using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Net;
using System.Web.Script.Serialization;

using Nuclex.Networking.Gallery3.Responses;
using System.Web;

namespace Nuclex.Networking.Gallery3.Requests {

  /// <summary>Creates requests to read or write resources</summary>
  public class RequestFactory : IRequestFactory {

    /// <summary>Initializs a new simple request factory</summary>
    /// <param name="galleryUrl">URL of the gallery installation</param>
    /// <remarks>
    ///   If the URL doesn't end with 'index.php', it will automatically
    ///   be appended to the URL. For gallery installations where index.php
    ///   is not required in the path, use the second constructor overload.
    /// </remarks>
    public RequestFactory(string galleryUrl) :
      this(galleryUrl, false) { }

    /// <summary>Initializs a new simple request factory</summary>
    /// <param name="galleryUrl">URL of the gallery installation</param>
    /// <param name="asIs">
    ///   Whether to take to URL as it is or to append 'index.php' if it is missing
    /// </param>
    /// <remarks>
    ///   By default, gallery 3 installations require 'index.php' to be specified
    ///   in the URL with any REST request. If you have modified your gallery 3
    ///   installation, renamed index.php or do not want this for any other reason,
    ///   specifying true for the <paramref name="asIs" /> parameter makes
    ///   the request factory use the URL exactly as it is specified.
    /// </remarks>
    public RequestFactory(string galleryUrl, bool asIs) {
      if (!asIs) {
        if (!galleryUrl.EndsWith("/")) {
          galleryUrl += '/';
        }

        if (!galleryUrl.EndsWith("index.php/")) {
          galleryUrl += "index.php/";
        }
      }

      GalleryUri = new Uri(galleryUrl);

      initializeSerializer();
    }

    /// <summary>Creates a new request for the specified resource</summary>
    /// <param name="resourceUrl">Resource the request will access</param>
    /// <returns>The new request</returns>
    /// <remarks>
    ///   The <paramref name="resourceUrl" /> parameter is a relative path below
    ///   gallery's base URL. A typical resource URL would be 'rest/item/1'.
    /// </remarks>
    public IRequest CreateRequest(string resourceUrl) {
      Uri requestUri = new Uri(GalleryUri, resourceUrl);

      WebRequest request = HttpWebRequest.Create(requestUri);
      OnRequestCreated(request);

      return new Request(this.jsonSerializer, request);
    }

    /// <summary>Called when a new WebRequest is created</summary>
    /// <param name="request">The new WebRequest</param>
    /// <remarks>
    ///   This method can be overridden in derived classes to modify new requests
    ///   created by the factory, for example in order to add authentication options.
    /// </remarks>
    protected virtual void OnRequestCreated(WebRequest request) { }

    /// <summary>Base URL of the gallery installation</summary>
    /// <remarks>
    ///   Should include the 'index.php' part of the URL
    /// </remarks>
    protected Uri GalleryUri { get; private set; }

    /// <summary>Initializes the JSON serializer used to decode responses</summary>
    private void initializeSerializer() {
      this.jsonSerializer = new JavaScriptSerializer();
      this.jsonSerializer.RegisterConverters(
        new JavaScriptConverter[] { new GalleryDateTimeConverter() }
      );
    }

    /// <summary>JSON serializer used to decode responses to the requests</summary>
    private JavaScriptSerializer jsonSerializer;

  }

} // namespace Nuclex.Networking.Gallery3.Requests