gpstatemethodattribute.cs

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using System;
using System.Collections.Generic;
using System.Text;

namespace GPCore
{
    /// <summary>
    /// Use this attribute when defining you own Interface to extend IProtocol if you want to allow other people to add a method as an "Action" to a menu, and the method should only be activated in in a certain state.
    /// </summary>
    /// <remarks>
    /// This should be used for exposing methods to plugins that dont need to know anything about it, except its existence.
    /// If this attribute is present in the interface a method must be also be present with the name of the interface plus "State" 
    /// with its parameters being the same as this methods, to check for the <see cref="State"/> of the object to know if it should be displayed now.
    /// </remarks>
    /// <example>
    /// Here is a sample Interface and its implementation.
    /// <code>
    /// public interface IDoStuff
    /// {
    ///     [GPStateMethod("Turn On","Account","On",false)]
    ///     void TurnOn(SqlAccount a);
    ///     [GPStateMethod("Turn Off","Account","On",true)]
    ///     void TurnOff(SqlAccount a);
    ///     string IDoStuffState(SqlAccount a);
    /// }
    /// public class DoStuff : IDoStuff
    /// {
    ///     List&lt;SqlAccount&gt; AccountsOn = new List&lt;SqlAccount&gt;
    ///     public void TurnOn(SqlAccount a)
    ///     {
    ///         AccountsOn.Add(a);
    ///     }
    ///     public void TurnOff(SqlAccount a)
    ///     {
    ///         AccountsOn.Remove(a);
    ///     }
    ///     public string IDoStuffState(SqlAccount a)
    ///     {
    ///         return (AccountsOn.Contains(a) ? "On" : "Off");
    ///     }
    /// }
    /// </code>
    /// </example>
    [global::System.AttributeUsage(AttributeTargets.Method, Inherited = true, AllowMultiple = true)]
    public sealed class GPStateMethodAttribute : Attribute , IGPMethodAttribute
    {
        // See the attribute guidelines at 
        //  http://msdn.microsoft.com/library/default.asp?url=/library/en-us/cpgenref/html/cpconusingattributeclasses.asp

        /// <summary>
        /// Creates a new GPMethodAttribute.
        /// </summary>
        /// <param name="name">The Text that will be put in the menu.</param>
        /// <param name="action">What kind of feature is this. Presently Core only supports "Gib" or "Account".</param>
        /// <param name="state">A string representing an on/off type state.</param>
        /// <param name="onstate">True if you want to show this action when the state is equal to <paramref name="state"/>; otherwise false.</param>
        /// <param name="methodname">The name of the state method to call.</param>
        public GPStateMethodAttribute(String name, Type action, object state, bool onstate, string methodname)
        {
            this.m_action = action;
            this.m_name = name;
            this.m_onstate = onstate;
            this.m_state = state;
            this.m_method_name = methodname;
        }

        private string m_name;
        /// <summary>
        /// The text that will be put in the menu.
        /// </summary>
        public string Name
        {
            get { return m_name; }
        }

        private Type m_action;
        /// <summary>
        /// The type of the element it modifies.
        /// </summary>
        public Type Action
        {
            get { return m_action; }
        }
        private object m_state;
        /// <summary>
        /// A string representing an on/off type state.
        /// </summary>
        public object State
        {
            get { return m_state; }
        }
        private bool m_onstate;

        /// <summary>
        /// True if you want to show this action when the state is equal to <see cref="State"/>; otherwise false.
        /// </summary>
        public bool OnState
        {
            get { return m_onstate; }
        }

        private string m_method_name;
        public string MethodName
        {
            get { return m_method_name; }
        }



        #region IGPMethodAttribute Members

        public bool Show(object target, GPCore.Protocols.IProtocol caller)
        {
            if (!m_action.IsAssignableFrom(target.GetType())) return false;
            else
            {
                object o = caller.GetType().GetMethod(m_method_name).Invoke(caller, new object[] { target });
                return (m_state.Equals(o) == m_onstate);
            }
        }

        public void PerformAction(object target, GPCore.Protocols.IProtocol caller, System.Reflection.MethodInfo method)
        {
            try
            {
                if (m_action == typeof(User))
                    method.Invoke(caller,null);
                else
                    method.Invoke(caller, new object[] { target });
            }
            catch (Exception e)
            {
                Logger.Log(e);
            }

        }

        #endregion
    }

}