/*
 * Copyright 2007 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.dom.struts.impl;

import com.intellij.openapi.util.Comparing;
import com.intellij.psi.ElementManipulators;
import com.intellij.psi.PsiElement;
import com.intellij.psi.PsiFile;
import com.intellij.psi.PsiReference;
import com.intellij.psi.impl.source.resolve.reference.impl.providers.FilePathReferenceProvider;
import com.intellij.psi.xml.XmlElement;
import com.intellij.psi.xml.XmlFile;
import com.intellij.struts2.dom.struts.IncludeFileResolvingConverter;
import com.intellij.struts2.dom.struts.model.StrutsManager;
import com.intellij.struts2.dom.struts.model.StrutsModel;
import com.intellij.util.xml.ConvertContext;
import com.intellij.util.xml.GenericDomValue;
import org.jetbrains.annotations.NonNls;
import org.jetbrains.annotations.NotNull;
import org.jetbrains.annotations.Nullable;

import java.util.Collection;
import java.util.Collections;
import java.util.Set;

/**
 * @author Gregory.Shrago
 * @author Yann Cébron
 */
public class IncludeFileResolvingConverterImpl extends IncludeFileResolvingConverter {

  public PsiFile fromString(@Nullable @NonNls final String value, final ConvertContext context) {
    if (value == null) {
      return null;
    }

    final XmlElement xmlElement = context.getReferenceXmlElement();
    if (xmlElement == null) {
      return null;
    }

    final PsiReference[] references = createReferences((GenericDomValue) context.getInvocationElement(),
                                                       xmlElement,
                                                       context);
    if (references.length == 0) {
      return null;
    }

    final PsiElement element = references[references.length - 1].resolve();
    return element instanceof PsiFile ? (PsiFile) element : null;
  }

  @NotNull
  public Collection<? extends PsiFile> getVariants(final ConvertContext context) {
    return Collections.emptyList();
  }

  public PsiElement resolve(final PsiFile psiFile, final ConvertContext context) {
    // recursive self-inclusion
    if (context.getFile().equals(psiFile)) {
      return null;
    }

    return isFileAccepted(psiFile) ? super.resolve(psiFile, context) : null;
  }

  @NotNull
  public PsiReference[] createReferences(@NotNull final GenericDomValue genericDomValue,
                                         @NotNull final PsiElement element,
                                         @NotNull final ConvertContext context) {
    final String s = genericDomValue.getStringValue();
    if (s == null) {
      return PsiReference.EMPTY_ARRAY;
    }

    final int offset = ElementManipulators.getOffsetInElement(element);
    return new FilePathReferenceProvider() {
      protected boolean isPsiElementAccepted(final PsiElement element) {
        return super.isPsiElementAccepted(element) &&
               (!(element instanceof PsiFile) || isFileAccepted((PsiFile) element));
      }
    }.getReferencesByElement(element, s, offset, true);
  }

  private static boolean isFileAccepted(@NotNull final PsiFile file) {
    if (file instanceof XmlFile) {
      final XmlFile xmlFile = (XmlFile) file;
      final StrutsModel model = StrutsManager.getInstance(file.getProject()).getModelByFile(xmlFile);
      if (model == null) {
        return false;
      }

      final Set<XmlFile> files = model.getConfigFiles();
      return files.contains(xmlFile);
    }

    return false;
  }

  public String getErrorMessage(@Nullable final String value, final ConvertContext context) {
    // check if user tries to include current file
    if (Comparing.equal(context.getFile().getName(), value)) {
      return "Recursive inclusion of current file";
    }

    // TODO check for cyclic include

    return "Cannot resolve file ''" + value + "'' (not included in file sets?)";
  }

}