using System;
using System.CodeDom.Compiler;
using System.Reflection;
using System.Windows.Forms;
using CommonLib;
using System.Data;
using Microsoft.CSharp;
using System.Text;

namespace Lskj.Common {
    /**/
    /// <summary>
    /// 动态求值
    /// </summary>
    public class Evaluator {
        /**/
        /// <summary>
        /// 计算结果,如果表达式出错则抛出异常
        /// </summary>
        /// <param name="statement">表达式,如"1+2+3+4"</param>
        /// <returns>结果</returns>
        public static object Eval(string statement)
        {
            object obj = string.Empty;
            try
            {
                if ((!string.IsNullOrEmpty(statement)) && (statement.Substring(0, 1) == "@"))
                {
                    DataTable dt = SqlHelper.ExecuteDataSet(statement.Substring(1)).Tables[0];
                    if (dt == null)
                        return 0;
                    if (dt.Rows.Count < 1)
                        return 0;
                    return dt.Rows[0][0];
                }
                if (string.IsNullOrEmpty(statement))
                    statement = "1==1";


                JSCaller caller = new JSCaller();
                obj = caller.Eval(statement);
                //obj = _evaluatorType.InvokeMember(
                //           "Eval",
                //           BindingFlags.InvokeMethod,
                //           null,
                //           _evaluator,
                //           new object[] { statement }
                // );
            }
            catch (Exception ex)
            {
                //MessageBox.Show("请仔细检查配置列条件[" + statement + "]" + ex.StackTrace + "\r\n" + ex.Message);
                PubUtil.WriteLog("请仔细检查配置列条件[" + statement + "]" + ex.Message);
            }
            //if (string.IsNullOrEmpty(obj + ""))
            //    return true;
            return obj;
        }
        /**/
        /// <summary>
        /// 
        /// </summary>
        static Evaluator() {
            try
            {
                CodeDomProvider provider = CodeDomProvider.CreateProvider("JScript");
                CompilerParameters options = new CompilerParameters
                {
                    ReferencedAssemblies = { 
                        "System.dll",
                        AppDomain.CurrentDomain.BaseDirectory + @"Microsoft.JScript.dll"
                    },
                    GenerateInMemory = false
                };

                CompilerResults results;
                results = provider.CompileAssemblyFromSource(options, _jscriptSource);
                Assembly assembly = results.CompiledAssembly;
                _evaluatorType = assembly.GetType("Evaluator");
                _evaluator = Activator.CreateInstance(_evaluatorType);
            }
            catch (Exception)
            {
            }
        }

        private static object _evaluator = null;
        private static Type _evaluatorType = null;
        /**/
        /// <summary>
        /// JScript代码
        /// </summary>
        private static readonly string _jscriptSource =

            @"class Evaluator
              {
                  public function Eval(expr : String) : String 
                  {
                     return eval(expr); 
                  }
              }";

        public static object Eval_Ex(string statement) {
            return null;
        }
    }
}