/*
 * Copyright 2011 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.reference.jsp;

import com.intellij.codeInsight.daemon.EmptyResolveMessageProvider;
import com.intellij.codeInsight.lookup.LookupElement;
import com.intellij.codeInsight.lookup.LookupElementBuilder;
import com.intellij.openapi.module.ModuleUtil;
import com.intellij.openapi.util.Comparing;
import com.intellij.psi.*;
import com.intellij.psi.xml.XmlAttributeValue;
import com.intellij.psi.xml.XmlTag;
import com.intellij.struts2.dom.struts.model.StrutsManager;
import com.intellij.struts2.dom.struts.model.StrutsModel;
import com.intellij.struts2.dom.struts.strutspackage.StrutsPackage;
import com.intellij.util.ArrayUtil;
import com.intellij.util.Function;
import com.intellij.util.ProcessingContext;
import com.intellij.util.SmartList;
import com.intellij.util.containers.ContainerUtil;
import org.jetbrains.annotations.NotNull;

import java.util.List;

/**
 * Custom tags attribute "namespace".
 *
 * @author Yann Cébron
 */
public class NamespaceReferenceProvider extends PsiReferenceProvider {

  @NotNull
  public PsiReference[] getReferencesByElement(@NotNull final PsiElement psiElement,
                                               @NotNull final ProcessingContext context) {

    final StrutsManager strutsManager = StrutsManager.getInstance(psiElement.getProject());
    final StrutsModel strutsModel = strutsManager.getCombinedModel(ModuleUtil.findModuleForPsiElement(psiElement));
    if (strutsModel == null) {
      return PsiReference.EMPTY_ARRAY;
    }

    return new PsiReference[]{new NamespaceReference((XmlAttributeValue) psiElement, strutsModel)
    };
  }


  private static class NamespaceReference extends PsiReferenceBase.Poly<XmlAttributeValue>
      implements EmptyResolveMessageProvider {

    private static final Function<StrutsPackage, LookupElement> STRUTS_PACKAGE_LOOKUP_ELEMENT_FUNCTION =
        new Function<StrutsPackage, LookupElement>() {
          public LookupElement fun(final StrutsPackage strutsPackage) {
            return LookupElementBuilder.create(strutsPackage.getXmlTag(),
                                               strutsPackage.searchNamespace())
                                       .setTypeText(strutsPackage.getName().getStringValue());
          }
        };

    private final StrutsModel strutsModel;

    private NamespaceReference(final XmlAttributeValue psiElement, final StrutsModel strutsModel) {
      super(psiElement);
      this.strutsModel = strutsModel;
    }

    @NotNull
    public ResolveResult[] multiResolve(final boolean incompleteCode) {
      final String namespace = myElement.getValue();
      final List<ResolveResult> resolveResults = new SmartList<ResolveResult>();
      for (final StrutsPackage strutsPackage : strutsModel.getStrutsPackages()) {
        if (Comparing.equal(namespace, strutsPackage.searchNamespace())) {
          final XmlTag packageTag = strutsPackage.getXmlTag();
          assert packageTag != null;
          resolveResults.add(new PsiElementResolveResult(packageTag));
        }
      }
      return ArrayUtil.toObjectArray(resolveResults, ResolveResult.class);
    }

    @NotNull
    public Object[] getVariants() {
      return ContainerUtil.map2Array(strutsModel.getStrutsPackages(), LookupElement.class,
                                     STRUTS_PACKAGE_LOOKUP_ELEMENT_FUNCTION);
    }

    public String getUnresolvedMessagePattern() {
      return "Cannot resolve namespace ''" + getCanonicalText() + "''";
    }
  }

}