/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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 org.apache.wicket.markup.head;

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Map;
import java.util.Objects;

import org.apache.wicket.model.IModel;
import org.apache.wicket.model.Model;
import org.apache.wicket.request.Response;
import org.apache.wicket.util.lang.Args;
import org.apache.wicket.util.string.Strings;
import org.apache.wicket.util.value.ValueMap;

/**
 * {@link HeaderItem} for meta information such as &lt;meta&gt; tags or
 * canonical &lt;link&gt;
 * 
 * @author andrea del bene
 * @since 6.17.0
 */
public class MetaDataHeaderItem extends HeaderItem
{
	private static final long serialVersionUID = 1L;

	/**
	 * The meta tag name
	 */
	public static final String META_TAG = "meta";
	/**
	 * the link tag name
	 */
	public static final String LINK_TAG = "link";

	private final Map<String, Object> tagAttributes;
	private final List<String> tagMinimizedAttributes;
	private final String tagName;

	/**
	 * Build a new {@link MetaDataHeaderItem} having {@code tagName} as tag.
	 * 
	 * @param tagName
	 * 		the name of the tag
	 */
	public MetaDataHeaderItem(String tagName)
	{
		this.tagName = Args.notEmpty(tagName, "tagName");
		this.tagAttributes = new ValueMap();
		this.tagMinimizedAttributes = new ArrayList<>();
	}

	/**
	 * Add a tag attribute to the item. If the attribute value is a {@link IModel}, 
	 * the object wrapped inside the model is used as actual value.
	 * 
	 * @param attributeName
	 * 		the attribute name
	 * @param attributeValue
	 * 		the attribute value
	 * @return
	 * 		The current item.
	 */
	public MetaDataHeaderItem addTagAttribute(String attributeName, Object attributeValue)
	{
		Args.notEmpty(attributeName, "attributeName");
		Args.notNull(attributeValue, "attributeValue");

		tagAttributes.put(attributeName, attributeValue);
		return this;
	}
	
	/**
	 * Add a minimized tag attribute to the item. The attribute has no value and 
	 * only its name is rendered (for example 'async')
	 * 
	 * @param attributeName
	 * 		the attribute name
	 * @return
	 * 		The current item.
	 */
	public MetaDataHeaderItem addTagAttribute(String attributeName)
	{
		Args.notEmpty(attributeName, "attributeName");
		
		tagMinimizedAttributes.add(attributeName);
		return this;
	}

	/**
	 * Generate the string representation for the current item.
	 * 
	 * @return
	 * 		The string representation for the current item.
	 */
	public String generateString()
	{
		StringBuilder buffer = new StringBuilder();

		buffer.append('<').append(tagName);

		for (Map.Entry<String, Object> entry : tagAttributes.entrySet())
		{
			Object value = entry.getValue();

			if (value instanceof IModel)
			{
				value = ((IModel<?>)value).getObject();
			}

			buffer.append(' ')
				.append(Strings.escapeMarkup(entry.getKey()));

			if (value != null)
			{
				buffer.append('=')
					.append('"')
					.append(Strings.replaceAll(value.toString(), "\"", "\\\""))
					.append('"');
			}
		}
		
		for (String attrName : tagMinimizedAttributes)
		{
			buffer.append(' ')
				.append(Strings.escapeMarkup(attrName));
		}

		buffer.append(" />\n");

		return buffer.toString();
	}

	@Override
	public Iterable<?> getRenderTokens()
	{
		return Collections.singletonList(generateString());
	}

	@Override
	public void render(Response response)
	{
		response.write(generateString());
	}

	/**
	 * Factory method to create &lt;meta&gt; tag.
	 * 
	 * @param httpEquiv
	 * 		the 'httpEquiv' attribute of the tag
	 * @param content
	 * 		the 'content' attribute of the tag
	 * @return
	 * 		A new {@link MetaDataHeaderItem}
	 */
	public static MetaDataHeaderItem forHttpEquiv(String httpEquiv, String content)
	{
		return forHttpEquiv(Model.of(httpEquiv), Model.of(content));
	}

	/**
	 * Factory method to create &lt;meta&gt; tag.
	 * 
	 * @param httpEquiv
	 * 		the 'httpEquiv' attribute of the tag
	 * @param content
	 * 		the 'content' attribute of the tag
	 * @return
	 * 		A new {@link MetaDataHeaderItem}
	 */
	public static MetaDataHeaderItem forHttpEquiv(IModel<String> httpEquiv, IModel<String> content)
	{
		MetaDataHeaderItem headerItem = new MetaDataHeaderItem(META_TAG);

		headerItem.addTagAttribute("http-equiv", httpEquiv);
		headerItem.addTagAttribute("content", content);

		return headerItem;
	}

	/**
	 * Factory method to create &lt;meta&gt; tag.
	 * 
	 * @param name
	 * 		the 'name' attribute of the tag
	 * @param content
	 * 		the 'content' attribute of the tag
	 * @return
	 * 		A new {@link MetaDataHeaderItem}
	 */
	public static MetaDataHeaderItem forMetaTag(String name, String content)
	{
		return forMetaTag(Model.of(name), Model.of(content));
	}

	/**
	 * Factory method to create &lt;meta&gt; tag.
	 * 
	 * @param name
	 * 		the 'name' attribute of the tag as String model
	 * @param content
	 * 		the 'content' attribute of the tag as String model
	 * @return
	 * 		A new {@link MetaDataHeaderItem}
	 */
	public static MetaDataHeaderItem forMetaTag(IModel<String> name, IModel<String> content)
	{
		MetaDataHeaderItem headerItem = new MetaDataHeaderItem(META_TAG);

		headerItem.addTagAttribute("name", name);
		headerItem.addTagAttribute("content", content);

		return headerItem;
	}

	/**
	 * Factory method to create &lt;link&gt; tag.
	 *  
	 * @param rel
	 * 		the 'rel' attribute of the tag
	 * @param href
	 * 		the 'href' attribute of the tag
	 * @return
	 * 		A new {@link MetaDataHeaderItem}
	 */
	public static MetaDataHeaderItem forLinkTag(String rel, String href)
	{
		return forLinkTag(Model.of(rel), Model.of(href));
	}
	
	/**
	 * Factory method to create &lt;link&gt; tag.
	 *  
	 * @param rel
	 * 		the 'rel' attribute of the tag as String model
	 * @param href
	 * 		the 'href' attribute of the tag as String model
	 * @return
	 * 		A new {@link MetaDataHeaderItem}
	 */
	public static MetaDataHeaderItem forLinkTag(IModel<String> rel, IModel<String> href)
	{
		MetaDataHeaderItem headerItem = new MetaDataHeaderItem(LINK_TAG);

		headerItem.addTagAttribute("rel", rel);
		headerItem.addTagAttribute("href", href);

		return headerItem;
	}

	@Override
	public boolean equals(Object o)
	{
		if (this == o) return true;
		if (o == null || getClass() != o.getClass()) return false;
		MetaDataHeaderItem that = (MetaDataHeaderItem) o;
		return Objects.equals(tagAttributes, that.tagAttributes) &&
				Objects.equals(tagMinimizedAttributes, that.tagMinimizedAttributes) &&
				Objects.equals(tagName, that.tagName);
	}

	@Override
	public int hashCode()
	{
		// Not using `Objects.hash` for performance reasons
		int result = tagAttributes != null ? tagAttributes.hashCode() : 0;
		result = 31 * result + (tagMinimizedAttributes != null ? tagMinimizedAttributes.hashCode() : 0);
		result = 31 * result + (tagName != null ? tagName.hashCode() : 0);
		return result;
	}
}
