using System;
using System.Collections.Generic;
using System.IO;
using System.Reflection;
using UnityEngine;

namespace MSCO
{
    /// <summary>
    /// Unfallschäden (verbeulte Karosserie): Das Spiel verformt die Meshes der Fahrzeuge bei Kollisionen
    /// (CarDamage, CarDamage2, Deformable). Das lässt sich nicht nachspielen, also übertragen wir das Ergebnis:
    /// Wer das Fahrzeug fährt (oder bei freien Fahrzeugen: bei wem es passiert), schickt die geänderten Eckpunkte.
    /// </summary>
    public class DamageSync
    {
        const float ScanInterval = 10f;
        const float CheckInterval = 0.5f;    // so oft nach einem Aufprall prüfen
        const float ImpactWindow = 4f;       // so lange nach einem Aufprall prüfen (Verformung läuft ein paar Frames)
        const float ImpactDeltaV = 2.5f;     // plötzliche Geschwindigkeitsänderung (m/s pro Frame) = Aufprall
        const float SafetyCheckInterval = 2f;  // sonst nur ab und zu EIN Mesh (z.B. Reparatur in der Werkstatt) - verteilt statt alle auf einmal
        const float MinMove = 0.002f;
        const int MaxPerMessage = 4000;

        static readonly string[] DamageTypes = { "CarDamage", "CarDamage2", "Deformable" };

        class DamageMesh
        {
            public int Key;
            public string Root;
            public MeshFilter Filter;
            public Rigidbody Body;  // Fahrzeug, zu dem das Mesh gehört
            public Vector3[] Known; // zuletzt gesendet/empfangen
        }

        readonly Dictionary<int, DamageMesh> meshes = new Dictionary<int, DamageMesh>();
        readonly HashSet<MeshFilter> seen = new HashSet<MeshFilter>();
        readonly List<int> changed = new List<int>();
        float nextScan, nextCheck, nextSafetyCheck;
        int safetyIndex;
        // Mesh-Daten lesen ist teuer (große Arrays, Speicher-Müll) - nur nach einem Aufprall
        readonly Dictionary<Rigidbody, Vector3> lastVelocity = new Dictionary<Rigidbody, Vector3>();
        readonly Dictionary<Rigidbody, float> lastImpact = new Dictionary<Rigidbody, float>();
        readonly List<Rigidbody> bodies = new List<Rigidbody>();
        static List<Type> types;

        public int Count { get { return meshes.Count; } }

        public void Reset()
        {
            meshes.Clear();
            seen.Clear();
            lastVelocity.Clear();
            lastImpact.Clear();
            bodies.Clear();
            nextScan = -1f; // erster Suchlauf verteilt, siehe Update
        }

        public void Update(ObjectSync objects, int localId, Action<MsgType, byte[]> send)
        {
            if (nextScan < 0f) nextScan = Time.time + 1.0f; // nicht alle Sync-Teile im selben Frame suchen lassen
            if (Time.time >= nextScan)
            {
                nextScan = Time.time + ScanInterval;
                Scan();
            }
            // Aufprall erkennen: Geschwindigkeit ändert sich schlagartig (billig, jedes Frame)
            for (int i = 0; i < bodies.Count; i++)
            {
                Rigidbody rb = bodies[i];
                if (rb == null || rb.isKinematic) continue;
                Vector3 v = rb.velocity, before;
                if (lastVelocity.TryGetValue(rb, out before) && (v - before).sqrMagnitude > ImpactDeltaV * ImpactDeltaV)
                    lastImpact[rb] = Time.time;
                lastVelocity[rb] = v;
            }

            if (Time.time < nextCheck) return;
            nextCheck = Time.time + CheckInterval;
            bool safety = Time.time >= nextSafetyCheck;
            if (safety) { nextSafetyCheck = Time.time + SafetyCheckInterval; safetyIndex++; }
            int index = -1;

            foreach (DamageMesh m in meshes.Values)
            {
                index++;
                if (m.Filter == null) continue;
                bool safetyThis = safety && meshes.Count > 0 && index == safetyIndex % meshes.Count;
                int owner = objects.VehicleOwner(m.Root);
                if (owner != SyncedBody.NoOwner && owner != localId) continue; // der Fahrer schickt die Schäden
                float impact;
                bool recentImpact = m.Body != null && lastImpact.TryGetValue(m.Body, out impact) && Time.time - impact < ImpactWindow;
                if (!recentImpact && !safetyThis) continue;

                Mesh mesh = m.Filter.sharedMesh;
                if (mesh == null) continue;
                Vector3[] now = mesh.vertices;
                if (now.Length != m.Known.Length) { m.Known = now; continue; }

                changed.Clear();
                for (int i = 0; i < now.Length; i++)
                    if ((now[i] - m.Known[i]).sqrMagnitude > MinMove * MinMove) changed.Add(i);
                if (changed.Count == 0) continue;

                for (int start = 0; start < changed.Count; start += MaxPerMessage)
                {
                    int from = start, count = Math.Min(MaxPerMessage, changed.Count - start);
                    int key = m.Key, total = now.Length;
                    send(MsgType.VehicleDamage, NetSession.Build(w =>
                    {
                        w.Write(key);
                        w.Write(total);
                        w.Write(count);
                        for (int i = from; i < from + count; i++)
                        {
                            int idx = changed[i];
                            Vector3 v = now[idx];
                            w.Write(idx); w.Write(v.x); w.Write(v.y); w.Write(v.z);
                        }
                    }));
                }
                m.Known = now;
            }
        }

        public void Handle(BinaryReader r)
        {
            int key = r.ReadInt32();
            int total = r.ReadInt32();
            int count = r.ReadInt32();
            DamageMesh m;
            if (!meshes.TryGetValue(key, out m) || m.Filter == null) { nextScan = 0f; return; }
            Mesh mesh = m.Filter.mesh; // eigene Kopie, falls das Mesh (noch) mit anderen geteilt ist
            if (mesh == null) return;
            Vector3[] verts = mesh.vertices;
            if (verts.Length != total) return; // anderes Mesh (anderes Teil verbaut)

            for (int i = 0; i < count; i++)
            {
                int idx = r.ReadInt32();
                var v = new Vector3(r.ReadSingle(), r.ReadSingle(), r.ReadSingle());
                if (idx < 0 || idx >= verts.Length || float.IsNaN(v.x) || float.IsNaN(v.y) || float.IsNaN(v.z)) continue;
                if (v.sqrMagnitude > 1e6f) continue; // Unsinn nie übernehmen
                verts[idx] = v;
            }
            mesh.vertices = verts;
            mesh.RecalculateNormals();
            mesh.RecalculateBounds();
            m.Known = verts;
        }

        void Scan()
        {
            if (types == null)
            {
                types = new List<Type>();
                foreach (Assembly a in AppDomain.CurrentDomain.GetAssemblies())
                {
                    if (a.GetName().Name != "Assembly-CSharp") continue;
                    foreach (string n in DamageTypes)
                    {
                        Type t = a.GetType(n);
                        if (t != null) types.Add(t);
                    }
                }
            }

            int before = meshes.Count;
            foreach (Type t in types)
            {
                foreach (UnityEngine.Object o in UnityEngine.Object.FindObjectsOfType(t))
                {
                    var c = o as Component;
                    if (c == null || !IsVehicle(c.transform.root.name)) continue;
                    foreach (FieldInfo f in t.GetFields(BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance))
                    {
                        if (f.FieldType == typeof(MeshFilter)) Register(f.GetValue(c) as MeshFilter);
                        else if (f.FieldType == typeof(MeshFilter[]))
                        {
                            var arr = f.GetValue(c) as MeshFilter[];
                            if (arr != null) foreach (MeshFilter mf in arr) Register(mf);
                        }
                    }
                }
            }
            if (meshes.Count != before) MscoLog.Info("[MSCO] Crash damage: " + meshes.Count + " body meshes synced");
        }

        void Register(MeshFilter mf)
        {
            if (mf == null || !seen.Add(mf)) return;
            Mesh mesh = mf.sharedMesh;
            if (mesh == null || mesh.vertexCount == 0 || mesh.vertexCount > 65000) return;
            int key = Hash(FsmSync.PathOf(mf.transform));
            if (meshes.ContainsKey(key)) return; // nicht eindeutig
            Rigidbody body = mf.transform.root.GetComponent<Rigidbody>();
            meshes[key] = new DamageMesh { Key = key, Root = mf.transform.root.name, Filter = mf, Body = body, Known = mesh.vertices };
            if (body != null && !bodies.Contains(body)) bodies.Add(body);
        }

        static bool IsVehicle(string root)
        {
            foreach (string v in ObjectSync.VehicleRoots) if (root.StartsWith(v)) return true;
            return false;
        }

        static int Hash(string s)
        {
            unchecked
            {
                uint h = 2166136261;
                foreach (char c in s) { h ^= c; h *= 16777619; }
                return (int)h;
            }
        }
    }
}