using System.Collections.Generic;
using UnityEngine;

namespace IdleSpectator;

/// <summary>
/// Soft ~70/30 event-led vs character-led mix with decaying novelty penalties.
/// </summary>
public static class InterestVariety
{
    public static float EventLedTarget => InterestScoringConfig.W.eventLedTarget;
    public static int MixWindow => Mathf.Max(1, InterestScoringConfig.W.mixWindow);
    public static float HardCooldownSeconds => InterestScoringConfig.W.hardCooldownSeconds;

    private static readonly List<InterestLeadKind> RecentMix = new List<InterestLeadKind>(32);
    private static readonly Dictionary<string, float> CooldownUntil = new Dictionary<string, float>(64);
    private static readonly System.Random Rng = new System.Random();

    private static readonly List<InterestCandidate> EventPool = new List<InterestCandidate>(64);
    private static readonly List<InterestCandidate> CharPool = new List<InterestCandidate>(64);
    private static readonly List<InterestCandidate> Ranked = new List<InterestCandidate>(16);

    /// <summary>Whether the last <see cref="Pick"/> saw both pools non-empty (for mix metering).</summary>
    public static bool LastPickHadBothPools { get; private set; }

    public static void Clear()
    {
        RecentMix.Clear();
        CooldownUntil.Clear();
        LastPickHadBothPools = false;
    }

    /// <summary>Harness: seed the rolling mix meter without touching cooldowns.</summary>
    public static void HarnessSeedMix(int eventLedCount, int characterLedCount)
    {
        RecentMix.Clear();
        int e = Mathf.Max(0, eventLedCount);
        int c = Mathf.Max(0, characterLedCount);
        for (int i = 0; i < e; i++)
        {
            RecentMix.Add(InterestLeadKind.EventLed);
        }

        for (int i = 0; i < c; i++)
        {
            RecentMix.Add(InterestLeadKind.CharacterLed);
        }

        while (RecentMix.Count > MixWindow)
        {
            RecentMix.RemoveAt(0);
        }
    }

    public static void NoteSelection(InterestCandidate chosen)
    {
        NoteSelection(chosen, updateMix: LastPickHadBothPools);
    }

    public static void NoteSelection(InterestCandidate chosen, bool updateMix)
    {
        if (chosen == null)
        {
            return;
        }

        if (updateMix)
        {
            RecentMix.Add(chosen.LeadKind);
            while (RecentMix.Count > MixWindow)
            {
                RecentMix.RemoveAt(0);
            }
        }

        float until = Time.unscaledTime + (updateMix ? HardCooldownSeconds : HardCooldownSeconds * 0.5f);
        StampCooldown("unit:" + chosen.SubjectId, until);
        if (!string.IsNullOrEmpty(chosen.SpeciesId))
        {
            StampCooldown("species:" + chosen.SpeciesId, until * 0.7f);
        }

        if (!string.IsNullOrEmpty(chosen.Category))
        {
            StampCooldown("cat:" + chosen.Category, until * 0.5f);
        }

        if (!string.IsNullOrEmpty(chosen.CityKey))
        {
            StampCooldown("city:" + chosen.CityKey, until * 0.6f);
        }

        if (!string.IsNullOrEmpty(chosen.KingdomKey))
        {
            StampCooldown("kingdom:" + chosen.KingdomKey, until * 0.6f);
        }

        if (!string.IsNullOrEmpty(chosen.RegionKey))
        {
            StampCooldown("region:" + chosen.RegionKey, until * 0.5f);
        }

        if (!string.IsNullOrEmpty(chosen.Verb))
        {
            StampCooldown("verb:" + chosen.Verb, until * 0.4f);
        }
    }

    /// <summary>
    /// Pick next candidate. Soft 70/30: prefer event-led when below target and pool non-empty.
    /// Empty event pool → character-led without inventing events (mix meter not updated for empty-side windows).
    /// </summary>
    public static InterestCandidate Pick(List<InterestCandidate> pending, InterestCandidate current)
    {
        if (pending == null || pending.Count == 0)
        {
            return null;
        }

        EventPool.Clear();
        CharPool.Clear();
        float now = Time.unscaledTime;
        for (int i = 0; i < pending.Count; i++)
        {
            InterestCandidate c = pending[i];
            if (c == null || !c.HasValidPosition)
            {
                continue;
            }

            if (current != null && c.Key == current.Key)
            {
                continue;
            }

            if (c.LeadKind == InterestLeadKind.CharacterLed)
            {
                CharPool.Add(c);
            }
            else
            {
                EventPool.Add(c);
            }
        }

        bool bothHadCandidates = EventPool.Count > 0 && CharPool.Count > 0;
        bool preferEvent = EventPool.Count > 0;
        if (bothHadCandidates)
        {
            // Empty mix biases event-led; otherwise prefer event until share reaches target.
            preferEvent = MixSampleCount == 0 || EventShare() < EventLedTarget;
        }
        else if (EventPool.Count == 0)
        {
            preferEvent = false;
        }

        // Soft mix: empty event pool → character-led without inventing events.
        // Mix meter is updated in NoteSelection only when both pools were non-empty at pick time.
        LastPickHadBothPools = bothHadCandidates;

        List<InterestCandidate> pool = preferEvent
            ? (EventPool.Count > 0 ? EventPool : CharPool)
            : (CharPool.Count > 0 ? CharPool : EventPool);

        if (pool.Count == 0)
        {
            return null;
        }

        Ranked.Clear();
        for (int i = 0; i < pool.Count; i++)
        {
            InterestCandidate c = pool[i];
            float penalty = NoveltyPenalty(c, now);
            // Epic / favorites bypass most novelty.
            if (InterestScoring.IsHotScore(c.TotalScore) || InterestScoring.IsNotable(c.FollowUnit))
            {
                penalty *= 0.15f;
            }

            c.Novelty = Mathf.Clamp01(1f - penalty);
            InterestScoring.RecalcTotal(c);
            Ranked.Add(c);
        }

        Ranked.Sort(InterestScoring.CompareByUrgencyThenScore);
        InterestScoring.EnrichTopK(Ranked);

        int topN = Mathf.Min(3, Ranked.Count);
        if (topN <= 0)
        {
            return null;
        }

        // Probabilistic among top-N after penalties.
        int pick = Rng.Next(topN);
        return Ranked[pick];
    }

    public static float EventShare()
    {
        if (RecentMix.Count == 0)
        {
            return EventLedTarget;
        }

        int events = 0;
        for (int i = 0; i < RecentMix.Count; i++)
        {
            if (RecentMix[i] == InterestLeadKind.EventLed)
            {
                events++;
            }
        }

        return events / (float)RecentMix.Count;
    }

    public static int MixSampleCount => RecentMix.Count;

    private static float NoveltyPenalty(InterestCandidate c, float now)
    {
        float p = 0f;
        p += CooldownWeight("unit:" + c.SubjectId, now, 0.55f);
        if (!string.IsNullOrEmpty(c.SpeciesId))
        {
            p += CooldownWeight("species:" + c.SpeciesId, now, 0.25f);
        }

        if (!string.IsNullOrEmpty(c.Category))
        {
            p += CooldownWeight("cat:" + c.Category, now, 0.2f);
        }

        if (!string.IsNullOrEmpty(c.CityKey))
        {
            p += CooldownWeight("city:" + c.CityKey, now, 0.2f);
        }

        if (!string.IsNullOrEmpty(c.KingdomKey))
        {
            p += CooldownWeight("kingdom:" + c.KingdomKey, now, 0.2f);
        }

        if (!string.IsNullOrEmpty(c.Verb))
        {
            p += CooldownWeight("verb:" + c.Verb, now, 0.15f);
        }

        return Mathf.Clamp01(p);
    }

    private static float CooldownWeight(string key, float now, float weight)
    {
        if (!CooldownUntil.TryGetValue(key, out float until) || now >= until)
        {
            return 0f;
        }

        float remain = until - now;
        float frac = Mathf.Clamp01(remain / HardCooldownSeconds);
        return weight * frac;
    }

    private static void StampCooldown(string key, float until)
    {
        if (string.IsNullOrEmpty(key))
        {
            return;
        }

        if (CooldownUntil.TryGetValue(key, out float existing))
        {
            CooldownUntil[key] = Mathf.Max(existing, until);
        }
        else
        {
            CooldownUntil[key] = until;
        }
    }
}