/*
 * Copyright (c) MuleSoft, Inc.  All rights reserved.  http://www.mulesoft.com
 * The software in this package is published under the terms of the CPAL v1.0
 * license, a copy of which has been included with this distribution in the
 * LICENSE.txt file.
 */
package org.mule.runtime.config.spring.parsers.processors;

import org.mule.runtime.config.spring.parsers.PreProcessor;
import org.mule.runtime.config.spring.parsers.assembly.configuration.PropertyConfiguration;
import org.mule.runtime.config.spring.util.SpringXMLUtils;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.HashSet;
import java.util.List;
import java.util.Set;

import org.w3c.dom.Attr;
import org.w3c.dom.Element;
import org.w3c.dom.NamedNodeMap;

/**
 * All attributes from at least one set must be provided
 */
public class CheckRequiredAttributes implements PreProcessor {

  Collection<List<String>> attributeSets;

  public CheckRequiredAttributes(String[][] attributeNames) {
    super();

    attributeSets = new ArrayList<List<String>>();
    for (int i = 0; i < attributeNames.length; i++) {
      String[] currentSet = attributeNames[i];
      if (currentSet.length > 0) {
        List<String> list = Arrays.asList(currentSet);
        attributeSets.add(list);
      }
    }
  }

  public void preProcess(PropertyConfiguration config, Element element) {
    for (List<String> currentSet : attributeSets) {
      if (containsAllRequiredAttributes(currentSet, element)) {
        return;
      }
    }

    throw new CheckRequiredAttributesException(element, attributeSets);
  }

  private boolean containsAllRequiredAttributes(List<String> currentSet, Element element) {
    Set<String> attributes = collectAttributes(element);
    if (attributes.size() == 0) {
      return false;
    }

    // Clone the set of attribute names and subtract all the element's attribute names from it.
    // If the remaining set is empty, all required attributes of this set were present.
    Set<String> remainingElementNames = new HashSet<String>(currentSet);
    remainingElementNames.removeAll(attributes);
    return (remainingElementNames.size() == 0);
  }

  private Set<String> collectAttributes(Element element) {
    Set<String> attributeNames = new HashSet<String>();

    NamedNodeMap attributes = element.getAttributes();
    for (int i = 0; i < attributes.getLength(); i++) {
      String alias = SpringXMLUtils.attributeName((Attr) attributes.item(i));
      attributeNames.add(alias);
    }

    return attributeNames;
  }

  public static class CheckRequiredAttributesException extends IllegalStateException {

    private static String summary(Collection<List<String>> attributeSets) {
      StringBuilder buf = new StringBuilder();
      for (List<String> set : attributeSets) {
        if (buf.length() > 0) {
          buf.append(" ");
        }

        if (set.isEmpty()) {
          continue;
        }

        buf.append(set.toString());
      }
      return buf.toString();
    }

    private CheckRequiredAttributesException(Element element, Collection<List<String>> attributeSets) {
      super("Element " + SpringXMLUtils.elementToString(element) + " must have all attributes for one of the sets: "
          + summary(attributeSets) + ".");
    }
  }
}