/*
 *  Yet Another Tiger Compiler (YATC)
 *
 *  Copyright 2014 Damian Valdés Santiago, Juan Carlos Pujol Mainegra
 *  
 *  Permission is hereby granted, free of charge, to any person obtaining a copy
 *  of this software and associated documentation files (the "Software"), to deal
 *  in the Software without restriction, including without limitation the rights
 *  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 *  copies of the Software, and to permit persons to whom the Software is
 *  furnished to do so, subject to the following conditions:
 *  
 *  The above copyright notice and this permission notice shall be included in all
 *  copies or substantial portions of the Software.
 *  
 *  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 *  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 *  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 *  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 *  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 *  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 *  SOFTWARE.  
 *
 */

using System;
using System.Linq.Expressions;
using System.Reflection;
using System.Reflection.Emit;
using Antlr.Runtime;
using YATC.Scope;

namespace YATC.ASTNodes
{
    abstract class OrderNode : RelationalNode
    {
        protected OrderNode(IToken payload)
            : base(payload)
        {
        }

        public override void CheckSemantics(TigerScope scope, Report report)
        {
            base.CheckSemantics(scope, report);
            bool bothOk = this.LeftOperandNode.IsOk && this.RightOperandNode.IsOk;

            if (this.LeftOperandNode.IsOk)
            {
                if (this.LeftOperandNode.TigerType.Basetype == BaseType.Void)
                {
                    report.AddError(this.Line, this.Column,
                                    "Type mismatch: Invalid use of binary order operator with a non-valued left expression.");
                    this.TigerType = TigerType.Error;
                    bothOk = false;
                }
                else
                    if (this.LeftOperandNode.TigerType.Basetype != BaseType.Int &&
                        this.LeftOperandNode.TigerType.Basetype != BaseType.String)
                    {
                        report.AddError(this.Line, this.Column,
                                        "Type mismatch: Invalid use of binary order operator with a non-int or non-string left expression: '{0}' was found.",
                                        this.LeftOperandNode.TigerType.Name);
                        this.TigerType = TigerType.Error;
                        bothOk = false;
                    }
            }

            if (this.RightOperandNode.IsOk)
            {
                if (this.RightOperandNode.TigerType.Basetype == BaseType.Void)
                {
                    report.AddError(this.Line, this.Column,
                                    "Type mismatch: Invalid use of binary order operator with a non-valued right expression.");
                    this.TigerType = TigerType.Error;
                    bothOk = false;
                }
                else
                    if (this.RightOperandNode.TigerType.Basetype != BaseType.Int && 
                        this.RightOperandNode.TigerType.Basetype != BaseType.String)
                    {
                        report.AddError(this.Line, this.Column,
                                        "Type mismatch: Invalid use of binary order operator with a non-int or non-string right expression: '{0}' was found.",
                                        this.RightOperandNode.TigerType.Name);
                        this.TigerType = TigerType.Error;
                        bothOk = false;
                    }
            }

            if (bothOk && this.LeftOperandNode.TigerType.Basetype != this.RightOperandNode.TigerType.Basetype)
            {
                report.AddError(this.Line, this.Column,
                    "Type mismatch: Invalid use of binary order operator with string and int expressions.");
                this.TigerType = TigerType.Error;
                return;
            }

            this.TigerType = bothOk ? TigerType.Int : TigerType.Error;
        }

        internal override void GenerateCode(ModuleBuilder moduleBuilder)
        {
            this.LeftOperandNode.GenerateCode(moduleBuilder);
            this.RightOperandNode.GenerateCode(moduleBuilder);

            if (this.LeftOperandNode.TigerType.Basetype == BaseType.String &&
                this.RightOperandNode.TigerType.Basetype == BaseType.String)
            {
                MethodInfo compareString = ((Func<string, string, int>)String.Compare).Method;

                ParameterExpression value = Expression.Parameter(typeof (int));
                Expression compareCall = Expression.Call(compareString,
                                                     this.LeftOperandNode.VmExpression,
                                                     this.RightOperandNode.VmExpression);

                Expression condition = null;
                switch (this.ExpressionType)
                {
                    case ExpressionType.GreaterThan:
                        condition = Expression.GreaterThan(value, Expression.Constant(0));
                        break;
                    case ExpressionType.GreaterThanOrEqual:
                        condition = Expression.GreaterThanOrEqual(value, Expression.Constant(0));
                        break;
                    case ExpressionType.LessThan:
                        condition = Expression.LessThan(value, Expression.Constant(0));
                        break;
                    case ExpressionType.LessThanOrEqual:
                        condition = Expression.LessThanOrEqual(value, Expression.Constant(0));
                        break;
                }

                Expression block = Expression.Block(
                    new ParameterExpression[] {value}, 
                    new Expression[]
                        {
                            Expression.Assign(value, compareCall),
                            Expression.Condition(condition, Expression.Constant(1), Expression.Constant(0))
                        }
                );

                this.VmExpression = block;
            }
            else
            {
                Expression opHolds = Expression.MakeBinary(this.ExpressionType,
                                                           this.LeftOperandNode.VmExpression,
                                                           this.RightOperandNode.VmExpression);

                this.VmExpression = Expression.Condition(opHolds, Expression.Constant(1), Expression.Constant(0));
            }
        }
    }
}