using Amazon.SQS;
using Amazon.SQS.Model;
using Utility.Environment;
using Utility.Queue.Handler;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading;
using System.Threading.Tasks;

namespace Utility.Queue.Subscribers
{
    public class SQSQueueSubscriber
    {
        private readonly IEnvironmentRequester EnvironmentRequester;
        private readonly IServiceProvider ServiceProvider;
        private readonly string QueueBaseUrl;
        private readonly string AccessKey;
        private readonly string SecretAccessKey;
        private readonly AmazonSQSConfig SQSConfig;
        private string QueueUrl;

        public SQSSubscriber(IEnvironmentRequester environmentRequester,
            IServiceProvider serviceProvider)
        {
            AccessKey = environmentRequester.GetVariable("AWSAccessKeyId");
            SecretAccessKey = environmentRequester.GetVariable("AWSSecretAccessKey");

            QueueBaseUrl = environmentRequester.GetVariable("SQSEndpointBase");

            SQSConfig = new AmazonSQSConfig
            {
                // Locally /queue will be added for elasticmq, remove. Live urls will never have /queue.
                ServiceURL = QueueBaseUrl.Replace("/queue", "")
            };

            EnvironmentRequester = environmentRequester;
            ServiceProvider = serviceProvider;
        }

        public async Task SetQueueName(string queueName)
        {
            QueueUrl = QueueBaseUrl + "/" + queueName;

            using (var client = new AmazonSQSClient(AccessKey, SecretAccessKey, SQSConfig))
            {
                CreateQueueRequest createQueueRequest = new CreateQueueRequest
                {
                    QueueName = queueName
                };

                await client.CreateQueueAsync(createQueueRequest);
            }
        }

        public async Task Poll<T, U>(IServiceProvider serviceProvider, CancellationToken stoppingToken) where T : IMessageHandler<U>
        {
            using (var client = new AmazonSQSClient(AccessKey, SecretAccessKey, SQSConfig))
            {
                while (!stoppingToken.IsCancellationRequested)
                {
                    string receiptHandle = "";

                    try
                    {
                        var request = new ReceiveMessageRequest
                        {
                            QueueUrl = QueueUrl,
                            MaxNumberOfMessages = 1,
                            WaitTimeSeconds = 20
                        };

                        var response = await client.ReceiveMessageAsync(request);

                        if (response.Messages.Count > 0)
                        {
                            var sqsMessage = response.Messages.FirstOrDefault();

                            receiptHandle = sqsMessage.ReceiptHandle;

                            var caller = new HandlerCaller(EnvironmentRequester, ServiceProvider);

                            Task task = Task.Run(() => caller.CallHandler<T, U>(sqsMessage.MessageId, sqsMessage.Body));

                            await client.DeleteMessageAsync(QueueUrl, sqsMessage.ReceiptHandle);
                        }
                    }
                    catch (Exception ex)
                    {
                        Console.WriteLine(ex.ToString());

                        if (!string.IsNullOrEmpty(receiptHandle))
                        {
                            await client.DeleteMessageAsync(QueueUrl, receiptHandle);
                        }
                    }
                }
            }
        }
    }
}