using MailKit;
using MailKit.Net.Smtp;
using MailKit.Security;
using MailKit.Search;
using System;
using System.Collections.Generic;
using System.Data;
using System.IO;
using System.Linq;
using System.Web;
using System.Threading.Tasks;
using CommonTool.MailKit;
using MailKit.Net.Imap;
using MimeKit;
using System.Configuration;

namespace CommonTool.MailKit
{
    public static class MailHelper
    {

        /// <summary>
        /// 发送邮件
        /// </summary>
        /// <param name="mailBodyEntity">邮件基础信息</param>
        /// <param name="sendServerConfiguration">发件人基础信息</param>
        public static SendResultEntity SendMail(MailBodyEntity mailBodyEntity,
            SendServerConfigurationEntity sendServerConfiguration)
        {
            if (mailBodyEntity == null)
            {
                throw new ArgumentNullException();
            }

            if (sendServerConfiguration == null)
            {
                throw new ArgumentNullException();
            }

            var sendResultEntity = new SendResultEntity();

            using (var client = new SmtpClient(new ProtocolLogger(MailMessage.CreateMailLog())))
            {
                client.ServerCertificateValidationCallback = (s, c, h, e) => true;

                Connection(mailBodyEntity, sendServerConfiguration, client, sendResultEntity);

                if (sendResultEntity.ResultStatus == false)
                {
                    return sendResultEntity;
                }

                SmtpClientBaseMessage(client);

                // Note: since we don't have an OAuth2 token, disable
                // the XOAUTH2 authentication mechanism.
                client.AuthenticationMechanisms.Remove("XOAUTH2");

                Authenticate(mailBodyEntity, sendServerConfiguration, client, sendResultEntity);

                if (sendResultEntity.ResultStatus == false)
                {
                    return sendResultEntity;
                }

                Send(mailBodyEntity, sendServerConfiguration, client, sendResultEntity);

                if (sendResultEntity.ResultStatus == false)
                {
                    return sendResultEntity;
                }
                client.Disconnect(true);
            }
            return sendResultEntity;
        }


        /// <summary>
        /// 连接服务器
        /// </summary>
        /// <param name="mailBodyEntity">邮件内容</param>
        /// <param name="sendServerConfiguration">发送配置</param>
        /// <param name="client">客户端对象</param>
        /// <param name="sendResultEntity">发送结果</param>
        public static void Connection(MailBodyEntity mailBodyEntity, SendServerConfigurationEntity sendServerConfiguration,
            SmtpClient client, SendResultEntity sendResultEntity)
        {
            try
            {
                client.Connect(sendServerConfiguration.SmtpHost, sendServerConfiguration.SmtpPort);
            }
            catch (SmtpCommandException ex)
            {
                sendResultEntity.ResultInformation = $"尝试连接时出错:{0}" + ex.Message;
                sendResultEntity.ResultStatus = false;
            }
            catch (SmtpProtocolException ex)
            {
                sendResultEntity.ResultInformation = $"尝试连接时的协议错误:{0}" + ex.Message;
                sendResultEntity.ResultStatus = false;
            }
            catch (Exception ex)
            {
                sendResultEntity.ResultInformation = $"服务器连接错误:{0}" + ex.Message;
                sendResultEntity.ResultStatus = false;
            }
        }

        /// <summary>
        /// 账户认证
        /// </summary>
        /// <param name="mailBodyEntity">邮件内容</param>
        /// <param name="sendServerConfiguration">发送配置</param>
        /// <param name="client">客户端对象</param>
        /// <param name="sendResultEntity">发送结果</param>
        public static void Authenticate(MailBodyEntity mailBodyEntity, SendServerConfigurationEntity sendServerConfiguration,
            SmtpClient client, SendResultEntity sendResultEntity)
        {
            try
            {
                client.Authenticate(sendServerConfiguration.SenderAccount, sendServerConfiguration.SenderPassword);
            }
            catch (AuthenticationException ex)
            {
                sendResultEntity.ResultInformation = $"无效的用户名或密码:{0}" + ex.Message;
                sendResultEntity.ResultStatus = false;
            }
            catch (SmtpCommandException ex)
            {
                sendResultEntity.ResultInformation = $"尝试验证错误:{0}" + ex.Message;
                sendResultEntity.ResultStatus = false;
            }
            catch (SmtpProtocolException ex)
            {
                sendResultEntity.ResultInformation = $"尝试验证时的协议错误:{0}" + ex.Message;
                sendResultEntity.ResultStatus = false;
            }
            catch (Exception ex)
            {
                sendResultEntity.ResultInformation = $"账户认证错误:{0}" + ex.Message;
                sendResultEntity.ResultStatus = false;
            }
        }

        /// <summary>
        /// 发送邮件
        /// </summary>
        /// <param name="mailBodyEntity">邮件内容</param>
        /// <param name="sendServerConfiguration">发送配置</param>
        /// <param name="client">客户端对象</param>
        /// <param name="sendResultEntity">发送结果</param>
        public static void Send(MailBodyEntity mailBodyEntity, SendServerConfigurationEntity sendServerConfiguration,
            SmtpClient client, SendResultEntity sendResultEntity)
        {
            try
            {
                client.Send(MailMessage.AssemblyMailMessage(mailBodyEntity));
            }
            catch (SmtpCommandException ex)
            {
                switch (ex.ErrorCode)
                {
                    case SmtpErrorCode.RecipientNotAccepted:
                        sendResultEntity.ResultInformation = $"收件人未被接受:{ex.Message}";
                        break;
                    case SmtpErrorCode.SenderNotAccepted:
                        sendResultEntity.ResultInformation = $"发件人未被接受:{ex.Message}";
                        break;
                    case SmtpErrorCode.MessageNotAccepted:
                        sendResultEntity.ResultInformation = $"消息未被接受:{ex.Message}";
                        break;
                }
                sendResultEntity.ResultStatus = false;
            }
            catch (SmtpProtocolException ex)
            {
                sendResultEntity.ResultInformation = $"发送消息时的协议错误:{ex.Message}";
                sendResultEntity.ResultStatus = false;
            }
            catch (Exception ex)
            {
                sendResultEntity.ResultInformation = $"邮件接收失败:{ex.Message}";
                sendResultEntity.ResultStatus = false;
            }
        }

        /// <summary>
        /// 获取SMTP基础信息
        /// </summary>
        /// <param name="client">客户端对象</param>
        /// <returns></returns>
        public static MailServerInformation SmtpClientBaseMessage(SmtpClient client)
        {
            var mailServerInformation = new MailServerInformation
            {
                Authentication = client.Capabilities.HasFlag(SmtpCapabilities.Authentication),
                BinaryMime = client.Capabilities.HasFlag(SmtpCapabilities.BinaryMime),
                Dsn = client.Capabilities.HasFlag(SmtpCapabilities.Dsn),
                EightBitMime = client.Capabilities.HasFlag(SmtpCapabilities.EightBitMime),
                Size = client.MaxSize
            };

            return mailServerInformation;
        }

    }


    /*接收邮件*/
    public static class ReceiveEmailHelper
    {
        /// <summary>
        /// 设置发件人信息
        /// </summary>
        /// <returns></returns>
        public static SendServerConfigurationEntity SetSendMessage()
        {
            var sendServerConfiguration = new SendServerConfigurationEntity
            {
                SmtpHost = ConfigurationManager.AppSettings["SmtpServer"],
                SmtpPort = int.Parse(ConfigurationManager.AppSettings["SmtpPort"]),
                IsSsl = Convert.ToBoolean(ConfigurationManager.AppSettings["IsSsl"]),
                MailEncoding = ConfigurationManager.AppSettings["MailEncoding"],
                SenderAccount = ConfigurationManager.AppSettings["SenderAccount"],
                SenderPassword = ConfigurationManager.AppSettings["SenderPassword"]
            };
            return sendServerConfiguration;
        }

        /// <summary>
        /// 接收邮件
        /// </summary>
        public static void ReceiveEmail()
        {
            var sendServerConfiguration = SetSendMessage();

            if (sendServerConfiguration == null)
            {
                throw new ArgumentNullException();
            }

            using (var client = new ImapClient(new ProtocolLogger(MailMessage.CreateMailLog())))
            {
                client.Connect(sendServerConfiguration.SmtpHost, sendServerConfiguration.SmtpPort,
                    SecureSocketOptions.SslOnConnect);
                client.Authenticate(sendServerConfiguration.SenderAccount, sendServerConfiguration.SenderPassword);
                client.Inbox.Open(FolderAccess.ReadOnly);
                var uids = client.Inbox.Search(SearchQuery.All);
                foreach (var uid in uids)
                {
                    var message = client.Inbox.GetMessage(uid);
                    message.WriteTo($"{uid}.eml");
                }

                client.Disconnect(true);
            }
        }

        /// <summary>
        /// 下载邮件内容
        /// </summary>
        public static void DownloadBodyParts()
        {
            var sendServerConfiguration = SetSendMessage();

            using (var client = new ImapClient())
            {
                client.Connect(sendServerConfiguration.SmtpHost, sendServerConfiguration.SmtpPort,
                    SecureSocketOptions.SslOnConnect);
                client.Authenticate(sendServerConfiguration.SenderAccount, sendServerConfiguration.SenderPassword);
                client.Inbox.Open(FolderAccess.ReadOnly);

                // 搜索Subject标题包含“MimeKit”或“MailKit”的邮件
                var query = SearchQuery.SubjectContains("MimeKit").Or(SearchQuery.SubjectContains("MailKit"));
                var uids = client.Inbox.Search(query);

                // 获取搜索结果的摘要信息（我们需要UID和BODYSTRUCTURE每条消息，以便我们可以提取文本正文和附件）
                var items = client.Inbox.Fetch(uids, MessageSummaryItems.UniqueId | MessageSummaryItems.BodyStructure);

                foreach (var item in items)
                {
                    // 确定一个目录来保存内容
                    var directory = Path.Combine(AppDomain.CurrentDomain.BaseDirectory + "/MailBody", item.UniqueId.ToString());

                    Directory.CreateDirectory(directory);

                    // IMessageSummary.TextBody是一个便利的属性，可以为我们找到“文本/纯文本”的正文部分
                    var bodyPart = item.TextBody;

                    // 下载'text / plain'正文部分
                    var body = (TextPart)client.Inbox.GetBodyPart(item.UniqueId, bodyPart);

                    // TextPart.Text是一个便利的属性，它解码内容并将结果转换为我们的字符串
                    var text = body.Text;

                    File.WriteAllText(Path.Combine(directory, "body.txt"), text);

                    // 现在遍历所有附件并将其保存到磁盘
                    foreach (var attachment in item.Attachments)
                    {
                        // 像我们对内容所做的那样下载附件
                        var entity = client.Inbox.GetBodyPart(item.UniqueId, attachment);

                        // 附件可以是message / rfc822部件或常规MIME部件
                        var messagePart = entity as MessagePart;
                        if (messagePart != null)
                        {
                            var rfc822 = messagePart;

                            var path = Path.Combine(directory, attachment.PartSpecifier + ".eml");

                            rfc822.Message.WriteTo(path);
                        }
                        else
                        {
                            var part = (MimePart)entity;

                            // 注意：这可能是空的，但大多数会指定一个文件名
                            var fileName = part.FileName;

                            var path = Path.Combine(directory, fileName);

                            // decode and save the content to a file
                            using (var stream = File.Create(path))
                                part.Content.DecodeTo(stream);
                        }
                    }
                }

                client.Disconnect(true);
            }
        }
    }

}