using System;

using System.Collections.Generic;

using System.Linq;

using System.Text.RegularExpressions;

public class Program

{

    public static void Main()

    {

        Console.WriteLine("Hello World");

    }

    public FreemarkerTagEntity ExtractTags(string content, string entityName)

        {

            FreemarkerTagEntity entityTag = new FreemarkerTagEntity() { EntityName = entityName };

            var validfieldNameRegex = new Regex(@"^(\w|_|:)(\w|\d|\.|-|_|:)*$");

            Regex r = new Regex(string.Format("Recipient.{0}.", entityName));

            Match m = r.Match(content);

            while (m.Success) 

            {

                int startIndex = m.Index;

                List<int> iEnds = new List<int>();

                iEnds.Add(content.IndexOf(".@value[0]", startIndex));

                iEnds.Add(content.IndexOf("[0]", startIndex));

                iEnds.Add(content.IndexOf("}", startIndex));

                iEnds.Add(content.IndexOf("!", startIndex));

                iEnds.Add(content.IndexOf("?", startIndex));

                iEnds.Add(content.IndexOf(" ", startIndex));

                while (iEnds.Contains(-1)) iEnds.Remove(-1);

                int endIndex = 0;

                if (iEnds.Count > 0)

                {

                    endIndex = iEnds.Min();

                }

                if (endIndex > startIndex)

                {

                    string[] tag = content.Substring(startIndex, endIndex - startIndex).Split('.');

​

                    if (tag.Length == 3)

                    {

                        if (!entityTag.Tags.Contains(tag[2]) && validfieldNameRegex.IsMatch(tag[2]))

                            entityTag.Tags.Add(tag[2]);

                    }

                    else if (tag.Length == 5)

                    {

                        if (entityTag.LookupTags.GetTagEntity(tag[3]) == null)

                        {

                            entityTag.LookupTags.Add(new FreemarkerTagEntity() { EntityName = tag[3], LookupField = tag[2] });

                        }

                        if (!entityTag.LookupTags.GetTagEntity(tag[3]).Tags.Contains(tag[4]) && validfieldNameRegex.IsMatch(tag[4]))

                        {

                            entityTag.LookupTags.GetTagEntity(tag[3]).Tags.Add(tag[4]);

                        }

                    }

                }

                m = m.NextMatch();

            }

            return entityTag;

        }

    public class FreemarkerTagEntity : IEquatable<FreemarkerTagEntity>

    {

        #region Properties

​

        public string EntityName { get; set; }

​

        public string LookupField { get; set; }

​

        public FreemarkerTagEntityCollection LookupTags { get; set; }

​

        public List<string> Tags { get; set; }

​

        #endregion

​

        #region Constructors

​

        public FreemarkerTagEntity()

        {

            EntityName = string.Empty;

            Tags = new List<string>();

            LookupTags = new FreemarkerTagEntityCollection();

            LookupField = string.Empty;

        }

​

        #endregion

​

        #region Methods

​

        public bool Equals(FreemarkerTagEntity other)

        {

            return this.EntityName.Equals(other.EntityName);

        }

​

        public void Merge(FreemarkerTagEntity other)

        {

            Tags = Tags.Union(other.Tags).Distinct().ToList();

            foreach (var ot in other.LookupTags)

            {

                if (this.LookupTags.GetTagEntity(ot.EntityName) == null)

                {

                    this.LookupTags.Add(ot);

                }

                else

                {

                    this.LookupTags.GetTagEntity(ot.EntityName).Tags = this.LookupTags.GetTagEntity(ot.EntityName).Tags.Union(ot.Tags).Distinct().ToList();

                }

            }

        }

​

        #endregion

    }

    public class FreemarkerTagEntityCollection : List<FreemarkerTagEntity>

    {

        #region Methods

​

        public FreemarkerTagEntity GetTagEntity(string entityName)

        {

            return this.Find(delegate (FreemarkerTagEntity e) { return e.EntityName.Equals(entityName); });

        }

​

        #endregion

    }

}