#nullable enable
using System;
using System.Collections.Generic;
using System.Globalization;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;
using BTCPayServer.Configuration;
using BTCPayServer.Data;
using BTCPayServer.HostedServices;
using BTCPayServer.Lightning;
using BTCPayServer.Logging;
using BTCPayServer.Models;
using BTCPayServer.Models.InvoicingModels;
using BTCPayServer.Client.Models;
using BTCPayServer.Services;
using BTCPayServer.Services.Invoices;
using BTCPayServer.Services.Rates;
using Microsoft.Extensions.Options;
using NBitcoin;

namespace BTCPayServer.Payments.Lightning
{
    public class LightningLikePaymentHandler : PaymentMethodHandlerBase<LightningSupportedPaymentMethod, BTCPayNetwork>
    {
        public static int LIGHTNING_TIMEOUT = 5000;
        readonly NBXplorerDashboard _Dashboard;
        private readonly LightningClientFactoryService _lightningClientFactory;
        private readonly BTCPayNetworkProvider _networkProvider;
        private readonly SocketFactory _socketFactory;
        private readonly CurrencyNameTable _currencyNameTable;

        public LightningLikePaymentHandler(
            NBXplorerDashboard dashboard,
            LightningClientFactoryService lightningClientFactory,
            BTCPayNetworkProvider networkProvider,
            SocketFactory socketFactory, 
            CurrencyNameTable currencyNameTable,
            IOptions<LightningNetworkOptions> options)
        {
            _Dashboard = dashboard;
            _lightningClientFactory = lightningClientFactory;
            _networkProvider = networkProvider;
            _socketFactory = socketFactory;
            _currencyNameTable = currencyNameTable;
            Options = options;
        }

        public override PaymentType PaymentType => PaymentTypes.LightningLike;

        public IOptions<LightningNetworkOptions> Options { get; }

        public override async Task<IPaymentMethodDetails> CreatePaymentMethodDetails(
            InvoiceLogs logs,
            LightningSupportedPaymentMethod supportedPaymentMethod, PaymentMethod paymentMethod, Data.StoreData store,
            BTCPayNetwork network, object preparePaymentObject)
        {
            if (supportedPaymentMethod.DisableBOLT11PaymentOption)
            {
                throw new PaymentMethodUnavailableException("BOLT11 payment method is disabled");
            }
            if (paymentMethod.ParentEntity.Type == InvoiceType.TopUp) {
                throw new PaymentMethodUnavailableException("Lightning Network payment method is not available for top-up invoices");
            }

            if (preparePaymentObject is null)
            {
                return new LightningLikePaymentMethodDetails()
                {
                    Activated = false
                };
            }
            var storeBlob = store.GetStoreBlob();
            var nodeInfo = GetNodeInfo(supportedPaymentMethod, network, logs, paymentMethod.PreferOnion);
            
            var invoice = paymentMethod.ParentEntity;
            decimal due = Extensions.RoundUp(invoice.Price / paymentMethod.Rate, network.Divisibility);
            try
            {
                due = paymentMethod.Calculate().Due.ToDecimal(MoneyUnit.BTC);
            }
            catch (Exception)
            {
                // ignored
            }
            var client = supportedPaymentMethod.CreateLightningClient(network, Options.Value, _lightningClientFactory);
            var expiry = invoice.ExpirationTime - DateTimeOffset.UtcNow;
            if (expiry < TimeSpan.Zero)
                expiry = TimeSpan.FromSeconds(1);

            LightningInvoice? lightningInvoice = null;

            string description = storeBlob.LightningDescriptionTemplate;
            description = description.Replace("{StoreName}", store.StoreName ?? "", StringComparison.OrdinalIgnoreCase)
                                     .Replace("{ItemDescription}", invoice.Metadata.ItemDesc ?? "", StringComparison.OrdinalIgnoreCase)
                                     .Replace("{OrderId}", invoice.Metadata.OrderId ?? "", StringComparison.OrdinalIgnoreCase);
            using (var cts = new CancellationTokenSource(LIGHTNING_TIMEOUT))
            {
                try
                {
                    var request = new CreateInvoiceParams(new LightMoney(due, LightMoneyUnit.BTC), description, expiry);
                    request.PrivateRouteHints = storeBlob.LightningPrivateRouteHints;
                    lightningInvoice = await client.CreateInvoice(request, cts.Token);
                }
                catch (OperationCanceledException) when (cts.IsCancellationRequested)
                {
                    throw new PaymentMethodUnavailableException("The lightning node did not reply in a timely manner");
                }
                catch (Exception ex)
                {
                    throw new PaymentMethodUnavailableException($"Impossible to create lightning invoice ({ex.Message})", ex);
                }
            }

            return new LightningLikePaymentMethodDetails
            {
                Activated = true,
                BOLT11 = lightningInvoice.BOLT11,
                PaymentHash = BOLT11PaymentRequest.Parse(lightningInvoice.BOLT11, network.NBitcoinNetwork).PaymentHash,
                InvoiceId = lightningInvoice.Id,
                NodeInfo = (await nodeInfo).FirstOrDefault()?.ToString()
            };
        }

        public async Task<NodeInfo[]> GetNodeInfo(LightningSupportedPaymentMethod supportedPaymentMethod, BTCPayNetwork network, InvoiceLogs invoiceLogs, bool? preferOnion = null, bool throws=false)
        {
            if (!_Dashboard.IsFullySynched(network.CryptoCode, out var summary))
                throw new PaymentMethodUnavailableException("Full node not available");

            try
            {
                using (var cts = new CancellationTokenSource(LIGHTNING_TIMEOUT))
                {
                    var client = CreateLightningClient(supportedPaymentMethod, network);
                    LightningNodeInformation info;
                    try
                    {
                        info = await client.GetInfo(cts.Token);
                    }
                    catch (OperationCanceledException) when (cts.IsCancellationRequested)
                    {
                        throw new PaymentMethodUnavailableException("The lightning node did not reply in a timely manner");
                    }
                    catch (Exception ex)
                    {
                        throw new PaymentMethodUnavailableException($"Error while connecting to the API: {ex.Message}" + 
                                                                    (!string.IsNullOrEmpty(ex.InnerException?.Message) ? $" ({ex.InnerException.Message})" : ""));
                    }

                    var nodeInfo = preferOnion != null && info.NodeInfoList.Any(i => i.IsTor == preferOnion)
                        ? info.NodeInfoList.Where(i => i.IsTor == preferOnion.Value).ToArray()
                        : info.NodeInfoList.Select(i => i).ToArray();
                
                    // Maybe the user does not have an  easily accessible ln node. Node info should be optional. The UI also supports this.
                    // if (!nodeInfo.Any())
                    // {
                    //     throw new PaymentMethodUnavailableException("No lightning node public address has been configured");
                    // }

                    var blocksGap = summary.Status.ChainHeight - info.BlockHeight;
                    if (blocksGap > 10)
                    {
                        throw new PaymentMethodUnavailableException($"The lightning node is not synched ({blocksGap} blocks left)");
                    }

                    return nodeInfo;
                }
            }
            catch(Exception e) when (!throws)
            {
                invoiceLogs.Write($"NodeInfo failed to be fetched: {e.Message}", InvoiceEventData.EventSeverity.Error);
            }

            return Array.Empty<NodeInfo>();
        }

        public ILightningClient CreateLightningClient(LightningSupportedPaymentMethod supportedPaymentMethod, BTCPayNetwork network)
        {
            var external = supportedPaymentMethod.GetExternalLightningUrl();
            if (external != null)
            {
                return _lightningClientFactory.Create(external, network);
            }
            else
            {
                if (!Options.Value.InternalLightningByCryptoCode.TryGetValue(network.CryptoCode, out var connectionString))
                    throw new PaymentMethodUnavailableException("No internal node configured");
                return _lightningClientFactory.Create(connectionString, network);
            }
        }

        public async Task TestConnection(NodeInfo nodeInfo, CancellationToken cancellation)
        {
            try
            {
                if (!Utils.TryParseEndpoint(nodeInfo.Host, nodeInfo.Port, out var endpoint))
                    throw new PaymentMethodUnavailableException($"Could not parse the endpoint {nodeInfo.Host}");

                using (var tcp = await _socketFactory.ConnectAsync(endpoint, cancellation))
                {
                }
            }
            catch (Exception ex)
            {
                throw new PaymentMethodUnavailableException($"Error while connecting to the lightning node via {nodeInfo.Host}:{nodeInfo.Port} ({ex.Message})");
            }
        }

        public override IEnumerable<PaymentMethodId> GetSupportedPaymentMethods()
        {
            return _networkProvider
                .GetAll()
                .OfType<BTCPayNetwork>()
                .Where(network => network.NBitcoinNetwork.Consensus.SupportSegwit && network.SupportLightning)
                .Select(network => new PaymentMethodId(network.CryptoCode, PaymentTypes.LightningLike));
        }

        public override void PreparePaymentModel(PaymentModel model, InvoiceResponse invoiceResponse,
            StoreBlob storeBlob, IPaymentMethod paymentMethod)
        {
            var paymentMethodId = paymentMethod.GetId();

            var cryptoInfo = invoiceResponse.CryptoInfo.First(o => o.GetpaymentMethodId() == paymentMethodId);
            var network = _networkProvider.GetNetwork<BTCPayNetwork>(model.CryptoCode);
            model.PaymentMethodName = GetPaymentMethodName(network);
            model.InvoiceBitcoinUrl = cryptoInfo.PaymentUrls?.BOLT11;
            model.InvoiceBitcoinUrlQR = $"lightning:{cryptoInfo.PaymentUrls?.BOLT11?.ToUpperInvariant()?.Substring("LIGHTNING:".Length)}";

            model.PeerInfo = ((LightningLikePaymentMethodDetails) paymentMethod.GetPaymentMethodDetails()).NodeInfo;
            if (storeBlob.LightningAmountInSatoshi && model.CryptoCode == "BTC")
            {
                var satoshiCulture = new CultureInfo(CultureInfo.InvariantCulture.Name);
                satoshiCulture.NumberFormat.NumberGroupSeparator = " ";
                model.CryptoCode = "Sats";
                model.BtcDue = Money.Parse(model.BtcDue).ToUnit(MoneyUnit.Satoshi).ToString("N0", satoshiCulture);
                model.BtcPaid = Money.Parse(model.BtcPaid).ToUnit(MoneyUnit.Satoshi).ToString("N0", satoshiCulture);
                model.OrderAmount = Money.Parse(model.OrderAmount).ToUnit(MoneyUnit.Satoshi).ToString("N0", satoshiCulture);
                model.NetworkFee = new Money(model.NetworkFee, MoneyUnit.BTC).ToUnit(MoneyUnit.Satoshi);
                model.Rate = _currencyNameTable.DisplayFormatCurrency(paymentMethod.Rate / 100_000_000, model.InvoiceCurrency);
            }
        }
        public override string GetCryptoImage(PaymentMethodId paymentMethodId)
        {
            var network = _networkProvider.GetNetwork<BTCPayNetwork>(paymentMethodId.CryptoCode);
            return GetCryptoImage(network);
        }

        private string GetCryptoImage(BTCPayNetworkBase network)
        {
            return ((BTCPayNetwork)network).LightningImagePath;
        }
        public override string GetPaymentMethodName(PaymentMethodId paymentMethodId)
        {
            var network = _networkProvider.GetNetwork<BTCPayNetwork>(paymentMethodId.CryptoCode);
            return GetPaymentMethodName(network);
        }

        public override CheckoutUIPaymentMethodSettings GetCheckoutUISettings()
        {
            return new CheckoutUIPaymentMethodSettings()
            {
                ExtensionPartial = "Lightning/LightningLikeMethodCheckout",
                CheckoutBodyVueComponentName = "LightningLikeMethodCheckout",
                CheckoutHeaderVueComponentName = "LightningLikeMethodCheckoutHeader",
                NoScriptPartialName = "Lightning/LightningLikeMethodCheckoutNoScript"
            };
        }

        private string GetPaymentMethodName(BTCPayNetworkBase network)
        {
            return $"{network.DisplayName} (Lightning)";
        }

        public override object PreparePayment(LightningSupportedPaymentMethod supportedPaymentMethod, Data.StoreData store,
            BTCPayNetworkBase network)
        {
            // pass a non null obj, so that if lazy payment feature is used, it has a marker to trigger activation
            return new { };
        }
    }
}