using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;
using FinlyticCore.Dtos.TechnicalAnalysis;
using FinlyticCore.Dtos.Trading;
using FinlyticCore.Services;
using FinlyticEngine.Database;
using FinlyticEngine.Database.Entities;
using FinlyticEngine.Services.Mqtt;
using FinlyticEngine.Settings;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;

namespace FinlyticEngine.Services.Trading;

public record GetSetupsRpcRequest(
    bool TopPicksOnly = true,
    int Limit = 30,
    decimal? MinScore = 70.0m
);

public class OpportunityPollerBackgroundService : BackgroundService
{
    private readonly IServiceScopeFactory _scopeFactory;
    private readonly IEngineRpcClient _rpcClient;
    private readonly ISettingsService _settingsService;
    private readonly IFinlyticLogger<OpportunityPollerBackgroundService> _logger;

    public OpportunityPollerBackgroundService(
        IServiceScopeFactory scopeFactory,
        IEngineRpcClient rpcClient,
        ISettingsService settingsService,
        IFinlyticLogger<OpportunityPollerBackgroundService> logger)
    {
        _scopeFactory = scopeFactory;
        _rpcClient = rpcClient;
        _settingsService = settingsService;
        _logger = logger;
    }

    protected override async Task ExecuteAsync(CancellationToken stoppingToken)
    {
        await _logger.LogInfoAsync(EngineSettingKeys.EngineChannel,
            "[OpportunityPoller] Starting background opportunity scanner.");

        // Initial grace delay for MQTT network stabilization
        await Task.Delay(TimeSpan.FromSeconds(5), stoppingToken);

        while (!stoppingToken.IsCancellationRequested)
        {
            try
            {
                var intervalSec = await _settingsService.GetSettingAsync(EngineSettingKeys.PollingIntervalSeconds, stoppingToken);

                await _logger.LogInfoAsync(EngineSettingKeys.EngineChannel,
                    "[OpportunityPoller] Querying active top-picks from FinlyticTechnicals...");

                var minScore = await _settingsService.GetSettingAsync(EngineSettingKeys.PollerMinScore, stoppingToken);
                var topPicksOnly = await _settingsService.GetSettingAsync(EngineSettingKeys.PollerTopPicksOnly, stoppingToken);
                var limit = await _settingsService.GetSettingAsync(EngineSettingKeys.PollerLimit, stoppingToken);

                var req = new GetSetupsRpcRequest(TopPicksOnly: topPicksOnly, Limit: limit, MinScore: minScore);
                var topPicks = await _rpcClient.SendRpcRequestAsync<List<StrategyResultDto>, GetSetupsRpcRequest>(
                    "ta_GetSetups",
                    req,
                    TimeSpan.FromSeconds(5)
                );

                // Task 3 (scan-universe visibility): only persist a cycle row once FinlyticTechnicals actually
                // answered - topPicks == null means the RPC itself timed out/failed (already logged/handled
                // below), which is a transport failure, not a legitimate "zero candidates this cycle" scan
                // outcome, so it deliberately does not get a row here.
                if (topPicks != null)
                {
                    await PersistScanCycleAsync(req, topPicks, stoppingToken);
                }

                if (topPicks != null && topPicks.Count > 0)
                {
                    await _logger.LogInfoAsync(EngineSettingKeys.EngineChannel,
                        "[OpportunityPoller] Received {Count} top-picks from FinlyticTechnicals. Evaluating opportunities...",
                        topPicks.Count);

                    using var scope = _scopeFactory.CreateScope();
                    var lifecycleService = scope.ServiceProvider.GetRequiredService<ITradeLifecycleService>();

                    foreach (var pick in topPicks)
                    {
                        if (stoppingToken.IsCancellationRequested) break;

                        try
                        {
                            // Result is intentionally not surfaced anywhere beyond this log line: the poller is
                            // an autonomous background scanner with no human waiting on a per-asset rejection
                            // reason, unlike the on-demand RPC callers (AnalyzeController/EngineController).
                            var evaluation = await lifecycleService.EvaluateAssetAsync(
                                pick.Isin, pick.Symbol, forceAiEvaluation: false,
                                triggerSource: TriggerSource.Automatic, triggeredByUserId: null,
                                cancellationToken: stoppingToken);
                            if (evaluation.Proposal == null)
                            {
                                await _logger.LogInfoAsync(EngineSettingKeys.EngineChannel,
                                    "[OpportunityPoller] {Isin} evaluated, no proposal (COS={Cos:F1}, AiApproved={AiApproved}): {Reason}",
                                    pick.Isin, evaluation.CompositeScore, evaluation.AiApproved, evaluation.AiThesisSummary);
                            }
                        }
                        catch (Exception ex)
                        {
                            await _logger.LogWarningAsync(EngineSettingKeys.EngineChannel, ex,
                                "[OpportunityPoller] Failed to evaluate top-pick ISIN {Isin}", pick.Isin);
                        }

                        // Gentle throttle between evaluations
                        await Task.Delay(250, stoppingToken);
                    }
                }
                else
                {
                    await _logger.LogInfoAsync(EngineSettingKeys.EngineChannel,
                        "[OpportunityPoller] No active top-picks available at this time.");
                }

                await Task.Delay(TimeSpan.FromSeconds(Math.Max(10, intervalSec)), stoppingToken);
            }
            catch (OperationCanceledException) when (stoppingToken.IsCancellationRequested)
            {
                break;
            }
            catch (Exception ex)
            {
                await _logger.LogErrorAsync(EngineSettingKeys.EngineChannel, ex,
                    "[OpportunityPoller] Unexpected error in scanner cycle. Retrying in 30 seconds.");
                await Task.Delay(TimeSpan.FromSeconds(30), stoppingToken);
            }
        }

        await _logger.LogInfoAsync(EngineSettingKeys.EngineChannel,
            "[OpportunityPoller] Background opportunity scanner stopped.");
    }

    /// <summary>
    /// Persists a minimal <see cref="EngineScanCycleEntity"/> row recording exactly which ISINs
    /// FinlyticTechnicals returned as technical top-picks for this poll cycle - i.e. the engine-side candidate
    /// set that <c>ITradeLifecycleService.EvaluateAssetAsync</c> is about to be called for (Task 3:
    /// scan-universe visibility).
    /// This is deliberately NOT the full universe FinlyticTechnicals monitors before that top-picks filter is
    /// applied (favorites/discovery/sentiment-spike ISINs live entirely inside
    /// <c>FinlyticTechnicals.Services.TechnicalUniverseManager</c>, out of scope for this table) - see the
    /// implementing task's report for why that broader pre-filter visibility was not added here.
    /// </summary>
    private async Task PersistScanCycleAsync(GetSetupsRpcRequest request, List<StrategyResultDto> topPicks, CancellationToken cancellationToken)
    {
        using var scope = _scopeFactory.CreateScope();
        var db = scope.ServiceProvider.GetRequiredService<EngineDbContext>();

        db.ScanCycles.Add(new EngineScanCycleEntity
        {
            Id = Guid.NewGuid(),
            CycleStartedAtUtc = DateTime.UtcNow,
            RequestedLimit = request.Limit,
            RequestedMinScore = request.MinScore,
            CandidatesReturnedCount = topPicks.Count,
            CandidateIsins = topPicks.Select(p => p.Isin).ToList()
        });

        await db.SaveChangesAsync(cancellationToken);
    }
}