using System.Collections.Generic;
using System.Diagnostics;
using UnityEngine;

namespace IdleSpectator;

public sealed class EpisodeShotProposal
{
    public InterestCandidate Candidate;
    public NarrativeInterruptClass InterruptClass;
    public string Reason = "";
    public float EditorialScore;
    public EpisodeShotRole Role;
    public string SemanticKey = "";
}

/// <summary>Selects the best presentable shot that can explain its place in the active episode.</summary>
public static class EpisodeShotSelector
{
    public static float LastReplayFilterMs { get; private set; }
    public static float LastPresentabilityMs { get; private set; }
    public static float LastClassificationMs { get; private set; }
    public static float LastScoringMs { get; private set; }
    public static int LastPresentabilityChecks { get; private set; }
    public static string LastSlowCandidateKey { get; private set; } = "";
    public static float LastSlowCandidateMs { get; private set; }

    public static EpisodeShotProposal Pick(
        IList<InterestCandidate> candidates,
        EpisodePlan episode,
        NarrativeThread thread,
        bool requirePresentable = true)
    {
        ResetTiming();
        if (candidates == null || candidates.Count == 0 || episode == null) return null;
        bool trace = IdleHitchProbe.Enabled;
        InterestCandidate bestRelatedCandidate = null;
        NarrativeInterruptClass bestRelatedKind = NarrativeInterruptClass.OrdinaryInteresting;
        EpisodeShotRole bestRelatedRole = EpisodeShotRole.Unknown;
        string bestRelatedSemanticKey = "";
        float bestRelatedScore = float.MinValue;

        InterestCandidate bestInterruptCandidate = null;
        NarrativeInterruptClass bestInterruptKind = NarrativeInterruptClass.OrdinaryInteresting;
        EpisodeShotRole bestInterruptRole = EpisodeShotRole.Unknown;
        float bestInterruptScore = float.MinValue;

        for (int i = 0; i < candidates.Count; i++)
        {
            InterestCandidate c = candidates[i];
            bool harness = c != null && string.Equals(c.Source, "harness", System.StringComparison.OrdinalIgnoreCase);
            if (c == null || c.Selected) continue;

            long stageStarted = trace ? Stopwatch.GetTimestamp() : 0L;
            bool replayCooled =
                InterestVariety.IsEditorialReplayCooled(c)
                || InterestVariety.IsExactReplayCooled(c)
                || InterestVariety.IsRoutineReplayCooled(c);
            if (trace)
            {
                LastReplayFilterMs += ElapsedMs(stageStarted);
            }
            if (replayCooled || !StoryScheduler.MayUseCombatShot(episode, c)) continue;

            if (requirePresentable && !harness)
            {
                stageStarted = trace ? Stopwatch.GetTimestamp() : 0L;
                bool presentable = EventPresentability.WouldShow(c);
                if (trace)
                {
                    float elapsed = ElapsedMs(stageStarted);
                    LastPresentabilityMs += elapsed;
                    LastPresentabilityChecks++;
                    if (elapsed > LastSlowCandidateMs)
                    {
                        LastSlowCandidateMs = elapsed;
                        LastSlowCandidateKey = c.Key ?? "";
                    }
                }
                if (!presentable) continue;
            }

            stageStarted = trace ? Stopwatch.GetTimestamp() : 0L;
            NarrativeFunction function = NarrativeFunctionPolicy.Classify(c);
            if (function == NarrativeFunction.Noise)
            {
                if (trace)
                {
                    LastClassificationMs += ElapsedMs(stageStarted);
                }
                continue;
            }
            NarrativeInterruptClass kind = InterruptPolicy.Classify(c, episode, thread);
            EpisodeShotRole role = RoleFor(c, function, kind, episode);
            bool related = kind == NarrativeInterruptClass.RelatedEscalation;
            bool advances = related && AdvancesEpisode(episode, role);
            string semanticKey = related && !advances ? SemanticKey(c, role) : "";
            if (trace)
            {
                LastClassificationMs += ElapsedMs(stageStarted);
            }
            if (related
                && !advances
                && episode.RecentSemanticKeys.Contains(semanticKey))
            {
                continue;
            }

            if (related && function == NarrativeFunction.CharacterTexture
                && role != EpisodeShotRole.Reintroduction)
            {
                continue;
            }

            stageStarted = trace ? Stopwatch.GetTimestamp() : 0L;
            float score = EditorialScore(c, episode, kind, function, role);
            if (trace)
            {
                LastScoringMs += ElapsedMs(stageStarted);
            }
            if (kind == NarrativeInterruptClass.RelatedEscalation)
            {
                if (bestRelatedCandidate == null || score > bestRelatedScore)
                {
                    bestRelatedCandidate = c;
                    bestRelatedKind = kind;
                    bestRelatedRole = role;
                    bestRelatedSemanticKey = string.IsNullOrEmpty(semanticKey)
                        ? SemanticKey(c, role)
                        : semanticKey;
                    bestRelatedScore = score;
                }
            }
            else if (InterruptPolicy.MayInterrupt(kind)
                     && (bestInterruptCandidate == null || score > bestInterruptScore))
            {
                bestInterruptCandidate = c;
                bestInterruptKind = kind;
                bestInterruptRole = role;
                bestInterruptScore = score;
            }
        }

        // A productive related development owns the episode. Critical/payoff material interrupts
        // only when no related shot is ready, or when its editorial advantage is decisive.
        if (bestRelatedCandidate != null
            && (bestInterruptCandidate == null || bestInterruptScore < bestRelatedScore + 25f))
        {
            return BuildProposal(
                bestRelatedCandidate,
                bestRelatedKind,
                bestRelatedRole,
                bestRelatedSemanticKey,
                bestRelatedScore);
        }

        if (bestInterruptCandidate != null)
        {
            return BuildProposal(
                bestInterruptCandidate,
                bestInterruptKind,
                bestInterruptRole,
                SemanticKey(bestInterruptCandidate, bestInterruptRole),
                bestInterruptScore);
        }

        return null;
    }

    private static void ResetTiming()
    {
        LastReplayFilterMs = 0f;
        LastPresentabilityMs = 0f;
        LastClassificationMs = 0f;
        LastScoringMs = 0f;
        LastPresentabilityChecks = 0;
        LastSlowCandidateKey = "";
        LastSlowCandidateMs = 0f;
    }

    private static float ElapsedMs(long started) =>
        (float)((Stopwatch.GetTimestamp() - started) * 1000d / Stopwatch.Frequency);

    private static EpisodeShotProposal BuildProposal(
        InterestCandidate candidate,
        NarrativeInterruptClass kind,
        EpisodeShotRole role,
        string semanticKey,
        float score)
    {
        return new EpisodeShotProposal
        {
            Candidate = candidate,
            InterruptClass = kind,
            EditorialScore = score,
            Role = role,
            SemanticKey = semanticKey ?? "",
            Reason = Reason(kind) + ":" + role
        };
    }

    private static float EditorialScore(
        InterestCandidate c,
        EpisodePlan episode,
        NarrativeInterruptClass kind,
        NarrativeFunction function,
        EpisodeShotRole role)
    {
        float relation = c.SubjectId == episode.ProtagonistId ? 40f
            : c.RelatedId == episode.ProtagonistId ? 30f : 0f;
        float interrupt = kind == NarrativeInterruptClass.WorldCritical ? 90f
            : kind == NarrativeInterruptClass.StoryPayoff ? 35f
            : kind == NarrativeInterruptClass.RelatedEscalation ? 25f : 0f;
        float roleProgress = kind == NarrativeInterruptClass.RelatedEscalation
            ? (AdvancesEpisode(episode, role) ? 32f : -12f)
            : 0f;
        float subjectRepeat = c.SubjectId != 0 && c.SubjectId == episode.LastSubjectId
            ? -8f * Mathf.Min(3, episode.RepeatedSubjectCount)
            : 0f;
        float balance = NarrativeExposureLedger.CharacterDebt(episode.ProtagonistId) * 1.5f;
        float repetition = NarrativeExposureLedger.RepetitionPenalty(
            episode.ProtagonistId, StoryScheduler.SemanticFamily(c));
        return relation + interrupt + roleProgress + subjectRepeat
               + balance - repetition
               + NarrativeFunctionPolicy.EditorialBonus(function)
               + c.EventStrength * 0.35f
               + c.VisualConfidence * 10f + c.Novelty * 3f;
    }

    public static EpisodeShotRole RoleFor(
        InterestCandidate candidate,
        NarrativeFunction function,
        NarrativeInterruptClass interrupt,
        EpisodePlan episode)
    {
        if (interrupt == NarrativeInterruptClass.WorldCritical)
            return EpisodeShotRole.WorldContext;
        switch (function)
        {
            case NarrativeFunction.ThreadOpener: return EpisodeShotRole.Establish;
            case NarrativeFunction.Development: return EpisodeShotRole.Development;
            case NarrativeFunction.Escalation: return EpisodeShotRole.Pressure;
            case NarrativeFunction.TurningPoint: return EpisodeShotRole.TurningPoint;
            case NarrativeFunction.Resolution: return EpisodeShotRole.Payoff;
            case NarrativeFunction.Consequence: return EpisodeShotRole.Consequence;
            case NarrativeFunction.CharacterTexture:
                return episode != null && episode.CoveredRoles.Count == 0
                    ? EpisodeShotRole.Reintroduction
                    : EpisodeShotRole.Unknown;
            case NarrativeFunction.WorldContext: return EpisodeShotRole.WorldContext;
            default: return EpisodeShotRole.Unknown;
        }
    }

    public static bool AdvancesEpisode(EpisodePlan episode, EpisodeShotRole role)
    {
        if (episode == null || role == EpisodeShotRole.Unknown
            || role == EpisodeShotRole.WorldContext)
            return false;
        return episode.PendingRoles.Contains(role) || !episode.HasCovered(role);
    }

    public static string SemanticKey(InterestCandidate candidate, EpisodeShotRole role)
    {
        if (candidate == null) return "";
        string action = candidate.NarrativePresentation?.ActionId;
        if (string.IsNullOrEmpty(action))
            action = candidate.HappinessEffectId;
        if (string.IsNullOrEmpty(action))
            action = candidate.AssetId;
        return role + ":" + (action ?? "") + ":" + candidate.SubjectId;
    }

    private static string Reason(NarrativeInterruptClass kind)
    {
        switch (kind)
        {
            case NarrativeInterruptClass.RelatedEscalation: return "active_episode";
            case NarrativeInterruptClass.WorldCritical: return "world_critical_interrupt";
            case NarrativeInterruptClass.StoryPayoff: return "story_payoff_interrupt";
            default: return "not_episode_worthy";
        }
    }
}