using System;
using System.Collections.Generic;
using System.Text;
using CLab.Auxiliary;
using CLab.Exceptions;

namespace CLab
{
    /// <summary>
    /// Superclass for the different types of Expressions
    /// </summary>
    abstract public class Expression
    {
        private Common.ExprType type;
        /// <summary>
        /// Constructor
        /// </summary>
        /// <param name="type">The type of the expression: This can be either an operator 
        /// working on a left and right side, or an id or integer expression</param>
        public Expression(Common.ExprType type)
        {
            this.type = type;
        }

        /// <summary>
        /// Returns the type
        /// </summary>
        public Common.ExprType Type
        { 
            get { return this.type; } 
        }

        /// <summary>
        /// Converts the type to an operator sign for printout
        /// </summary>
        /// <param name="type">The operator to print out</param>
        /// <returns></returns>
        public String Type2oper(Common.ExprType type)
        {
            String setOper;
            switch (type)
            {
                case Common.ExprType.et_impl:
                    setOper = ">>";
                    break;
                case Common.ExprType.et_or:
                    setOper = "|";
                    break;
                case Common.ExprType.et_and:
                    setOper = "&";
                    break;
                case Common.ExprType.et_lte:
                    setOper = "<=";
                    break;
                case Common.ExprType.et_gte:
                    setOper = ">=";
                    break;
                case Common.ExprType.et_lt:
                    setOper = "<";
                    break;
                case Common.ExprType.et_gt:
                    setOper = ">";
                    break;
                case Common.ExprType.et_ne:
                    setOper = "!=";
                    break;
                case Common.ExprType.et_eq:
                    setOper = "==";
                    break;
                case Common.ExprType.et_minus:
                    setOper = "-";
                    break;
                case Common.ExprType.et_plus:
                    setOper = "+";
                    break;
                case Common.ExprType.et_mod:
                    setOper = "%";
                    break;
                case Common.ExprType.et_div:
                    setOper = "/";
                    break;
                case Common.ExprType.et_times:
                    setOper = "*";
                    break;
                default:
                    throw new ClabInternalErrorException("Invalid ExpressionGammel type");
            }
            return setOper;
        }
        public override string ToString()
        {
            if (this.type.Equals(Common.ExprType.et_id))
            {
                IdExpression idExpression = (IdExpression)this;
                return (String.Format("{0}", idExpression.Id));
            }
            else if (this.type.Equals(Common.ExprType.et_val))
            {
                IntExpression intExpression = (IntExpression)this;
                return (String.Format("{0}", intExpression.IntegerValue));
            }
            else if (this.type.Equals(Common.ExprType.et_neg))
            {
                NotNegExpression nnExpression = (NotNegExpression)this;
                return (String.Format("(-{0})", nnExpression.Left));
            }
            else if (this.type.Equals(Common.ExprType.et_not))
            {
                NotNegExpression nnExpression = (NotNegExpression)this;
                return (String.Format("(!{0})", nnExpression.Left));
            }
            else
            {
                BinaryExpression binExpression = (BinaryExpression)this;
                return (String.Format("({0} {1} {2})", binExpression.Left, Type2oper(binExpression.Type), binExpression.Right));
            }
        }
    }

}