// Copyright 2018 The Bazel Authors. All rights reserved.
//
// 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.
package com.google.devtools.build.lib.includescanning;

import com.google.common.base.Preconditions;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.Sets;
import com.google.devtools.build.lib.actions.ActionExecutionContext;
import com.google.devtools.build.lib.actions.Artifact;
import com.google.devtools.build.lib.actions.Artifact.TreeFileArtifact;
import com.google.devtools.build.lib.actions.EnvironmentalExecException;
import com.google.devtools.build.lib.actions.ExecException;
import com.google.devtools.build.lib.actions.UserExecException;
import com.google.devtools.build.lib.profiler.Profiler;
import com.google.devtools.build.lib.profiler.ProfilerTask;
import com.google.devtools.build.lib.profiler.SilentCloseable;
import com.google.devtools.build.lib.rules.cpp.CppCompileAction;
import com.google.devtools.build.lib.rules.cpp.CppIncludeScanningContext;
import com.google.devtools.build.lib.rules.cpp.IncludeScanner;
import com.google.devtools.build.lib.rules.cpp.IncludeScanner.IncludeScanningHeaderData;
import com.google.devtools.build.lib.server.FailureDetails;
import com.google.devtools.build.lib.server.FailureDetails.FailureDetail;
import com.google.devtools.build.lib.server.FailureDetails.IncludeScanning.Code;
import com.google.devtools.build.lib.vfs.FileSystemUtils;
import com.google.devtools.build.lib.vfs.PathFragment;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Collection;
import java.util.LinkedHashSet;
import java.util.List;
import java.util.Set;
import java.util.function.Supplier;
import javax.annotation.Nullable;

/** Include scanning context implementation. */
public final class CppIncludeScanningContextImpl implements CppIncludeScanningContext {
  private final Supplier<IncludeScannerSupplier> includeScannerSupplier;

  public CppIncludeScanningContextImpl(Supplier<IncludeScannerSupplier> includeScannerSupplier) {
    this.includeScannerSupplier = includeScannerSupplier;
  }

  @Override
  @Nullable
  public List<Artifact> findAdditionalInputs(
      CppCompileAction action,
      ActionExecutionContext actionExecutionContext,
      IncludeScanningHeaderData includeScanningHeaderData)
      throws ExecException, InterruptedException {
    Preconditions.checkNotNull(includeScannerSupplier, action);

    Set<Artifact> includes = Sets.newConcurrentHashSet();
    includes.addAll(action.getBuiltInIncludeFiles());

    // Deduplicate include directories. This can occur especially with "built-in" and "system"
    // include directories because of the way we retrieve them. Duplicate include directories
    // really mess up #include_next directives.
    Set<PathFragment> includeDirs = new LinkedHashSet<>(action.getIncludeDirs());
    List<PathFragment> quoteIncludeDirs = action.getQuoteIncludeDirs();
    List<PathFragment> frameworkIncludeDirs = action.getFrameworkIncludeDirs();
    List<String> cmdlineIncludes = includeScanningHeaderData.getCmdlineIncludes();

    includeDirs.addAll(includeScanningHeaderData.getSystemIncludeDirs());

    // Add the system include paths to the list of include paths.
    List<PathFragment> absoluteBuiltInIncludeDirs = new ArrayList<>();
    for (PathFragment pathFragment : action.getBuiltInIncludeDirectories()) {
      if (pathFragment.isAbsolute()) {
        absoluteBuiltInIncludeDirs.add(pathFragment);
      }
      includeDirs.add(pathFragment);
    }

    List<PathFragment> includeDirList = ImmutableList.copyOf(includeDirs);
    IncludeScanner scanner =
        includeScannerSupplier
            .get()
            .scannerFor(quoteIncludeDirs, includeDirList, frameworkIncludeDirs);

    Artifact mainSource = action.getMainIncludeScannerSource();
    Collection<Artifact> sources = action.getIncludeScannerSources();

    try (SilentCloseable c =
        Profiler.instance()
            .profile(ProfilerTask.SCANNER, action.getSourceFile().getExecPathString())) {
      scanner.processAsync(
          mainSource,
          sources,
          includeScanningHeaderData,
          cmdlineIncludes,
          includes,
          action,
          actionExecutionContext,
          action.getGrepIncludes());
      if (actionExecutionContext.getEnvironmentForDiscoveringInputs().valuesMissing()) {
        return null;
      }
      return collect(actionExecutionContext, includes, absoluteBuiltInIncludeDirs);
    } catch (IOException e) {
      throw new EnvironmentalExecException(
          e, createFailureDetail("Include scanning IOException", Code.SCANNING_IO_EXCEPTION));
    }
  }

  private static List<Artifact> collect(
      ActionExecutionContext actionExecutionContext,
      Set<Artifact> includes,
      List<PathFragment> absoluteBuiltInIncludeDirs)
      throws ExecException {
    // Collect inputs and output
    List<Artifact> inputs = new ArrayList<>(includes.size());
    for (Artifact included : includes) {
      // Check for absolute includes -- we assign the file system root as
      // the root path for such includes
      if (included.getRoot().getRoot().isAbsolute()) {
        if (FileSystemUtils.startsWithAny(
            actionExecutionContext.getInputPath(included).asFragment(),
            absoluteBuiltInIncludeDirs)) {
          // Skip include files found in absolute include directories.
          continue;
        }
        throw new UserExecException(
            createFailureDetail(
                "illegal absolute path to include file: "
                    + actionExecutionContext.getInputPath(included),
                Code.ILLEGAL_ABSOLUTE_PATH));
      }
      if (included.hasParent() && included.getParent().isTreeArtifact()) {
        // Note that this means every file in the TreeArtifact becomes an input to the action, and
        // we have spurious rebuilds if non-included files change.
        Preconditions.checkArgument(
            included instanceof TreeFileArtifact, "Not a TreeFileArtifact: %s", included);
        inputs.add(included.getParent());
      } else {
        inputs.add(included);
      }
    }
    return inputs;
  }

  private static FailureDetail createFailureDetail(String message, Code detailedCode) {
    return FailureDetail.newBuilder()
        .setMessage(message)
        .setIncludeScanning(FailureDetails.IncludeScanning.newBuilder().setCode(detailedCode))
        .build();
  }
}