using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Reflection;
using System.Xml;
using IwbZero.Expr;
using IwbZero.IwbBase;
using IwbZero.ToolCommon.AssemblyHelpers;
using IwbZero.ToolCommon.StringModel;

namespace IwbZero.ExprFunctions
{
    public class IwbFunction:IIwbId
    {
        protected IIwbFunction Function;

        public string Id { get; set; }
        public string FunctionId { get; set; }
        public string FunctionClass{ get; set; }
        public string FunctionName{ get; set; }
        public string FunctionDesc { get; set; }
        public string FunctionParam { get; set; }
        /// <summary>
        /// 根据ID加载函数
        /// </summary>
        /// <param name="functionId"></param>
        /// <returns></returns>
        public static IwbFunction LoadById(string functionId)
        {
            return QueryFunById(LoadFunXmlNode(), functionId);
        }
     
        /// <summary>
        /// 查询函数
        /// </summary>
        /// <param name="xmlNode"></param>
        /// <param name="functionId"></param>
        /// <returns></returns>
        public static IwbFunction QueryFunById(XmlNode xmlNode,string functionId)
        {
            if (!xmlNode.HasChildNodes)
            {
                return null;
            }
            foreach (XmlNode child in xmlNode.ChildNodes)
            {
                if (child.Attributes?["id"] != null && child.Attributes["id"].Value.UAndT()==functionId)
                {
                    return Xml2Fun(child);

                    //IwbFunction function = new IwbFunction()
                    //{
                    //    FunctionId = child.Attributes["id"].Value,
                    //    Id = functionId,
                    //};
                    //if (child.HasChildNodes)
                    //{
                    //    foreach (XmlNode node in child.ChildNodes)
                    //    {
                    //        switch (node.Name.Trim())
                    //        {
                    //            case "Name":
                    //                function.FunctionName = node.FirstChild?.Value;
                    //                break;
                    //            case "ClassName":
                    //                function.FunctionClass = node.FirstChild?.Value;
                    //                break;
                    //            case "Description":
                    //                function.FunctionDesc = node.FirstChild?.Value;
                    //                break;
                    //            case "Param":
                    //                function.FunctionParam = node.FirstChild?.Value;
                    //                break;
                    //        }
                    //    }
                    //}

                }
            }

            return null;
        }

        /// <summary>
        /// 执行函数
        /// </summary>
        /// <param name="poRoot"></param>
        /// <returns></returns>
        public virtual string InvokeFunction(ExprObject poRoot)
        {
            string result = "";
            if (Function == null)
            {
                LoadFunction();
            }
            if (Function != null)
            {
                result = Function.Invoke(poRoot);
            }
            return result;
        }
        /// <summary>
        /// 加载函数
        /// </summary>
        protected virtual void LoadFunction()
        {
            if (FunctionClass != "")
            {
                object obj = AssemblyHelper.CreateInstance(FunctionClass);
                if (obj != null && obj is IIwbFunction function)
                {
                    Function = function;
                }
            }
            if (Function == null)
            {
                throw new Exception($"Unable to load '{FunctionClass}' for function {FunctionName}.");
            }
        }

        public static List<IwbFunction> FunctionList => QueryAllFuns();

        public static List<IwbFunction> QueryAllFuns()
        {
            var funs = LoadByXml(LoadFunXmlNode());
            foreach (var fun in funs)
            {
                fun.FunctionParam = fun.FunctionParam.IsEmpty()
                    ? ""
                    : string.Join(",", fun.FunctionParam.Replace("，",",").Split(',').Select(a => $"'{a}'"));
            }
            return funs;
        }
        /// <summary>
        /// 加载Fun资源
        /// </summary>
        /// <returns></returns>
        private static XmlNode LoadFunXmlNode()
        {
            string fileName = "IwbZero.ExprFunctions.Functions.function.xml";
            XmlDocument xDoc = new XmlDocument();
            Assembly asm = Assembly.GetExecutingAssembly();
            //读取嵌入式资源
            Stream sm = asm.GetManifestResourceStream(fileName);
            if (sm != null)
            {
                xDoc.Load(sm);
            }

            if (!xDoc.HasChildNodes)
            {
                return null;
            }

            XmlNode xmlNode = xDoc.LastChild;
            return xmlNode;
        }

        /// <summary>
        /// 加载函数
        /// </summary>
        /// <param name="xmlNode"></param>
        /// <returns></returns>
        public static List<IwbFunction> LoadByXml(XmlNode xmlNode)
        {
            if (!xmlNode.HasChildNodes)
            {
                return null;
            }
            var funList = new List<IwbFunction>();
            foreach (XmlNode child in xmlNode.ChildNodes)
            {
                if (child.Attributes != null)
                {
                    IwbFunction function = Xml2Fun(child);
                    funList.Add(function);
                }
            }
            return funList;
        }

        /// <summary>
        /// XML 转成 FUN
        /// </summary>
        /// <param name="xmlNode"></param>
        /// <returns></returns>
        public static IwbFunction Xml2Fun(XmlNode xmlNode)
        {
            IwbFunction function = new IwbFunction
            {
                FunctionId = xmlNode.Attributes != null ? xmlNode.Attributes["id"]?.Value : ""
            };
            function.Id = function.FunctionId;
            if (xmlNode.HasChildNodes)
            {
                foreach (XmlNode node in xmlNode.ChildNodes)
                {
                    switch (node.Name.Trim())
                    {
                        case "Name":
                            function.FunctionName = node.FirstChild?.Value;
                            break;
                        case "ClassName":
                            function.FunctionClass = node.FirstChild?.Value;
                            break;
                        case "Description":
                            function.FunctionDesc = node.FirstChild?.Value;
                            break;
                        case "Param":
                            function.FunctionParam = node.FirstChild?.Value;
                            break;
                    }
                }
            }

            return function;
        }

      

        public override string ToString()
        {
            return FunctionName;
        }
    }
}