/*
 * Copyright © 2024-2026 Apple Inc. and the Pkl project 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
 *
 *     https://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 org.pkl.gradle.task;

import static org.pkl.gradle.utils.PluginUtils.mapAndGetOrNull;

import java.io.File;
import java.util.Collections;
import java.util.Set;
import java.util.concurrent.Callable;
import javax.annotation.Nullable;
import org.gradle.api.file.DirectoryProperty;
import org.gradle.api.file.FileCollection;
import org.gradle.api.file.RegularFileProperty;
import org.gradle.api.provider.Property;
import org.gradle.api.tasks.CacheableTask;
import org.gradle.api.tasks.Input;
import org.gradle.api.tasks.Internal;
import org.gradle.api.tasks.Optional;
import org.gradle.api.tasks.OutputDirectories;
import org.gradle.api.tasks.OutputFiles;
import org.pkl.cli.CliEvaluator;
import org.pkl.cli.CliEvaluatorOptions;

@CacheableTask
public abstract class EvalTask extends ModulesTask {

  // not tracked because it might contain placeholders
  // required
  @Internal
  public abstract RegularFileProperty getOutputFile();

  // not tracked because it might contain placeholders
  // optional
  @Internal
  public abstract DirectoryProperty getMultipleFileOutputDir();

  @Input
  public abstract Property<String> getOutputFormat();

  @Input
  public abstract Property<String> getModuleOutputSeparator();

  @Input
  @Optional
  public abstract Property<String> getExpression();

  private CliEvaluator createCliEvaluator() {
    return new CliEvaluator(
        new CliEvaluatorOptions(
            getCliBaseOptions(),
            getOutputFile().get().getAsFile().getAbsolutePath(),
            getOutputFormat().get(),
            getModuleOutputSeparator().get(),
            mapAndGetOrNull(getMultipleFileOutputDir(), it -> it.getAsFile().getAbsolutePath()),
            getExpression().getOrNull()));
  }

  @SuppressWarnings("unused")
  @OutputFiles
  @Optional
  public FileCollection getEffectiveOutputFiles() {
    return getObjects()
        .fileCollection()
        .from(
            getProviders()
                .provider(
                    () ->
                        exceptionToEmpty(
                            () -> nullToEmpty(createCliEvaluator().getOutputFiles()))));
  }

  @OutputDirectories
  @Optional
  public FileCollection getEffectiveOutputDirs() {
    return getObjects()
        .fileCollection()
        .from(
            getProviders()
                .provider(
                    () ->
                        exceptionToEmpty(
                            () -> nullToEmpty(createCliEvaluator().getOutputDirectories()))));
  }

  private static <T> Set<T> nullToEmpty(@Nullable Set<T> set) {
    return set == null ? Collections.emptySet() : set;
  }

  private static <T> Set<T> exceptionToEmpty(Callable<? extends Set<T>> provider) {
    try {
      return provider.call();
    } catch (Exception e) {
      return Collections.emptySet();
    }
  }

  @Override
  protected void doRunTask() {
    //noinspection ResultOfMethodCallIgnored
    getOutputs().getPreviousOutputFiles().forEach(File::delete);
    createCliEvaluator().run();
  }
}
