/*
 * Greenshot - a free and open source screenshot tool
 * Copyright (C) 2007-2012  Thomas Braun, Jens Klingen, Robin Krom
 * 
 * For more information see: http://getgreenshot.org/
 * The Greenshot project is hosted on Sourceforge: http://sourceforge.net/projects/greenshot/
 * 
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 1 of the License, or
 * (at your option) any later version.
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
using System;
using System.Drawing;
using System.IO;
using System.Net;
using System.Text;
using System.Collections.Generic;
using System.Collections.Specialized;
using System.Text.RegularExpressions;
using Greenshot.IniFile;
using System.Security.Cryptography.X509Certificates;
using System.Net.Security;
using System.Web;

namespace GreenshotPlugin.Core {
	/// <summary>
	/// Description of NetworkHelper.
	/// </summary>
	public static class NetworkHelper {
		private static readonly log4net.ILog LOG = log4net.LogManager.GetLogger(typeof(NetworkHelper));
		private static CoreConfiguration config = IniConfig.GetIniSection<CoreConfiguration>();

		static NetworkHelper() {
			// Disable certificate checking
			System.Net.ServicePointManager.ServerCertificateValidationCallback +=
			delegate(object sender, X509Certificate cert, X509Chain chain, SslPolicyErrors sslError) {
				bool validationResult = true;
				return validationResult;
			};
		}
		/// <summary>
		/// Download a file as string
		/// </summary>
		/// <param name=url">An Uri to specify the download location</param>
		/// <param name=encoding">The encoding to use</param>
		/// <returns>string with the file content</returns>
		public static string DownloadFileAsString(Uri url, Encoding encoding) {
			try {
				HttpWebRequest request = (HttpWebRequest)CreateWebRequest(url);
				HttpWebResponse response = (HttpWebResponse)request.GetResponse();
				if (request.HaveResponse) {
					StreamReader reader = new StreamReader(response.GetResponseStream(), encoding);
					return reader.ReadToEnd();
				}
				
			} catch (Exception e) {
				LOG.Error("Problem downloading from: " + url.ToString(), e);
			}
			return null;
		}

		/// <summary>
		/// Download the FavIcon as a Bitmap
		/// </summary>
		/// <param name="baseUri"></param>
		/// <returns>Bitmap with the FavIcon</returns>
		public static Bitmap DownloadFavIcon(Uri baseUri) {
			Uri url = new Uri(baseUri, new Uri("favicon.ico"));
			try {
				HttpWebRequest request = (HttpWebRequest)NetworkHelper.CreateWebRequest(url);
				HttpWebResponse response = (HttpWebResponse)request.GetResponse();
				if (request.HaveResponse) {
					using (Image image = Image.FromStream(response.GetResponseStream())) {
						return (image.Height > 16 && image.Width > 16) ? new Bitmap(image, 16, 16) : new Bitmap(image);
					}
				}
				
			} catch (Exception e) {
				LOG.Error("Problem downloading the FavIcon from: " + baseUri.ToString(), e);
			}
			return null;
		}
		
		/// <summary>
		/// Helper method to create a web request, eventually with proxy
		/// </summary>
		/// <param name="uri">string with uri to connect to</param>
		/// <returns>WebRequest</returns>
		public static WebRequest CreateWebRequest(string uri) {
			return CreateWebRequest(new Uri(uri));
		}
		
		/// <summary>
		/// Helper method to create a web request, eventually with proxy
		/// </summary>
		/// <param name="uri">Uri with uri to connect to</param>
		/// <returns>WebRequest</returns>
		public static WebRequest CreateWebRequest(Uri uri) {
			WebRequest webRequest = WebRequest.Create(uri);
			if (config.UseProxy) {
				webRequest.Proxy = GreenshotPlugin.Core.NetworkHelper.CreateProxy(uri);
				//webRequest.Proxy.Credentials = CredentialCache.DefaultCredentials;
			}
			return webRequest;
		}

		/// <summary>
		/// Create a IWebProxy Object which can be used to access the Internet
		/// This method will check the configuration if the proxy is allowed to be used.
		/// Usages can be found in the DownloadFavIcon or Jira and Confluence plugins
		/// </summary>
		/// <param name="url"></param>
		/// <returns>IWebProxy filled with all the proxy details or null if none is set/wanted</returns>
		public static IWebProxy CreateProxy(Uri uri) {
			IWebProxy proxyToUse = null;
			if (config.UseProxy) {
				proxyToUse = WebRequest.DefaultWebProxy;
				if (proxyToUse != null) {
					proxyToUse.Credentials = CredentialCache.DefaultCredentials;
					if (LOG.IsDebugEnabled) {
						// check the proxy for the Uri
						if (!proxyToUse.IsBypassed(uri)) {
							Uri proxyUri = proxyToUse.GetProxy(uri);
							if (proxyUri != null) {
								LOG.Debug("Using proxy: " + proxyUri.ToString() + " for " + uri.ToString());
							} else {
								LOG.Debug("No proxy found!");
							}
						} else {
							LOG.Debug("Proxy bypass for: " + uri.ToString());
						}
					}
				} else {
					LOG.Debug("No proxy found!");
				}
			}
			return proxyToUse;
		}
		
		/// <summary>
		/// UrlEncodes a string without the requirement for System.Web
		/// </summary>
		/// <param name="String"></param>
		/// <returns></returns>
		// [Obsolete("Use System.Uri.EscapeDataString instead")]
		public static string UrlEncode(string text) {
			if (!string.IsNullOrEmpty(text)) {
				// Sytem.Uri provides reliable parsing, but doesn't encode spaces.
				return System.Uri.EscapeDataString(text).Replace("%20", "+");
			}
			return null;
		}

		/// <summary>
		/// A wrapper around the EscapeDataString, as the limit is 32766 characters
		/// See: http://msdn.microsoft.com/en-us/library/system.uri.escapedatastring%28v=vs.110%29.aspx
		/// </summary>
		/// <param name="text"></param>
		/// <returns>escaped data string</returns>
		public static string EscapeDataString(string text) {
			if (!string.IsNullOrEmpty(text)) {
				StringBuilder result = new StringBuilder();
				int currentLocation = 0;
				while (currentLocation < text.Length) {
					string process = text.Substring(currentLocation, Math.Min(16384, text.Length - currentLocation));
					result.Append(Uri.EscapeDataString(process));
					currentLocation = currentLocation + 16384;
				}
				return result.ToString();
			}
			return null;
		}

		/// <summary>
		/// UrlDecodes a string without requiring System.Web
		/// </summary>
		/// <param name="text">String to decode.</param>
		/// <returns>decoded string</returns>
		public static string UrlDecode(string text) {
			// pre-process for + sign space formatting since System.Uri doesn't handle it
			// plus literals are encoded as %2b normally so this should be safe
			text = text.Replace("+", " ");
			return System.Uri.UnescapeDataString(text);
		}

		/// <summary>
		/// ParseQueryString without the requirement for System.Web
		/// </summary>
		/// <param name="s"></param>
		/// <returns>Dictionary<string, string></returns>
		public static IDictionary<string, string> ParseQueryString(string s) {
			IDictionary<string, string> parameters = new SortedDictionary<string, string>();
			// remove anything other than query string from url
			if (s.Contains("?")) {
				s = s.Substring(s.IndexOf('?') + 1);
			}
			foreach (string vp in Regex.Split(s, "&")) {
				if (string.IsNullOrEmpty(vp)) {
					continue;
				}
				string[] singlePair = Regex.Split(vp, "=");
				if (parameters.ContainsKey(singlePair[0])) {
					parameters.Remove(singlePair[0]);
				}
				if (singlePair.Length == 2) {
					parameters.Add(singlePair[0], singlePair[1]);
				} else {
					// only one key with no value specified in query string
					parameters.Add(singlePair[0], string.Empty);
				}
			}
			return parameters;
		}
		
		/// <summary>
        /// Generate the query paramters
        /// </summary>
        /// <param name="queryParameters">the list of query parameters</param>
        /// <returns>a string with the query parameters</returns>
        public static string GenerateQueryParameters(IDictionary<string, string> queryParameters) {
            if (queryParameters == null || queryParameters.Count == 0) {
                return string.Empty;
            }
        	
        	queryParameters = new SortedDictionary<string, string>(queryParameters);

			StringBuilder sb = new StringBuilder();
			foreach(string key in queryParameters.Keys) {
				sb.AppendFormat(System.Globalization.CultureInfo.InvariantCulture, "{0}={1}&", key, UrlEncode(queryParameters[key]));
			}
			sb.Remove(sb.Length-1,1);

			return sb.ToString();
        }
	}
}