/*
 * 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.haskell;

import com.facebook.buck.io.ProjectFilesystem;
import com.facebook.buck.model.BuildTarget;
import com.facebook.buck.model.BuildTargets;
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.args.Arg;
import com.facebook.buck.shell.ShellStep;
import com.facebook.buck.step.ExecutionContext;
import com.facebook.buck.step.Step;
import com.facebook.buck.step.fs.MakeCleanDirectoryStep;
import com.facebook.buck.util.MoreIterables;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableMap;
import com.google.common.collect.Iterables;
import java.nio.file.Path;

public class HaskellLinkRule extends AbstractBuildRule {

  @AddToRuleKey private final Tool linker;

  @AddToRuleKey private final String name;

  @AddToRuleKey private final ImmutableList<Arg> args;

  @AddToRuleKey private final ImmutableList<Arg> linkerArgs;

  private final boolean cacheable;

  public HaskellLinkRule(
      BuildRuleParams buildRuleParams,
      Tool linker,
      String name,
      ImmutableList<Arg> args,
      ImmutableList<Arg> linkerArgs,
      boolean cacheable) {
    super(buildRuleParams);
    this.linker = linker;
    this.name = name;
    this.args = args;
    this.linkerArgs = linkerArgs;
    this.cacheable = cacheable;
  }

  protected static Path getOutputDir(BuildTarget target, ProjectFilesystem filesystem) {
    return BuildTargets.getGenPath(filesystem, target, "%s");
  }

  private Path getOutput() {
    return getOutputDir(getBuildTarget(), getProjectFilesystem()).resolve(name);
  }

  @Override
  public ImmutableList<Step> getBuildSteps(
      BuildContext buildContext, BuildableContext buildableContext) {
    buildableContext.recordArtifact(getOutput());
    return new ImmutableList.Builder<Step>()
        .addAll(
            MakeCleanDirectoryStep.of(
                getProjectFilesystem(), getOutputDir(getBuildTarget(), getProjectFilesystem())))
        .add(
            new ShellStep(getProjectFilesystem().getRootPath()) {

              @Override
              public ImmutableMap<String, String> getEnvironmentVariables(
                  ExecutionContext context) {
                return ImmutableMap.<String, String>builder()
                    .putAll(super.getEnvironmentVariables(context))
                    .putAll(linker.getEnvironment(buildContext.getSourcePathResolver()))
                    .build();
              }

              @Override
              protected ImmutableList<String> getShellCommandInternal(ExecutionContext context) {
                return ImmutableList.<String>builder()
                    .addAll(linker.getCommandPrefix(buildContext.getSourcePathResolver()))
                    .add("-o", getProjectFilesystem().resolve(getOutput()).toString())
                    .addAll(Arg.stringify(args, buildContext.getSourcePathResolver()))
                    .addAll(
                        MoreIterables.zipAndConcat(
                            Iterables.cycle("-optl"),
                            Arg.stringify(linkerArgs, buildContext.getSourcePathResolver())))
                    .build();
              }

              @Override
              public String getShortName() {
                return "haskell-link";
              }
            })
        .build();
  }

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

  @Override
  public boolean isCacheable() {
    return cacheable;
  }
}