/*
 * Copyright 2015 The authors
 * 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.intellij.struts2.facet.ui;

import com.intellij.openapi.module.Module;
import com.intellij.openapi.vfs.JarFileSystem;
import com.intellij.openapi.vfs.VirtualFile;
import com.intellij.psi.JavaPsiFacade;
import com.intellij.psi.PsiClass;
import com.intellij.psi.PsiFile;
import com.intellij.psi.search.GlobalSearchScope;
import com.intellij.struts2.facet.Struts2LibraryType;
import org.jetbrains.annotations.NotNull;
import org.jetbrains.annotations.Nullable;

import java.io.IOException;
import java.io.InputStream;
import java.util.Properties;

/**
 * Detects the Struts2 version from attached struts-2core.jar.
 *
 * @author Yann Cébron
 */
public class StrutsVersionDetector {
  private StrutsVersionDetector() {
  }

  @Nullable
  public static String detectStrutsVersion(@NotNull final Module module) {
    final VirtualFile jarRoot = getStrutsJarRoot(module);
    if (jarRoot == null) {
      return null;
    }

    final VirtualFile entry = jarRoot.findFileByRelativePath("META-INF/maven/org.apache.struts/struts2-core/pom.properties");
    if (entry == null) {
      return null;
    }

    try {
      final InputStream stream = entry.getInputStream();
      try {
        final Properties properties = new Properties();
        properties.load(stream);
        return properties.getProperty("version");
      }
      finally {
        stream.close();
      }
    }
    catch (IOException e) {
      return null;
    }
  }

  @Nullable
  private static VirtualFile getStrutsJarRoot(final Module module) {
    final GlobalSearchScope scope = GlobalSearchScope.moduleRuntimeScope(module, false);
    final JavaPsiFacade psiManager = JavaPsiFacade.getInstance(module.getProject());

    final VirtualFile virtualFile = getStrutsClass(scope, psiManager);
    if (virtualFile == null || !(virtualFile.getFileSystem() instanceof JarFileSystem)) {
      return null;
    }

    final VirtualFile jarFile = JarFileSystem.getInstance().getLocalVirtualFileFor(virtualFile);
    if (jarFile == null) {
      return null;
    }

    return JarFileSystem.getInstance().getJarRootForLocalFile(jarFile);
  }

  @Nullable
  private static VirtualFile getStrutsClass(final GlobalSearchScope scope, final JavaPsiFacade psiManager) {
    final PsiClass psiClass = psiManager.findClass(Struts2LibraryType.STRUTS_VERSION_CLASS, scope);
    if (psiClass == null) {
      return null;
    }

    final PsiFile psiFile = psiClass.getContainingFile();
    if (psiFile == null) {
      return null;
    }

    return psiFile.getVirtualFile();
  }
}