using System;
using System.Net;
using System.Security.Authentication;
using System.Text;
using Newtonsoft.Json.Linq;
using RedditSharp.Things;

namespace RedditSharp
{
    public class AuthProvider
    {
        private const string AccessUrl = "https://ssl.reddit.com/api/v1/access_token";
        private const string OauthGetMeUrl = "https://oauth.reddit.com/api/v1/me";

        public static string OAuthToken { get; set; }
        public static string RefreshToken { get; set; }

        [Flags]
        public enum Scope
        {
            none = 0x0,
            identity = 0x1,
            edit = 0x2,
            flair = 0x4,
            history = 0x8,
            modconfig = 0x10,
            modflair = 0x20,
            modlog = 0x40,
            modposts = 0x80,
            modwiki = 0x100,
            mysubreddits = 0x200,
            privatemessages = 0x400,
            read = 0x800,
            report = 0x1000,
            save = 0x2000,
            submit = 0x4000,
            subscribe = 0x8000,
            vote = 0x10000,
            wikiedit = 0x20000,
            wikiread = 0x40000
        }
        private readonly IWebAgent _webAgent;
        private readonly string _redirectUri;
        private readonly string _clientId;
        private readonly string _clientSecret;

        /// <summary>
        /// Allows use of reddit's OAuth interface, using an app set up at https://ssl.reddit.com/prefs/apps/.
        /// </summary>
        /// <param name="clientId">Granted by reddit as part of app.</param>
        /// <param name="clientSecret">Granted by reddit as part of app.</param>
        /// <param name="redirectUri">Selected as part of app. Reddit will send users back here.</param>
        public AuthProvider(string clientId, string clientSecret, string redirectUri)
        {
            _clientId = clientId;
            _clientSecret = clientSecret;
            _redirectUri = redirectUri;
            _webAgent = new WebAgent();
        }

        /// <summary>
        /// Creates the reddit OAuth2 Url to redirect the user to for authorization. 
        /// </summary>
        /// <param name="state">Used to verify that the user received is the user that was sent</param>
        /// <param name="scope">Determines what actions can be performed against the user.</param>
        /// <param name="permanent">Set to true for access lasting longer than one hour.</param>
        /// <returns></returns>
        public string GetAuthUrl(string state, Scope scope, bool permanent = false)
        {
            return String.Format("https://ssl.reddit.com/api/v1/authorize?client_id={0}&response_type=code&state={1}&redirect_uri={2}&duration={3}&scope={4}", _clientId, state, _redirectUri, permanent ? "permanent" : "temporary", scope.ToString().Replace(" ",""));
        }

        /// <summary>
        /// Gets the OAuth token for the user associated with the provided code.
        /// </summary>
        /// <param name="code">Sent by reddit as a parameter in the return uri.</param>
        /// <param name="isRefresh">Set to true for refresh requests.</param>
        /// <returns></returns>
        public string GetOAuthToken(string code, bool isRefresh = false)
        {
            if (Type.GetType("Mono.Runtime") != null)
                ServicePointManager.ServerCertificateValidationCallback = (s, c, ch, ssl) => true;
            _webAgent.Cookies = new CookieContainer();

            var request = _webAgent.CreatePost(AccessUrl);

            request.Headers["Authorization"] = "Basic " + Convert.ToBase64String(Encoding.Default.GetBytes(_clientId + ":" + _clientSecret));
            var stream = request.GetRequestStream();

            if (isRefresh)
            {
                _webAgent.WritePostBody(stream, new
                {
                    grant_type = "refresh_token",
                    refresh_token = code
                });
            }
            else
            {
                _webAgent.WritePostBody(stream, new
                {
                    grant_type = "authorization_code",
                    code,
                    redirect_uri = _redirectUri
                });
            }

            stream.Close();
            var json = _webAgent.ExecuteRequest(request);
            if (json["access_token"] != null)
            {
                if (json["refresh_token"] != null)
                    RefreshToken = json["refresh_token"].ToString();
                OAuthToken = json["access_token"].ToString();
                return json["access_token"].ToString();
            }
            throw new AuthenticationException("Could not log in.");
        }

        /// <summary>
        /// Gets the OAuth token for the user.
        /// </summary>
        /// <param name="username">The username.</param>
        /// <param name="password">The user's password.</param>
        /// <returns>The access token</returns>
        public string GetOAuthToken(string username, string password)
        {
            if (Type.GetType("Mono.Runtime") != null)
                ServicePointManager.ServerCertificateValidationCallback = (s, c, ch, ssl) => true;
            _webAgent.Cookies = new CookieContainer();

            var request = _webAgent.CreatePost(AccessUrl);

            request.Headers["Authorization"] = "Basic " + Convert.ToBase64String(Encoding.Default.GetBytes(_clientId + ":" + _clientSecret));
            var stream = request.GetRequestStream();

            _webAgent.WritePostBody(stream, new
            {
                grant_type = "password",
                username,
                password,
                redirect_uri = _redirectUri
            });

            stream.Close();
            var json = _webAgent.ExecuteRequest(request);
            if (json["access_token"] != null)
            {
                if (json["refresh_token"] != null)
                    RefreshToken = json["refresh_token"].ToString();
                OAuthToken = json["access_token"].ToString();
                return json["access_token"].ToString();
            }
            throw new AuthenticationException("Could not log in.");
        }
		
        /// <summary>
        /// Gets a user authenticated by OAuth2.
        /// </summary>
        /// <param name="accessToken">Obtained using GetOAuthToken</param>
        /// <returns></returns>
        [Obsolete("Reddit.InitOrUpdateUser is preferred")]
        public AuthenticatedUser GetUser(string accessToken)
        {
            var request = _webAgent.CreateGet(OauthGetMeUrl);
            request.Headers["Authorization"] = String.Format("bearer {0}", accessToken);
            var response = (HttpWebResponse)request.GetResponse();
            var result = _webAgent.GetResponseString(response.GetResponseStream());
            var thingjson = "{\"kind\": \"t2\", \"data\": " + result + "}";
            var json = JObject.Parse(thingjson);
            return new AuthenticatedUser().Init(new Reddit(), json, _webAgent);
        }
    }
}