using Island.StandardLib;
using System.Collections.Generic;

namespace EXTS
{
    public abstract class Statement
    {
        internal EXTSEngine engine;
        public Statement() => engine = EXTSEngine.CompilingEngine;
        public abstract EValue Eval();
    }

    public class StatementList : Statement
    {
        internal static StatementList runningStatement;
        internal List<Statement> statements;
        Dictionary<string, EValue> val;
        internal StatementList parentVarlst;
        internal bool stop;

        public StatementList() => val = new Dictionary<string, EValue>();

        public EValue this[string name]
        {
            get
            {
                if (val.ContainsKey(name))
                    return val[name];
                StatementList lst = this;
                while (lst.parentVarlst != null)
                {
                    lst = lst.parentVarlst;
                    if (lst.val.ContainsKey(name))
                        return lst.val[name];
                }
                return new EValue();
            }
            set
            {
                if (val.ContainsKey(name))
                {
                    val[name] = value;
                    return;
                }
                StatementList lst = this;
                while (lst.parentVarlst != null)
                {
                    lst = lst.parentVarlst;
                    if (lst.val.ContainsKey(name))
                    {
                        lst.val[name] = value;
                        return;
                    }
                }
                val.Add(name, value);
            }
        }

        public StatementList(params Statement[] sms)
        {
            statements = new List<Statement>(sms);
        }

        public void AddStatement(Statement statement)
        {
            statements.Add(statement);
        }

        public virtual bool BeforeEval() { return true; }

        public override EValue Eval()
        {
            stop = false;
            runningStatement = this;
            val = new Dictionary<string, EValue>();
            val.Set("return", new EValue());
            if (!BeforeEval())
                return new EValue(new EString(engine.funcptrs.PushRandom((FuncStatement)this)));
            for (int i = 0; i < statements.Count; i++)
            {
                statements[i].Eval();
                if (stop) break;
            }
            EValue ret = val.Get("return", new EValue());
            val.Clear();
            return ret;
        }
    }

    public class SetValStatement : Statement
    {
        StatementList env;
        string name;
        Statement value;

        public SetValStatement(StatementList elist, string valname, Statement val)
        {
            env = elist;
            name = valname;
            value = val;
        }

        public override EValue Eval()
        {
            EValue val = value.Eval();
            env[name] = val;
            return val;
        }
    }

    public class GetValStatement : Statement
    {
        StatementList env;
        string name;

        public GetValStatement(StatementList elist, string valname)
        {
            env = elist;
            name = valname;
        }

        public override EValue Eval() => env[name];
    }

    public class ImmediateStatement : Statement
    {
        EValue val;
        public ImmediateStatement(string immval)
        {
            if (float.TryParse(immval, out float f))
                val = new EValue(new ENumber(f));
            else val = new EValue(new EString(immval));
        }
        public override EValue Eval() => val;
    }

    public class ReturnStatement : Statement
    {
        public override EValue Eval()
        {
            StatementList.runningStatement.stop = true;
            return new EValue();
        }
    }

    public class FuncStatement : StatementList
    {
        internal string name;
        internal EValue[] parameters;
        public bool runfunc = true;
        public FuncStatement(params Statement[] statements) : base(statements) { }

        public override bool BeforeEval()
        {
            if (parameters != null)
            {
                for (int i = 0; i < parameters.Length; i++)
                    this["pmt" + i] = parameters[i];
            }
            parameters = null;
            return runfunc;
        }

        public EValue Eval(EValue[] pmts)
        {
            parameters = pmts;
            return base.Eval();
        }
    }

    public class BodyFuncStatement : StatementList
    {
        internal KeyValuePair<string, EValue>[] parameters;
        public BodyFuncStatement(params Statement[] statements) : base(statements) { }

        public override bool BeforeEval()
        {
            if (parameters != null)
            {
                for (int i = 0; i < parameters.Length; i++)
                    this[parameters[i].Key] = parameters[i].Value;
            }
            parameters = null;
            return true;
        }

        public EValue Eval(params KeyValuePair<string, EValue>[] pmts)
        {
            parameters = pmts;
            return base.Eval();
        }
    }

    public class CallFuncStatement : Statement
    {
        string func;
        Statement[] pmts;

        public CallFuncStatement(string funcName, params Statement[] parameters)
        {
            for (int i = 0; i < parameters.Length; i++)
                parameters[i].engine = engine;
            func = funcName;
            pmts = parameters;
        }

        public override EValue Eval() => engine.RunFuncBase(func, pmts.Do((p) => p.Eval()));
    }
}