Comment.cs

namespace BlogEngine.Core
{
    using System;
    using System.Collections.Generic;
    using System.ComponentModel;
    using System.Xml.Serialization;

    /// <summary>
    /// Represents a comment to a blog post.
    /// </summary>
    [Serializable]
    public sealed class Comment : IComparable<Comment>, IPublishable
    {
        #region Constants and Fields

        /// <summary>
        /// The comments.
        /// </summary>
        private List<Comment> comments;

        /// <summary>
        /// The date created.
        /// </summary>
        private DateTime dateCreated = DateTime.MinValue;

        #endregion

        #region Events

        /// <summary>
        ///     Occurs after a comment is approved by the comment moderator.
        /// </summary>
        public static event EventHandler<EventArgs> Approved;

        /// <summary>
        ///     Occurs just before a comment is approved by the comment moderator.
        /// </summary>
        public static event EventHandler<CancelEventArgs> Approving;

        /// <summary>
        ///     Occurs after a comment is disapproved by the comment moderator.
        /// </summary>
        public static event EventHandler<EventArgs> Disapproved;

        /// <summary>
        ///     Occurs just before a comment is disapproved by the comment moderator.
        /// </summary>
        public static event EventHandler<CancelEventArgs> Disapproving;

        /// <summary>
        ///     Occurs when the post is being served to the output stream.
        /// </summary>
        public static event EventHandler<ServingEventArgs> Serving;

        /// <summary>
        ///     Occurs when the page is being attacked by robot spam.
        /// </summary>
        public static event EventHandler<EventArgs> SpamAttack;

        #endregion

        #region Properties

        /// <summary>
        ///     Gets the absolute link.
        /// </summary>
        /// <value>The absolute link.</value>
        public Uri AbsoluteLink
        {
            get
            {
                return new Uri($"{Parent.AbsoluteLink}#id_{Id}");
            }
        }

        /// <summary>
        ///     Gets or sets the author.
        /// </summary>
        /// <value>The author.</value>
        public string Author { get; set; }

        /// <summary>
        ///     Gets or sets the Avatar of the comment.
        /// </summary>
        public string Avatar { get; set; }

        /// <summary>
        ///     Gets a list of Comments.
        /// </summary>
        public List<Comment> Comments
        {
            get
            {
                return comments ?? (comments = new List<Comment>());
            }
        }

        /// <summary>
        ///     Gets or sets the content.
        /// </summary>
        /// <value>The content.</value>
        public string Content { get; set; }  // Do Not HtmlEncode, leads to double, triple, etc encoding.

        /// <summary>
        ///     Gets or sets the country.
        /// </summary>
        /// <value>The country.</value>
        public string Country { get; set; }

        /// <summary>
        ///     Gets or sets when the comment was created.
        /// </summary>
        public DateTime DateCreated
        {
            get
            {
                return dateCreated;
            }

            set
            {
                dateCreated = value;
            }
        }

        /// <summary>
        ///     Gets the description. Returns always string.empty.
        /// </summary>
        /// <value>The description.</value>
        public string Description
        {
            get
            {
                return string.Empty;
            }
        }

        /// <summary>
        ///     Gets or sets the email.
        /// </summary>
        /// <value>The email.</value>
        public string Email { get; set; }

        /// <summary>
        ///     Gets or sets the IP address.
        /// </summary>
        /// <value>The IP address.</value>
        public string IP { get; set; }

        /// <summary>
        ///     Gets or sets the Id of the comment.
        /// </summary>
        public Guid Id { get; set; }

        /// <summary>
        ///     Gets or sets a value indicating whether the Comment is approved.
        /// </summary>
        public bool IsApproved { get; set; }

        /// <summary>
        ///     Indicate if comment is spam
        /// </summary>
        public bool IsSpam { get; set; }

        /// <summary>
        ///     indicate if comment is deleted
        /// </summary>
        public bool IsDeleted { get; set; }

        /// <summary>
        ///     Gets a value indicating whether or not this comment has been published
        /// </summary>
        public bool IsPublished
        {
            get
            {
                return IsApproved && !IsSpam && !IsDeleted;
            }
        }

        /// <summary>
        ///     Gets a value indicating whether or not this comment should be shown
        /// </summary>
        /// <value></value>
        public bool IsVisible
        {
            get
            {
                return IsApproved && !IsSpam && !IsDeleted;
            }
        }

        /// <summary>
        ///     Gets a value indicating whether or not this comment is visible to visitors not logged into the blog.
        /// </summary>
        /// <value></value>
        public bool IsVisibleToPublic
        {
            get
            {
                return IsApproved && !IsSpam && !IsDeleted;
            }
        }

        /// <summary>
        ///    Gets or sets process that approved or rejected comment
        /// </summary>
        [XmlElement]
        public string ModeratedBy { get; set; }

        /// <summary>
        /// Gets or sets the parent.
        /// </summary>
        /// <value>The parent.</value>
        public IPublishable Parent { get; set; }

        /// <summary>
        ///     Gets or sets the Blog instance this object is under.
        /// </summary>
        public Guid BlogId { get { return this.Parent == null ? Guid.Empty : this.Parent.BlogId; } }

        /// <summary>
        ///     Gets the Blog instance this object is under.
        /// </summary>
        public Blog Blog
        {
            get { return Blog.GetBlog(BlogId); }
        }

        /// <summary>
        ///     Gets or sets the Id of the parent comment.
        /// </summary>
        public Guid ParentId { get; set; }

        /// <summary>
        ///     Gets the relative link of the comment.
        /// </summary>
        /// <value>The relative link.</value>
        public string RelativeLink
        {
            get
            {
                return $"{Parent.RelativeLink}#id_{Id}";
            }
        }

        /// <summary>
        ///     Returns a relative link if possible if the hostname of this blog instance matches the
        ///     hostname of the site aggregation blog.  If the hostname is different, then the
        ///     absolute link is returned.
        /// </summary>
        public string RelativeOrAbsoluteLink
        {
            get
            {
                if (this.Blog.DoesHostnameDifferFromSiteAggregationBlog)
                    return this.AbsoluteLink.ToString();
                else
                    return this.RelativeLink;
            }
        }

        /// <summary>
        ///     Gets abbreviated content
        /// </summary>
        public string Teaser
        {
            get
            {
                var ret = Utils.StripHtml(Content).Trim();
                return ret.Length > 120 ? $"{ret.Substring(0, 116)} ..." : ret;
            }
        }

        /// <summary>
        /// Pingbacks and trackbacks are identified by email
        /// </summary>
        public bool IsPingbackOrTrackback
        {
            get { return (Email.ToLowerInvariant() == "pingback" || Email.ToLowerInvariant() == "trackback") ? true : false; }
        }

        /// <summary>
        ///     Gets the title of the object
        /// </summary>
        /// <value></value>
        public string Title
        {
            get
            {
                if (Website != null)
                {
                    return string.Format("<a class=\"comment_auth\" href=\"{2}\" alt=\"{2}\" title=\"{2}\">{0}</a> on <a href=\"{3}\" alt=\"{3}\">{1}</a>", Author, Parent.Title, Website.ToString(), RelativeLink);
                }
                return string.Format("{0} on <a href=\"{2}\" alt=\"{2}\">{1}</a>", Author, Parent.Title, RelativeLink);             
            }
        }

        /// <summary>
        ///     Gets or sets the website.
        /// </summary>
        /// <value>The website.</value>
        public Uri Website { get; set; }

        /// <summary>
        /// Gets Categories.
        /// </summary>
        StateList<Category> IPublishable.Categories
        {
            get
            {
                return null;
            }
        }

        /// <summary>
        /// Gets Categories.
        /// </summary>
        StateList<string> IPublishable.Tags
        {
            get
            {
                return null;
            }
        }

        /// <summary>
        /// Gets DateModified.
        /// </summary>
        DateTime IPublishable.DateModified
        {
            get
            {
                return DateCreated;
            }
        }

        #endregion

        #region Public Methods

        /// <summary>
        /// Called when [serving].
        /// </summary>
        /// <param name="comment">The comment.</param>
        /// <param name="arg">The <see cref="BlogEngine.Core.ServingEventArgs"/> instance containing the event data.</param>
        public static void OnServing(Comment comment, ServingEventArgs arg)
        {
            if (Serving != null)
            {
                Serving(comment, arg);
            }
        }

        /// <summary>
        /// Called when [spam attack].
        /// </summary>
        public static void OnSpamAttack()
        {
            if (SpamAttack != null)
            {
                SpamAttack(null, EventArgs.Empty);
            }
        }

        #endregion

        #region Implemented Interfaces

        #region IComparable<Comment>

        /// <summary>
        /// Compares the current object with another object of the same type.
        /// </summary>
        /// <param name="other">
        /// An object to compare with this object.
        /// </param>
        /// <returns>
        /// A 32-bit signed integer that indicates the relative order of the 
        ///     objects being compared. The return value has the following meanings: 
        ///     Value Meaning Less than zero This object is less than the other parameter.
        ///     Zero This object is equal to other. Greater than zero This object is greater than other.
        /// </returns>
        public int CompareTo(Comment other)
        {
            return DateCreated.CompareTo(other.DateCreated);
        }

        #endregion

        #region IPublishable

        /// <summary>
        /// Raises the <see cref="Serving"/> event.
        /// </summary>
        /// <param name="eventArgs">The <see cref="BlogEngine.Core.ServingEventArgs"/> instance containing the event data.</param>
        public void OnServing(ServingEventArgs eventArgs)
        {
            if (Serving != null)
            {
                Serving(this, eventArgs);
            }
        }

        #endregion

        #endregion

        #region Methods

        /// <summary>
        /// Called when [approved].
        /// </summary>
        /// <param name="comment">The comment.</param>
        internal static void OnApproved(Comment comment)
        {
            if (Approved != null)
            {
                Approved(comment, EventArgs.Empty);
            }
        }

        /// <summary>
        /// Called when [approving].
        /// </summary>
        /// <param name="comment">The comment.</param>
        /// <param name="e">The <see cref="System.ComponentModel.CancelEventArgs"/> instance containing the event data.</param>
        internal static void OnApproving(Comment comment, CancelEventArgs e)
        {
            if (Approving != null)
            {
                Approving(comment, e);
            }
        }

        /// <summary>
        /// Called when [disapproved].
        /// </summary>
        /// <param name="comment">The comment.</param>
        internal static void OnDisapproved(Comment comment)
        {
            if (Disapproved != null)
            {
                Disapproved(comment, EventArgs.Empty);
            }
        }

        /// <summary>
        /// Called when [disapproving].
        /// </summary>
        /// <param name="comment">The comment.</param>
        /// <param name="e">The <see cref="System.ComponentModel.CancelEventArgs"/> instance containing the event data.</param>
        internal static void OnDisapproving(Comment comment, CancelEventArgs e)
        {
            if (Disapproving != null)
            {
                Disapproving(comment, e);
            }
        }

        #endregion
    }
}