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

public static class ReflectionHelper
{
    private const BindingFlags Flags = BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic;

    // --- 寻址缓存核心区 ---
    private static readonly Dictionary<string, DeepAccessor> _accessors = new Dictionary<string, DeepAccessor>();

    public static DeepAccessor GetAccessor(Type rootType, string path)
    {
        string key = $"{rootType.FullName}:{path}";
        if (!_accessors.TryGetValue(key, out var accessor))
        {
            accessor = new DeepAccessor(rootType, path);
            _accessors[key] = accessor;
        }
        return accessor;
    }

    // --- 【无感替换口】设置深层递归值 ---
    public static void SetDeepValue(object target, string path, object newValue)
    {
        if (target == null || string.IsNullOrEmpty(path)) return;
        GetAccessor(target.GetType(), path).SetValue(target, newValue);
    }

    // --- 【无感替换口】获取深层递归值 ---
    public static object GetDeepValue(object target, string path)
    {
        if (target == null || string.IsNullOrEmpty(path)) return null;
        return GetAccessor(target.GetType(), path).GetValue(target);
    }

    /// <summary>
    /// 遍历对象的所有字段和属性（递归地），查找值与目标值匹配的参数路径。
    /// </summary>
    /// <param name="target">要搜索的对象实例。</param>
    /// <param name="targetValue">要匹配的目标值。</param>
    /// <param name="maxDepth">递归搜索的最大深度，防止无限循环。</param>
    /// <returns>返回匹配参数的完整路径列表 (例如: "position.x")。</returns>
    public static List<string> FindParametersByValue(object target, object targetValue, int maxDepth = 10)
    {
        if (target == null || targetValue == null) return new List<string>();

        // 用于存储找到的路径
        var results = new List<string>();

        // 用于防止循环引用（比如类 A 内部引用了类 B，类 B 内部又引用了类 A）
        var visited = new HashSet<object>();

        // 启动递归搜索
        FindRecursive(target, targetValue, "", 0, results, visited, maxDepth);

        return results;
    }

    private static void FindRecursive(
        object currentObject,
        object targetValue,
        string currentPath,
        int depth,
        List<string> results,
        HashSet<object> visited,
        int maxDepth)
    {
        if (currentObject == null || depth >= maxDepth) return;

        // 避免无限循环和重复搜索
        // 对于值类型 (Struct) 不需要加入 visited，因为它们是副本
        if (!currentObject.GetType().IsValueType)
        {
            // 如果对象已经被搜索过，则跳过
            if (visited.Contains(currentObject)) return;
            visited.Add(currentObject);
        }

        Type currentType = currentObject.GetType();

        // 1. 遍历 Field 字段
        foreach (var field in currentType.GetFields(Flags))
        {
            // 跳过内部字段，如编译器生成的 backing fields
            if (field.IsDefined(typeof(System.Runtime.CompilerServices.CompilerGeneratedAttribute), false)) continue;

            object value = field.GetValue(currentObject);
            string newPath = string.IsNullOrEmpty(currentPath) ? field.Name : $"{currentPath}.{field.Name}";

            CheckAndRecurse(field.FieldType, value, targetValue, newPath, depth, results, visited, maxDepth);
        }

        // 2. 遍历 Property 属性
        foreach (var prop in currentType.GetProperties(Flags).Where(p => p.CanRead))
        {
            // 跳过索引器
            if (prop.GetIndexParameters().Length > 0) continue;

            object value = prop.GetValue(currentObject);
            string newPath = string.IsNullOrEmpty(currentPath) ? prop.Name : $"{currentPath}.{prop.Name}";

            CheckAndRecurse(prop.PropertyType, value, targetValue, newPath, depth, results, visited, maxDepth);
        }
    }

    /// <summary>
    /// 检查当前值是否匹配，如果不是基础类型则继续递归
    /// </summary>
    private static void CheckAndRecurse(
        Type valueType,
        object value,
        object targetValue,
        string newPath,
        int depth,
        List<string> results,
        HashSet<object> visited,
        int maxDepth)
    {
        if (value == null) return;

        // 【值匹配检查】
        if (value.Equals(targetValue))
        {
            results.Add(newPath);
            return;
        }

        // 【递归检查】
        // 只有当值是一个复杂类型（Class 或 Struct）时才需要递归
        // 排除字符串和集合（List, Array等，如果你需要搜索集合内部，逻辑会更复杂）
        if (valueType.IsClass || valueType.IsValueType && !valueType.IsPrimitive)
        {
            // 排除 String (虽然是 Class，但我们视其为基础值)
            if (valueType == typeof(string)) return;

            // 排除集合（如果需要支持 List<T> 的内部搜索，你需要在这里添加处理逻辑）
            if (valueType.IsArray || valueType.IsGenericType && valueType.GetInterfaces().Any(i => i == typeof(System.Collections.IEnumerable))) return;

            // 递归进入下一层
            FindRecursive(value, targetValue, newPath, depth + 1, results, visited, maxDepth);
        }
    }

    /// <summary>
    /// 查找对象中第一个与目标值相等的字段/属性路径（可直接用于 SetDeepValue）。找不到则返回 null。
    /// </summary>
    public static string FindFirstParameterPathByValue(object target, object targetValue, int maxDepth = 10)
    {
        if (target == null || targetValue == null) return null;
        var results = FindParametersByValue(target, targetValue, maxDepth);
        return results.Count > 0 ? results[0] : null;
    }
}

// --- 以下为全自动高速路由存取器 ---
public class DeepAccessor
{
    private abstract class PathNode
    {
        public abstract object Get(object target);
        public abstract void Set(object target, object value);
        public abstract Type ReturnType { get; }
        public abstract bool IsValueType { get; }
    }

    private class FieldNode : PathNode
    {
        private FieldInfo field;
        public FieldNode(FieldInfo f) { field = f; }
        public override object Get(object target) => field.GetValue(target);
        public override void Set(object target, object value) => field.SetValue(target, value);
        public override Type ReturnType => field.FieldType;
        public override bool IsValueType => field.FieldType.IsValueType;
    }

    private class PropertyNode : PathNode
    {
        private PropertyInfo prop;
        public PropertyNode(PropertyInfo p) { prop = p; }
        public override object Get(object target) => prop.GetValue(target);
        public override void Set(object target, object value) { if(prop.CanWrite) prop.SetValue(target, value); }
        public override Type ReturnType => prop.PropertyType;
        public override bool IsValueType => prop.PropertyType.IsValueType;
    }

    private class IndexNode : PathNode
    {
        private int index;
        private Type returnType;

        public IndexNode(int idx, Type colType) 
        { 
            index = idx;
            if (colType.IsArray) returnType = colType.GetElementType();
            else if (typeof(System.Collections.IList).IsAssignableFrom(colType))
            {
                var dictArgs = colType.GetGenericArguments();
                returnType = dictArgs.Length > 0 ? dictArgs[0] : typeof(object);
            }
        }
        
        public override object Get(object target)
        {
            if (target is System.Collections.IList list && index >= 0 && index < list.Count) return list[index];
            if (target is Array arr && index >=0 && index < arr.Length) return arr.GetValue(index);
            return null;
        }
        
        public override void Set(object target, object value)
        {
            if (target is System.Collections.IList list && index >= 0 && index < list.Count) list[index] = value;
            else if (target is Array arr && index >=0 && index < arr.Length) arr.SetValue(value, index);
        }
        
        public override Type ReturnType => returnType ?? typeof(object);
        public override bool IsValueType => ReturnType.IsValueType;
    }

    private PathNode[] nodes;
    public bool IsValid { get; private set; }

    public DeepAccessor(Type rootType, string path)
    {
        string[] parts = path.Split('.');
        nodes = new PathNode[parts.Length];
        Type currentType = rootType;

        for (int i = 0; i < parts.Length; i++)
        {
            string part = parts[i];
            
            // 数组/列表处理口
            if (int.TryParse(part, out int idx))
            {
                nodes[i] = new IndexNode(idx, currentType);
                currentType = nodes[i].ReturnType;
                continue;
            }

            FieldInfo field = currentType.GetField(part, BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic);
            if (field != null)
            {
                nodes[i] = new FieldNode(field);
                currentType = field.FieldType;
                continue;
            }

            PropertyInfo prop = currentType.GetProperty(part, BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic);
            if (prop != null)
            {
                nodes[i] = new PropertyNode(prop);
                currentType = prop.PropertyType;
                continue;
            }

            // 路径断裂或找不到
            IsValid = false;
            return;
        }
        IsValid = true;
    }

    public object GetValue(object target)
    {
        if (!IsValid) return null;
        object current = target;
        for (int i = 0; i < nodes.Length; i++)
        {
            if (current == null) return null;
            current = nodes[i].Get(current);
        }
        return current;
    }

    public void SetValue(object target, object value)
    {
        if (!IsValid || target == null) return;
        SetRecursive(target, 0, value);
    }

    // 严丝合缝拦截所有嵌套 Struct 被传值拷贝吃掉而不回写的底层 C# 坑
    private void SetRecursive(object currentObj, int index, object finalValue)
    {
        PathNode node = nodes[index];

        if (index == nodes.Length - 1)
        {
            node.Set(currentObj, finalValue);
            return;
        }

        object nextObj = node.Get(currentObj);
        if (nextObj == null) return;

        SetRecursive(nextObj, index + 1, finalValue);

        if (node.IsValueType)
        {
            node.Set(currentObj, nextObj);
        }
    }
}

public class FastReflection
{
    // 定义一个节点，用来缓存每一层的 Field 或 Property 信息
    private class MemberNode
    {
        public FieldInfo Field;
        public PropertyInfo Property;
        public bool IsField => Field != null;

        public MemberNode(MemberInfo info)
        {
            if (info is FieldInfo f) Field = f;
            else if (info is PropertyInfo p) Property = p;
        }

        // 快速获取值
        public object GetValue(object target)
        {
            return IsField ? Field.GetValue(target) : Property.GetValue(target);
        }

        // 快速设置值
        public void SetValue(object target, object value)
        {
            if (IsField) Field.SetValue(target, value);
            else if (Property != null && Property.CanWrite) Property.SetValue(target, value);
        }

        // 判断这一层是否是 Struct (值类型)，如果是，修改后需要回写
        public bool IsStructType()
        {
            return IsField ? Field.FieldType.IsValueType : Property.PropertyType.IsValueType;
        }
    }

    // 访问器链条
    private readonly List<MemberNode> _nodes = new List<MemberNode>();
    private bool _isValid = false;

    /// <summary>
    /// 构造函数：初始化时进行昂贵的解析操作（只做一次）
    /// </summary>
    public FastReflection(object rootTarget, string path)
    {
        if (rootTarget == null || string.IsNullOrEmpty(path)) return;

        Type currentType = rootTarget.GetType();
        string[] parts = path.Split('.');
        BindingFlags flags = BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic;

        foreach (var part in parts)
        {
            // 查找字段或属性
            FieldInfo field = currentType.GetField(part, flags);
            PropertyInfo prop = currentType.GetProperty(part, flags);

            if (field == null && prop == null)
            {
                Debug.LogError($"[FastReflection] 路径中断: 找不到成员 '{part}' 在类型 '{currentType.Name}' 中");
                return;
            }

            // 创建节点并添加到链条
            MemberNode node = new MemberNode(field ?? (MemberInfo)prop);
            _nodes.Add(node);

            // 更新 currentType 为下一层的类型
            currentType = field != null ? field.FieldType : prop.PropertyType;
        }

        _isValid = true;
    }

    /// <summary>
    /// 获取值（运行时极快）
    /// </summary>
    public float GetValue(object rootTarget)
    {
        if (!_isValid) return 0f;

        object current = rootTarget;
        for (int i = 0; i < _nodes.Count; i++)
        {
            current = _nodes[i].GetValue(current);
            if (current == null) return 0f;
        }

        return (float)current; // 假设最后一定是 float
    }

    /// <summary>
    /// 设置值（运行时极快，自动处理 Struct 回写）
    /// </summary>
    public void SetValue(object rootTarget, float newValue)
    {
        if (!_isValid) return;

        // 开始递归处理回写
        SetRecursive(rootTarget, 0, newValue);
    }

    // 递归函数：处理“获取-修改-回写”逻辑
    private void SetRecursive(object currentObj, int index, float finalValue)
    {
        MemberNode node = _nodes[index];

        // 1. 如果是链条的最后一个节点（即那个 float 变量）
        if (index == _nodes.Count - 1)
        {
            node.SetValue(currentObj, finalValue);
            return;
        }

        // 2. 如果是中间节点，先获取下一层对象
        object nextObj = node.GetValue(currentObj);
        if (nextObj == null) return;

        // 3. 递归进入下一层
        SetRecursive(nextObj, index + 1, finalValue);

        // 4. 【关键】回写阶段
        // 如果 nextObj 是 Struct（值类型），比如 Vector3，
        // 我们刚才在递归里修改了 nextObj 的副本，现在必须把它赋值回 currentObj
        if (node.IsStructType())
        {
            node.SetValue(currentObj, nextObj);
        }
    }
}