using System;
using System.Collections.Specialized;
using System.IO;
using System.Net;
using System.Xml;

namespace eBay_Images {
	struct ImgurResponse {
		// Raw response for logging or debugging.
		public string Raw { get; set; }

		public string Image { get; set; }
		public string Thumbnail { get; set; }
	}

	class ImgurV3 {
		public static string THUMBNAIL_SUFFIX = "t";

		public static ImgurResponse Upload(byte[] image, string name) {
			var ret = new ImgurResponse();

			var response = DoUpload(image, name);
			ret.Raw = GetUploadResponse(response);

			var xml = new XmlDocument();
			xml.LoadXml(ret.Raw);

			ret.Image = GetDirectLink(xml);
			ret.Thumbnail = GetThumbnailLinkFromDirectLink(ret.Image);

			return ret;
		}

		private static string CLIENT_ID = "5a2f9a4c3da3908";
		private static string ENDPOINT = "https://api.imgur.com/3/";
		private static string ENDPOINT_IMAGE = ENDPOINT + "image.xml";

		private static HttpWebResponse DoUpload(byte[] image, string name) {
			var spec = new UploadSpec(image, name, "image");

			var headers = new NameValueCollection();
			headers.Add("Authorization", String.Format("Client-ID {0}", CLIENT_ID));

			var fields = new StringDictionary();
			fields.Add("name", name);
			fields.Add("description", name);

			return HttpUpload.Upload(new Uri(ENDPOINT_IMAGE), headers, fields, null, null, spec);
		}

		private static string GetUploadResponse(HttpWebResponse response) {
			var reply = new StreamReader(response.GetResponseStream());
			var str = reply.ReadToEnd();
			return str;
		}

		private static string GetDirectLink(XmlDocument xml) {
			var link = xml.SelectSingleNode("//link");

			if (link == null || link.InnerText == null || link.InnerText.Length == 0)
				throw new ApplicationException("link node has no value");

			return link.InnerText;
		}

		private static string GetThumbnailLinkFromDirectLink(string link) {
			var uri = new UriBuilder(link);
			// Remove port if it is the default for http.
			if (uri.Scheme == "http" && uri.Port == 80)
				uri.Port = -1;
			var path = uri.Path;
			var filename = Path.GetFileNameWithoutExtension(path);
			var thumbFilename = filename + THUMBNAIL_SUFFIX;
			var thumbPath = path.Replace(filename, thumbFilename);
			uri.Path = thumbPath;
			return uri.ToString();
		}
	}
}