using System.Collections.Generic;
using UnityEngine;
using UnityEngine.Rendering;

namespace Code.OfficeGame.BattleMode.HitBoxes
{
    public static class HitboxDrawer
    {
        private struct ActiveBox
        {
            public Matrix4x4 Matrix;
            public Color Color;
            public float ExpireTime;
        }

        private static readonly List<ActiveBox> _boxes = new(16);
        private static Mesh _cubeMesh;
        private static Material _material;
        private static MaterialPropertyBlock _propertyBlock;
        private static readonly int BaseColorPropId = Shader.PropertyToID("_BaseColor");

        private static bool _initialized;

        /// <summary>
        /// Отрисовка хитбокса напрямую по BoxCollider
        /// </summary>
        public static void DrawBox(BoxCollider collider, Color color, float duration = 1.0f)
        {
            if (collider == null) return;

            Transform t = collider.transform;
            Vector3 worldCenter = t.TransformPoint(collider.center);
            Vector3 worldSize = Vector3.Scale(collider.size, t.lossyScale);

            DrawBox(worldCenter, worldSize, t.rotation, color, duration);
        }

        /// <summary>
        /// Отрисовка хитбокса по параметрам позиции, габаритов и вращения
        /// </summary>
        public static void DrawBox(Vector3 center, Vector3 size, Quaternion rotation, Color color,
            float duration = 1.0f)
        {
            EnsureInitialized();
            if (_material == null) return;

            _boxes.Add(new ActiveBox
            {
                Matrix = Matrix4x4.TRS(center, rotation, size),
                Color = color,
                ExpireTime = Time.unscaledTime + duration
            });
        }

        /// <summary>
        /// Принудительная очистка всех активных хитбоксов
        /// </summary>
        public static void Clear()
        {
            _boxes.Clear();
        }

        private static void EnsureInitialized()
        {
            if (_initialized) return;

            _cubeMesh = GenerateUnitCubeMesh();
            _propertyBlock = new MaterialPropertyBlock();

            var shader = Shader.Find("Custom/HitboxVisualizer");
            if (shader != null)
            {
                _material = new Material(shader) { hideFlags = HideFlags.HideAndDontSave };
            }
            else
            {
                Debug.LogError("[HitboxDrawer] Не найден шейдер 'Custom/HitboxVisualizer'!");
                return;
            }

            RenderPipelineManager.beginContextRendering += OnRender;
            Camera.onPreCull += OnPreCullLegacy;

            _initialized = true;
        }

        private static void OnRender(ScriptableRenderContext ctx, List<Camera> cameras) => RenderBoxes();

        private static void OnPreCullLegacy(Camera cam)
        {
            if (GraphicsSettings.currentRenderPipeline == null) RenderBoxes();
        }

        private static void RenderBoxes()
        {
            int count = _boxes.Count;
            if (count == 0) return;

            float now = Time.unscaledTime;

            for (int i = count - 1; i >= 0; i--)
            {
                ActiveBox box = _boxes[i];

                if (now >= box.ExpireTime)
                {
                    // Быстрое удаление за O(1)
                    _boxes[i] = _boxes[_boxes.Count - 1];
                    _boxes.RemoveAt(_boxes.Count - 1);
                    continue;
                }

                _propertyBlock.SetColor(BaseColorPropId, box.Color);

                Graphics.DrawMesh(
                    _cubeMesh,
                    box.Matrix,
                    _material,
                    0,
                    null,
                    0,
                    _propertyBlock,
                    castShadows: false,
                    receiveShadows: false,
                    useLightProbes: false
                );
            }
        }

        private static Mesh GenerateUnitCubeMesh()
        {
            Mesh mesh = new Mesh { name = "Hitbox_UnitCube" };

            // 24 вершины с уникальными UV на каждой грани для точной границы
            Vector3[] vertices = new Vector3[24]
            {
                // Передняя (+Z)
                new(-0.5f, -0.5f, 0.5f), new(0.5f, -0.5f, 0.5f), new(0.5f, 0.5f, 0.5f), new(-0.5f, 0.5f, 0.5f),
                // Задняя (-Z)
                new(0.5f, -0.5f, -0.5f), new(-0.5f, -0.5f, -0.5f), new(-0.5f, 0.5f, -0.5f), new(0.5f, 0.5f, -0.5f),
                // Правая (+X)
                new(0.5f, -0.5f, 0.5f), new(0.5f, -0.5f, -0.5f), new(0.5f, 0.5f, -0.5f), new(0.5f, 0.5f, 0.5f),
                // Левая (-X)
                new(-0.5f, -0.5f, -0.5f), new(-0.5f, -0.5f, 0.5f), new(-0.5f, 0.5f, 0.5f), new(-0.5f, 0.5f, -0.5f),
                // Верхняя (+Y)
                new(-0.5f, 0.5f, 0.5f), new(0.5f, 0.5f, 0.5f), new(0.5f, 0.5f, -0.5f), new(-0.5f, 0.5f, -0.5f),
                // Нижняя (-Y)
                new(-0.5f, -0.5f, -0.5f), new(0.5f, -0.5f, -0.5f), new(0.5f, -0.5f, 0.5f), new(-0.5f, -0.5f, 0.5f)
            };

            Vector2[] uvs = new Vector2[24];
            int[] triangles = new int[36];

            for (int face = 0; face < 6; face++)
            {
                int v = face * 4;
                uvs[v + 0] = new Vector2(0, 0);
                uvs[v + 1] = new Vector2(1, 0);
                uvs[v + 2] = new Vector2(1, 1);
                uvs[v + 3] = new Vector2(0, 1);

                int t = face * 6;
                triangles[t + 0] = v + 0;
                triangles[t + 1] = v + 2;
                triangles[t + 2] = v + 1;
                triangles[t + 3] = v + 0;
                triangles[t + 4] = v + 3;
                triangles[t + 5] = v + 2;
            }

            mesh.vertices = vertices;
            mesh.uv = uvs;
            mesh.triangles = triangles;
            mesh.RecalculateBounds();
            return mesh;
        }
    }
}