using System;
using System.Collections;
using System.Globalization;
using System.IO;
using System.Web;
using System.Xml.Linq;

using Composite.Core;
using Composite.Data;
using Composite.Functions;

using Composite.Core.Xml;
using Composite.Core.WebClient.Renderings.Page;
using Composite.Core.WebClient;

/// <summary>
/// Executes a C1 Function. The name of the function is copied from the name of this .ashx file,
/// i.e. if this file is named "Composite.Pages.QuickSitemap.ashx" the function "Composite.Pages.QuickSitemap" will be called
/// Parameters specified in the URL will be passed on to the function.
/// 
/// You control the data culture through the URL parameter "cultureScope", like "cultureScope=en-US".
/// 
/// To use this class - create a .ashx file which inherit from this class (ExecuteC1FunctionHttpHandler) and name it
/// (full function name).ashx
/// </summary>
public abstract class ExecuteC1FunctionHttpHandler : IHttpHandler
{
    public void ProcessRequest(HttpContext context)
    {
        // Get the name of the function to execute by copying the current file name (without the .ashx extension)
        string functionName = Path.GetFileNameWithoutExtension(context.Request.Path);
        // Locate the data culture to use - like en-US or nl-NL
        CultureInfo dataCulture = GetCurrentDataCulture(context);

        using (DataScope dataScope = new DataScope(DataScopeIdentifier.Public, dataCulture))
        {
            // Grab a function object to execute
            IFunction function = FunctionFacade.GetFunction(functionName);

            // Execute the function, passing all query string parameters as input parameters
            object functionResult = FunctionFacade.Execute<object>(function, context.Request.QueryString);

            // output result
            if (functionResult != null)
            {
                if (functionResult is XhtmlDocument)
                {
                    //fixes sub xhtmldocuments, does not "merge" head elements, just combines?
                    PageRenderer.NormalizeXhtmlDocument(functionResult as XhtmlDocument);

                    //fix page urls
                    string xhtml = PageUrlHelper.ChangeRenderingPageUrlsToPublic(functionResult.ToString());

                    //fix media urls
                    xhtml = MediaUrlHelper.ChangeInternalMediaUrlsToPublic(xhtml);

                    //format the xml, needed?
                    xhtml = Composite.Core.Xml.XhtmlPrettifier.Prettify(xhtml);
                    context.Response.Write(xhtml);
                }
                else
                {
                    context.Response.Write(functionResult.ToString());
                    if (functionResult is XNode && function.ReturnType != typeof(Composite.Core.Xml.XhtmlDocument))
                        context.Response.ContentType = "text/xml";
                }
            }
        }
    }

    
    public bool IsReusable
    {
        get
        {
            return true;
        }
    }


    /// <summary>
    /// Locates the data scope culture that the function should be scoped to.
    /// I.e. the 'language' of the data to work on. 
    /// The Query String variable 'cultureScope' will be used, or the systems 
    /// default culure is this parameter is not specified.
    /// </summary>
    private CultureInfo GetCurrentDataCulture(HttpContext context)
    {
        string cultureScope = context.Request.QueryString["cultureScope"];
        if (string.IsNullOrEmpty(cultureScope)==false)
        {
            return new CultureInfo(cultureScope);
        }
        
        return DataLocalizationFacade.DefaultLocalizationCulture;
    }
}