using System;
using System.Xml;

namespace MetroWpf
{
  /// <summary>
  /// Extension methods for the XmlNode / XmlDocument classes and its sub classes
  /// </summary>
  public static class XmlNodeExtensions
  {
    #region · Extensions ·

    /// <summary>
    /// Appends a child to a XML node
    /// </summary>
    /// <param name="parentNode">The parent node.</param>
    /// <param name="name">The name of the child node.</param>
    /// <returns>The newly cerated XML node</returns>
    public static XmlNode CreateChildNode(this XmlNode parentNode, string name)
    {
      XmlDocument document = (parentNode is XmlDocument ? (XmlDocument)parentNode : parentNode.OwnerDocument);
      XmlNode node = document.CreateElement(name);

      parentNode.AppendChild(node);

      return node;
    }

    /// <summary>
    /// Appends a child to a XML node
    /// </summary>
    /// <param name="parentNode">The parent node.</param>
    /// <param name="name">The name of the child node.</param>
    /// <param name="namespaceUri">The node namespace.</param>
    /// <returns>The newly cerated XML node</returns>
    public static XmlNode CreateChildNode(this XmlNode parentNode, string name, string namespaceUri)
    {
      XmlDocument document = (parentNode is XmlDocument ? (XmlDocument)parentNode : parentNode.OwnerDocument);
      XmlNode node = document.CreateElement(name, namespaceUri);

      parentNode.AppendChild(node);

      return node;
    }

    /// <summary>
    /// Appends a CData section to a XML node
    /// </summary>
    /// <param name="parentNode">The parent node.</param>
    /// <returns>The created CData Section</returns>
    public static XmlCDataSection CreateCDataSection(this XmlNode parentNode)
    {
      return parentNode.CreateCDataSection(string.Empty);
    }

    /// <summary>
    /// Appends a CData section to a XML node and prefills the provided data
    /// </summary>
    /// <param name="parentNode">The parent node.</param>
    /// <param name="data">The CData section value.</param>
    /// <returns>The created CData Section</returns>
    public static XmlCDataSection CreateCDataSection(this XmlNode parentNode, string data)
    {
      XmlDocument document = (parentNode is XmlDocument ? (XmlDocument)parentNode : parentNode.OwnerDocument);
      XmlCDataSection node = document.CreateCDataSection(data);

      parentNode.AppendChild(node);

      return node;
    }

    /// <summary>
    /// Returns the value of a nested CData section.
    /// </summary>
    /// <param name="parentNode">The parent node.</param>
    /// <returns>The CData section content</returns>
    public static string GetCDataSection(this XmlNode parentNode)
    {
      foreach (var node in parentNode.ChildNodes)
      {
        if (node is XmlCDataSection)
        {
          return ((XmlCDataSection)node).Value;
        }
      }

      return null;
    }

    /// <summary>
    /// Gets an attribute value
    /// </summary>
    /// <param name="node">The node.</param>
    /// <param name="attributeName">The Name of the attribute.</param>
    /// <returns>The attribute value</returns>
    public static string GetAttribute(this XmlNode node, string attributeName)
    {
      return GetAttribute(node, attributeName, null);
    }

    /// <summary>
    /// Gets an attribute value
    /// </summary>
    /// <param name="node">The node.</param>
    /// <param name="attributeName">The Name of the attribute.</param>
    /// <param name="defaultValue">The default value to be returned if no matching attribute exists.</param>
    /// <returns>The attribute value</returns>
    public static string GetAttribute(this XmlNode node, string attributeName, string defaultValue)
    {
      XmlAttribute attribute = node.Attributes[attributeName];

      return (attribute != null ? attribute.InnerText : defaultValue);
    }

    /// <summary>
    /// Gets an attribute value converted to the specified data type
    /// </summary>
    /// <typeparam name="T">The desired return data type</typeparam>
    /// <param name="node">The node.</param>
    /// <param name="attributeName">The Name of the attribute.</param>
    /// <returns>The attribute value</returns>
    public static T GetAttribute<T>(this XmlNode node, string attributeName)
    {
      return GetAttribute<T>(node, attributeName, default(T));
    }

    /// <summary>
    /// Gets an attribute value converted to the specified data type
    /// </summary>
    /// <typeparam name="T">The desired return data type</typeparam>
    /// <param name="node">The node.</param>
    /// <param name="attributeName">The Name of the attribute.</param>
    /// <param name="defaultValue">The default value to be returned if no matching attribute exists.</param>
    /// <returns>The attribute value</returns>
    public static T GetAttribute<T>(this XmlNode node, string attributeName, T defaultValue)
    {
      var value = GetAttribute(node, attributeName);

      return (value.IsNotEmpty() ? value.ConvertTo<T>(defaultValue) : defaultValue);
    }

    /// <summary>
    /// Creates or updates an attribute with the passed value.
    /// </summary>
    /// <param name="node">The node.</param>
    /// <param name="name">The name.</param>
    /// <param name="value">The value.</param>
    public static void SetAttribute(this XmlNode node, string name, object value)
    {
      SetAttribute(node, name, value != null ? value.ToString() : null);
    }

    /// <summary>
    /// Creates or updates an attribute with the passed value.
    /// </summary>
    /// <param name="node">The node.</param>
    /// <param name="name">The name.</param>
    /// <param name="value">The value.</param>
    public static void SetAttribute(this XmlNode node, string name, string value)
    {
      if (node != null)
      {
        var attribute = node.Attributes[name, node.NamespaceURI];

        if (attribute == null)
        {
          attribute = node.OwnerDocument.CreateAttribute(name, node.OwnerDocument.NamespaceURI);
          node.Attributes.Append(attribute);
        }

        attribute.InnerText = value;
      }
    }

    #endregion
  }
}