/*
 * Copyright 2013 Dart project authors.
 * 
 * Licensed under the Eclipse Public License v1.0 (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.eclipse.org/legal/epl-v10.html
 * 
 * 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.dart.tools.core.snapshot;

import com.google.dart.engine.element.LibraryElement;
import com.google.dart.tools.core.DartCore;

import org.eclipse.core.resources.IFile;
import org.eclipse.core.resources.ResourcesPlugin;
import org.eclipse.core.runtime.IStatus;
import org.eclipse.core.runtime.Status;

import java.io.File;

/**
 * This class uses the {@link SnapshotCompiler} class to automatically recompile Dart snapshots if
 * any of the referenced source has changed.
 * 
 * @see SnapshotCompiler
 * @coverage dart.tools.core
 */
public class SnapshotCompilationServer {

  private final File sourceFile;

  /**
   * Create a compilation server which can recompile the given Dart source file.
   * 
   * @param sourceFile
   */
  public SnapshotCompilationServer(File sourceFile) {
    if (!DartCore.isDartLikeFileName(sourceFile.getName())) {
      throw new IllegalArgumentException("expected dart file");
    }

    this.sourceFile = sourceFile;
  }

  /**
   * Check if a re-compilation is necessary and perform the recompile.
   * 
   * @return
   */
  public IStatus compile() {
    if (needsRecompilation()) {
      return performCompile();
    }

    return Status.OK_STATUS;
  }

  /**
   * @return the destination snapshot file
   */
  public File getDestFile() {
    return SnapshotCompiler.createDestFileName(getSourceFile());
  }

  /**
   * @return the source Dart file
   */
  public File getSourceFile() {
    return sourceFile;
  }

  /**
   * Return whether the snapshot file needs to be recompiled (i.e., if any of its source files are
   * newer then it).
   * <p>
   * The compile() method will call this automatically.
   * 
   * @return whether the snapshot file needs to be recompiled
   */
  public boolean needsRecompilation() {
    if (!getDestFile().exists()) {
      return true;
    }

    if (!getSourceFile().exists()) {
      return false;
    }

    IFile[] resources = ResourcesPlugin.getWorkspace().getRoot().findFilesForLocationURI(
        sourceFile.toURI());

    if (resources.length > 0) {
      IFile file = resources[0];

      LibraryElement library = DartCore.getProjectManager().getLibraryElement(file);

      if (library == null) {
        return true;
      } else {
        return !library.isUpToDate(getDestFile().lastModified());
      }

    }

    return false;
  }

  protected IStatus performCompile() {
    SnapshotCompiler compiler = new SnapshotCompiler();

    return compiler.compile(getSourceFile(), getDestFile());
  }

}