBufferPointer());
        result.failed = true;
        return result;
      }
    }
  }

  FreeLibrary(fxcLib);

  if (!found_an_entrypoint) {
    result.output = "No entrypoint found";
    result.failed = true;
    return result;
  }

  return result;
}
#endif  // _WIN32

}  // namespace val
}  // namespace tint