// Memory accepts radio-delivered reports at one boundary. Entity references are
// opaque identity keys: this module never reads a target's current world state.
enum ERR_HQMemoryKind
{
 SIGHTING,
 DISTRESS,
 BODY
}

class ERR_HQMemoryRules
{
 static bool Finite(float value) { return value == value && Math.AbsFloat(value) <= 1000000000000.0; }
 static bool PositionValid(vector value)
 {
  for (int i = 0; i < 3; i++)
   if (!Finite(value[i]) || Math.AbsFloat(value[i]) > 1000000) return false;
  return true;
 }
 static bool DeliveryFresh(float observedAt, float now)
 {
  return Finite(observedAt) && Finite(now) && observedAt >= 0 && now >= observedAt && now - observedAt <= 120000;
 }
 static int Kind(ERR_HQReport report)
 {
  if (report.Distress) return ERR_HQMemoryKind.DISTRESS;
  if (report.TravelMode == "body" || report.TravelMode == "dead body") return ERR_HQMemoryKind.BODY;
  return ERR_HQMemoryKind.SIGHTING;
 }
 static float Confidence(float ageSeconds, float halfLife = 600)
 {
  if (!Finite(ageSeconds) || !Finite(halfLife) || ageSeconds < 0 || halfLife <= 0) return 0;
  return Math.Pow(0.5, ageSeconds / halfLife);
 }
 static float BaseConfidence(int kind)
 {
  if (kind == ERR_HQMemoryKind.DISTRESS) return 0.3;
  if (kind == ERR_HQMemoryKind.BODY) return 0.2;
  return 1;
 }
 static float HalfLife(int kind)
 {
  if (kind == ERR_HQMemoryKind.DISTRESS) return 180;
  if (kind == ERR_HQMemoryKind.BODY) return 300;
  return 600;
 }
 static float RadiusFloor(int kind, string travel)
 {
  if (kind == ERR_HQMemoryKind.DISTRESS) return 150;
  if (kind == ERR_HQMemoryKind.BODY) return 75;
  if (travel == "aircraft") return 120;
  if (travel == "vehicle" || travel == "in vehicle") return 60;
  return 25;
 }
 static float RadiusGrowth(int kind, string travel)
 {
  if (kind == ERR_HQMemoryKind.DISTRESS) return 2;
  if (kind == ERR_HQMemoryKind.BODY) return 1.2;
  if (travel == "aircraft") return 8;
  if (travel == "vehicle" || travel == "in vehicle") return 4;
  return 1.2;
 }
 static float Radius(float ageSeconds, float growth, float floor)
 {
  if (!Finite(ageSeconds) || !Finite(growth) || !Finite(floor)) return 2001;
  if (ageSeconds < 0 || growth < 0 || floor < 0) return 2001;
  return floor + ageSeconds * growth;
 }
 static float SpeedLimit(string travel)
 {
  if (travel == "on foot") return 12;
  if (travel == "vehicle" || travel == "in vehicle") return 55;
  if (travel == "aircraft") return 120;
  return 0;
 }
 static bool MotionCredible(float seconds, float distance, string previousMode, string currentMode)
 {
  if (!Finite(seconds) || !Finite(distance) || seconds < 2 || seconds > 120 || distance < 0) return false;
  float limit = SpeedLimit(currentMode);
  return previousMode == currentMode && limit > 0 && distance / seconds <= limit;
 }
 static vector Predict(vector position, vector velocity, float ageSeconds)
 {
  if (!PositionValid(position) || !PositionValid(velocity) || !Finite(ageSeconds) || ageSeconds < 0)
   return position;
  vector offset = velocity * Math.Clamp(ageSeconds, 0, 30);
  offset[1] = 0;
  if (offset.Length() > 300) offset = offset.Normalized() * 300;
  return position + offset;
 }
 static bool Actionable(float confidence, float radius)
 {
  return Finite(confidence) && Finite(radius) && confidence >= 0.1 && confidence <= 1 && radius <= 2000 && radius >= 0;
 }
 static bool NewMessage(int id, bool alreadySeen)
 {
  if (id <= 0 || alreadySeen) return false;
  return true;
 }
 static float Value(float confidence, float radius) { return confidence / (1 + radius / 500); }
}

// Detached read model. Mutating it (or Report) cannot alter the stored history.
class ERR_HQBelief
{
 int BeliefId;
 int BeliefRevision;
 float EvaluatedAt;
 IEntity Target;
 vector Position;
 vector PredictedPosition;
 vector Velocity;
 bool HasVelocity;
 float Speed;
 float HeadingDegrees;
 float Confidence;
 float Radius;
 float ObservedAt;
 float LastDeliveredAt;
 float PredictionSeconds;
 int MessageId;
 int SampleCount;
 int Kind;
 string PredictionSource;
 string TravelMode;
 ref ERR_HQReport Report;
 bool Actionable() { return Kind == ERR_HQMemoryKind.SIGHTING && ERR_HQMemoryRules.Actionable(Confidence, Radius); }
}

class ERR_HQMemoryTrack
{
 int BeliefId;
 int BeliefRevision;
 int NegativeRevision = -1;
 float SearchConfidence = 1;
 IEntity Key;
 int Kind;
 float DeliveredAt;
 protected ref array<ref ERR_HQReport> m_Samples = {};

 ERR_HQReport Latest() { return m_Samples[m_Samples.Count() - 1]; }
 int Count() { return m_Samples.Count(); }
 void Append(ERR_HQReport report, float now)
 {
  if (m_Samples.Count() >= 8) m_Samples.Remove(0);
  m_Samples.Insert(report.Snapshot());
  DeliveredAt = now;
  BeliefRevision++;
  SearchConfidence = 1;
 }
 float ConfidenceAt(float now)
 {
  float seconds = Math.Max(0, (now - Latest().ObservedAt) / 1000);
  return SearchConfidence * ERR_HQMemoryRules.BaseConfidence(Kind)
   * ERR_HQMemoryRules.Confidence(seconds, ERR_HQMemoryRules.HalfLife(Kind));
 }
 float RadiusAt(float now)
 {
  ERR_HQReport last = Latest();
  return ERR_HQMemoryRules.Radius(Math.Max(0, (now - last.ObservedAt) / 1000),
   ERR_HQMemoryRules.RadiusGrowth(Kind, last.TravelMode), ERR_HQMemoryRules.RadiusFloor(Kind, last.TravelMode));
 }
 ERR_HQBelief Evaluate(float now)
 {
  ERR_HQReport last = Latest();
  ERR_HQBelief belief = new ERR_HQBelief();
  belief.BeliefId = BeliefId;
  belief.BeliefRevision = BeliefRevision;
  belief.EvaluatedAt = now;
  belief.Report = last.Snapshot();
  belief.Target = last.Target;
  belief.Position = last.Position;
  belief.PredictedPosition = last.Position;
  belief.ObservedAt = last.ObservedAt;
  belief.LastDeliveredAt = DeliveredAt;
  belief.MessageId = last.MessageId;
  belief.SampleCount = Count();
  belief.Kind = Kind;
  belief.TravelMode = last.TravelMode;
  belief.Confidence = ConfidenceAt(now);
  belief.Radius = RadiusAt(now);
  belief.PredictionSource = "delivered sighting; motion unknown";
  if (Kind == ERR_HQMemoryKind.DISTRESS)
  {
   belief.Target = null;
   belief.PredictionSource = "delivered distress; enemy position and motion unknown";
   return belief;
  }
  if (Kind == ERR_HQMemoryKind.BODY)
  {
   belief.PredictionSource = "reported body location; no moving-target inference";
   return belief;
  }
  if (Count() < 2) return belief;
  ERR_HQReport previous = m_Samples[Count() - 2];
  float seconds = (last.ObservedAt - previous.ObservedAt) / 1000;
  float distance = vector.DistanceXZ(previous.Position, last.Position);
  if (!ERR_HQMemoryRules.MotionCredible(seconds, distance, previous.TravelMode, last.TravelMode))
  {
   belief.PredictionSource = "delivered sighting; motion history not credible";
   return belief;
  }
  belief.Velocity = (last.Position - previous.Position) / seconds;
  belief.Velocity[1] = 0;
  belief.Speed = belief.Velocity.Length();
  belief.HasVelocity = true;
  float age = Math.Max(0, (now - last.ObservedAt) / 1000);
  belief.PredictionSeconds = Math.Clamp(age, 0, 30);
  belief.PredictedPosition = ERR_HQMemoryRules.Predict(last.Position, belief.Velocity, age);
  belief.HeadingDegrees = Math.Atan2(belief.Velocity[0], belief.Velocity[2]) * Math.RAD2DEG;
  if (belief.HeadingDegrees < 0) belief.HeadingDegrees += 360;
  belief.PredictionSource = "successive delivered sightings; 30s/300m prediction limit";
  if (belief.Speed < 0.5) belief.PredictionSource = "successive delivered sightings; approximately stationary";
  return belief;
 }
}

class ERR_HQMemory
{
 protected ref array<ref ERR_HQMemoryTrack> m_Tracks = {};
 protected ref array<int> m_Seen = {};
 protected ref array<float> m_SeenAt = {};
 protected int m_NextBeliefId;
 protected float m_Now = -1;
 protected string m_LastRefusal;

 string LastRefusal() { return m_LastRefusal; }
 int Count() { return m_Tracks.Count(); }
 protected bool Refuse(string reason) { m_LastRefusal = reason; return false; }
 protected int Find(IEntity key, int kind)
 {
  for (int i = 0; i < m_Tracks.Count(); i++)
   if (m_Tracks[i].Key == key && m_Tracks[i].Kind == kind) return i;
  return -1;
 }
 void Clear()
 {
  m_Tracks.Clear(); m_Seen.Clear(); m_SeenAt.Clear();
  m_Now = -1; m_LastRefusal = "";
  // Do not recycle belief IDs: an order retained across Clear cannot bind to a new track.
 }
 // A slow HQ tick advances only the observation clock and bounded retirement.
 // Confidence/radius are calculated on read; there is no per-frame decay work.
 void Tick(float now)
 {
  if (!ERR_HQMemoryRules.Finite(now) || now < 0 || now < m_Now) return;
  m_Now = now;
  for (int message = m_Seen.Count() - 1; message >= 0; message--)
  {
   if (now - m_SeenAt[message] <= 120000) continue;
   m_Seen.Remove(message); m_SeenAt.Remove(message);
  }
  for (int i = m_Tracks.Count() - 1; i >= 0; i--)
   if (m_Tracks[i].RadiusAt(now) > 2000) m_Tracks.Remove(i);
 }
 // Call exclusively after the radio network accepts delivery. No other method
 // can inject a report, and no stored report object is exposed to a caller.
 bool Ingest(ERR_HQReport report, float now)
 {
  if (!ERR_HQMemoryRules.Finite(now) || now < m_Now || now < 0) return Refuse("invalid memory clock");
  Tick(now);
  if (!report || !ERR_HQMemoryRules.DeliveryFresh(report.ObservedAt, now)) return Refuse("stale or future report");
  if (!ERR_HQMemoryRules.PositionValid(report.Position)) return Refuse("invalid observed position");
  if (!ERR_HQMemoryRules.NewMessage(report.MessageId, m_Seen.Contains(report.MessageId)))
   return Refuse("replayed or expired message");
  if (m_Seen.Count() >= 4096) return Refuse("delivered-report replay guard full");
  int kind = ERR_HQMemoryRules.Kind(report);
  IEntity key = report.Target;
  if (kind == ERR_HQMemoryKind.DISTRESS) key = report.Source;
  if (!key) return Refuse("report has no observation identity");
  int index = Find(key, kind);
  if (index >= 0 && report.ObservedAt <= m_Tracks[index].Latest().ObservedAt)
   return Refuse("observation does not advance trajectory");
  if (index < 0 && m_NextBeliefId >= 2147483646) return Refuse("belief identity space exhausted");
  if (index < 0 && m_Tracks.Count() >= 64)
  {
   int weakest = -1;
   float least = 2;
   for (int i = 0; i < m_Tracks.Count(); i++)
   {
    float value = ERR_HQMemoryRules.Value(m_Tracks[i].ConfidenceAt(now), m_Tracks[i].RadiusAt(now));
    if (value < least) { least = value; weakest = i; }
   }
   float age = (now - report.ObservedAt) / 1000;
   float incoming = ERR_HQMemoryRules.BaseConfidence(kind);
   incoming *= ERR_HQMemoryRules.Confidence(age, ERR_HQMemoryRules.HalfLife(kind));
   float radius = ERR_HQMemoryRules.Radius(age, ERR_HQMemoryRules.RadiusGrowth(kind, report.TravelMode),
    ERR_HQMemoryRules.RadiusFloor(kind, report.TravelMode));
   if (weakest < 0 || ERR_HQMemoryRules.Value(incoming, radius) <= least)
    return Refuse("memory full; stronger observations retained");
   m_Tracks.Remove(weakest);
  }
  ERR_HQMemoryTrack track;
  if (index >= 0) track = m_Tracks[index];
  else
  {
   track = new ERR_HQMemoryTrack();
   track.BeliefId = ++m_NextBeliefId; track.Key = key; track.Kind = kind;
   m_Tracks.Insert(track);
  }
  track.Append(report, now);
  m_Seen.Insert(report.MessageId); m_SeenAt.Insert(report.ObservedAt);
  m_LastRefusal = "";
  return true;
 }
 ERR_HQBelief Get(IEntity target)
 {
  if (!target) return null;
  int index = Find(target, ERR_HQMemoryKind.SIGHTING);
  if (index < 0) return null;
  return m_Tracks[index].Evaluate(m_Now);
 }
 ERR_HQBelief GetById(int beliefId)
 {
  for (int i = 0; i < m_Tracks.Count(); i++)
   if (m_Tracks[i].BeliefId == beliefId) return m_Tracks[i].Evaluate(m_Now);
  return null;
 }
 // This is negative evidence from an actually delivered sweep report, not a
 // synthetic sighting. A duplicate cannot compound the same observation's loss.
 bool NegativeSearch(int beliefId, int revision, float now)
 {
  if (!ERR_HQMemoryRules.Finite(now) || now < m_Now || now < 0) return false;
  Tick(now);
  for (int i = 0; i < m_Tracks.Count(); i++)
  {
   ERR_HQMemoryTrack track = m_Tracks[i];
   if (track.BeliefId != beliefId || track.Kind != ERR_HQMemoryKind.SIGHTING) continue;
   if (track.BeliefRevision != revision || track.NegativeRevision == revision) return false;
   track.SearchConfidence = 0.65;
   track.NegativeRevision = revision;
   return true;
  }
  return false;
 }
 ERR_HQBelief At(int index)
 {
  if (index < 0 || index >= m_Tracks.Count()) return null;
  return m_Tracks[index].Evaluate(m_Now);
 }
}