/*
 * Copyright 2016-present Facebook, Inc.
 *
 * 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.facebook.buck.cxx;

import com.facebook.buck.model.BuildTarget;
import com.facebook.buck.model.Flavor;
import com.facebook.buck.model.InternalFlavor;
import com.facebook.buck.rules.AbstractBuildRule;
import com.facebook.buck.rules.AddToRuleKey;
import com.facebook.buck.rules.BuildContext;
import com.facebook.buck.rules.BuildRuleParams;
import com.facebook.buck.rules.BuildableContext;
import com.facebook.buck.rules.ExplicitBuildTargetSourcePath;
import com.facebook.buck.rules.SourcePath;
import com.facebook.buck.rules.Tool;
import com.facebook.buck.rules.keys.SupportsInputBasedRuleKey;
import com.facebook.buck.step.Step;
import com.facebook.buck.step.fs.CopyStep;
import com.google.common.base.Preconditions;
import com.google.common.collect.ImmutableList;
import java.nio.file.Path;
import java.util.Optional;

/**
 * Controls how strip tool is invoked. To have better understanding please refer to `man strip`. If
 * you don't want stripping, you should depend on CxxLink directly.
 */
public class CxxStrip extends AbstractBuildRule implements SupportsInputBasedRuleKey {

  /**
   * Used to identify this rule in the graph. This should be appended ONLY to build target that is
   * passed to the CxxStrip constructor when you create instance of this class. Appending it in
   * other places is does nothing except adds a unnecessary flavor that will skew output paths of
   * other build rules.
   */
  public static final Flavor RULE_FLAVOR = InternalFlavor.of("stripped");

  @AddToRuleKey private final StripStyle stripStyle;
  @AddToRuleKey private final SourcePath cxxLinkSourcePath;
  @AddToRuleKey private final Tool strip;

  @AddToRuleKey(stringify = true)
  private final Path output;

  public CxxStrip(
      BuildRuleParams buildRuleParams,
      StripStyle stripStyle,
      SourcePath cxxLinkSourcePath,
      Tool strip,
      Path output) {
    super(buildRuleParams);
    this.stripStyle = stripStyle;
    this.cxxLinkSourcePath = cxxLinkSourcePath;
    this.strip = strip;
    this.output = output;
    performChecks(buildRuleParams.getBuildTarget());
  }

  private void performChecks(BuildTarget buildTarget) {
    Preconditions.checkArgument(
        buildTarget.getFlavors().contains(RULE_FLAVOR),
        "CxxStrip rule %s should contain %s flavor",
        this,
        RULE_FLAVOR);
    Preconditions.checkArgument(
        StripStyle.FLAVOR_DOMAIN.containsAnyOf(buildTarget.getFlavors()),
        "CxxStrip rule %s should contain one of the strip style flavors (%s)",
        this,
        StripStyle.FLAVOR_DOMAIN.getFlavors());
  }

  public static BuildRuleParams removeStripStyleFlavorInParams(
      BuildRuleParams params, Optional<StripStyle> flavoredStripStyle) {
    params = params.withoutFlavor(CxxStrip.RULE_FLAVOR);
    if (flavoredStripStyle.isPresent()) {
      params = params.withoutFlavor(flavoredStripStyle.get().getFlavor());
    }
    return params;
  }

  public static BuildRuleParams restoreStripStyleFlavorInParams(
      BuildRuleParams params, Optional<StripStyle> flavoredStripStyle) {
    if (flavoredStripStyle.isPresent()) {
      // we should not append CxxStrip.RULE_FLAVOR here because it must be appended
      // to CxxStrip rule only. Other users of CxxStrip flavors must not append it.
      params = params.withAppendedFlavor(flavoredStripStyle.get().getFlavor());
    }
    return params;
  }

  @Override
  public ImmutableList<Step> getBuildSteps(
      BuildContext context, BuildableContext buildableContext) {
    buildableContext.recordArtifact(output);
    return ImmutableList.of(
        CopyStep.forFile(
            getProjectFilesystem(),
            context.getSourcePathResolver().getAbsolutePath(cxxLinkSourcePath),
            output),
        new StripSymbolsStep(
            output,
            strip.getCommandPrefix(context.getSourcePathResolver()),
            strip.getEnvironment(context.getSourcePathResolver()),
            stripStyle.getStripToolArgs(),
            getProjectFilesystem()));
  }

  public StripStyle getStripStyle() {
    return stripStyle;
  }

  @Override
  public SourcePath getSourcePathToOutput() {
    return new ExplicitBuildTargetSourcePath(getBuildTarget(), output);
  }
}