/*
 * Copyright 2016 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.idea.blaze.base.projectview;

import com.google.common.collect.Lists;
import com.google.idea.blaze.base.projectview.parser.ProjectViewParser;
import com.intellij.openapi.diagnostic.Logger;
import com.intellij.openapi.project.Project;
import com.intellij.openapi.ui.Messages;

import java.io.File;
import java.io.IOException;
import java.util.List;

/**
 * Represents a modification to one or more project view files.
 */
public class ProjectViewEdit {

  private static final Logger LOG = Logger.getInstance(ProjectViewEdit.class);
  private final Project project;
  private final List<Modification> modifications;

  ProjectViewEdit(Project project, List<Modification> modifications) {
    this.project = project;
    this.modifications = modifications;
  }

  private static class Modification {
    ProjectView oldProjectView;
    ProjectView newProjectView;
    File projectViewFile;
  }

  /**
   * Creates a new edit that modifies all reachable project views in the project view set.
   */
  public static ProjectViewEdit editProjectViewSet(Project project, ProjectViewEditor editor) {
    ProjectViewSet oldProjectViewSet = ProjectViewManager.getInstance(project).getProjectViewSet();
    List<Modification> modifications = Lists.newArrayList();
    if (oldProjectViewSet != null) {
      for (ProjectViewSet.ProjectViewFile projectViewFile : oldProjectViewSet.getProjectViewFiles()) {
        ProjectView.Builder builder = ProjectView.builder(projectViewFile.projectView);
        if (editor.editProjectView(builder)) {
          Modification modification = new Modification();
          modification.newProjectView = builder.build();
          modification.oldProjectView = projectViewFile.projectView;
          modification.projectViewFile = projectViewFile.projectViewFile;
          modifications.add(modification);
        }
      }
    }
    return new ProjectViewEdit(project, modifications);
  }

  /**
   * Creates a new edit that modifies the local project view only.
   */
  public static ProjectViewEdit editLocalProjectView(Project project, ProjectViewEditor editor) {
    List<Modification> modifications = Lists.newArrayList();
    ProjectViewSet oldProjectViewSet = ProjectViewManager.getInstance(project).getProjectViewSet();
    if (oldProjectViewSet != null) {
      ProjectViewSet.ProjectViewFile projectViewFile = oldProjectViewSet.getTopLevelProjectViewFile();
      if (projectViewFile != null) {
        ProjectView.Builder builder = ProjectView.builder(projectViewFile.projectView);
        if (editor.editProjectView(builder)) {
          Modification modification = new Modification();
          modification.newProjectView = builder.build();
          modification.oldProjectView = projectViewFile.projectView;
          modification.projectViewFile = projectViewFile.projectViewFile;
          modifications.add(modification);
        }
      }
    }
    return new ProjectViewEdit(project, modifications);
  }

  public void apply() {
    apply(true);
  }

  public void undo() {
    apply(false);
  }

  private void apply(boolean isApply) {
    for (Modification modification : modifications) {
      ProjectView projectView = isApply ? modification.newProjectView : modification.oldProjectView;
      String projectViewText = ProjectViewParser.projectViewToString(projectView);
      try {
        ProjectViewStorageManager.getInstance().writeProjectView(projectViewText, modification.projectViewFile);
      }
      catch (IOException e) {
        LOG.error(e);
        Messages.showErrorDialog(
          project,
          "Could not write updated project view. Is the file write protected?",
          "Edit Failed");
      }
    }
  }

  public boolean hasModifications() {
    return !modifications.isEmpty();
  }

  public interface ProjectViewEditor {
    boolean editProjectView(ProjectView.Builder builder);
  }
}