Generic Multi-Field/Property Sorting for Lists of Business Objects

using System;
using System.ComponentModel;
using System.Collections.Generic;
using System.Diagnostics;

// Source code by Owen Emlen (owene_1998@yahoo.com, owen@binarynorthwest.com)

namespace MultiSortDemo
{
    /// <summary>
    /// Stores a "work item" pseudo-business object.  
    /// Lists of work items are sorted to test multi-property sort speed in this demo.
    /// Note the addition of Marc Gravell's HyperTypeDescriptionProvider attribute.  This greatly speeds property
    /// value retrieval speed.  If you like, just for kicks, try removing it and note the relative performance :P
    /// </summary>
    [TypeDescriptionProvider(typeof(Hyper.ComponentModel.HyperTypeDescriptionProvider))]
    public class WorkItem
    {
        public WorkItem() { dtAssigned = DateTime.MinValue; }

        /// <summary>
        /// Stores a mapping between a property name and the underlying field that stores the
        /// property's value.  Could be generated dynamically.
        /// </summary>
        public static PropertyFieldMappings<WorkItem> htPropertyToFieldNameMapping =
          new PropertyFieldMappings<WorkItem>();

        // IMPORTANT NOTE: if we access PROTECTED or PRIVATE *fields*, security is 
        // checked on each value retrieval, slowing everything down.

        // let's make our fields public for demonstration purposes
        public bool fItemFinished;
        public DateTime dtAssigned;
        public DateTime dtItemFinished;
        public string sAssignedTo;
        public string sAssignedBy;
        public int nPriority;

        // Let's throw in an enum field to demonstrate how enums can be sorted by their string representations
        public BoredomRating nTaskBoredom;

        /// <summary>
        /// Gets or sets to whom this work item is assigned
        /// </summary>
        [PropertyFieldName("sAssignedTo")]
        public string AssignedTo
        {
            get { return (sAssignedTo == null) ? "(Unassigned)" : sAssignedTo; }
            set
            {
                if (value == null) sAssignedTo = null;
                else
                {
                    if (sAssignedTo == null)
                    {
                        // new assignment, record the date/time assigned
                        sAssignedTo = value;
                        dtAssigned = DateTime.Now.Date;
                    }
                    else
                    {
                        sAssignedTo = value;
                    }
                }
            }
        }

        /// <summary>
        /// Gets or sets who assigned this work item
        /// </summary>
        [PropertyFieldName("sAssignedBy")]
        public string AssignedBy
        {
            get { return (sAssignedBy == null) ? "(Management)" : sAssignedBy; }
            set { sAssignedBy = value; }
        }

        /// <summary>
        /// Gets or sets the date/time at which this work item was assigned
        /// Default to 1/1/2000 if the work item was never formally assigned
        /// </summary>
        [PropertyFieldName("dtAssigned")]
        public DateTime DateAssigned
        {
            get { return (dtAssigned == DateTime.MinValue) ? new DateTime(2000, 1, 1, 1, 1, 1) : dtAssigned; }
            set { dtAssigned = value; }
        }

        /// <summary>
        /// Gets or sets the priority of the work item
        /// </summary>
        [PropertyFieldName("nPriority")]
        public int Priority
        {
            get { return nPriority; }
            set { nPriority = value; }
        }

        /// <summary>
        /// Gets or sets the anticipated task 'interest' level
        /// </summary>
        [PropertyFieldName("nTaskBoredom")]
        public BoredomRating TaskBoredom
        {
            get { return nTaskBoredom; }
            set
            {
                //if (value == BoredomRating.EvenWorseThanCodingASPWebPages)
                //{
                //    Debug.WriteLine("Stop complaining and get back to work!");
                //    CompanySecurity.ReportSuspiciousActivity("Employee is bored.  Assign more work and dock pay.");
                //}
                nTaskBoredom = value;
            }
        }

        /// <summary>
        /// Gets or sets whether the item has been finished or completed.  
        /// If switching from unfinished to finished, the date/time of completion is recorded.
        /// </summary>
        [PropertyFieldName("fItemFinished")]
        public bool ItemFinished
        {
            get { return fItemFinished; }
            set
            {
                // Completing an unfinished item, record the date/time
                if (!fItemFinished && value == true)
                {
                    dtItemFinished = DateTime.Now.Date;
                    fItemFinished = true;
                }
            }
        }

        // Return the time the item was completed/finished.  If the work item has not
        // been completed, return DateTime.MinValue
        [PropertyFieldName("dtItemFinished")]
        public DateTime DateFinished
        {
            get { return (fItemFinished ? dtItemFinished : DateTime.MinValue); }
        }

        /// <summary>
        /// Method used to alter the work item's assigned date
        /// </summary>
        /// <param name="nDays"></param>
        public void FoundOutAboutWorkItemDaysLater(int nDays)
        {
            dtAssigned = dtAssigned.AddDays(nDays);
        }

        /// <summary>
        /// Method to report the work item was completed several days ago
        /// </summary>
        /// <param name="nDays"></param>
        public void PretendCompleted(int nDays)
        {
            fItemFinished = true;
            dtItemFinished = DateTime.Now.Date.AddDays(-nDays);
        }

        /// <summary>
        /// This would be best done with Attributes on properties, but for demonstration
        /// purposes, the property<->field name link will be hardcoded
        /// </summary>
        public static void SetupQuickAndDirtyPropertyToFieldLinkLookup()
        {
            // In the real world we simply place attributes on the properties when a
            // quick-lookup-by-field is permitted.  Since this is a quick demo, I'm
            // hardcoding the mapping table below...
            // htPropertyToFieldNameMapping.Add("ItemFinished", "fItemFinished");
            // htPropertyToFieldNameMapping.Add("DateFinished", "dtItemFinished");
            // htPropertyToFieldNameMapping.Add("TaskBoredom", "nTaskBoredom");
            // htPropertyToFieldNameMapping.Add("Priority", "nPriority");
            // htPropertyToFieldNameMapping.Add("DateAssigned", "dtAssigned");
            // htPropertyToFieldNameMapping.Add("AssignedTo", "sAssignedTo");
            // htPropertyToFieldNameMapping.Add("AssignedBy", "sAssignedBy");
        }
    }

    /// <summary>
    /// Encapsulates a Work Item property name for easy data binding to UI/controls
    /// </summary>
    public class WorkItemPropertyName
    {
        private string sPropName;
        public string PropertyName { get { return sPropName; } set { sPropName = value; } }
        public WorkItemPropertyName(string sPropertyName) { sPropName = sPropertyName; }
    }

    /// <summary>
    /// Dummy ratings for work items.  Used to demonstrate sorting via enum values
    /// Not placed within the work item class because this may also be used to rate
    /// company social events...
    /// </summary>
    public enum BoredomRating 
    {
        NoRating = 0,
        EvenWorseThanCodingASPWebPages = 1,
        TediusAndDull = 2,
        BarelyTolerable = 3,
        Tolerable = 4,
        SomewhatFun = 5,
        DownrightExciting = 6,
        MaxExcitement = 7
    }
}