// Copyright (C) 2024, The Duplicati Team
// https://duplicati.com, hello@duplicati.com
// 
// Permission is hereby granted, free of charge, to any person obtaining a 
// copy of this software and associated documentation files (the "Software"), 
// to deal in the Software without restriction, including without limitation 
// the rights to use, copy, modify, merge, publish, distribute, sublicense, 
// and/or sell copies of the Software, and to permit persons to whom the 
// Software is furnished to do so, subject to the following conditions:
// 
// The above copyright notice and this permission notice shall be included in 
// all copies or substantial portions of the Software.
// 
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS 
// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING 
// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER 
// DEALINGS IN THE SOFTWARE.

using System;
using System.Net;
using System.Text;
using Newtonsoft.Json;
using Duplicati.Library.Utility;

namespace Duplicati.Library.Backend.Backblaze
{
    public class B2AuthHelper : JSONWebHelper
    {
        private readonly string m_credentials;
        private AuthResponse m_config;
        private DateTime m_configExpires;
        internal const string AUTH_URL = "https://api.backblazeb2.com/b2api/v1/b2_authorize_account";

        public B2AuthHelper(string userid, string password)
            : base()
        {
            m_credentials = Convert.ToBase64String(Encoding.UTF8.GetBytes(userid + ":" + password));
        }

        public override HttpWebRequest CreateRequest(string url, string method = null)
        {
            var r = base.CreateRequest(url, method);
            r.Headers["Authorization"] = AuthorizationToken;
            return r;
        }

        public string AuthorizationToken { get { return Config.AuthorizationToken; } }
        public string APIUrl { get { return Config.APIUrl; } }
        public string DownloadUrl { get { return Config.DownloadUrl; } }
        public string AccountID { get { return Config.AccountID; } }

        private string DropTrailingSlashes(string url)
        {
            while(url.EndsWith("/", StringComparison.Ordinal))
                url = url.Substring(0, url.Length - 1);
            return url;
        }

        public string APIDnsName
        {
            get
            {
                if (m_config == null || string.IsNullOrWhiteSpace(m_config.APIUrl))
                    return null;
                return new System.Uri(m_config.APIUrl).Host;
            }
        }

        public string DownloadDnsName
        {
            get
            {
                if (m_config == null || string.IsNullOrWhiteSpace(m_config.DownloadUrl))
                    return null;
                return new System.Uri(m_config.DownloadUrl).Host;
            }
        }

        private AuthResponse Config
        {
            get
            {
                if (m_config == null || m_configExpires < DateTime.UtcNow)
                {
                    var retries = 0;

                    while(true)
                    {
                        try
                        {
                            var req = base.CreateRequest(AUTH_URL);
                            req.Headers.Add("Authorization", string.Format("Basic {0}", m_credentials));
                            req.ContentType = "application/json; charset=utf-8";

                            using(var resp = (HttpWebResponse)new AsyncHttpRequest(req).GetResponse())
                                m_config = ReadJSONResponse<AuthResponse>(resp);

                            m_config.APIUrl = DropTrailingSlashes(m_config.APIUrl);
                            m_config.DownloadUrl = DropTrailingSlashes(m_config.DownloadUrl);

                            m_configExpires = DateTime.UtcNow + TimeSpan.FromHours(1);
                            return m_config;
                        }
                        catch (Exception ex)
                        {
                            var clienterror = false;

                            try
                            {
                                // Only retry once on client errors
                                if (ex is WebException exception && exception.Response is HttpWebResponse response)
                                {
                                    var sc = (int)response.StatusCode;
                                    clienterror = (sc >= 400 && sc <= 499);
                                }
                            }
                            catch
                            {
                            }

                            if (retries >= (clienterror ? 1 : 5))
                            {
                                AttemptParseAndThrowException(ex);
                                throw;
                            }

                            System.Threading.Thread.Sleep(TimeSpan.FromSeconds(Math.Pow(2, retries)));
                            retries++;
                        }
                    }
                }

                return m_config;
            }
        }

        public static void AttemptParseAndThrowException(Exception ex)
        {
            Exception newex = null;
            try
            {
                if (ex is WebException exception && exception.Response is HttpWebResponse hs)
                {
                    string rawdata = null;
                    using(var rs = Library.Utility.AsyncHttpRequest.TrySetTimeout(hs.GetResponseStream()))
                    using(var sr = new System.IO.StreamReader(rs))
                        rawdata = sr.ReadToEnd();

                    newex = new Exception("Raw message: " + rawdata);

                    var msg = JsonConvert.DeserializeObject<ErrorResponse>(rawdata);
                    newex = new Exception(string.Format("{0} - {1}: {2}", msg.Status, msg.Code, msg.Message));
                }
            }
            catch
            {
            }

            if (newex != null)
                throw newex;
        }

        protected override void ParseException(Exception ex)
        {
            AttemptParseAndThrowException(ex);
        }

        public static HttpStatusCode GetExceptionStatusCode(Exception ex)
        {
            if (ex is WebException exception && exception.Response is HttpWebResponse response)
                return response.StatusCode;
            else
                return default(HttpStatusCode);
        }
            

        private class ErrorResponse
        {
            [JsonProperty("code")]
            public string Code { get; set; }
            [JsonProperty("message")]
            public string Message { get; set; }
            [JsonProperty("status")]
            public long Status { get; set; }

        }

        private class AuthResponse 
        {
            [JsonProperty("accountId")]
            public string AccountID { get; set; }
            [JsonProperty("apiUrl")]
            public string APIUrl { get; set; }
            [JsonProperty("authorizationToken")]
            public string AuthorizationToken { get; set; }
            [JsonProperty("downloadUrl")]
            public string DownloadUrl { get; set; }
        }

    }

}