using System;
using System.Collections.Generic;
using System.Linq;
using AutoBidder.Models;
using AutoBidder.Utilities;

namespace AutoBidder.Services
{
    /// <summary>
    /// Servizio per strategie avanzate di puntata.
    /// Implementa: adaptive latency, jitter, dynamic offset, heat metric,
    /// competition detection, soft retreat, probabilistic bidding, opponent profiling.
    /// </summary>
    public class BidStrategyService
    {
        private readonly Random _random = new();
        private int _sessionTotalBids = 0;
        private DateTime _sessionStartedAt = DateTime.UtcNow;
        
        /// <summary>
        /// Calcola l'offset ottimale per una puntata considerando tutti i fattori
        /// </summary>
        public BidTimingResult CalculateOptimalTiming(AuctionInfo auction, AppSettings settings)
        {
            var result = new BidTimingResult
            {
                BaseOffsetMs = auction.BidBeforeDeadlineMs,
                FinalOffsetMs = auction.BidBeforeDeadlineMs,
                ShouldBid = true
            };
            
            // 1. Adaptive Latency Compensation
            if (settings.AdaptiveLatencyEnabled)
            {
                result.LatencyCompensationMs = (int)auction.AverageLatencyMs;
                result.FinalOffsetMs += result.LatencyCompensationMs;
            }
            
            // 2. Dynamic Offset (basato su heat, storico, volatilità)
            if (settings.DynamicOffsetEnabled)
            {
                var dynamicAdjustment = CalculateDynamicOffset(auction, settings);
                result.DynamicAdjustmentMs = dynamicAdjustment;
                result.FinalOffsetMs += dynamicAdjustment;
            }
            
            // 3. Jitter (randomizzazione)
            if (settings.JitterEnabled || (auction.JitterEnabledOverride ?? settings.JitterEnabled))
            {
                result.JitterMs = _random.Next(-settings.JitterRangeMs, settings.JitterRangeMs + 1);
                result.FinalOffsetMs += result.JitterMs;
            }
            
            // 4. Clamp ai limiti
            result.FinalOffsetMs = Math.Clamp(result.FinalOffsetMs, settings.MinimumOffsetMs, settings.MaximumOffsetMs);
            
            // Salva offset calcolato nell'asta
            auction.DynamicOffsetMs = result.FinalOffsetMs;
            
            return result;
        }
        
        /// <summary>
        /// Calcola offset dinamico basato su heat, storico e volatilità
        /// </summary>
        private int CalculateDynamicOffset(AuctionInfo auction, AppSettings settings)
        {
            int adjustment = 0;
            
            // Più l'asta è "calda", più anticipo serve
            if (auction.HeatMetric > 50)
            {
                adjustment += (auction.HeatMetric - 50) / 2; // +0-25ms per heat 50-100
            }
            
            // Se ci sono state collisioni recenti, anticipa di più
            if (auction.ConsecutiveCollisions > 0)
            {
                adjustment += auction.ConsecutiveCollisions * 10; // +10ms per ogni collisione
            }
            
            // Se la latenza è volatile (alta deviazione), aggiungi margine
            if (auction.LatencyHistory.Count >= 5)
            {
                var avg = auction.LatencyHistory.Average();
                var variance = auction.LatencyHistory.Sum(x => Math.Pow(x - avg, 2)) / auction.LatencyHistory.Count;
                var stdDev = Math.Sqrt(variance);
                
                if (stdDev > 20) // Alta variabilità
                {
                    adjustment += (int)(stdDev / 2);
                }
            }
            
            return adjustment;
        }
        
        /// <summary>
        /// Aggiorna heat metric per un'asta
        /// </summary>
        public void UpdateHeatMetric(AuctionInfo auction, AppSettings settings, string currentUsername = "")
        {
            if (!settings.CompetitionDetectionEnabled) return;
            
            var now = DateTimeOffset.UtcNow.ToUnixTimeSeconds();
            var windowStart = now - settings.CompetitionWindowSeconds;
            
            // Conta bidder unici nella finestra temporale (escludo me stesso)
            var recentBids = auction.RecentBids
                .Where(b => b.Timestamp >= windowStart)
                .Where(b => !b.Username.Equals(currentUsername, StringComparison.OrdinalIgnoreCase))
                .ToList();
            
            auction.ActiveBiddersCount = recentBids
                .Select(b => b.Username)
                .Distinct(StringComparer.OrdinalIgnoreCase)
                .Count();
            
            // Conta collisioni (puntate nello stesso secondo)
            var bidsBySecond = recentBids
                .GroupBy(b => b.Timestamp)
                .Where(g => g.Count() > 1)
                .Count();
            
            auction.CollisionCount = bidsBySecond;
            
            // Calcola heat metric (0-100)
            // Fattori: bidder attivi (40%), frequenza puntate (30%), collisioni (30%)
            
            int bidderScore = Math.Min(auction.ActiveBiddersCount * 15, 40); // Max 40 punti
            int frequencyScore = Math.Min(recentBids.Count * 3, 30); // Max 30 punti
            int collisionScore = Math.Min(auction.CollisionCount * 10, 30); // Max 30 punti
            
            auction.HeatMetric = bidderScore + frequencyScore + collisionScore;
            
            // Identifica bidder aggressivi e situazioni di duello
            if (settings.OpponentProfilingEnabled)
            {
                UpdateAggressiveBidders(auction, settings, currentUsername);
                DetectDuelSituation(auction, settings, currentUsername);
            }
        }
        
        /// <summary>
        /// Identifica e tracca bidder aggressivi (basato su ultime N puntate, esclude utente corrente)
        /// </summary>
        private void UpdateAggressiveBidders(AuctionInfo auction, AppSettings settings, string currentUsername)
        {
            // ?? FIX: Usa finestra scorrevole di ultime N puntate
            var windowSize = settings.AggressiveBidderWindowSize > 0 ? settings.AggressiveBidderWindowSize : 30;
            var recentWindow = auction.RecentBids
                .Take(windowSize)
                .ToList();
            
            var bidCounts = recentWindow
                .GroupBy(b => b.Username, StringComparer.OrdinalIgnoreCase)
                .Select(g => new { Username = g.Key, Count = g.Count(), Percentage = (double)g.Count() / recentWindow.Count * 100 })
                .ToList();
            
            auction.AggressiveBidders.Clear();
            
            foreach (var bidder in bidCounts)
            {
                // ?? FIX: NON aggiungere l'utente corrente come aggressivo!
                if (bidder.Username.Equals(currentUsername, StringComparison.OrdinalIgnoreCase))
                    continue;
                
                // ?? FIX: Soglia più permissiva - usa percentuale invece di conteggio assoluto
                // Un bidder è "aggressivo" se ha più del 40% delle puntate nella finestra (configurabile)
                var percentageThreshold = settings.AggressiveBidderPercentageThreshold > 0 ? settings.AggressiveBidderPercentageThreshold : 40.0;
                
                if (bidder.Percentage >= percentageThreshold || bidder.Count >= settings.AggressiveBidderThreshold)
                {
                    auction.AggressiveBidders.Add(bidder.Username);
                }
            }
        }
        
        /// <summary>
        /// Rileva situazione di "duello" (solo 2 bidder attivi che si contendono l'asta)
        /// In questa situazione bisogna essere pronti perché se uno si ritira l'altro vince
        /// </summary>
        private void DetectDuelSituation(AuctionInfo auction, AppSettings settings, string currentUsername)
        {
            var windowSize = settings.DuelDetectionWindowSize > 0 ? settings.DuelDetectionWindowSize : 20;
            var recentWindow = auction.RecentBids.Take(windowSize).ToList();
            
            if (recentWindow.Count < 6) // Serve un minimo di puntate per rilevare un pattern
            {
                auction.IsDuelSituation = false;
                auction.DuelOpponent = null;
                return;
            }
            
            var bidders = recentWindow
                .GroupBy(b => b.Username, StringComparer.OrdinalIgnoreCase)
                .Select(g => new { Username = g.Key, Count = g.Count(), Percentage = (double)g.Count() / recentWindow.Count * 100 })
                .OrderByDescending(b => b.Count)
                .ToList();
            
            // Duello: esattamente 2 bidder dominanti che coprono almeno l'80% delle puntate
            if (bidders.Count >= 2)
            {
                var top2Percentage = bidders.Take(2).Sum(b => b.Percentage);
                
                if (top2Percentage >= 80 && bidders.Count <= 3)
                {
                    auction.IsDuelSituation = true;
                    
                    // Trova l'avversario (chi NON sono io)
                    var opponent = bidders.FirstOrDefault(b => 
                        !b.Username.Equals(currentUsername, StringComparison.OrdinalIgnoreCase));
                    
                    auction.DuelOpponent = opponent?.Username;
                    
                    // Calcola chi sta dominando
                    var myStats = bidders.FirstOrDefault(b => 
                        b.Username.Equals(currentUsername, StringComparison.OrdinalIgnoreCase));
                    
                    auction.DuelAdvantage = myStats != null && opponent != null 
                        ? myStats.Percentage - opponent.Percentage 
                        : 0;
                }
                else
                {
                    auction.IsDuelSituation = false;
                    auction.DuelOpponent = null;
                    auction.DuelAdvantage = 0;
                }
            }
            else
            {
                auction.IsDuelSituation = false;
                auction.DuelOpponent = null;
            }
        }
        
        /// <summary>
        /// Verifica se è il caso di puntare considerando tutte le strategie
        /// </summary>
        public BidDecision ShouldPlaceBid(AuctionInfo auction, AuctionState state, AppSettings settings, string currentUsername)
        {
            var decision = new BidDecision { ShouldBid = true };
            
            // Se le strategie avanzate sono disabilitate per questa asta, salta tutto
            if (auction.AdvancedStrategiesEnabled == false)
            {
                return decision;
            }
            
            // ?? 1. ENTRY POINT - Verifica se il prezzo è conveniente
            // Punta solo se prezzo < (MaxPrice * 0.7)
            if (settings.EntryPointEnabled && auction.MaxPrice > 0)
            {
                var entryThreshold = auction.MaxPrice * 0.7;
                if (state.Price >= entryThreshold)
                {
                    decision.ShouldBid = false;
                    decision.Reason = $"Entry point: €{state.Price:F2} >= 70% di max €{auction.MaxPrice:F2}";
                    return decision;
                }
            }
            
            // ?? 2. ANTI-BOT - Rileva pattern bot (timing identico)
            if (settings.AntiBotDetectionEnabled && !string.IsNullOrEmpty(state.LastBidder))
            {
                var botCheck = DetectBotPattern(auction, state.LastBidder, currentUsername);
                if (botCheck.IsBot)
                {
                    decision.ShouldBid = false;
                    decision.Reason = $"Anti-bot: {state.LastBidder} pattern sospetto (var={botCheck.TimingVarianceMs:F0}ms)";
                    return decision;
                }
            }
            
            // ?? 3. USER EXHAUSTION - Sfrutta utenti stanchi (info solo, non blocca)
            if (settings.UserExhaustionEnabled && !string.IsNullOrEmpty(state.LastBidder))
            {
                var exhaustionCheck = CheckUserExhaustion(auction, state.LastBidder, currentUsername);
                // Non blocchiamo, ma potremmo loggare per info
            }
            
            // 4. Verifica soft retreat
            if (settings.SoftRetreatEnabled || (auction.SoftRetreatEnabledOverride ?? settings.SoftRetreatEnabled))
            {
                if (auction.IsInSoftRetreat)
                {
                    var retreatEnd = auction.LastSoftRetreatAt?.AddSeconds(settings.SoftRetreatDurationSeconds);
                    if (retreatEnd > DateTime.UtcNow)
                    {
                        decision.ShouldBid = false;
                        decision.Reason = $"Soft retreat attivo (termina tra {(retreatEnd.Value - DateTime.UtcNow).TotalSeconds:F0}s)";
                        return decision;
                    }
                    else
                    {
                        // Fine soft retreat
                        auction.IsInSoftRetreat = false;
                        auction.ConsecutiveCollisions = 0;
                    }
                }
                
                // Verifica se attivare soft retreat
                if (auction.ConsecutiveCollisions >= settings.SoftRetreatAfterCollisions)
                {
                    auction.IsInSoftRetreat = true;
                    auction.LastSoftRetreatAt = DateTime.UtcNow;
                    decision.ShouldBid = false;
                    decision.Reason = $"Soft retreat attivato dopo {auction.ConsecutiveCollisions} collisioni";
                    return decision;
                }
            }
            
            // 2. Verifica competition threshold
            if (settings.CompetitionDetectionEnabled)
            {
                if (auction.ActiveBiddersCount >= settings.CompetitionThreshold)
                {
                    // Controlla se l'ultimo bidder sono io - se sì, posso continuare
                    var lastBid = auction.RecentBids.OrderByDescending(b => b.Timestamp).FirstOrDefault();
                    if (lastBid != null && !lastBid.Username.Equals(currentUsername, StringComparison.OrdinalIgnoreCase))
                    {
                        if (settings.AutoPauseHotAuctions && auction.HeatMetric >= settings.HeatThresholdForPause)
                        {
                            decision.ShouldBid = false;
                            decision.Reason = $"Asta troppo calda (heat={auction.HeatMetric}%, bidder={auction.ActiveBiddersCount})";
                            return decision;
                        }
                    }
                }
            }
            
            // 3. Verifica opponent profiling
            if (settings.OpponentProfilingEnabled && auction.AggressiveBidders.Count > 0)
            {
                if (settings.AggressiveBidderAction == "Avoid")
                {
                    decision.ShouldBid = false;
                    decision.Reason = $"Bidder aggressivi rilevati: {string.Join(", ", auction.AggressiveBidders.Take(3))}";
                    return decision;
                }
            }
            
            // 4. Probabilistic bidding
            if (settings.ProbabilisticBiddingEnabled)
            {
                var probability = CalculateBidProbability(auction, settings);
                var roll = _random.NextDouble();
                
                if (roll > probability)
                {
                    decision.ShouldBid = false;
                    decision.Reason = $"Skip probabilistico (p={probability:P0}, roll={roll:P0})";
                    return decision;
                }
            }
            
            // 5. Bankroll manager
            if (settings.BankrollManagerEnabled)
            {
                var bankrollCheck = CheckBankrollLimits(auction, settings);
                if (!bankrollCheck.CanBid)
                {
                    decision.ShouldBid = false;
                    decision.Reason = bankrollCheck.Reason;
                    return decision;
                }
            }
            
            return decision;
        }
        
        /// <summary>
        /// Rileva pattern bot analizzando i delta timing degli ultimi bid
        /// </summary>
        private (bool IsBot, double TimingVarianceMs) DetectBotPattern(AuctionInfo auction, string? lastBidder, string currentUsername)
        {
            if (string.IsNullOrEmpty(lastBidder) || lastBidder.Equals(currentUsername, StringComparison.OrdinalIgnoreCase))
                return (false, 999);
            
            // Ottieni gli ultimi 3+ bid di questo utente
            var userBids = auction.RecentBids
                .Where(b => b.Username.Equals(lastBidder, StringComparison.OrdinalIgnoreCase))
                .OrderByDescending(b => b.Timestamp)
                .Take(4)
                .ToList();
            
            if (userBids.Count < 3)
                return (false, 999);
            
            // Calcola i delta tra bid consecutivi
            var deltas = new List<long>();
            for (int i = 0; i < userBids.Count - 1; i++)
            {
                deltas.Add(userBids[i].Timestamp - userBids[i + 1].Timestamp);
            }
            
            if (deltas.Count < 2)
                return (false, 999);
            
            // Calcola varianza dei delta
            var avg = deltas.Average();
            var variance = deltas.Sum(d => Math.Pow(d - avg, 2)) / deltas.Count;
            var stdDev = Math.Sqrt(variance) * 1000; // Converti in ms
            
            // Se la varianza è < 50ms, probabilmente è un bot
            return (stdDev < 50, stdDev);
        }
        
        /// <summary>
        /// Verifica se un utente è esausto (molte puntate, può mollare)
        /// </summary>
        private (bool ShouldExploit, string Reason) CheckUserExhaustion(AuctionInfo auction, string? lastBidder, string currentUsername)
        {
            if (string.IsNullOrEmpty(lastBidder) || lastBidder.Equals(currentUsername, StringComparison.OrdinalIgnoreCase))
                return (false, "");
            
            // Verifica se l'utente è un "heavy user" (>50 puntate totali)
            if (auction.BidderStats.TryGetValue(lastBidder, out var stats))
            {
                if (stats.BidCount > 50)
                {
                    // Se ci sono pochi altri bidder attivi, può essere un buon momento
                    var activeBidders = auction.BidderStats.Values.Count(b => b.BidCount > 5);
                    if (activeBidders <= 3)
                    {
                        return (true, $"{lastBidder} ha {stats.BidCount} puntate, potrebbe mollare");
                    }
                }
            }
            
            return (false, "");
        }
        
        /// <summary>
        /// Calcola probabilità di puntata basata su competizione e ROI
        /// </summary>
        private double CalculateBidProbability(AuctionInfo auction, AppSettings settings)
        {
            var probability = settings.BaseBidProbability;
            
            // Riduci probabilità per ogni bidder attivo oltre la soglia
            var extraBidders = Math.Max(0, auction.ActiveBiddersCount - settings.CompetitionThreshold);
            probability -= extraBidders * settings.ProbabilityReductionPerBidder;
            
            // Riduci per heat metric alto
            if (auction.HeatMetric > 70)
            {
                probability -= 0.1;
            }
            
            // Aumenta se abbiamo un buon ROI potenziale
            if (auction.CalculatedValue?.Savings > 0)
            {
                probability += 0.1;
            }
            
            return Math.Clamp(probability, 0.1, 1.0);
        }
        
        /// <summary>
        /// Verifica limiti bankroll
        /// </summary>
        private BankrollCheckResult CheckBankrollLimits(AuctionInfo auction, AppSettings settings)
        {
            var result = new BankrollCheckResult { CanBid = true };
            
            // Limite puntate per asta
            var maxPerAuction = auction.MaxBidsOverride ?? settings.MaxBidsPerAuction;
            if (maxPerAuction > 0 && auction.SessionBidCount >= maxPerAuction)
            {
                result.CanBid = false;
                result.Reason = $"Limite puntate per asta raggiunto ({auction.SessionBidCount}/{maxPerAuction})";
                return result;
            }
            
            // Limite puntate per sessione
            if (settings.MaxBidsPerSession > 0 && _sessionTotalBids >= settings.MaxBidsPerSession)
            {
                result.CanBid = false;
                result.Reason = $"Limite puntate per sessione raggiunto ({_sessionTotalBids}/{settings.MaxBidsPerSession})";
                return result;
            }
            
            // Budget giornaliero
            if (settings.DailyBudgetEuro > 0)
            {
                var spent = _sessionTotalBids * settings.AverageBidCostEuro;
                if (spent >= settings.DailyBudgetEuro)
                {
                    result.CanBid = false;
                    result.Reason = $"Budget giornaliero esaurito (€{spent:F2}/€{settings.DailyBudgetEuro:F2})";
                    return result;
                }
            }
            
            return result;
        }
        
        /// <summary>
        /// Registra una puntata effettuata (per tracking)
        /// </summary>
        public void RecordBidAttempt(AuctionInfo auction, bool success, bool collision = false)
        {
            auction.SessionBidCount++;
            _sessionTotalBids++;
            
            if (success)
            {
                auction.SuccessfulBidCount++;
                auction.ConsecutiveCollisions = 0;
            }
            else
            {
                auction.FailedBidCount++;
            }
            
            if (collision)
            {
                auction.CollisionCount++;
                auction.ConsecutiveCollisions++;
            }
        }
        
        /// <summary>
        /// Registra un timer scaduto
        /// </summary>
        public void RecordTimerExpired(AuctionInfo auction)
        {
            auction.TimerExpiredCount++;
            auction.ConsecutiveCollisions++; // Conta come "mancato"
        }
        
        /// <summary>
        /// Reset contatori sessione
        /// </summary>
        public void ResetSession()
        {
            _sessionTotalBids = 0;
            _sessionStartedAt = DateTime.UtcNow;
        }
        
        /// <summary>
        /// Ottiene statistiche sessione corrente
        /// </summary>
        public SessionStats GetSessionStats()
        {
            return new SessionStats
            {
                TotalBids = _sessionTotalBids,
                SessionDuration = DateTime.UtcNow - _sessionStartedAt
            };
        }
    }
    
    /// <summary>
    /// Risultato calcolo timing puntata
    /// </summary>
    public class BidTimingResult
    {
        public int BaseOffsetMs { get; set; }
        public int LatencyCompensationMs { get; set; }
        public int DynamicAdjustmentMs { get; set; }
        public int JitterMs { get; set; }
        public int FinalOffsetMs { get; set; }
        public bool ShouldBid { get; set; }
    }
    
    /// <summary>
    /// Decisione se puntare
    /// </summary>
    public class BidDecision
    {
        public bool ShouldBid { get; set; }
        public string? Reason { get; set; }
    }
    
    /// <summary>
    /// Risultato verifica bankroll
    /// </summary>
    public class BankrollCheckResult
    {
        public bool CanBid { get; set; }
        public string? Reason { get; set; }
    }
    
    /// <summary>
    /// Statistiche sessione
    /// </summary>
    public class SessionStats
    {
        public int TotalBids { get; set; }
        public TimeSpan SessionDuration { get; set; }
    }
}