namespace tlang
{
    internal class Parser
    {
        
        public Parser(List<LexToken> tokens)
        {
            int i=0;
            Node = ParseExpression(tokens,ref i,true);
        }
        public Node Node {get;set;}

        public TObject Execute(IScopeEnvironment env,params TObject[] args)
        {
            var res=Node.Execute(env);
            var main = env["main"] as ICallable;
            if(main != null)
            {
                res=main.Call(args);
            }
            return res;
        }
        private Node ParseExpression(List<LexToken> tokens,ref int i,bool isFirst=false)
        {
            if(i>= tokens.Count) return new ConstNode(new TNumber(0));
            if(tokens[i].Text == "{" || isFirst) 
            {
                if(!isFirst)
                i++;
                ScopeNode scopeNode = new ScopeNode(){First=isFirst};
                while(i<tokens.Count && tokens[i].Text != "}")
                {
                    scopeNode.Body.Add(ParseExpression(tokens,ref i));
                    if(i<tokens.Count && tokens[i].Text == ";")
                    {
                        i++;
                    }

                }
                i++;
                return scopeNode;
            }else{
                return ParseAssignable(tokens,ref i);
            }
        }
        private Node ParseAssignable(List<LexToken> tokens,ref int i)
        {
            Node myExpression = ParseSum(tokens,ref i);
            while(i<tokens.Count && (tokens[i].Text == "="))
            {
                if(i<tokens.Count && tokens[i].Text == "=")
                {
                    i++;
                    var gvar = myExpression as GetVariableValue;
                    if(gvar != null)
                    {
                       myExpression= new SetVariableNode(gvar,ParseSum(tokens,ref i));
                       
                    }
                }
                
            }
            return myExpression;
        }
        private Node ParseSum(List<LexToken> tokens,ref int i)
        {
            Node myExpression = ParseFactor(tokens,ref i);
            while(i<tokens.Count && (tokens[i].Text == "+" || tokens[i].Text == "-"))
            {
                
                 if(i<tokens.Count && tokens[i].Text == "+"){
                    i++;
                    myExpression = new AddNode(myExpression,ParseFactor(tokens,ref i));
                    }
               
                   
                    if(i<tokens.Count && tokens[i].Text == "-")
                    {
                        i++;
                    myExpression = new SubtractNode(myExpression,ParseFactor(tokens,ref i));
                    }
               
                
            } 
            return myExpression;
        }
        private Node ParseValue(List<LexToken> tokens,ref int i)
        {
            var token=tokens[i++];
            if(token.IsString) return new ConstNode(new TString(token.Text));
            if(token.IsChar)
            {
                return new ConstNode(new TChar(token.Text.SingleOrDefault()));
            }

            long val;
            if(long.TryParse(token.Text,out val))
            {
                if(i<tokens.Count && tokens[i].Text == "." && !tokens[i].IsChar && !tokens[i].IsString)
                {
                    i++;
                    if(i<tokens.Count)
                    {
                        var token2=tokens[i++];
                        double dblR;
                        if(double.TryParse($"{val}.{token2.Text}",out dblR))
                        {
                            return new ConstNode(new TNumber(dblR));
                        }
                    }
                }else{
                return new ConstNode(new TNumber( val ));
                }
            }
            else {
                if(i<tokens.Count && tokens[i].Text=="(")
                {
                    if(token.Text == "func")
                    {
                        List<string> args = new List<string>();
                        i++;
                        while(i<tokens.Count && tokens[i].Text != ")")
                        {

                            if(tokens[i].Text == ",") {i++;continue;}

                            if(i<tokens.Count)
                            {
                                var exp = ParseExpression(tokens,ref i);
                                var gvExp = exp as GetVariableValue;
                                if(gvExp != null)
                                {
                                    args.Add(gvExp.Name);
                                }else{
                                    throw new Exception("not a getvariablenode");
                                }
                            }

                        }
                        i++;
                        return new ClosureNode(args,ParseExpression(tokens,ref i));
                    } 
                    else if(token.Text == "for")
                    {
                        i++;
                        //init;condition;inc)

                        Node init = new ConstNode(new TUninit());
                        Node condition = new ConstNode(new TUninit());
                        Node inc = new ConstNode(new TUninit());
                        Node body = new ConstNode(new TUninit());
                        if(i<tokens.Count && (tokens[i].Text != ")" || tokens[i].Text != ";"))
                        {
                            init = ParseExpression(tokens,ref i);
                        }
                        if(i<tokens.Count && tokens[i].Text == ";")
                            i++;
                        if(i<tokens.Count && (tokens[i].Text != ")" || tokens[i].Text != ";"))
                        {
                            condition = ParseExpression(tokens,ref i);
                        }
                        if(i<tokens.Count && tokens[i].Text == ";")
                            i++;
                        if(i<tokens.Count && (tokens[i].Text != ")" || tokens[i].Text != ";"))
                        {
                            inc = ParseExpression(tokens,ref i);
                        }
                        if(i<tokens.Count && tokens[i].Text == ")")
                            i++;
                        if(i<tokens.Count)
                        body = ParseExpression(tokens,ref i);

                        return new ForLoop(init,condition,inc,body);
                    }
                    else if(token.Text == "each")
                    {
                        i++;
                        Node ls = ParseExpression(tokens,ref i);
                        var name  = new GetVariableValue("item");
                        if(i<tokens.Count && tokens[i].Text == ":")
                        {
                            i++;
                            var n=ls as GetVariableValue;
                            if(n != null) name = n;
                            ls = ParseExpression(tokens,ref i);
                        }
                        i++;
                        if(i<tokens.Count)
                        {
                            return new EachLoop(name,ls,ParseExpression(tokens,ref i));
                        }
                    }
                    else if(token.Text == "while")
                    {
                        i++;
                        var condition=ParseExpression(tokens,ref i);
                        i++;
                        Node yes = new ConstNode(new TUninit());
                        if(i<tokens.Count && tokens[i].Text != ";")
                        yes = ParseExpression(tokens,ref i);
                        return new WhileLoop(condition,yes,false);
                    }
                    else if(token.Text == "do")
                    {
                        i++;
                        var condition=ParseExpression(tokens,ref i);
                        i++;
                        Node yes = new ConstNode(new TUninit());
                        if(i<tokens.Count && tokens[i].Text != ";")
                        yes = ParseExpression(tokens,ref i);
                        return new WhileLoop(condition,yes,true);
                    }
                    else if(token.Text == "if")
                    {
                        i++;
                        var condition=ParseExpression(tokens,ref i);
                        i++;
                        Node yes = new ConstNode(new TUninit());
                        Node no = new ConstNode(new TUninit());
                        if(i<tokens.Count && tokens[i].Text != "else")
                        yes=ParseExpression(tokens,ref i);

                        if(i<tokens.Count && tokens[i].Text == "else")
                        {
                            i++;
                            no = ParseExpression(tokens,ref i);
                        }

                        return new IfNode(condition,yes,no);
                    }
                    else{
                    i++;
                    List<Node> args = new List<Node>();
                    //function call baby
                    while(i<tokens.Count && tokens[i].Text != ")")
                    {

                        if(tokens[i].Text == ",") {i++;continue;}

                        if(i<tokens.Count)
                        {
                            args.Add(ParseExpression(tokens,ref i));
                        }

                    }
                    i++;
                    Node ret = new FunctionCallNode(token.Text,args);
                    while(i<tokens.Count && tokens[i].Text == "[")
                    {
                            
                           i++;
                            var arg = ParseExpression(tokens,ref i);
                            i++;
                            ret  = new ArraySubscriptNode(ret,token.Text,arg);
                    }
                    while(i<tokens.Count && tokens[i].Text == ".")
                    {
                        i++;
                        
                        var token2 = tokens[i++];

                        if(i<tokens.Count && tokens[i].Text == "(")
                        {
                             i++;
                             args = new List<Node>();
                             //function call baby
                             while(i<tokens.Count && tokens[i].Text != ")")
                             {

                                if(tokens[i].Text == ",") {i++;continue;}

                                if(i<tokens.Count)
                                {
                                    args.Add(ParseExpression(tokens,ref i));
                                }

                            }
                            i++;
                            ret = new MemberFunctionCallNode(ret,token2.Text,args);
                        }
                        else if(i<tokens.Count && tokens[i].Text == "[")
                        {
                            i++;
                            var arg = ParseExpression(tokens,ref i);
                            i++;
                            ret  = new ArraySubscriptNode(ret,token2.Text,arg);
                        }
                        else{
                            ret = new MemberGetVariableValue(ret,token2.Text);
                        }

                    }
                    if(i<tokens.Count && tokens[i].Text == "++")
                    {
                        var mgvn = ret as GetVariableValue;
                        i++;
                        if(mgvn != null)
                        {
                            return new PostfixIncrementVariableNode(mgvn);
                        }

                    }
                    if(i<tokens.Count && tokens[i].Text == "--")
                    {
                        var mgvn = ret as GetVariableValue;
                        i++;
                        if(mgvn != null)
                        {
                            return new PostfixDecrementVariableNode(mgvn);
                        }
                        
                    }
                    return ret;
                    }
                }else{
                    Node ret;
                    switch(token.Text)
                    {
                        case "null":
                            ret= new ConstNode(TObject.Null);
                            break;
                        case "undefined":
                            ret= new ConstNode(TObject.Uninit);
                            break;
                        case "true":
                            ret= new ConstNode(new TNumber(1));
                            break;
                        case "false":
                            ret= new ConstNode(new TNumber(0));
                            break;
                        default:
                            ret= new GetVariableValue(token.Text);
                            break;
                    }
                    while(i<tokens.Count && tokens[i].Text == "[")
                    {
                            
                           i++;
                            var arg = ParseExpression(tokens,ref i);
                            i++;
                            ret  = new ArraySubscriptNode(ret,token.Text,arg);
                    }

                     while(i<tokens.Count && tokens[i].Text == ".")
                    {
                        i++;
                        
                        var token2 = tokens[i++];

                        if(i<tokens.Count && tokens[i].Text == "(")
                        {
                             i++;
                                var args = new List<Node>();
                             //function call baby
                             while(i<tokens.Count && tokens[i].Text != ")")
                             {

                                if(tokens[i].Text == ",") {i++;continue;}

                                if(i<tokens.Count)
                                {
                                    args.Add(ParseExpression(tokens,ref i));
                                }

                            }
                            i++;
                            ret = new MemberFunctionCallNode(ret,token2.Text,args);
                        }
                        else if(i<tokens.Count && tokens[i].Text == "[")
                        {
                            i++;
                            var arg = ParseExpression(tokens,ref i);
                            i++;
                            ret  = new ArraySubscriptNode(ret,token2.Text,arg);
                        }
                        else{
                            ret = new MemberGetVariableValue(ret,token2.Text);
                        }

                    }
                    if(i<tokens.Count && tokens[i].Text == "++")
                    {
                        var mgvn = ret as GetVariableValue;
                        i++;
                        if(mgvn != null)
                        {
                            return new PostfixIncrementVariableNode(mgvn);
                        }

                    }
                    if(i<tokens.Count && tokens[i].Text == "--")
                    {
                        var mgvn = ret as GetVariableValue;
                        i++;
                        if(mgvn != null)
                        {
                            return new PostfixDecrementVariableNode(mgvn);
                        }
                        
                    }
                    return ret;
                    
                }
            }
            
           throw new Exception();
        }
        
        private Node ParseFactor(List<LexToken> tokens,ref int i)
        {
            Node myExpression = ParseValue(tokens,ref i);
            while(i<tokens.Count && (tokens[i].Text == "*" || tokens[i].Text == "/" || tokens[i].Text == "%"))
            {
               
                    if(i<tokens.Count && tokens[i].Text == "*"){
                        i++;
                    myExpression = new MultiplyNode(myExpression,ParseValue(tokens,ref i));
                    }
                    if(i<tokens.Count && tokens[i].Text == "/")
                    {
                        i++;
                    myExpression = new DivideNode(myExpression,ParseValue(tokens,ref i));
                    }
                    if(i<tokens.Count && tokens[i].Text == "%")
                    {
                        i++;
                        myExpression = new ModuloNode(myExpression,ParseValue(tokens,ref i));
                    }
                
            }
            return myExpression;
        }
        private TObject CreateStream(Stream strm)
        {
            TDictionary dict = new TDictionary();
            dict["setposition"] = new TExternalMethod((args2)=>{
                if(args2.Length ==1)
                {
                    var pos = args2[0] as TNumber;
                    if(pos != null)
                    {
                        strm.Position = (long)pos.Value;
                    }
                }
                return TObject.Null;
            });
            dict["getposition"] = new TExternalMethod((args2)=>{
                return new TNumber(strm.Position);
            });
            dict["getlength"] = new TExternalMethod((args2)=>{
                return new TNumber(strm.Length);
            });
            dict["getcount"] = new TExternalMethod((args2)=>{
                return new TNumber(strm.Length);
            });
            dict["canread"] = new TExternalMethod((args2)=>{
                return new TNumber(strm.CanRead ? 1 : 0);
            });
            dict["canwrite"] = new TExternalMethod((args2)=>{
                return new TNumber(strm.CanWrite ? 1 : 0);
            });
            dict["canseek"] = new TExternalMethod((args2)=>{
                return new TNumber(strm.CanSeek ? 1 : 0);
            });
            dict["write"] = new TExternalMethod((args2)=>{
                if(args2.Length >= 2)
                {
                    var bufAr = args2[0] as TArray;
                    

               
                if(args2.Length == 3)
                {
                    //buffer,offset,len
                    var _offset = args2[1] as TNumber;
                    var _len = args2[2] as TNumber;

                    if(bufAr != null && _offset != null && _len != null)
                    {
                        int count = (int)_len.Value;
                        int offset = (int)_offset.Value;
                        int totalRead =  Math.Min(bufAr.Items.Count  - offset,count);
                        byte[] buffer = new byte[totalRead];
                       
                        for(int i = 0;i<totalRead;i++)
                        {
                            var item = bufAr.Items[i+offset];
                            var c = item as TChar;
                            var n = item as TNumber;
                            if(c != null) buffer[i] = (byte)c.Value;
                            if(n != null) buffer[i] = (byte)n.Value;
                            
                        }
                        
                         strm.Write(buffer,0,buffer.Length);
                         return new TNumber(totalRead);
                    }
                }
                else
                {
                     var _len = args2[1] as TNumber;

                    if(bufAr != null  && _len != null)
                    {
                        int count = (int)_len.Value;
                        
                        int totalRead =  Math.Min(bufAr.Items.Count,count);
                        byte[] buffer = new byte[totalRead];
                         
                        for(int i = 0;i<totalRead;i++)
                        {
                            var item = bufAr.Items[i];
                            var c = item as TChar;
                            var n = item as TNumber;
                            if(c != null) buffer[i] = (byte)c.Value;
                            if(n != null) buffer[i] = (byte)n.Value;
                            
                        }
                        
                         strm.Write(buffer,0,buffer.Length);
                         return new TNumber(totalRead);
                    }
                }
               
                }return new TNumber(0);
            });
            dict["read"] = new TExternalMethod((args2)=>{
                
                
                
                if(args2.Length >= 2)
                {
                    var bufAr = args2[0] as TArray;
                    

               
                if(args2.Length == 3)
                {
                    //buffer,offset,len
                    var _offset = args2[1] as TNumber;
                    var _len = args2[2] as TNumber;

                    if(bufAr != null && _offset != null && _len != null)
                    {
                        int count = (int)_len.Value;
                        int offset = (int)_offset.Value;
                        int totalRead =  Math.Min(bufAr.Items.Count  - offset,count);
                        byte[] buffer = new byte[totalRead];
                        totalRead=strm.Read(buffer,0,buffer.Length);
                        for(int i = 0;i<totalRead;i++)
                        {
                            bufAr.Items[i+offset] = new TNumber(buffer[i]);
                        }
                         return new TNumber(totalRead);
                    }
                }
                else
                {
                     var _len = args2[1] as TNumber;

                    if(bufAr != null  && _len != null)
                    {
                        int count = (int)_len.Value;
                        
                        int totalRead =  Math.Min(bufAr.Items.Count,count);
                        byte[] buffer = new byte[totalRead];
                        totalRead=strm.Read(buffer,0,buffer.Length);
                        for(int i = 0;i<totalRead;i++)
                        {
                            bufAr.Items[i] = new TNumber(buffer[i]);
                        }
                         return new TNumber(totalRead);
                    }
                }
               
                }return new TNumber(0);

                
            }); 
            dict["close"] = new TExternalMethod((args2)=>{
                strm.Dispose();
                return TObject.Uninit;
            });
            dict["flush"] = new TExternalMethod((args2)=>{
                strm.Flush();
                return TObject.Uninit;
            });
            return dict;
        }
        public void LoadEnvironment(RootEnvironment env)
        {
            TDictionary fs = new TDictionary();
            fs["file_exists"] = new TExternalMethod((args2)=>{
                if(args2.Length > 0)
                {
                     var fileName=args2[0].ToString();
                     if(!string.IsNullOrWhiteSpace(fileName))
                     {
                        try{
                        if(File.Exists(fileName)) return new TNumber(1);
                       }catch(Exception ex)
                        {
                            _=ex;

                        }
                     }
                }
                return new TNumber(0);
            });
            fs["dir_exists"] = new TExternalMethod((args2)=>{
                if(args2.Length > 0)
                {
                     var fileName=args2[0].ToString();
                     if(!string.IsNullOrWhiteSpace(fileName))
                     {
                        try{
                        if(Directory.Exists(fileName)) return new TNumber(1);
                       }catch(Exception ex)
                        {
                            _=ex;

                        }
                     }
                }
                return new TNumber(0);
            });
            fs["mkdir"] = new TExternalMethod((args2)=>{
                if(args2.Length > 0)
                {
                     var fileName=args2[0].ToString();
                     if(!string.IsNullOrWhiteSpace(fileName))
                     {
                        try{
                        if(Directory.Exists(fileName)) return new TNumber(2);
                        Directory.CreateDirectory(fileName);
                        return new TNumber(1);
                        }catch(Exception ex)
                        {
                            _=ex;

                        }
                     }
                }
                return new TNumber(0);
            });
            fs["create"] = new TExternalMethod((args2)=>{
                 if(args2.Length > 0)
                {
                     var fileName=args2[0].ToString();
                     if(!string.IsNullOrWhiteSpace(fileName))
                     {
                        try{
                            return CreateStream(File.Create(fileName));
                        }catch(Exception ex){
                            _=ex;
                        }
                     }
                }
                return TObject.Null; 
            });
            fs["openread"] = new TExternalMethod((args2)=>{
                 if(args2.Length > 0)
                {
                     var fileName=args2[0].ToString();
                     if(!string.IsNullOrWhiteSpace(fileName))
                     {
                        try{
                            return CreateStream(File.OpenRead(fileName));
                        }catch(Exception ex){
                            _=ex;
                        }
                     }
                }
                return TObject.Null; 
            });
             fs["openwrite"] = new TExternalMethod((args2)=>{
                 if(args2.Length > 0)
                {
                     var fileName=args2[0].ToString();
                     if(!string.IsNullOrWhiteSpace(fileName))
                     {
                        try{
                            return CreateStream(File.OpenWrite(fileName));
                        }catch(Exception ex){
                            _=ex;
                        }
                     }
                }
                return TObject.Null; 
            });
             fs["append"] = new TExternalMethod((args2)=>{
                 if(args2.Length > 0)
                {
                     var fileName=args2[0].ToString();
                     if(!string.IsNullOrWhiteSpace(fileName))
                     {
                        try{
                            return CreateStream(File.Open(fileName,FileMode.Append));
                        }catch(Exception ex){
                            _=ex;
                        }
                     }
                }
                return TObject.Null; 
            });

            fs["readalltext"] = new TExternalMethod((args2)=>{
                 if(args2.Length > 0)
                {
                     var fileName=args2[0].ToString();
                     if(!string.IsNullOrWhiteSpace(fileName))
                     {
                        try{
                        if(!File.Exists(fileName)) return  TObject.Null;
                       return new TString(File.ReadAllText(fileName));
                        }catch(Exception ex)
                        {
                            _=ex;

                        }
                     }
                }
                return TObject.Null;
            });
            fs["writealltext"] = new TExternalMethod((args2)=>{
                if(args2.Length >= 2)
                {
                    var fileName=args2[0].ToString();
                    var text = args2[1].ToString();
                    if(!string.IsNullOrWhiteSpace(fileName) && text != null)
                    {
                        try{
                        File.WriteAllText(fileName,text);
                        return new TNumber(1);
                        }catch(Exception ex)
                        {
                            _=ex;
                        }
                    }
                }
                return new TNumber(0);
            });
            fs["home"] = new TString(Environment.GetFolderPath(Environment.SpecialFolder.UserProfile));
            fs["enumerate_files"]  = new TExternalMethod((args)=>{
                if(args.Length > 0)
                {
                    var fileName=args[0].ToString();
                    if(!string.IsNullOrWhiteSpace(fileName) && Directory.Exists(fileName))
                    {
                        var dict = new TDictionary();
                        dict["getIttr"] = new TExternalMethod((args2)=>{
                            var enumerable=Directory.EnumerateFiles(fileName).GetEnumerator();
                            TDictionary dict2 = new TDictionary();
                           
                            dict2["movenext"] = new TExternalMethod((args3)=>{
                                
                                return new TNumber(enumerable.MoveNext() ? 1 : 0);
                            });
                            dict2["getCurrent"] = new TExternalMethod((args3)=>{
                                return new TString(enumerable.Current);
                            });

                            return dict2;
                        });
                        return dict;
                    }
                }   
                return TObject.Null;
            });
             
            fs["enumerate_dirs"]  = new TExternalMethod((args)=>{
                if(args.Length > 0)
                {
                    var fileName=args[0].ToString();
                    if(!string.IsNullOrWhiteSpace(fileName) && Directory.Exists(fileName))
                    {
                        var dict = new TDictionary();
                        dict["getIttr"] = new TExternalMethod((args2)=>{
                            var enumerable=Directory.EnumerateDirectories(fileName).GetEnumerator();
                            TDictionary dict2 = new TDictionary();
                           
                            dict2["movenext"] = new TExternalMethod((args3)=>{
                                
                                return new TNumber(enumerable.MoveNext() ? 1 : 0);
                            });
                            dict2["getCurrent"] = new TExternalMethod((args3)=>{
                                return new TString(enumerable.Current);
                            });

                            return dict2;
                        });
                        return dict;
                    }
                }   
                return TObject.Null;
            });
            env["fs"]=fs;
            TDictionary reflection = new TDictionary();
            reflection["parse_code"] = new TExternalMethod((args2)=>{
                
                if(args2.Length > 0)
                {
                    var str = args2[0] as TString;
                    if(str != null)
                    {
                        Lexer lexer = new Lexer(new StringReader(str.Value));
                        try{
                        Parser _parser=new Parser(lexer.Tokens);
                        
                   
                        RootEnvironment env2 = new RootEnvironment();
                        TDictionary rootDict = new TRootDict(env2);
                        LoadEnvironment(env2);
                        TDictionary parseCodeVal = new TDictionary();
                        var argsArray= new TArray();
                        parseCodeVal["root"] = rootDict;
                        parseCodeVal["args"] = argsArray;
                        parseCodeVal["run"] = new TExternalMethod((args4)=>{
                            //run()
                            try{
                               return _parser.Execute(env2,argsArray.Items.ToArray());
                            }catch(Exception ex)
                            {
                               
                                _=ex;
                                return TObject.Null;
                            }
                        });
                        return parseCodeVal;

                        }catch(Exception ex)
                        {
                            _=ex;
                            return TObject.Null;
                        }
                        
                    }
                }   


                return TObject.Uninit;
                
            });

            env["reflection"] = reflection;
        var con = new TDictionary();
        con["write"] =  new TExternalMethod((args2)=>{
            foreach(var arg in args2)
            {
                Console.Write(arg);
            }
            return new TNumber(args2.Length);
        });
        con["writeln"] =  new TExternalMethod((args2)=>{
            foreach(var arg in args2)
            {
                Console.Write(arg);
            }
            Console.WriteLine();
            return new TNumber(args2.Length);
        });
            
            var instance = new TDictionary();
                instance["array"] = new TExternalMethod((args2)=>{

                    
                return new TArray();
            });
            instance["dict"] = new TExternalMethod((args2)=>{
                return new TDictionary();
            });
            env["create"] =instance;
            env["console"]=con;
            env["int"] = new TExternalMethod((args2)=>{

            if(args2.Length == 1)
            {
                var arg = args2[0];
                var sArg = arg as TString;
                var dArg = arg as TNumber;
                if(sArg != null)
                {
                    long val;
                    if(long.TryParse(sArg.Value,out val))
                    {
                        return new TNumber(val);
                    }
                }
                if(dArg != null)
                {
                    return new TNumber(Math.Round(dArg.Value));
                }

            }
            return TObject.Null;
        });
        }

        
    }
}