using System.Collections.Generic;
using UnityEngine;

namespace MSCO
{
    /// <summary>
    /// Mitspieler als MSC-Mensch: Alle Leute im Spiel benutzen denselben Körper ("bodymesh", 20 Knochen) und
    /// unterscheiden sich nur durch drei Materialien - Hemd (char_shirtXX), Hose (char_pantsXX) und Gesicht
    /// (char_faceXX). MSCO nimmt nur dieses Mesh, baut ein eigenes Skelett aus seiner Bind-Pose und gibt jedem
    /// Spieler ein normales Hemd/Hose/Gesicht (keine Kleider, Vorhänge oder Geister). Die Knochen werden jedes Frame
    /// direkt aus den Gelenkpunkten der MSCO-Figur gesetzt (laufen, springen, ducken, sitzen, Items halten).
    ///
    /// Knochen-Reihenfolge ist bei allen MSC-Menschen gleich (nur die Namen unterscheiden sich):
    /// 0 Becken, 1-2 Wirbelsäule, 3 Kopf, 4/9 Schlüsselbein, 5/10 Schulter, 6/11 Ellbogen, 7/12 Hand, 8/13 Finger,
    /// 14/17 Hüfte, 15/18 Knie, 16/19 Knöchel (links/rechts). Bind-Pose: Z oben, X vorne, -Y links.
    /// </summary>
    public class GameCharacter
    {
        /// <summary>Gelenkpunkte der MSCO-Figur im lokalen Raum des Spielers (jedes Frame von RemotePlayer.Pose).</summary>
        public class Rig
        {
            public Vector3 Hip, NeckBase, Head;
            public Vector3 Up = Vector3.up;
            public float Pitch;
            public readonly Vector3[] HipJoint = new Vector3[2], Knee = new Vector3[2], Ankle = new Vector3[2];
            public readonly Vector3[] Shoulder = new Vector3[2], Elbow = new Vector3[2], Hand = new Vector3[2];
        }

        const int BoneCount = 20;
        const int Pelvis = 0, Head = 3;
        static readonly int[] Torso = { 0, 1, 2, 4, 9 };
        static readonly int[] Shoulder = { 5, 10 }, Elbow = { 6, 11 }, Wrist = { 7, 12 }, Finger = { 8, 13 };
        static readonly int[] HipBone = { 14, 17 }, Knee = { 15, 18 }, Ankle = { 16, 19 };

        // ---------------------------------------------------------------- Mesh und Kleidung aus dem Spiel

        static Mesh bodyMesh;
        static List<Material> shirts, pants, faces;
        static float nextSearch;

        static bool FindAssets()
        {
            if (bodyMesh != null && shirts.Count > 0 && pants.Count > 0 && faces.Count > 0) return true;
            if (Time.realtimeSinceStartup < nextSearch) return false;
            nextSearch = Time.realtimeSinceStartup + 10f;

            var users = new Dictionary<Mesh, int>();
            var shirtByName = new Dictionary<string, Material>();
            var pantsByName = new Dictionary<string, Material>();
            var faceByName = new Dictionary<string, Material>();
            foreach (SkinnedMeshRenderer smr in Resources.FindObjectsOfTypeAll<SkinnedMeshRenderer>())
            {
                if (smr == null || smr.name != "bodymesh") continue;
                Mesh m = smr.sharedMesh;
                if (m == null || m.bindposes == null || m.bindposes.Length != BoneCount || m.subMeshCount != 3) continue;
                int n;
                users.TryGetValue(m, out n);
                users[m] = n + 1;
                Material[] mats = smr.sharedMaterials;
                if (mats == null || mats.Length != 3) continue;
                Add(shirtByName, mats[0], "char_shirt");
                Add(pantsByName, mats[1], "char_pants");
                if (mats[2] != null && !mats[2].name.Contains("woman")) Add(faceByName, mats[2], "char_face");
            }
            // Das Mesh, das die meisten Leute benutzen = der normale Mann
            Mesh best = null;
            int bestUsers = 0;
            foreach (KeyValuePair<Mesh, int> kv in users)
                if (kv.Value > bestUsers && LooksHuman(kv.Key)) { best = kv.Key; bestUsers = kv.Value; }
            bodyMesh = best;
            shirts = Sorted(shirtByName);
            pants = Sorted(pantsByName);
            faces = Sorted(faceByName);
            bool ok = bodyMesh != null && shirts.Count > 0 && pants.Count > 0 && faces.Count > 0;
            if (ok) MscoLog.Info("[MSCO] Player models: MSC body with " + shirts.Count + " shirts, " + pants.Count + " trousers, " + faces.Count + " faces");
            return ok;
        }

        static void Add(Dictionary<string, Material> into, Material m, string prefix)
        {
            if (m != null && m.name.StartsWith(prefix) && !into.ContainsKey(m.name)) into[m.name] = m;
        }

        static List<Material> Sorted(Dictionary<string, Material> d)
        {
            var names = new List<string>(d.Keys);
            names.Sort(string.CompareOrdinal); // bei allen Spielern gleiche Reihenfolge -> gleiches Aussehen
            return names.ConvertAll(n => d[n]);
        }

        /// <summary>Prüft die erwartete Knochen-Reihenfolge an der Bind-Pose (Kopf oben, Knöchel unten, Beine lang).</summary>
        static bool LooksHuman(Mesh m)
        {
            Vector3[] p = BindPositions(m);
            if (p[Head].z < p[Pelvis].z + 0.4f) return false;
            for (int i = 0; i < 2; i++)
            {
                if (p[Ankle[i]].z > p[Knee[i]].z || p[Knee[i]].z > p[HipBone[i]].z) return false;
                if (p[Wrist[i]].z > p[Shoulder[i]].z) return false;
            }
            return p[Shoulder[0]].y < 0f && p[Shoulder[1]].y > 0f; // links = -Y
        }

        static Vector3[] BindPositions(Mesh m)
        {
            var p = new Vector3[BoneCount];
            for (int i = 0; i < BoneCount; i++) p[i] = m.bindposes[i].inverse.GetColumn(3);
            return p;
        }

        // ---------------------------------------------------------------- Instanz

        GameObject model;
        Transform owner;
        readonly Transform[] bones = new Transform[BoneCount];
        readonly Vector3[] restPos = new Vector3[BoneCount];     // relativ zum Spieler
        readonly Quaternion[] restRot = new Quaternion[BoneCount];
        Vector3 restHipCenter;
        public string Description { get; private set; }

        /// <summary>Figur bauen (variant wählt Hemd, Hose und Gesicht). null, wenn das Spiel-Mesh nicht gefunden wird.</summary>
        public static GameCharacter Create(Transform owner, int variant)
        {
            if (!FindAssets()) return null;
            var c = new GameCharacter();
            try
            {
                c.Build(owner, Mathf.Abs(variant));
                return c;
            }
            catch (System.Exception e)
            {
                MscoLog.Warning("[MSCO] Player model could not be built: " + e.Message);
                c.Destroy();
                return null;
            }
        }

        void Build(Transform owner, int variant)
        {
            this.owner = owner;
            Vector3[] bind = BindPositions(bodyMesh);
            float leg = (bind[Knee[0]] - bind[HipBone[0]]).magnitude + (bind[Ankle[0]] - bind[Knee[0]]).magnitude;
            float scale = 0.84f / Mathf.Max(0.1f, leg); // Bein der MSCO-Figur

            model = new GameObject("MSCO_Model");
            model.transform.SetParent(owner, false);
            // Bind-Pose: X vorne, Z oben -> Spieler: Z vorne, Y oben
            model.transform.localRotation = Quaternion.Inverse(Quaternion.LookRotation(Vector3.right, Vector3.forward));
            model.transform.localScale = Vector3.one * scale;

            Matrix4x4[] bindposes = bodyMesh.bindposes;
            for (int i = 0; i < BoneCount; i++)
            {
                var b = new GameObject("bone" + i).transform;
                b.SetParent(model.transform, false);
                Matrix4x4 m = bindposes[i].inverse;
                b.localPosition = m.GetColumn(3);
                b.localRotation = Quaternion.LookRotation(m.GetColumn(2), m.GetColumn(1));
                bones[i] = b;
                restPos[i] = owner.InverseTransformPoint(b.position);
                restRot[i] = Quaternion.Inverse(owner.rotation) * b.rotation;
            }
            restHipCenter = (restPos[HipBone[0]] + restPos[HipBone[1]]) * 0.5f;

            var smr = model.AddComponent<SkinnedMeshRenderer>();
            smr.sharedMesh = bodyMesh;
            smr.bones = bones;
            smr.rootBone = bones[Pelvis];
            smr.updateWhenOffscreen = true; // die Knochen bewegen sich weit weg von der gespeicherten Hülle
            Material shirt = shirts[(variant * 7 + 3) % shirts.Count];
            Material trousers = pants[(variant * 3 + 1) % pants.Count];
            Material face = faces[(variant * 5 + 2) % faces.Count];
            smr.sharedMaterials = new[] { shirt, trousers, face };
            Description = "MSC body (" + shirt.name + ", " + trousers.name + ", " + face.name + ")";
        }

        // ---------------------------------------------------------------- jedes Frame

        public void Apply(Rig rig)
        {
            if (model == null) return;
            Quaternion root = owner.rotation;
            Quaternion lean = Quaternion.FromToRotation(Vector3.up, rig.Up);
            Quaternion torso = root * lean;

            foreach (int i in Torso) Place(i, TorsoPoint(rig, lean, restPos[i]), torso * restRot[i]);
            Place(Head, TorsoPoint(rig, lean, restPos[Head]), root * Quaternion.Euler(rig.Pitch, 0f, 0f) * restRot[Head]);

            for (int s = 0; s < 2; s++)
            {
                // Bein: Hüfte am Becken, dann Richtung Knie bzw. Knöchel der MSCO-Figur
                Vector3 hip = TorsoPoint(rig, lean, restPos[HipBone[s]]);
                Quaternion thigh = AimDelta(HipBone[s], Knee[s], rig.Knee[s] - rig.HipJoint[s]);
                Place(HipBone[s], hip, root * thigh * restRot[HipBone[s]]);
                Vector3 knee = hip + root * (thigh * (restPos[Knee[s]] - restPos[HipBone[s]]));
                Quaternion shin = AimDelta(Knee[s], Ankle[s], rig.Ankle[s] - rig.Knee[s]);
                Place(Knee[s], knee, root * shin * restRot[Knee[s]]);
                Vector3 ankle = knee + root * (shin * (restPos[Ankle[s]] - restPos[Knee[s]]));
                Place(Ankle[s], ankle, root * restRot[Ankle[s]]); // Fuß bleibt flach

                // Arm: Schulter am Oberkörper, dann Richtung Ellbogen bzw. Hand
                Vector3 shoulder = TorsoPoint(rig, lean, restPos[Shoulder[s]]);
                Quaternion upper = AimDelta(Shoulder[s], Elbow[s], rig.Elbow[s] - rig.Shoulder[s]);
                Place(Shoulder[s], shoulder, root * upper * restRot[Shoulder[s]]);
                Vector3 elbow = shoulder + root * (upper * (restPos[Elbow[s]] - restPos[Shoulder[s]]));
                Quaternion fore = AimDelta(Elbow[s], Wrist[s], rig.Hand[s] - rig.Elbow[s]);
                Place(Elbow[s], elbow, root * fore * restRot[Elbow[s]]);
                Vector3 wrist = elbow + root * (fore * (restPos[Wrist[s]] - restPos[Elbow[s]]));
                Place(Wrist[s], wrist, root * fore * restRot[Wrist[s]]);
                Vector3 finger = wrist + root * (fore * (restPos[Finger[s]] - restPos[Wrist[s]]));
                Place(Finger[s], finger, root * fore * restRot[Finger[s]]);
            }
        }

        /// <summary>Punkt des Oberkörpers: an der Hüfte der MSCO-Figur, mit ihr geneigt.</summary>
        Vector3 TorsoPoint(Rig rig, Quaternion lean, Vector3 rest)
        {
            return owner.TransformPoint(rig.Hip + lean * (rest - restHipCenter));
        }

        /// <summary>Drehung, die das Knochenstück from->to aus der Ruhelage in die gewünschte Richtung bringt.</summary>
        Quaternion AimDelta(int from, int to, Vector3 desired)
        {
            Vector3 rest = restPos[to] - restPos[from];
            if (desired.sqrMagnitude < 1e-6f || rest.sqrMagnitude < 1e-6f) return Quaternion.identity;
            return Quaternion.FromToRotation(rest, desired);
        }

        void Place(int i, Vector3 pos, Quaternion rot)
        {
            bones[i].position = pos;
            bones[i].rotation = rot;
        }

        public void Destroy()
        {
            if (model != null) Object.Destroy(model);
            model = null;
        }
    }
}