using System;
using System.Text;
using System.Drawing;
using System.Collections;
using System.ComponentModel;
using System.Windows.Forms;
using System.Data;
using System.CodeDom;
using Microsoft.CSharp;
using System.CodeDom.Compiler;
using System.Reflection;
using System.IO;
using System.Text.RegularExpressions;

namespace ArdupilotMega
{
    static class CodeGen
    {
        public static string runCode(string code)
        {
            string answer = "";

            GetMathMemberNames();

            // change evaluation string to pick up Math class members
            string expression = RefineEvaluationString(code);

            // build the class using codedom
            BuildClass(expression);

            // compile the class into an in-memory assembly.
            // if it doesn't compile, show errors in the window
            CompilerResults results = CompileAssembly();

            Console.WriteLine("...........................\r\n");
            Console.WriteLine(_source.ToString());

            // if the code compiled okay,
            // run the code using the new assembly (which is inside the results)
            if (results != null && results.CompiledAssembly != null)
            {
                // run the evaluation function
                answer = RunCode(results);
            }
            else
            {
            }

            return answer;
        }

        static CodeDomProvider CreateCompiler()
        {
            //Create an instance of the C# compiler   
            CodeDomProvider codeProvider = CodeDomProvider.CreateProvider("CSharp");
            //ICodeCompiler compiler = codeProvider.CreateCompiler();
            return codeProvider;
        }

        /// <summary>
        /// Creawte parameters for compiling
        /// </summary>
        /// <returns></returns>
        static CompilerParameters CreateCompilerParameters()
        {
            //add compiler parameters and assembly references
            CompilerParameters compilerParams = new CompilerParameters();
            compilerParams.CompilerOptions = "/target:library /optimize";
            compilerParams.GenerateExecutable = false;
            compilerParams.GenerateInMemory = true;
            compilerParams.IncludeDebugInformation = false;
            compilerParams.ReferencedAssemblies.Add("mscorlib.dll");
            compilerParams.ReferencedAssemblies.Add("System.dll");
            compilerParams.ReferencedAssemblies.Add("System.Windows.Forms.dll");

            //add any aditional references needed
            //            foreach (string refAssembly in code.References)
            //              compilerParams.ReferencedAssemblies.Add(refAssembly);

            return compilerParams;
        }

        /// <summary>
        /// Compiles the code from the code string
        /// </summary>
        /// <param name="compiler"></param>
        /// <param name="parms"></param>
        /// <param name="source"></param>
        /// <returns></returns>
        static private CompilerResults CompileCode(CodeDomProvider compiler, CompilerParameters parms, string source)
        {
            //actually compile the code
            CompilerResults results = compiler.CompileAssemblyFromSource(
                                        parms, source);

            //Do we have any compiler errors?
            if (results.Errors.Count > 0)
            {
                foreach (CompilerError error in results.Errors)
                    Console.WriteLine("Compile Error:" + error.ErrorText);
                return null;
            }

            return results;
        }

        /// <summary>
        /// Need to change eval string to use .NET Math library
        /// </summary>
        /// <param name="eval">evaluation expression</param>
        /// <returns></returns>
        static string RefineEvaluationString(string eval)
        {
            // look for regular expressions with only letters
            Regex regularExpression = new Regex("[a-zA-Z_]+");

            // track all functions and constants in the evaluation expression we already replaced
            ArrayList replacelist = new ArrayList();

            // find all alpha words inside the evaluation function that are possible functions
            MatchCollection matches = regularExpression.Matches(eval);
            foreach (Match m in matches)
            {
                // if the word is found in the math member map, add a Math prefix to it
                bool isContainedInMathLibrary = _mathMembersMap[m.Value.ToUpper()] != null;
                if (replacelist.Contains(m.Value) == false && isContainedInMathLibrary)
                {
                    eval = eval.Replace(m.Value, "Math." + _mathMembersMap[m.Value.ToUpper()]);
                }

                // we matched it already, so don't allow us to replace it again
                replacelist.Add(m.Value);
            }

            // return the modified evaluation string
            return eval;
        }

        /// <summary>
        /// Compiles the c# into an assembly if there are no syntax errors
        /// </summary>
        /// <returns></returns>
        static private CompilerResults CompileAssembly()
        {
            // create a compiler
            CodeDomProvider compiler = CreateCompiler();
            // get all the compiler parameters
            CompilerParameters parms = CreateCompilerParameters();
            // compile the code into an assembly
            CompilerResults results = CompileCode(compiler, parms, _source.ToString());
            return results;

        }

        static ArrayList _mathMembers = new ArrayList();
        static Hashtable _mathMembersMap = new Hashtable();

        static void GetMathMemberNames()
        {
            // get a reflected assembly of the System assembly
            Assembly systemAssembly = Assembly.GetAssembly(typeof(System.Math));
            try
            {
                //cant call the entry method if the assembly is null
                if (systemAssembly != null)
                {
                    //Use reflection to get a reference to the Math class

                    Module[] modules = systemAssembly.GetModules(false);
                    Type[] types = modules[0].GetTypes();

                    //loop through each class that was defined and look for the first occurrance of the Math class
                    foreach (Type type in types)
                    {
                        if (type.Name == "Math")
                        {
                            // get all of the members of the math class and map them to the same member
                            // name in uppercase
                            MemberInfo[] mis = type.GetMembers();
                            foreach (MemberInfo mi in mis)
                            {
                                _mathMembers.Add(mi.Name);
                                _mathMembersMap[mi.Name.ToUpper()] = mi.Name;
                            }
                        }
                        //if the entry point method does return in Int32, then capture it and return it
                    }


                    //if it got here, then there was no entry point method defined.  Tell user about it
                }
            }
            catch (Exception ex)
            {
                Console.WriteLine("Error:  An exception occurred while executing the script", ex);
            }
        }

        /// <summary>
        /// Runs the Calculate method in our on-the-fly assembly
        /// </summary>
        /// <param name="results"></param>
        static private string RunCode(CompilerResults results)
        {
            Assembly executingAssembly = results.CompiledAssembly;
            try
            {
                //cant call the entry method if the assembly is null
                if (executingAssembly != null)
                {
                    object assemblyInstance = executingAssembly.CreateInstance("ExpressionEvaluator.Calculator");
                    //Use reflection to call the static Main function

                    Module[] modules = executingAssembly.GetModules(false);
                    Type[] types = modules[0].GetTypes();

                    //loop through each class that was defined and look for the first occurrance of the entry point method
                    foreach (Type type in types)
                    {
                        MethodInfo[] mis = type.GetMethods();
                        foreach (MethodInfo mi in mis)
                        {
                            if (mi.Name == "Calculate")
                            {
                                object result = mi.Invoke(assemblyInstance, null);
                                return result.ToString();
                            }
                        }
                    }

                }
            }
            catch (Exception ex)
            {
                Console.WriteLine("Error:  An exception occurred while executing the script", ex);
            }
            return "";
        }


        static CodeMemberField FieldVariable(string fieldName, string typeName, MemberAttributes accessLevel)
        {
            CodeMemberField field = new CodeMemberField(typeName, fieldName);
            field.Attributes = accessLevel;
            return field;
        }
        static CodeMemberField FieldVariable(string fieldName, Type type, MemberAttributes accessLevel)
        {
            CodeMemberField field = new CodeMemberField(type, fieldName);
            field.Attributes = accessLevel;
            return field;
        }

        /// <summary>
        /// Very simplistic getter/setter properties
        /// </summary>
        /// <param name="propName"></param>
        /// <param name="internalName"></param>
        /// <param name="type"></param>
        /// <returns></returns>
        static CodeMemberProperty MakeProperty(string propertyName, string internalName, Type type)
        {
            CodeMemberProperty myProperty = new CodeMemberProperty();
            myProperty.Name = propertyName;
            myProperty.Comments.Add(new CodeCommentStatement(String.Format("The {0} property is the returned result", propertyName)));
            myProperty.Attributes = MemberAttributes.Public;
            myProperty.Type = new CodeTypeReference(type);
            myProperty.HasGet = true;
            myProperty.GetStatements.Add(
                new CodeMethodReturnStatement(
                    new CodeFieldReferenceExpression(new CodeThisReferenceExpression(), internalName)));

            myProperty.HasSet = true;
            myProperty.SetStatements.Add(
                new CodeAssignStatement(
                    new CodeFieldReferenceExpression(new CodeThisReferenceExpression(), internalName),
                    new CodePropertySetValueReferenceExpression()));

            return myProperty;
        }


        static StringBuilder _source = new StringBuilder();

        /// <summary>
        /// Main driving routine for building a class
        /// </summary>
        static void BuildClass(string expression)
        {
            // need a string to put the code into
            _source = new StringBuilder();
            StringWriter sw = new StringWriter(_source);

            //Declare your provider and generator
            CSharpCodeProvider codeProvider = new CSharpCodeProvider();
            ICodeGenerator generator = codeProvider.CreateGenerator(sw);
            CodeGeneratorOptions codeOpts = new CodeGeneratorOptions();

            CodeNamespace myNamespace = new CodeNamespace("ExpressionEvaluator");
            myNamespace.Imports.Add(new CodeNamespaceImport("System"));
            myNamespace.Imports.Add(new CodeNamespaceImport("System.Windows.Forms"));

            //Build the class declaration and member variables			
            CodeTypeDeclaration classDeclaration = new CodeTypeDeclaration();
            classDeclaration.IsClass = true;
            classDeclaration.Name = "Calculator";
            classDeclaration.Attributes = MemberAttributes.Public;
            classDeclaration.Members.Add(FieldVariable("answer", typeof(string), MemberAttributes.Private));

            //default constructor
            CodeConstructor defaultConstructor = new CodeConstructor();
            defaultConstructor.Attributes = MemberAttributes.Public;
            defaultConstructor.Comments.Add(new CodeCommentStatement("Default Constructor for class", true));
            defaultConstructor.Statements.Add(new CodeSnippetStatement("//TODO: implement default constructor"));
            classDeclaration.Members.Add(defaultConstructor);

            //property
            classDeclaration.Members.Add(MakeProperty("Answer", "answer", typeof(string)));

            //Our Calculate Method
            CodeMemberMethod myMethod = new CodeMemberMethod();
            myMethod.Name = "Calculate";
            myMethod.ReturnType = new CodeTypeReference(typeof(string));
            myMethod.Comments.Add(new CodeCommentStatement("Calculate an expression", true));
            myMethod.Attributes = MemberAttributes.Public;
            myMethod.Statements.Add(new CodeAssignStatement(new CodeSnippetExpression("Object obj"), new CodeSnippetExpression(expression)));
            myMethod.Statements.Add(new CodeAssignStatement(new CodeSnippetExpression("Answer"), new CodeSnippetExpression("obj.ToString()")));
            myMethod.Statements.Add(
                           new CodeMethodReturnStatement(new CodeFieldReferenceExpression(new CodeThisReferenceExpression(), "Answer")));
            classDeclaration.Members.Add(myMethod);
            //write code
            myNamespace.Types.Add(classDeclaration);
            generator.GenerateCodeFromNamespace(myNamespace, sw, codeOpts);
            sw.Flush();
            sw.Close();
        }
    }
}