using System.Collections.Generic;
using System.IO;
using System.Linq;
using Luneraria.View;
using UnityEditor;
using UnityEditor.Animations;
using UnityEngine;
using UnityEngine.Rendering;

namespace Luneraria.EditorTools
{
    /// <summary>
    /// Builds what the unit views need (U2C): a one-mesh version of the rigid Kohlenbeißer (131
    /// named parts combined per material, like Godot's rig groups), animator controllers with the
    /// Blender clips of the rigged figures, team ring and bar meshes and their materials.
    /// </summary>
    public static class LuneUnitLibraryBuilder
    {
        public const string LibraryPath = "Assets/Luneraria/Settings/LuneUnits.asset";
        const string Generated = "Assets/Luneraria/Art/Generated";
        const string Art = "Assets/Luneraria/Art/";

        public static LuneUnitLibrary Build(LuneMaterialSet materials, LuneGround ground)
        {
            Directory.CreateDirectory(Generated);
            AssetDatabase.Refresh();
            var library = AssetDatabase.LoadAssetAtPath<LuneUnitLibrary>(LibraryPath);
            if (library == null)
            {
                library = ScriptableObject.CreateInstance<LuneUnitLibrary>();
                AssetDatabase.CreateAsset(library, LibraryPath);
            }
            library.Materials = materials;
            library.Ground = ground;
            library.Models = Models();
            library.RingRound = Keep(Ring("RingRound", 40, 0f));
            library.RingDiamond = Keep(Ring("RingDiamond", 4, 45f));
            library.RingHexagon = Keep(Ring("RingHexagon", 6, 0f));
            library.OwnerRingRound = Keep(Ring("OwnerRingRound", 40, 0f, 1f, 1.12f));
            library.OwnerRingDiamond = Keep(Ring("OwnerRingDiamond", 4, 45f, 1f, 1.12f));
            library.Quad = Keep(Quad());
            for (int team = 0; team < 3; team++)
            {
                library.TeamRing[team] = Marker("Ring_" + team, LuneMaterialFactory.TeamColor[team], team == 2 ? .6f : 1.4f, false);
                library.BarFill[team] = Marker("BarFill_" + team, Color.Lerp(LuneMaterialFactory.TeamColor[team], Color.white, .15f), 1f, true);
                library.Bolt[team] = Marker("Bolt_" + team, LuneMaterialFactory.TeamLight[team], 3f, false);
            }
            library.HeroRing = Marker("Ring_Hero", LuneMaterialFactory.Hex("f2c96b"), 2.2f, false);
            for (int team = 0; team < 2; team++)
            {
                library.OwnerRing[team] = Marker("Ring_Owner_" + team, LuneMaterialFactory.TeamColor[team], 3f, false);
                library.AncientBarFill[team] = Marker("AncientBarFill_" + team, Color.Lerp(LuneMaterialFactory.TeamLight[team], Color.white, .15f), 1f, true);
            }
            library.BarBack = Marker("BarBack", new Color(0f, 0f, 0f, .7f), 1f, true);
            EditorUtility.SetDirty(library);
            AssetDatabase.SaveAssets();
            return library;
        }

        /// <summary>Groups whose models stand for units; buildings and environment have their own views.</summary>
        static readonly string[] UnitGroups = { "Units", "Enemies", "Characters", "Peoples" };

        /// <summary>
        /// One entry per exported unit model (tools/blender/export_manifest.json): rigid models by
        /// their id, skinned figures with an animator controller. A skinned figure also stands in
        /// for the Godot id it replaced (w04 is Ringborke, worker is the Arbeiter, ...).
        /// </summary>
        static List<LuneUnitLibrary.UnitModel> Models()
        {
            var manifest = Newtonsoft.Json.Linq.JObject.Parse(File.ReadAllText(Path.Combine(Path.GetDirectoryName(Application.dataPath), "tools/blender/export_manifest.json")));
            var models = new List<LuneUnitLibrary.UnitModel>();
            var aliases = new List<LuneUnitLibrary.UnitModel>();
            foreach (var asset in manifest["assets"])
            {
                string id = (string)asset["id"];
                string group = (string)asset["group"];
                if (!UnitGroups.Contains(group))
                    continue;
                var prefab = AssetDatabase.LoadAssetAtPath<GameObject>(Art + group + "/" + id + ".fbx");
                if (prefab == null)
                    continue;
                bool skinned = (string)asset["kind"] == "skinned";
                var model = new LuneUnitLibrary.UnitModel { Id = id, Prefab = prefab, Controller = skinned ? Controller(id, Art + group + "/" + id + ".fbx") : null };
                models.Add(model);
                string godotId = (string)asset["godot_manifest"]?["id"];
                if (skinned && godotId != null && godotId != id)
                    aliases.Add(new LuneUnitLibrary.UnitModel { Id = godotId, Prefab = prefab, Controller = model.Controller });
            }
            // Skinned figures replace the rigid model of the same Godot id.
            foreach (LuneUnitLibrary.UnitModel alias in aliases)
            {
                models.RemoveAll(m => m.Id == alias.Id);
                models.Add(alias);
            }
            return models.OrderBy(m => m.Id, System.StringComparer.Ordinal).ToList();
        }

        /// <summary>One state per clip of the model (named like the Blender action), idle first.</summary>
        static RuntimeAnimatorController Controller(string id, string fbx)
        {
            // Updated in place (stable GUID, no duplicates): existing states are replaced.
            string path = Generated + "/" + id + ".controller";
            var controller = AssetDatabase.LoadAssetAtPath<AnimatorController>(path) ?? AnimatorController.CreateAnimatorControllerAtPath(path);
            AnimatorStateMachine machine = controller.layers[0].stateMachine;
            AnimationClip[] clips = AssetDatabase.LoadAllAssetsAtPath(fbx).OfType<AnimationClip>().Where(c => !c.name.StartsWith("__preview__"))
                .OrderBy(c => c.name == "idle" ? 0 : 1).ThenBy(c => c.name).ToArray();
            // Unchanged clips: keep the states (rebuilding them gave new file ids on every build).
            ChildAnimatorState[] current = machine.states;
            bool same = current.Length == clips.Length && current.Select((child, index) => child.state.name == clips[index].name && child.state.motion == clips[index]).All(match => match);
            if (same)
                return controller;
            foreach (ChildAnimatorState child in machine.states.ToArray())
                machine.RemoveState(child.state);
            foreach (AnimationClip clip in clips)
            {
                AnimatorState state = machine.AddState(clip.name);
                state.motion = clip;
                if (clip.name == "idle")
                    machine.defaultState = state;
            }
            EditorUtility.SetDirty(controller);
            return controller;
        }

        /// <summary>Flat ring on the ground (Godot: TorusMesh inner .42, outer .52, flattened).</summary>
        static Mesh Ring(string name, int sides, float offsetDegrees, float inner = .42f, float outer = .52f)
        {
            var vertices = new List<Vector3>();
            var triangles = new List<int>();
            for (int i = 0; i <= sides; i++)
            {
                float angle = (offsetDegrees + 360f * i / sides) * Mathf.Deg2Rad;
                var direction = new Vector3(Mathf.Cos(angle), 0f, Mathf.Sin(angle));
                vertices.Add(direction * inner);
                vertices.Add(direction * outer);
                if (i < sides)
                {
                    int a = i * 2;
                    triangles.AddRange(new[] { a, a + 1, a + 3, a, a + 3, a + 2 });
                }
            }
            var mesh = new Mesh { name = name };
            mesh.SetVertices(vertices);
            mesh.SetTriangles(triangles, 0);
            mesh.RecalculateNormals();
            mesh.RecalculateBounds();
            return mesh;
        }

        static Mesh Quad()
        {
            var mesh = new Mesh { name = "MarkerQuad" };
            mesh.SetVertices(new List<Vector3> { new Vector3(-.5f, -.5f, 0f), new Vector3(.5f, -.5f, 0f), new Vector3(-.5f, .5f, 0f), new Vector3(.5f, .5f, 0f) });
            mesh.SetTriangles(new[] { 0, 2, 1, 2, 3, 1 }, 0);
            mesh.RecalculateNormals();
            mesh.RecalculateBounds();
            return mesh;
        }

        static Mesh Keep(Mesh mesh)
        {
            string path = Generated + "/" + mesh.name + ".asset";
            var existing = AssetDatabase.LoadAssetAtPath<Mesh>(path);
            if (existing == null)
            {
                AssetDatabase.CreateAsset(mesh, path);
                return mesh;
            }
            EditorUtility.CopySerialized(mesh, existing);
            EditorUtility.SetDirty(existing);
            return existing;
        }

        /// <summary>Unshaded marker colour (Godot _flat with emission energy); bars draw on top.</summary>
        static Material Marker(string name, Color srgb, float energy, bool onTop)
        {
            string path = LuneMaterialFactory.Folder + "/Markers/" + name + ".mat";
            Directory.CreateDirectory(Path.GetDirectoryName(path));
            Shader shader = Shader.Find("Luneraria/Unlit");
            var material = AssetDatabase.LoadAssetAtPath<Material>(path);
            if (material == null)
            {
                material = new Material(shader);
                AssetDatabase.CreateAsset(material, path);
            }
            material.shader = shader;
            Color linear = srgb.linear * energy;
            material.SetColor("_Color", new Color(linear.r, linear.g, linear.b, srgb.a));
            material.SetFloat("_ZTest", onTop ? (float)CompareFunction.Always : (float)CompareFunction.LessEqual);
            material.enableInstancing = true;
            EditorUtility.SetDirty(material);
            return material;
        }
    }
}