// Copyright 2000-2020 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
package com.intellij.xml.util;

import com.intellij.codeInspection.*;
import com.intellij.lang.Language;
import com.intellij.lang.html.HTMLLanguage;
import com.intellij.lang.xhtml.XHTMLLanguage;
import com.intellij.openapi.project.Project;
import com.intellij.openapi.util.text.StringUtil;
import com.intellij.psi.PsiElement;
import com.intellij.psi.PsiElementVisitor;
import com.intellij.psi.XmlElementVisitor;
import com.intellij.psi.html.HtmlTag;
import com.intellij.psi.templateLanguages.OuterLanguageElement;
import com.intellij.psi.tree.IElementType;
import com.intellij.psi.xml.XmlChildRole;
import com.intellij.psi.xml.XmlTag;
import com.intellij.psi.xml.XmlToken;
import com.intellij.psi.xml.XmlTokenType;
import com.intellij.xml.XmlExtension;
import com.intellij.xml.analysis.XmlAnalysisBundle;
import org.jetbrains.annotations.NonNls;
import org.jetbrains.annotations.NotNull;

import java.util.Set;

import static com.intellij.xml.util.XmlUtil.isNotInjectedOrCustomHtmlFile;

/**
 * @author Maxim Mossienko
 */
public class CheckEmptyTagInspection extends XmlSuppressableInspectionTool {
  @NonNls private static final Set<String> ourTagsWithEmptyEndsNotAllowed =
    Set.of(HtmlUtil.SCRIPT_TAG_NAME, "div", "iframe");

  @Override
  public boolean isEnabledByDefault() {
    return true;
  }

  @Override
  @NotNull
  public PsiElementVisitor buildVisitor(@NotNull final ProblemsHolder holder, boolean isOnTheFly) {
    return new XmlElementVisitor() {
      @Override
      public void visitXmlTag(final @NotNull XmlTag tag) {
        if (XmlExtension.shouldIgnoreSelfClosingTag(tag) || !isTagWithEmptyEndNotAllowed(tag)) {
          return;
        }

        if (XmlChildRole.EMPTY_TAG_END_FINDER.findChild(tag.getNode()) == null || !tagIsWellFormed(tag)) {
          return;
        }

        ProblemHighlightType type = isNotInjectedOrCustomHtmlFile(tag.getContainingFile())
                                    ? ProblemHighlightType.GENERIC_ERROR_OR_WARNING
                                    : ProblemHighlightType.INFORMATION;
        // should not report INFORMATION in batch mode
        if (isOnTheFly || type != ProblemHighlightType.INFORMATION) {
          holder.registerProblem(tag,
                                 XmlAnalysisBundle.message("html.inspections.check.empty.script.message"),
                                 type,
                                 new MyLocalQuickFix());
        }
      }
    };
  }

  public static boolean isTagWithEmptyEndNotAllowed(final XmlTag tag) {
    String tagName = tag.getName();
    if (tag instanceof HtmlTag) tagName = StringUtil.toLowerCase(tagName);

    Language language = tag.getLanguage();
    return ourTagsWithEmptyEndsNotAllowed.contains(tagName) &&
           (language.isKindOf(HTMLLanguage.INSTANCE) || language.isKindOf(XHTMLLanguage.INSTANCE)) ||

           (language.isKindOf(HTMLLanguage.INSTANCE) &&
            !HtmlUtil.isSingleHtmlTag(tag, false) &&
            tagName.indexOf(':') == -1 &&
            !XmlExtension.isCollapsible(tag));
  }

  @Override
  @NotNull
  @NonNls
  public String getShortName() {
    return "CheckEmptyScriptTag";
  }

  public static boolean tagIsWellFormed(XmlTag tag) {
    boolean ok = false;
    final PsiElement[] children = tag.getChildren();
    for (PsiElement child : children) {
      if (child instanceof XmlToken) {
        final IElementType tokenType = ((XmlToken)child).getTokenType();
        if (tokenType.equals(XmlTokenType.XML_EMPTY_ELEMENT_END) &&
            "/>".equals(child.getText())) {
          ok = true;
        }
        else if (tokenType.equals(XmlTokenType.XML_END_TAG_START)) {
          ok = true;
        }
      }
      else if (child instanceof OuterLanguageElement) {
        return false;
      }
    }

    return ok;
  }

  private static class MyLocalQuickFix implements LocalQuickFix {
    @Override
    @NotNull
    public String getFamilyName() {
      return XmlAnalysisBundle.message("html.inspections.check.empty.script.tag.fix.message");
    }

    @Override
    public void applyFix(@NotNull Project project, @NotNull ProblemDescriptor descriptor) {
      final XmlTag tag = (XmlTag)descriptor.getPsiElement();
      if (tag == null) return;
      XmlUtil.expandTag(tag);
    }
  }
}
