using System;
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.Linq;
using System.Text.Json;
using System.Threading;
using System.Threading.Tasks;
using FinlyticAssets.Entities;
using FinlyticAssets.Services;
using FinlyticCore.Dtos;
using FinlyticCore.Dtos.Assets;
using FinlyticCore.Dtos.Settings;
using FinlyticCore.Dtos.TechnicalAnalysis;
using FinlyticCore.Models;
using FinlyticCore.Models.Assets;
using FinlyticCore.Services;
using FinlyticCore.Services.TradeRepublic;
using FinlyticCore.Util;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Logging;

namespace FinlyticAssets.Util;

/// <summary>
/// Managed MQTT client acting as an RPC provider for asset lookups, discovery, and on-demand derivatives.
/// </summary>
public class AssetsMqttClient : ManagedMqttClient, IHostedService
{
    private readonly ILogger<AssetsMqttClient> _logger;
    private readonly IServiceScopeFactory _scopeFactory;
    private readonly IConfiguration _configuration;
    private readonly ConcurrentDictionary<string, (LivePriceDto Price, DateTime CachedAt)> _priceCache = new(StringComparer.OrdinalIgnoreCase);

    public AssetsMqttClient(
        ILogger<AssetsMqttClient> logger, 
        IServiceScopeFactory scopeFactory, 
        IConfiguration configuration) : base(logger)
    {
        _logger = logger;
        _scopeFactory = scopeFactory;
        _configuration = configuration;
    }

    /// <summary>
    /// Starts the MQTT client and connects to the configured broker.
    /// </summary>
    public async Task StartAsync(CancellationToken cancellationToken)
    {
        var config = MqttConfiguration.FromConfiguration(_configuration, "FinlyticAssets");

        _logger.LogInformation("Starting Assets MQTT client. Host: {Host}, ClientId: {ClientId}", config.Host, config.ClientId);
        await ConnectAsync(config);
    }

    /// <summary>
    /// Gracefully stops and disconnects the MQTT client.
    /// </summary>
    public async Task StopAsync(CancellationToken cancellationToken)
    {
        _logger.LogInformation("Stopping Assets MQTT client.");
        await DisconnectAsync();
    }

    /// <summary>
    /// Invoked automatically once the connection to the MQTT broker is successfully established or restored.
    /// </summary>
    protected override async Task OnConnectedAsync()
    {
        _logger.LogInformation("Assets MQTT Client connected. Registering topic subscriptions...");

        await SubscribeAsync(MqttTopics.ResponseWildcard);
        await SubscribeRpcAsync<GetValidAssetRequest, List<AssetDto>>(MqttTopics.RequestFilter(MqttTopics.Channels.AssetsGet), HandleAssetsGetRpcAsync);
        await SubscribeRpcAsync<GetDiscoveryAssetsRequest, List<AssetDto>>(MqttTopics.RequestFilter(MqttTopics.Channels.AssetsGetDiscovery), HandleAssetsGetDiscoveryRpcAsync);
        await SubscribeRpcAsync<GetDerivativesRequest, List<DerivativeDto>>(MqttTopics.RequestFilter(MqttTopics.Channels.AssetsGetDerivatives), HandleAssetsGetDerivativesRpcAsync);
        await SubscribeRpcAsync<IsinRequest, LivePriceDto?>(MqttTopics.RequestFilter(MqttTopics.Channels.TrGetLivePrice), HandleGetLivePriceRpcAsync);
        await SubscribeRpcAsync<object, List<DynamicSettingDto>>(MqttTopics.RequestFilter(MqttTopics.Channels.AssetsSettingsGetAll), HandleSettingsGetAllRpcAsync);
        await SubscribeRpcAsync<Dictionary<string, object?>, List<DynamicSettingDto>>(MqttTopics.RequestFilter(MqttTopics.Channels.AssetsSettingsUpdate), HandleSettingsUpdateRpcAsync);
        await SubscribeAsync<object>(MqttTopics.RequestFilter(MqttTopics.Channels.HealthPing), HandleHealthPingRpcAsync);

        FinlyticLogBroadcaster.OnLogPublished = async (logDto) =>
        {
            if (IsConnected && string.Equals(logDto.ServiceName, "FinlyticAssets", StringComparison.OrdinalIgnoreCase))
            {
                await PublishAsync(MqttTopics.Logs("FinlyticAssets"), logDto);
            }
        };
    }

    private async Task<List<AssetDto>> HandleAssetsGetRpcAsync(GetValidAssetRequest? req, string correlationId)
    {
        if (req == null || string.IsNullOrWhiteSpace(req.Isin)) return [];

        using var scope = _scopeFactory.CreateScope();
        var dbService = scope.ServiceProvider.GetRequiredService<IAssetsDbService>();
        var assets = await dbService.GetValidAssetsByIsinAsync(req.Isin.Trim().ToUpperInvariant());
        return assets.ToDtoList();
    }

    private async Task<List<AssetDto>> HandleAssetsGetDiscoveryRpcAsync(GetDiscoveryAssetsRequest? req, string correlationId)
    {
        using var scope = _scopeFactory.CreateScope();
        var dbService = scope.ServiceProvider.GetRequiredService<IAssetsDbService>();
        int limit = req?.Limit > 0 ? req.Limit : 15;
        var discoveryAssets = await dbService.GetDiscoveryAssetsAsync(limit);
        return discoveryAssets.ToDtoList();
    }

    private async Task<List<DerivativeDto>> HandleAssetsGetDerivativesRpcAsync(GetDerivativesRequest? req, string correlationId)
    {
        if (req == null || string.IsNullOrWhiteSpace(req.UnderlyingIsin)) return [];

        using var scope = _scopeFactory.CreateScope();
        var dbService = scope.ServiceProvider.GetRequiredService<IAssetsDbService>();
        var derivatives = await dbService.GetDerivativesByUnderlyingAsync(
            req.UnderlyingIsin.Trim().ToUpperInvariant(),
            req.OptionType,
            req.TargetLeverage,
            req.After,
            req.Page,
            req.ShouldForceRefresh);
        return derivatives.ToDtoList();
    }

    private async Task<LivePriceDto?> HandleGetLivePriceRpcAsync(IsinRequest? req, string correlationId)
    {
        if (req == null || string.IsNullOrWhiteSpace(req.Isin)) return null;

        var cleanIsin = req.Isin.Trim().ToUpperInvariant();

        // Return fresh price from cache if less than 3 seconds old
        if (_priceCache.TryGetValue(cleanIsin, out var cached) && (DateTime.UtcNow - cached.CachedAt).TotalSeconds < 3)
        {
            return cached.Price;
        }

        using var scope = _scopeFactory.CreateScope();
        var trService = scope.ServiceProvider.GetRequiredService<ITradeRepublicService>();
        var finlyticLogger = scope.ServiceProvider.GetRequiredService<IFinlyticLogger<AssetsMqttClient>>();

        var tcs = new TaskCompletionSource<LivePriceDto?>(TaskCreationOptions.RunContinuationsAsynchronously);
        int? subId = null;

        try
        {
            subId = await trService.SubscribeRealtimeTickerAsync(cleanIsin, tick =>
            {
                decimal currentPrice = tick.Last?.PriceValue > 0 ? tick.Last.PriceValue :
                                      (tick.Bid?.PriceValue > 0 && tick.Ask?.PriceValue > 0 ? (tick.Bid.PriceValue + tick.Ask.PriceValue) / 2m :
                                      (tick.Ask?.PriceValue ?? tick.Bid?.PriceValue ?? 0m));

                decimal preClose = tick.Pre?.PriceValue > 0 ? tick.Pre.PriceValue : (tick.Open?.PriceValue ?? 0m);
                decimal dailyChange = preClose > 0m ? ((currentPrice - preClose) / preClose) * 100m : 0m;

                var livePrice = new LivePriceDto(
                    Isin: cleanIsin,
                    CurrentPrice: currentPrice,
                    DailyChangePercent: dailyChange,
                    Bid: tick.Bid?.PriceValue,
                    Ask: tick.Ask?.PriceValue
                );

                _priceCache[cleanIsin] = (livePrice, DateTime.UtcNow);
                tcs.TrySetResult(livePrice);
            });

            var result = await tcs.Task.WaitAsync(TimeSpan.FromSeconds(3));
            return result;
        }
        catch (Exception ex)
        {
            await finlyticLogger.LogWarningAsync(SettingKeys.AssetsChannel, "[AssetsMqttClient] Failed or timed out fetching live price for {Isin}: {Message}", cleanIsin, ex.Message);
            if (_priceCache.TryGetValue(cleanIsin, out var stale))
            {
                return stale.Price;
            }
            return null;
        }
        finally
        {
            if (subId.HasValue)
            {
                _ = trService.UnsubscribeRealtimeTickerAsync(subId.Value);
            }
        }
    }

    private async Task<List<DynamicSettingDto>> HandleSettingsGetAllRpcAsync(object? _, string correlationId)
    {
        using var scope = _scopeFactory.CreateScope();
        var finlyticLogger = scope.ServiceProvider.GetRequiredService<IFinlyticLogger<AssetsMqttClient>>();
        var settingsService = scope.ServiceProvider.GetRequiredService<ISettingsService>();

        await finlyticLogger.LogInfoAsync(SettingKeys.MqttChannel, "[FinlyticAssets] [Settings_GetAll] Retrieving service dynamic settings [CorrelationId: {CorrelationId}]", correlationId);
        return await settingsService.GetAllRegisteredSettingsAsync(new[] { typeof(SettingKeys) });
    }

    private async Task<List<DynamicSettingDto>> HandleSettingsUpdateRpcAsync(Dictionary<string, object?>? updates, string correlationId)
    {
        using var scope = _scopeFactory.CreateScope();
        var finlyticLogger = scope.ServiceProvider.GetRequiredService<IFinlyticLogger<AssetsMqttClient>>();
        var settingsService = scope.ServiceProvider.GetRequiredService<ISettingsService>();

        await finlyticLogger.LogInfoAsync(SettingKeys.MqttChannel, "[FinlyticAssets] [Settings_Update] Processing settings update RPC [CorrelationId: {CorrelationId}]", correlationId);
        if (updates != null && updates.Count > 0)
        {
            await settingsService.UpdateSettingsAsync(updates);
            await finlyticLogger.LogInfoAsync(SettingKeys.MqttChannel, "[FinlyticAssets] [Settings_Update] Successfully updated {Count} settings in database and cache.", updates.Count);
        }
        return await settingsService.GetAllRegisteredSettingsAsync(new[] { typeof(SettingKeys) });
    }

    private async Task HandleHealthPingRpcAsync(object? _, string topic, string correlationId)
    {
        if (topic.Contains("FinlyticAssets", StringComparison.OrdinalIgnoreCase))
        {
            string respTopic = MqttTopics.ResponseTopic(MqttTopics.Channels.HealthPing, correlationId);
            await PublishAsync(respTopic, new FinlyticCore.Dtos.ServiceHealthResponse("FinlyticAssets", "Online", DateTime.UtcNow, "Connected"));
            using var scope = _scopeFactory.CreateScope();
            var finlyticLogger = scope.ServiceProvider.GetRequiredService<IFinlyticLogger<AssetsMqttClient>>();
            await finlyticLogger.LogInfoAsync(SettingKeys.HealthPingChannel, "[AssetsMqttClient] Responded to health_Ping RPC request [CorrelationId: {CorrelationId}].", correlationId);
        }
    }
}