using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Net;
using System.Web;
using System.IO;
using System.Web.UI;
using Nuclex.Networking.Gallery3.Requests;

namespace Nuclex.Networking.Gallery3 {

  /// <summary>Connects to a gallery installation using the gallery REST API</summary>
  public class Gallery : ConnectionUser {

    /// <summary>Connects to a Gallery 3 installation</summary>
    /// <param name="galleryUrl">URL of the Gallery 3 installation</param>
    /// <param name="apiKey">API key for the user to connect as</param>
    /// <returns>
    ///   A new gallery connector through which the gallery can be accessed
    /// </returns>
    public static Gallery Connect(string galleryUrl, string apiKey) {
      return Connect(new RequestFactory(galleryUrl), apiKey);
    }

    /// <summary>Connects to a Gallery 3 installation</summary>
    /// <param name="requestFactory">
    ///   Interface through which requests to the Gallery 3 installation are created
    /// </param>
    /// <param name="apiKey">API key for the user to connect as</param>
    /// <returns>
    ///   A new gallery connector through which the gallery can be accessed
    /// </returns>
    public static Gallery Connect(IRequestFactory requestFactory, string apiKey) {
      if (apiKey == null) {
        throw new ArgumentNullException("apiKey", "The API key must not be null");
      }

      return connectInternal(requestFactory, apiKey);
    }

    /// <summary>Connects to a Gallery 3 installation as a guest user</summary>
    /// <param name="galleryUrl">URL of the Gallery 3 installation</param>
    /// <returns>
    ///   A new gallery connector through which the gallery can be accessed
    /// </returns>
    /// <remarks>
    ///   This method is named differently instead of as an overload to Connect() to
    ///   ensure it is not accidentally used. Without special preparations, Gallery3's
    ///   REST API does not allow guest access.
    /// </remarks>
    public static Gallery ConnectAsGuest(string galleryUrl) {
      return ConnectAsGuest(CreateRequestFactory(galleryUrl));
    }

    /// <summary>Connects to a Gallery 3 installation as a guest user</summary>
    /// <param name="requestFactory">
    ///   Interface through which requests to the Gallery 3 installation are created
    /// </param>
    /// <returns>
    ///   A new gallery connector through which the gallery can be accessed
    /// </returns>
    /// <remarks>
    ///   This method is named differently instead of as an overload to Connect() to
    ///   ensure it is not accidentally used. Without special preparations, Gallery3's
    ///   REST API does not allow guest access.
    /// </remarks>
    public static Gallery ConnectAsGuest(IRequestFactory requestFactory) {
      return connectInternal(requestFactory, null);
    }

    /// <summary>Queries gallery for the REST API key of the specified user</summary>
    /// <param name="galleryUrl">
    ///   URL of the gallery base installation
    ///   (for example, 'http://www.mydomain.com/gallery3/index.php')
    /// </param>
    /// <param name="user">Name of the user whose REST API key will be retrieved</param>
    /// <param name="password">Password for the user</param>
    /// <returns>The REST API key for the specified user</returns>
    public static string QueryApiKey(string galleryUrl, string user, string password) {
      return QueryApiKey(CreateRequestFactory(galleryUrl), user, password);
    }

    /// <summary>Queries gallery for the REST API key of the specified user</summary>
    /// <param name="requestFactory">
    ///   Interface through which requests to the Gallery 3 installation are created
    /// </param>
    ///   URL of the gallery base installation
    ///   (for example, 'http://www.mydomain.com/gallery3/index.php')
    /// </param>
    /// <param name="user">Name of the user whose REST API key will be retrieved</param>
    /// <param name="password">Password for the user</param>
    /// <returns>The REST API key for the specified user</returns>
    public static string QueryApiKey(
      IRequestFactory requestFactory, string user, string password
    ) {
      IRequest request = requestFactory.CreateRequest("rest");
      request.Method = "POST";
      request.ContentType = "application/x-www-form-urlencoded; charset=UTF-8";
      request.AddHeader("X-Gallery-Request-Method", "post");

      // Attach the url-encoded credentials we'll use to log in
      {
        StringBuilder builder = new StringBuilder();
        builder.Append("user=");
        builder.Append(HttpUtility.UrlEncode(user));
        builder.Append("&password=");
        builder.Append(HttpUtility.UrlEncode(password));
        byte[] credentials = Encoding.UTF8.GetBytes(builder.ToString());

        request.AttachContent(credentials);
      }

      // Execute the request and read its JSON response
      return request.GetJsonResponse<string>();
    }

    /// <summary>The root album in the gallery</summary>
    public Album RootAlbum {
      get { return this.rootAlbum; }
    }

    /// <summary>Creates the default request factory used for gallery requests</summary>
    /// <param name="url">Base URL of the gallery installation</param>
    /// <returns>The newly created request factory</returns>
    internal static IRequestFactory CreateRequestFactory(string url) {
      return new RequestFactory(url);
    }

    /// <summary>Initializes a new gallery 3 connector</summary>
    /// <param name="requestFactory">
    ///   Factory used to issue new requests to the gallery installation
    /// </param>
    /// <param name="apiKey">
    ///   API key for the user the requests will run as
    /// </param>
    /// <param name="rootAlbum">JSON data for the gallery's root album</param>
    private Gallery(
      IRequestFactory requestFactory, string apiKey, ref Responses.JsonItem rootAlbum
    ) :
      base(new GalleryConnection(requestFactory, apiKey)) {
      this.rootAlbum = new Album(Connection, ref rootAlbum);
    }

    /// <summary>Establishes a connection to a gallery installation</summary>
    /// <param name="requestFactory">
    ///   Request factory that will be used to contact the gallery REST API
    /// </param>
    /// <param name="apiKey">
    ///   API key of the user to access the gallery as. If this is null,
    ///   a connection will be made as the guest user.
    /// </param>
    /// <returns>A new gallery connector of the connection was successful</returns>
    private static Gallery connectInternal(IRequestFactory requestFactory, string apiKey) {
      IRequest request = requestFactory.CreateRequest("rest/item/1");
      request.Method = "GET";
      request.ContentType = "application/x-www-form-urlencoded; charset=UTF-8";
      request.AddHeader("X-Gallery-Request-Method", "get");
      if (apiKey != null) {
        request.AddHeader("X-Gallery-Request-Key", apiKey);
      }

      // Read the response to our request. Because the java script serializer mapping
      // is non-strict, if this connector is used to connect to something else (or
      // the server implementation is changed), we only notice this by our fields not
      // being assigned.
      var item = request.GetJsonResponse<Responses.JsonItem>();
      if (item.Entity.Id != 1) {
        throw new WebException("Could not understand reply from remote host");
      }

      return new Gallery(requestFactory, apiKey, ref item);
    }

    /// <summary>The root album in the gallery</summary>
    private Album rootAlbum;

  }

} // namespace Nuclex.Networking.Gallery3