using System;
namespace Wayne.Lib.StateEngine
{
    /// <summary>
    /// Describe the enter-transition for a state class.
    /// </summary>
    [AttributeUsage(AttributeTargets.Class, AllowMultiple = true, Inherited = true)]
    [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Design", "CA1036:OverrideMethodsOnComparableTypes")]
    public class EnterDescriptionAttribute : Attribute, IComparable
    {
        #region Fields

        private readonly string conditionText;
        private readonly object transitionType;
        private readonly bool unconditionalOverriding;

        #endregion

        #region Construction

        /// <summary>
        /// Drescribe a transition that is done unconditionally when entering a state.
        /// </summary>
        /// <param name="transitionType">Transition that is performed.</param>
        public EnterDescriptionAttribute(object transitionType):this("",transitionType)
        {
            this.transitionType = transitionType;
        }

        /// <summary>
        /// Drescribe a transitin that can be done when entering a state, and what condition that triggers the transition.
        /// </summary>
        /// <param name="conditionText">A descriptive text for the condition.</param>
        /// <param name="transitionType">Transition that is performed.</param>
        public EnterDescriptionAttribute(string conditionText, object transitionType)
        {
            this.conditionText = conditionText;
            this.transitionType = transitionType;
        }

        /// <summary>
        /// Drescribe a transitin that can be done when entering a state.
        /// </summary>
        /// <param name="conditionText">A descriptive text for the condition.</param>
        /// <param name="transitionType">Transition that is performed.</param>
        /// <param name="unconditionalOverriding">Tells whether this transition unconditionally overrides all inherited ones.</param>
        public EnterDescriptionAttribute(string conditionText, object transitionType,
            bool unconditionalOverriding)
        {
            this.conditionText = conditionText;
            this.transitionType = transitionType;
            this.unconditionalOverriding = unconditionalOverriding;
        }

        #endregion

        #region Properties

        /// <summary>
        /// A descriptive text for the condition.
        /// </summary>
        public string ConditionText
        {
            get { return conditionText; }
        }

        /// <summary>
        /// Transition type that is performed.
        /// </summary>
        public object TransitionType
        {
            get { return transitionType; }
        }

        /// <summary>
        /// Tells whether this transition unconditionally overrides all inherited ones.
        /// </summary>
        public bool UnconditionalOverriding
        {
            get { return unconditionalOverriding; }
        }

        #endregion

        #region IComparable Members

        /// <summary>
        /// Compares this attribute with another one.
        /// </summary>
        /// <param name="obj"></param>
        /// <returns></returns>
        public virtual int CompareTo(object obj)
        {
            int result = 0;
            EventDescriptionAttribute compareEventDescriptionAttribute = obj as EventDescriptionAttribute;
            if ((compareEventDescriptionAttribute != null) && (!(this is EventDescriptionAttribute)))
            {
                // An EnterDescriptionAttribute should come before an EventDescriptionAttribute.
                result = -1;
            }
            else
            {
                EnterDescriptionAttribute compareEnterDescriptionAttribute = obj as EnterDescriptionAttribute;
                if (compareEnterDescriptionAttribute != null)
                {
                    if ((TransitionType != null) && (compareEnterDescriptionAttribute.TransitionType != null))
                    {
                        result = TransitionType.ToString().CompareTo(compareEnterDescriptionAttribute.TransitionType.ToString());
                        if (result == 0)
                            result = ConditionText.CompareTo(compareEnterDescriptionAttribute.ConditionText);
                    }
                    else if (TransitionType != null)
                        result = 1;
                    else if (compareEnterDescriptionAttribute.TransitionType != null)
                        result = -1;
                }
            }
            return result;
        }

        /// <summary>
        /// Equals.
        /// </summary>
        /// <param name="obj"></param>
        /// <returns></returns>
        public override bool Equals(object obj)
        {
            EnterDescriptionAttribute compareEnterDescriptionAttribute = obj as EnterDescriptionAttribute;
            if (compareEnterDescriptionAttribute != null)
            {
                if (transitionType == null)
                    return (compareEnterDescriptionAttribute.transitionType == null);
                return transitionType.Equals(compareEnterDescriptionAttribute.transitionType);
            }
            return base.Equals(obj);
        }

        /// <summary>
        /// GetHashCode.
        /// <note>The compiler complained that this method also should be overriden when the Equals was.</note>
        /// </summary>
        /// <returns></returns>
        public override int GetHashCode()
        {
            return base.GetHashCode();
        }

        #endregion
    }
}