#pragma region CPL License
/*
Nuclex Native Framework
Copyright (C) 2002-2021 Nuclex Development Labs

This library is free software; you can redistribute it and/or
modify it under the terms of the IBM Common Public License as
published by the IBM Corporation; either version 1.0 of the
License, or (at your option) any later version.

This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
IBM Common Public License for more details.

You should have received a copy of the IBM Common Public
License along with this library
*/
#pragma endregion // CPL License

// If the library is compiled as a DLL, this ensures symbols are exported
#define NUCLEX_STORAGE_SOURCE 1

#include "StandardDirectoryResolver.h"

#if defined(NUCLEX_STORAGE_WIN32)

#include "../../Helpers/Utf8/checked.h"
#include "../../Helpers/WindowsApi.h"
#include "Nuclex/Support/Text/StringConverter.h"

#include <objbase.h> // for ::CoInitialize(), ::StringFromGUID2()
#include <comdef.h> // for _com_ptr_t and _COM_SMARTPTR_TYPEDEF

#include <vector> // for std::vector

/// <summary>Smart pointer for the known folder manager interface</summary>
_COM_SMARTPTR_TYPEDEF(IKnownFolderManager, IID_IKnownFolderManager);

/// <summary>Smart pointer for the interface to a known folder</summary>
_COM_SMARTPTR_TYPEDEF(IKnownFolder, IID_IKnownFolder);

using namespace Nuclex::Storage::Helpers;

namespace {

  // ------------------------------------------------------------------------------------------- //

  /// <summary>Initializes COM for the duration of the scope</summary>
  class ComScope {

    /// <summary>Initializes COM</summary>
    public: ComScope() :
      wasAlreadyInitialized(false) {

      // COM may have already been intiialized by the application using this library.
      // Redundant calls to CoInitialize() are okay (and need a matching call to
      // CoUninitialize(), too), unless another threading model was used, in which case
      // we can RPC_E_CHANGED_MODE (but that's fine, the threading model is irrelevant
      // for what we do)
      HRESULT resultHandle = ::CoInitialize(nullptr);
      if(FAILED(resultHandle)) {
        if(resultHandle == RPC_E_CHANGED_MODE) {
          this->wasAlreadyInitialized = true;
        } else {
          std::string errorMessage(u8"Could not initialize COM");
          Nuclex::Storage::Helpers::WindowsApi::ThrowExceptionForHResult(
            errorMessage, resultHandle
          );
        }
      }
    }

    /// <summary>Shuts down COM</summary>
    public: ~ComScope() {
      if(!this->wasAlreadyInitialized) {
        ::CoUninitialize();
      }
    }

    /// <summary>Set if CoInitialize() reported that COM was already initialized</summary>
    private: bool wasAlreadyInitialized;

  };

  // ------------------------------------------------------------------------------------------- //

  /// <summary>Releases COM task memory when the scope ends</summary>
  class ComTaskMemoryScope {

    /// <summary>Initializes a new COM task memory scope</summary>
    /// <param name="comTaskMemory">Memory the scope will free</param>
    public: ComTaskMemoryScope(void *comTaskMemory) :
      comTaskMemory(comTaskMemory) {}

    /// <summary>Shuts down COM</summary>
    public: ~ComTaskMemoryScope() {
      ::CoTaskMemFree(this->comTaskMemory);
    }

    /// <summary>COM task memory the scope will free</summary>
    private: void *comTaskMemory;

  };

  // ------------------------------------------------------------------------------------------- //

  /// <summary>Converts a known folder id GUID into a string</summary>
  /// <param name="knownFolderId">Known folder id GUID that will be converted</param
  /// <returns>A string representation of the specified GUID</returns>
  /// <remarks>
  ///   This is only used by error handling code and thus will return something
  ///   rather than throw even if Microsoft's string conversion function fails.
  /// </remarks>
  std::string stringFromKnownFolderId(const KNOWNFOLDERID &knownFolderId) {
    std::wstring buffer;
    buffer.resize(39);

    int result = ::StringFromGUID2(
      knownFolderId, buffer.data(), static_cast<int>(buffer.size())
    );
    if(result >= 1) {
      buffer.resize(static_cast<std::string::size_type>(result - 1));
      return Nuclex::Support::Text::StringConverter::Utf8FromWide(buffer);
    } else {
      DWORD errorCode = ::GetLastError();
      std::string errorMessage = u8"<StringFromGUID2() failed: ";
      errorMessage.append(WindowsApi::GetErrorMessage(errorCode));
      errorMessage.push_back('>');
      return errorMessage;
    }
  }

  // ------------------------------------------------------------------------------------------- //

  /// <summary>Fetches a path to a known folder from the known folder manager</summary>
  /// <param name="knownFolderManager">Known folder manager the path will be fetched from</param>
  /// <param name="knownFolderId">ID of the known folder that will be looked up</param>
  /// <returns>The path to the specified known folder</returns>
  std::wstring getFolderFromKnownFolderManager(
    const IKnownFolderManagerPtr &knownFolderManager, const KNOWNFOLDERID &knownFolderId
  ) {

    // Ask it for the known folder with the specified KNOWNFOLDERID value
    IKnownFolderPtr knownFolder;
    HRESULT resultHandle = knownFolderManager->GetFolder(knownFolderId, &knownFolder);
    if(FAILED(resultHandle)) {
      std::string errorMessage(u8"Could not query known folder ");
      errorMessage.append(stringFromKnownFolderId(knownFolderId));
      Nuclex::Storage::Helpers::WindowsApi::ThrowExceptionForHResult(errorMessage, resultHandle);
    }

    // Now that we've got the known folder object, ask it in turn to give us its path
    PWSTR knownFolderPath = nullptr;
    resultHandle = knownFolder->GetPath(0, &knownFolderPath);
    if(FAILED(resultHandle)) {
      std::string errorMessage(u8"Could not query path of known folder ");
      errorMessage.append(stringFromKnownFolderId(knownFolderId));
      Nuclex::Storage::Helpers::WindowsApi::ThrowExceptionForHResult(errorMessage, resultHandle);
    }

    // Success, but now we've been provided with a pointer to a string that has been
    // allocated via CoTaskMemAlloc() and we're responsible for freeing it, so copy it
    // into an std::string and then drop all that COM stuff.
    {
      ComTaskMemoryScope comTaskMemoryScope(knownFolderPath);
      return std::wstring(knownFolderPath);
    }

  }

  // ------------------------------------------------------------------------------------------- //

} // anonymous namespace

namespace Nuclex { namespace Storage { namespace FileSystem { namespace Windows {

  // ------------------------------------------------------------------------------------------- //

  std::string StandardDirectoryResolver::GetFolderPath(int csidl) {
    std::vector<wchar_t> directory(MAX_PATH);

    // MSDN states: "not supported"
    //BOOL result = ::SHGetSpecialFolderPathW(nullptr, &directory[0], csidl, create);

    // Ask for the folder
    HRESULT resultHandle = ::SHGetFolderPathW(
      nullptr, csidl, nullptr, SHGFP_TYPE_CURRENT, &directory[0]
    );
    if(FAILED(resultHandle)) {
      std::string errorMessage(u8"Could not obtain special folder path");
      Helpers::WindowsApi::ThrowExceptionForHResult(errorMessage, resultHandle);
    }

    return Nuclex::Support::Text::StringConverter::Utf8FromWide(std::wstring(&directory[0]));
  }

  // ------------------------------------------------------------------------------------------- //

  std::string StandardDirectoryResolver::GetKnownFolder(const KNOWNFOLDERID &knownFolderId) {
    {
      ComScope comScope;

      // Create a new instance of the "known folder manager" COM object which manages
      // (or at least looks up) the correct paths for special folders in Windows.
      IKnownFolderManagerPtr knownFolderManager;
      HRESULT resultHandle = knownFolderManager.CreateInstance(
        CLSID_KnownFolderManager, nullptr, CLSCTX_INPROC_SERVER
      );
      if(FAILED(resultHandle)) {
        std::string errorMessage(u8"Could not create instance of known folder manager");
        Helpers::WindowsApi::ThrowExceptionForHResult(errorMessage, resultHandle);
      }

      return Nuclex::Support::Text::StringConverter::Utf8FromWide(
        getFolderFromKnownFolderManager(knownFolderManager, knownFolderId)
      );
    } // COM initialization scope
  }

  // ------------------------------------------------------------------------------------------- //

  std::vector<std::string> StandardDirectoryResolver::GetMultipleKnownFolders(
    const std::vector<KNOWNFOLDERID> &knownFolderIds
  ) {
    std::vector<std::string> results;

    std::size_t requestedFolderCount = knownFolderIds.size();
    results.reserve(requestedFolderCount);

    // This API requires COM to be initialized for the process
    {
      ComScope comScope;

      // Create a new instance of the "known folder manager" COM object which manages
      // (or at least looks up) the correct paths for special folders in Windows.
      IKnownFolderManagerPtr knownFolderManager;
      HRESULT resultHandle = knownFolderManager.CreateInstance(
        CLSID_KnownFolderManager, nullptr, CLSCTX_INPROC_SERVER
      );
      if(FAILED(resultHandle)) {
        std::string errorMessage(u8"Could not create instance of known folder manager");
        Helpers::WindowsApi::ThrowExceptionForHResult(errorMessage, resultHandle);
      }

      // Now request each folder in succession
      for(std::size_t index = 0; index < requestedFolderCount; ++index) {
        results.push_back(
          Nuclex::Support::Text::StringConverter::Utf8FromWide(
            getFolderFromKnownFolderManager(knownFolderManager, knownFolderIds[index])
          )
        );
      }
    } // COM initialization scope

    return results;
  }

  // ------------------------------------------------------------------------------------------- //

}}}} // namespace Nuclex::Storage::FileSystem::Windows

#endif // defined(NUCLEX_STORAGE_WIN32)