namespace JeffWilcox.RichWebClient.Utilities
{
    using System;
    using System.Windows;
    using System.Windows.Browser;

    /// <summary>
    /// A set of C# 3.0 extension methods *as well* as a general 
    /// HTML DOM bridge helper & utility library
    /// </summary>
    public static class HtmlExtensions
    {
        /// <summary>
        /// Retrieve the first HtmlElement in the document that matches 
        /// the tag name
        /// </summary>
        /// <param name="tagName">HTML tag</param>
        /// <returns>The first HtmlElement of tagName on the page</returns>
        public static HtmlElement GetSingleElementByTagName(string tagName)
        {
            HtmlElementCollection hh = HtmlPage.Document.GetElementsByTagName(tagName);
            if (hh.Count > 0) {
                return hh[0];
            }

            throw new InvalidOperationException(
                String.Format(@"There were no ""{0}"" HTML tags found on the page.", tagName));
        }

        /// <summary>
        /// Property representing the &lt;body /&gt; element on 
        /// the page.
        /// </summary>
        /// <remarks>Although a static property, this get is actually 
        /// a method call</remarks>
        public static HtmlElement BodyElement
        {
            get { return GetSingleElementByTagName("body"); }
        }

        /// <summary>
        /// Evaluate some JavaScript code on the page body
        /// </summary>
        public static void Eval(string code)
        {
            HtmlElement js = CreateJavaScriptElement(code);
            BodyElement.AppendChild(js);
        }

        /// <summary>
        /// Popup a JavaScript alert message
        /// </summary>
        public static void Alert(string alertMessage)
        {
            Eval("alert('" 
                + alertMessage.Replace("'", "\\'") 
                + "')");
        }

        /// <summary>
        /// Create a JavaScript code block
        /// </summary>
        public static HtmlElement CreateJavaScriptElement(string code)
        {
            HtmlElement js = CreateJavaScriptElement();
            js.SetProperty("text", code);
            return js;
        }

        /// <summary>
        /// Create an HTML element that is a JavaScript include
        /// </summary>
        public static HtmlElement CreateJavaScriptInclude(string src)
        {
            HtmlElement js = CreateJavaScriptElement();
            js.SetAttribute("src", src);
            return js;
        }

        /// <summary>
        /// Create a new &lt;script /&gt; tag
        /// </summary>
        private static HtmlElement CreateJavaScriptElement()
        {
            HtmlElement js = HtmlPage.Document.CreateElement("script");
            js.SetAttribute("type", "text/javascript");
            return js;
        }

        /// <summary>
        /// Property representing the &lt;head /&gt; element on 
        /// the page.
        /// </summary>
        /// <remarks>Although a static property, this get is actually 
        /// a method call</remarks>
        public static HtmlElement HeadElement
        {
            get { return GetSingleElementByTagName("head"); }
        }

        /// <summary>
        /// Append multiple HtmlElements to a single HtmlElement
        /// </summary>
        public static void AppendChildren(this HtmlElement element, params HtmlElement[] children)
        {
            for (int i = 0; i < children.Length; ++i) {
                element.AppendChild(children[i]);
            }
        }

    }
}