using System;
using System.Collections.Generic;
using System.Threading.Tasks;
using Bit.Core.Models.Mail;
using System.Linq;
using Amazon.SimpleEmail;
using Amazon;
using Amazon.SimpleEmail.Model;
using Microsoft.AspNetCore.Hosting;
using Microsoft.Extensions.Logging;

namespace Bit.Core.Services
{
    public class AmazonSesMailDeliveryService : IMailDeliveryService, IDisposable
    {
        private readonly GlobalSettings _globalSettings;
        private readonly IHostingEnvironment _hostingEnvironment;
        private readonly ILogger<AmazonSesMailDeliveryService> _logger;
        private readonly AmazonSimpleEmailServiceClient _client;
        private readonly string _source;
        private readonly string _senderTag;

        public AmazonSesMailDeliveryService(
            GlobalSettings globalSettings,
            IHostingEnvironment hostingEnvironment,
            ILogger<AmazonSesMailDeliveryService> logger)
        {
            if(string.IsNullOrWhiteSpace(globalSettings.Amazon?.AccessKeyId))
            {
                throw new ArgumentNullException(nameof(globalSettings.Amazon.AccessKeyId));
            }
            if(string.IsNullOrWhiteSpace(globalSettings.Amazon?.AccessKeySecret))
            {
                throw new ArgumentNullException(nameof(globalSettings.Amazon.AccessKeySecret));
            }
            if(string.IsNullOrWhiteSpace(globalSettings.Amazon?.Region))
            {
                throw new ArgumentNullException(nameof(globalSettings.Amazon.Region));
            }

            _globalSettings = globalSettings;
            _hostingEnvironment = hostingEnvironment;
            _logger = logger;
            _client = new AmazonSimpleEmailServiceClient(globalSettings.Amazon.AccessKeyId,
                globalSettings.Amazon.AccessKeySecret, RegionEndpoint.GetBySystemName(globalSettings.Amazon.Region));
            _source = $"\"{globalSettings.SiteName}\" <{globalSettings.Mail.ReplyToEmail}>";
            _senderTag = $"Server: {globalSettings.ProjectName}";
        }

        public void Dispose()
        {
            _client?.Dispose();
        }

        public async Task SendEmailAsync(MailMessage message)
        {
            var request = new SendEmailRequest
            {
                ConfigurationSetName = "Email",
                Source = _source,
                Destination = new Destination
                {
                    ToAddresses = message.ToEmails.ToList()
                },
                Message = new Message
                {
                    Subject = new Content(message.Subject),
                    Body = new Body
                    {
                        Html = new Content
                        {
                            Charset = "UTF-8",
                            Data = message.HtmlContent
                        },
                        Text = new Content
                        {
                            Charset = "UTF-8",
                            Data = message.TextContent
                        }
                    }
                },
                Tags = new List<MessageTag>
                {
                    new MessageTag { Name = "Environment", Value = _hostingEnvironment.EnvironmentName },
                    new MessageTag { Name = "Sender", Value = _senderTag }
                }
            };

            if(message.BccEmails?.Any() ?? false)
            {
                request.Destination.BccAddresses = message.BccEmails.ToList();
            }

            if(message.MetaData?.ContainsKey("SendGridCategories") ?? false)
            {
                var cats = (message.MetaData["SendGridCategories"] as List<string>)
                    .Select(c => new MessageTag { Name = "Category", Value = c });
                request.Tags.AddRange(cats);
            }

            try
            {
                await SendAsync(request, false);
            }
            catch(Exception e)
            {
                _logger.LogWarning(e, "Failed to send email.");
                await SendAsync(request, true);
                throw e;
            }
        }

        private async Task SendAsync(SendEmailRequest request, bool retry)
        {
            if(retry)
            {
                // wait and try again
                await Task.Delay(2000);
            }

            await _client.SendEmailAsync(request);
        }
    }
}