// Copyright 2013 The Flutter Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include <filesystem>
#include <system_error>

#include "flutter/fml/backtrace.h"
#include "flutter/fml/command_line.h"
#include "flutter/fml/file.h"
#include "flutter/fml/mapping.h"
#include "impeller/compiler/compiler.h"
#include "impeller/compiler/runtime_stage_data.h"
#include "impeller/compiler/shader_bundle.h"
#include "impeller/compiler/source_options.h"
#include "impeller/compiler/switches.h"
#include "impeller/compiler/types.h"
#include "impeller/compiler/utilities.h"

namespace impeller {
namespace compiler {

static Reflector::Options CreateReflectorOptions(const SourceOptions& options,
                                                 const Switches& switches) {
  Reflector::Options reflector_options;
  reflector_options.target_platform = options.target_platform;
  reflector_options.entry_point_name = options.entry_point_name;
  reflector_options.shader_name =
      InferShaderNameFromPath(switches.source_file_name);
  reflector_options.header_file_name = Utf8FromPath(
      std::filesystem::path{switches.reflection_header_name}.filename());
  return reflector_options;
}

/// Run the shader compiler to geneate SkSL reflection data.
/// If there is an error, prints error text and returns `nullptr`.
static std::shared_ptr<RuntimeStageData::Shader> CompileSkSL(
    std::shared_ptr<fml::Mapping> source_file_mapping,
    const Switches& switches) {
  auto options = switches.CreateSourceOptions(TargetPlatform::kSkSL);

  Reflector::Options sksl_reflector_options =
      CreateReflectorOptions(options, switches);
  sksl_reflector_options.target_platform = TargetPlatform::kSkSL;

  Compiler sksl_compiler =
      Compiler(std::move(source_file_mapping), options, sksl_reflector_options);
  if (!sksl_compiler.IsValid()) {
    std::cerr << "Compilation to SkSL failed." << std::endl;
    std::cerr << sksl_compiler.GetErrorMessages() << std::endl;
    return nullptr;
  }
  return sksl_compiler.GetReflector()->GetRuntimeStageShaderData();
}

static bool OutputIPLR(
    const Switches& switches,
    const std::shared_ptr<fml::Mapping>& source_file_mapping) {
  FML_DCHECK(switches.iplr);

  RuntimeStageData stages;
  std::shared_ptr<RuntimeStageData::Shader> sksl_shader;
  if (TargetPlatformBundlesSkSL(switches.SelectDefaultTargetPlatform())) {
    sksl_shader = CompileSkSL(source_file_mapping, switches);
    if (!sksl_shader) {
      return false;
    }
    stages.AddShader(sksl_shader);
  }

  for (const auto& platform : switches.PlatformsToCompile()) {
    if (platform == TargetPlatform::kSkSL) {
      // Already handled above.
      continue;
    }
    SourceOptions options = switches.CreateSourceOptions(platform);

    // Invoke the compiler and generate reflection data for a single shader.

    Reflector::Options reflector_options =
        CreateReflectorOptions(options, switches);
    Compiler compiler(source_file_mapping, options, reflector_options);
    if (!compiler.IsValid()) {
      std::cerr << "Compilation failed." << std::endl;
      std::cerr << compiler.GetErrorMessages() << std::endl;
      return false;
    }

    auto reflector = compiler.GetReflector();
    if (reflector == nullptr) {
      std::cerr << "Could not create reflector." << std::endl;
      return false;
    }

    auto stage_data = reflector->GetRuntimeStageShaderData();
    if (!stage_data) {
      std::cerr << "Runtime stage information was nil." << std::endl;
      return false;
    }

    stages.AddShader(stage_data);
  }

  auto stage_data_mapping = switches.json_format ? stages.CreateJsonMapping()
                                                 : stages.CreateMapping();
  if (!stage_data_mapping) {
    std::cerr << "Runtime stage data could not be created." << std::endl;
    return false;
  }
  if (!fml::WriteAtomically(*switches.working_directory,                  //
                            Utf8FromPath(switches.sl_file_name).c_str(),  //
                            *stage_data_mapping                           //
                            )) {
    std::cerr << "Could not write file to " << switches.sl_file_name
              << std::endl;
    return false;
  }
  // Tools that consume the runtime stage data expect the access mode to
  // be 0644.
  if (!SetPermissiveAccess(switches.sl_file_name)) {
    return false;
  }
  return true;
}

static bool OutputSLFile(const Compiler& compiler, const Switches& switches) {
  // --------------------------------------------------------------------------
  /// 2. Output the source file. When in IPLR/RuntimeStage mode, output the
  ///    serialized IPLR flatbuffer.
  ///

  auto sl_file_name = std::filesystem::absolute(
      std::filesystem::current_path() / switches.sl_file_name);
  if (!fml::WriteAtomically(*switches.working_directory,
                            Utf8FromPath(sl_file_name).c_str(),
                            *compiler.GetSLShaderSource())) {
    std::cerr << "Could not write file to " << switches.sl_file_name
              << std::endl;
    return false;
  }
  return true;
}

static bool OutputReflectionData(const Compiler& compiler,
                                 const Switches& switches,
                                 const SourceOptions& options) {
  // --------------------------------------------------------------------------
  /// 3. Output shader reflection data.
  ///    May include a JSON file, a C++ header, and/or a C++ TU.
  ///

  if (TargetPlatformNeedsReflection(options.target_platform)) {
    if (!switches.reflection_json_name.empty()) {
      auto reflection_json_name = std::filesystem::absolute(
          std::filesystem::current_path() / switches.reflection_json_name);
      if (!fml::WriteAtomically(
              *switches.working_directory,
              Utf8FromPath(reflection_json_name).c_str(),
              *compiler.GetReflector()->GetReflectionJSON())) {
        std::cerr << "Could not write reflection json to "
                  << switches.reflection_json_name << std::endl;
        return false;
      }
    }

    if (!switches.reflection_header_name.empty()) {
      auto reflection_header_name =
          std::filesystem::absolute(std::filesystem::current_path() /
                                    switches.reflection_header_name.c_str());
      if (!fml::WriteAtomically(
              *switches.working_directory,
              Utf8FromPath(reflection_header_name).c_str(),
              *compiler.GetReflector()->GetReflectionHeader())) {
        std::cerr << "Could not write reflection header to "
                  << switches.reflection_header_name << std::endl;
        return false;
      }
    }

    if (!switches.reflection_cc_name.empty()) {
      auto reflection_cc_name =
          std::filesystem::absolute(std::filesystem::current_path() /
                                    switches.reflection_cc_name.c_str());
      if (!fml::WriteAtomically(*switches.working_directory,
                                Utf8FromPath(reflection_cc_name).c_str(),
                                *compiler.GetReflector()->GetReflectionCC())) {
        std::cerr << "Could not write reflection CC to "
                  << switches.reflection_cc_name << std::endl;
        return false;
      }
    }
  }
  return true;
}

static bool OutputDepfile(const Compiler& compiler, const Switches& switches) {
  // --------------------------------------------------------------------------
  /// 4. Output a depfile.
  ///

  if (!switches.depfile_path.empty()) {
    std::string result_file;
    switch (switches.SelectDefaultTargetPlatform()) {
      case TargetPlatform::kMetalDesktop:
      case TargetPlatform::kMetalIOS:
      case TargetPlatform::kOpenGLES:
      case TargetPlatform::kOpenGLDesktop:
      case TargetPlatform::kRuntimeStageMetal:
      case TargetPlatform::kRuntimeStageGLES:
      case TargetPlatform::kRuntimeStageVulkan:
      case TargetPlatform::kSkSL:
      case TargetPlatform::kVulkan:
        result_file = switches.sl_file_name;
        break;
      case TargetPlatform::kUnknown:
        result_file = switches.spirv_file_name;
        break;
    }
    auto depfile_path = std::filesystem::absolute(
        std::filesystem::current_path() / switches.depfile_path.c_str());
    if (!fml::WriteAtomically(*switches.working_directory,
                              Utf8FromPath(depfile_path).c_str(),
                              *compiler.CreateDepfileContents({result_file}))) {
      std::cerr << "Could not write depfile to " << switches.depfile_path
                << std::endl;
      return false;
    }
  }

  return true;
}

bool Main(const fml::CommandLine& command_line) {
  fml::InstallCrashHandler();
  if (command_line.HasOption("help")) {
    Switches::PrintHelp(std::cout);
    return true;
  }

  Switches switches(command_line);
  if (!switches.AreValid(std::cerr)) {
    std::cerr << "Invalid flags specified." << std::endl;
    Switches::PrintHelp(std::cerr);
    return false;
  }

  if (!switches.shader_bundle.empty()) {
    // Invoke the compiler multiple times to build a shader bundle with the
    // given shader_bundle spec.
    return GenerateShaderBundle(switches);
  }

  std::shared_ptr<fml::FileMapping> source_file_mapping =
      fml::FileMapping::CreateReadOnly(switches.source_file_name);
  if (!source_file_mapping) {
    std::cerr << "Could not open input file." << std::endl;
    return false;
  }

  if (switches.iplr && !OutputIPLR(switches, source_file_mapping)) {
    return false;
  }

  // Create at least one compiler to output the SL file, reflection data, and a
  // depfile.
  // TODO(dnfield): This seems off. We should more explicitly handle how we
  // generate reflection and depfile data for the runtime stage case.
  // https://github.com/flutter/flutter/issues/140841

  SourceOptions options = switches.CreateSourceOptions();

  // Invoke the compiler and generate reflection data for a single shader.

  Reflector::Options reflector_options =
      CreateReflectorOptions(options, switches);

  Compiler compiler(source_file_mapping, options, reflector_options);
  if (!compiler.IsValid()) {
    std::cerr << "Compilation failed." << std::endl;
    std::cerr << compiler.GetErrorMessages() << std::endl;
    return false;
  }

  auto spriv_file_name = std::filesystem::absolute(
      std::filesystem::current_path() / switches.spirv_file_name);
  if (!fml::WriteAtomically(*switches.working_directory,
                            Utf8FromPath(spriv_file_name).c_str(),
                            *compiler.GetSPIRVAssembly())) {
    std::cerr << "Could not write file to " << switches.spirv_file_name
              << std::endl;
    return false;
  }

  if (!switches.iplr && !OutputSLFile(compiler, switches)) {
    return false;
  }

  if (!OutputReflectionData(compiler, switches, options)) {
    return false;
  }

  if (!OutputDepfile(compiler, switches)) {
    return false;
  }

  return true;
}

}  // namespace compiler
}  // namespace impeller

int main(int argc, char const* argv[]) {
  return impeller::compiler::Main(
             fml::CommandLineFromPlatformOrArgcArgv(argc, argv))
             ? EXIT_SUCCESS
             : EXIT_FAILURE;
}