using FastReport.Utils;
using System;
using System.Collections.Generic;
using System.IO;
using System.Net;
using System.Security.Cryptography;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.Xml;

namespace FastReport.Cloud.StorageClient.S3
{
    /// <summary>
    /// Simple Storage Service client.
    /// </summary>
    public class S3StorageClient : CloudStorageClient
    {
        private int chunkLength = 1 * 1024 * 1024; // 10MB
        private int timeout = 8000000;

        private string currentBucket;
        private string fileName;
        private string host;
        private S3Signer signer;

        public event EventHandler AfterUpload;
        public event EventHandler BeforeUpload;
        /// <summary>
        /// Gets or sets bucket where will saved export.
        /// </summary>
        public string CurrentBucket
        {
            get { return currentBucket; }
            set { currentBucket = value; }
        }

        /// <summary>
        /// Gets or sets filename.
        /// </summary>
        public string FileName
        {
            get { return fileName; }
            set { fileName = value; }
        }

        /// <summary>
        /// Gets or sets host S3.
        /// </summary>
        public string Host
        {
            get { return host; }
            set
            {
                host = value;
                if (host.EndsWith("/"))
                    host = host.Remove(host.Length - 1);
            }
        }

        /// <inheritdoc/>
        protected override void SaveMemoryStream(MemoryStream ms)
        {
            try
            {
                ServicePointManager.SecurityProtocol = (SecurityProtocolType)(0xc0 | 0x300 | 0xc00);
                ms.Position = 0;

                if (ms.Length <= chunkLength)
                {
                    BeforeUpload?.Invoke(this, null);

                    HttpWebRequest httpRequest = CreatePut($"{host}/{currentBucket}/{fileName}");
                    httpRequest.Headers.Add(HttpRequestHeader.ContentMd5, Convert.ToBase64String(MD5.Create().ComputeHash(ms)));
                    ms.Position = 0;

                    ms.CopyTo(httpRequest.GetRequestStream());
                    ms.Position = 0;

                    signer.Sign(httpRequest, ms);

                    var response = httpRequest.GetResponse();
                    AfterUpload?.Invoke(this, null);
                }
                else
                {
                    BeforeUpload?.Invoke(this, null);
                    MemoryStream memoryStream = new MemoryStream();
                    ms.CopyTo(memoryStream);
                    Task.Factory.StartNew(() =>
                    {
                        HttpWebRequest httpRequest = CreatePut($"{host}/{currentBucket}/{fileName}");
                        httpRequest.SendChunked = true;
                        httpRequest.ReadWriteTimeout = 32000;
                        httpRequest.Timeout = timeout;

                        memoryStream.Position = 0;
                        httpRequest.Headers.Add(HttpRequestHeader.ContentMd5, Convert.ToBase64String(MD5.Create().ComputeHash(memoryStream)));
                        memoryStream.Position = 0;

                        SendChunked(httpRequest, memoryStream, signer);
                        AfterUpload?.Invoke(this, null);
                        memoryStream.Close();
                    });
                }
            }
            catch (Exception ex)
            {
                throw new CloudStorageException(ex.Message, ex);
            }
        }

        private HttpWebRequest CreatePut(string url)
        {
            HttpWebRequest httpRequest = (HttpWebRequest)WebRequest.Create(url);
            httpRequest.Method = WebRequestMethods.Http.Put;
            return httpRequest;
        }

        private void SendChunked(HttpWebRequest httpRequest, MemoryStream ms, S3Signer signer)
        {
            try
            {
                var data = DateTimeOffset.UtcNow;
                string previousSign = signer.SignSeed(httpRequest, ms.Length, data);
                int chunkLength = this.chunkLength;
                Stream requestStream = httpRequest.GetRequestStream();
                int chunkCount = (int)Math.Ceiling((decimal)ms.Length / chunkLength);

                int currentCunkLength = chunkLength;
                for (int i = 0; i < chunkCount; i++)
                {
                    if (i == chunkCount - 1 && ms.Length % chunkLength > 0)
                        currentCunkLength = (int)(ms.Length % chunkLength);

                    using (MemoryStream chunkData = new MemoryStream())
                    {
                        for (int j = 0; j < currentCunkLength; j++)
                        {
                            chunkData.WriteByte((byte)ms.ReadByte());
                        }
                        chunkData.Position = 0;
                        previousSign = signer.SignChunk(httpRequest, previousSign, chunkData, requestStream, data);
                    }
                }

                signer.SignChunk(httpRequest, previousSign, null, requestStream, data);

                WebResponse response = httpRequest.GetResponse();
                requestStream.Close();
                GC.Collect();
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message, Res.Get("Messages,Error"), MessageBoxButtons.OK, MessageBoxIcon.Error);
            }
        }

        /// <summary>
        /// Get list of buckets names.
        /// </summary>
        /// <returns>List of buckets names</returns>
        public List<string> GetListBuckets()
        {
            List<string> buckets = new List<string>();
            try
            {
                ServicePointManager.SecurityProtocol = (SecurityProtocolType)(0xc0 | 0x300 | 0xc00);
                HttpWebRequest httpRequest = (HttpWebRequest)WebRequest.Create(host + "/");
                signer.Sign(httpRequest);
                var response = httpRequest.GetResponse();

                System.Xml.XmlDocument xmlReader = new System.Xml.XmlDocument();
                xmlReader.Load(response.GetResponseStream());

                foreach (XmlNode node in xmlReader.LastChild["Buckets"].ChildNodes)
                    buckets.Add(node["Name"].InnerText);
            }
            catch (System.Exception ex)
            {
                throw new CloudStorageException(ex.Message, ex);
            }

            return buckets;
        }

        /// <summary>
        /// Initialize signer.
        /// </summary>
        /// <param name="accessKeyId">Access key ID</param>
        /// <param name="secretAccessKey">Secret access key</param>
        /// <param name="region">Service region</param>
        public void InitSigner(string accessKeyId, string secretAccessKey, string region)
        {
            signer = new S3Signer(accessKeyId, secretAccessKey, region);
        }
    }
}