/*******************************************************************************
 * You may amend and distribute as you like, but don't remove this header!
 *
 * EPPlus provides server-side generation of Excel 2007/2010 spreadsheets.
 * See http://www.codeplex.com/EPPlus for details.
 *
 * Copyright (C) 2011  Jan Källman
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.

 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  
 * See the GNU Lesser General Public License for more details.
 *
 * The GNU Lesser General Public License can be viewed at http://www.opensource.org/licenses/lgpl-license.php
 * If you unfamiliar with this license or have questions about it, here is an http://www.gnu.org/licenses/gpl-faq.html
 *
 * All code and executables are provided "as is" with no warranty either express or implied. 
 * The author accepts no liability for any damage or loss of business that this product may cause.
 *
 * Code change notes:
 * 
 * Author							Change						Date
 * ******************************************************************************
 * Mats Alm   		                Added       		        2011-01-08
 * Jan Källman		    License changed GPL-->LGPL  2011-12-27
 *******************************************************************************/
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Xml;
using OfficeOpenXml.Utils;
using OfficeOpenXml.DataValidation.Formulas.Contracts;

namespace OfficeOpenXml.DataValidation.Formulas
{
    /// <summary>
    /// Enumeration representing the state of an <see cref="ExcelDataValidationFormulaValue{T}"/>
    /// </summary>
    internal enum FormulaState
    {
        /// <summary>
        /// Value is set
        /// </summary>
        Value,
        /// <summary>
        /// Formula is set
        /// </summary>
        Formula
    }

    /// <summary>
    /// Base class for a formula
    /// </summary>
    internal abstract class ExcelDataValidationFormula : XmlHelper
    {
        /// <summary>
        /// Constructor
        /// </summary>
        /// <param name="namespaceManager">Namespacemanger of the worksheet</param>
        /// <param name="topNode">validation top node</param>
        /// <param name="formulaPath">xml path of the current formula</param>
        public ExcelDataValidationFormula(XmlNamespaceManager namespaceManager, XmlNode topNode, string formulaPath)
            : base(namespaceManager, topNode)
        {
            Require.Argument(formulaPath).IsNotNullOrEmpty("formulaPath");
            FormulaPath = formulaPath;
        }

        private string _formula;

        protected string FormulaPath
        {
            get;
            private set;
        }

        /// <summary>
        /// State of the validationformula, i.e. tells if value or formula is set
        /// </summary>
        protected FormulaState State
        {
            get;
            set;
        }

        /// <summary>
        /// A formula which output must match the current validation type
        /// </summary>
        public string ExcelFormula
        {
            get
            {
                return _formula;
            }
            set
            {
                if (!string.IsNullOrEmpty(value))
                {
                    ResetValue();
                    State = FormulaState.Formula;
                }
                if (value != null && value.Length > 255)
                {
                    throw new InvalidOperationException("The length of a DataValidation formula cannot exceed 255 characters");
                }
                //var val = SqRefUtility.ToSqRefAddress(value);
                _formula = value;
                SetXmlNodeString(FormulaPath, value);
            }
        }

        internal abstract void ResetValue();

        /// <summary>
        /// This value will be stored in the xml. Can be overridden by subclasses
        /// </summary>
        internal virtual string GetXmlValue()
        {
            if (State == FormulaState.Formula)
            {
                return ExcelFormula;
            }
            return GetValueAsString();
        }

        /// <summary>
        /// Returns the value as a string. Must be implemented by subclasses
        /// </summary>
        /// <returns></returns>
        protected abstract string GetValueAsString();
    }
}
