//===- DependencyScanningWorker.cpp - Thread-Safe Scanning Worker ---------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//

#include "clang/DependencyScanning/DependencyScanningWorker.h"
#include "clang/Basic/Diagnostic.h"
#include "clang/Basic/DiagnosticFrontend.h"
#include "clang/DependencyScanning/DependencyConsumer.h"
#include "clang/DependencyScanning/DependencyScannerImpl.h"
#include "clang/Serialization/ObjectFilePCHContainerReader.h"
#include "llvm/ADT/IntrusiveRefCntPtr.h"
#include "llvm/Support/VirtualFileSystem.h"

using namespace clang;
using namespace dependencies;

DependencyScanningWorker::DependencyScanningWorker(
    DependencyScanningService &Service)
    : Service(Service) {
  PCHContainerOps = std::make_shared<PCHContainerOperations>();
  // We need to read object files from PCH built outside the scanner.
  PCHContainerOps->registerReader(
      std::make_unique<ObjectFilePCHContainerReader>());
  // The scanner itself writes only raw ast files.
  PCHContainerOps->registerWriter(std::make_unique<RawPCHContainerWriter>());

  auto BaseFS = Service.getOpts().MakeVFS();

  if (Service.getOpts().TraceVFS) {
    TracingFS = llvm::makeIntrusiveRefCnt<llvm::vfs::TracingFileSystem>(
        std::move(BaseFS));
    BaseFS = TracingFS;
  }

  DepFS = llvm::makeIntrusiveRefCnt<DependencyScanningWorkerFilesystem>(
      Service, std::move(BaseFS));
}

DependencyScanningWorker::~DependencyScanningWorker() = default;

static bool createAndRunToolInvocation(
    ArrayRef<std::string> CommandLine, DependencyScanningAction &Action,
    IntrusiveRefCntPtr<llvm::vfs::FileSystem> FS,
    std::shared_ptr<clang::PCHContainerOperations> &PCHContainerOps,
    DiagnosticsEngine &Diags) {
  auto Invocation = createCompilerInvocation(CommandLine, Diags);
  if (!Invocation)
    return false;

  return Action.runInvocation(CommandLine[0], std::move(Invocation),
                              std::move(FS), PCHContainerOps,
                              Diags.getClient());
}

IntrusiveRefCntPtr<llvm::vfs::FileSystem>
DependencyScanningWorker::makeEffectiveVFS(
    StringRef WorkingDirectory,
    IntrusiveRefCntPtr<llvm::vfs::FileSystem> OverlayFS) const {
  IntrusiveRefCntPtr<llvm::vfs::FileSystem> FS = DepFS;
  if (OverlayFS) {
    auto NewFS =
        llvm::makeIntrusiveRefCnt<llvm::vfs::OverlayFileSystem>(std::move(FS));
    NewFS->pushOverlay(std::move(OverlayFS));
    FS = std::move(NewFS);
  }
  FS->setCurrentWorkingDirectory(WorkingDirectory);
  return FS;
}

bool DependencyScanningWorker::computeDependencies(
    StringRef WorkingDirectory, ArrayRef<ArrayRef<std::string>> CommandLines,
    DependencyConsumer &DepConsumer, DependencyActionController &Controller,
    DiagnosticConsumer &DiagConsumer,
    IntrusiveRefCntPtr<llvm::vfs::FileSystem> OverlayFS) {
  auto FS = makeEffectiveVFS(WorkingDirectory, std::move(OverlayFS));

  DependencyScanningAction Action(Service, WorkingDirectory, DepConsumer,
                                  Controller, DepFS);

  const bool Success = llvm::all_of(CommandLines, [&](const auto &Cmd) {
    if (StringRef(Cmd[1]) != "-cc1") {
      // Non-clang command. Just pass through to the dependency consumer.
      DepConsumer.handleBuildCommand(
          {Cmd.front(), {Cmd.begin() + 1, Cmd.end()}});
      return true;
    }

    auto DiagEngineWithDiagOpts =
        DiagnosticsEngineWithDiagOpts(Cmd, FS, DiagConsumer);
    auto &Diags = *DiagEngineWithDiagOpts.DiagEngine;

    // Create an invocation that uses the underlying file system to ensure that
    // any file system requests that are made by the driver do not go through
    // the dependency scanning filesystem.
    return createAndRunToolInvocation(Cmd, Action, FS, PCHContainerOps, Diags);
  });

  return Success && Action.hasScanned();
}