using System;

using System.Collections.Generic;

using System.Linq;

​

namespace Example

{

    public enum Gender

    {

        Male, Female

    }

    public class DocumentMetadata

    {

        public DateTime DateOfBirth { get; set; }

        public Gender Gender { get; set; }

        public string RefNum { get; set; }

        public override string ToString()

        {

            return string.Format("DocumentMetadata: DOB={0:yyyy-MM-dd}, Gender={1}, RefNum={2}", DateOfBirth, Gender, RefNum);

        }

    }

    public delegate bool Parser(string line, DocumentMetadata dto);

    public interface IDocumentParser

    {

        DocumentMetadata Parse(IEnumerable<string> input);

    }

    public abstract class BaseParser : IDocumentParser

    {

        protected abstract List<Parser> GetParsers();

        public virtual DocumentMetadata Parse(IEnumerable<string> input)

        {

            var parsers = this.GetParsers();

            var instance = new DocumentMetadata();

            var successCount = input.Sum( line => parsers.Count( parser => parser(line, instance) ));

            Console.WriteLine("{0} lines successfully parsed.", successCount);

            return instance;

        }

    }

    public class DocumentParser : BaseParser

    {

        protected override List<Parser> GetParsers()

        {

            return new List<Parser>

            {

                ParseDateOfBirth,

                ParseGender,

                ParseRefNum

            };

        }

        private bool ParseDateOfBirth(string line, DocumentMetadata dto)

        {

            if (!line.StartsWith("DOB:")) return false;

            dto.DateOfBirth = DateTime.Parse(line.Substring(4));

            return true;

        }

        private bool ParseGender(string line, DocumentMetadata dto)

        {

            if (!line.StartsWith("Sex:")) return false;

            var s = line.Substring(4,1);

            if (s == "M")

            {

                dto.Gender = Gender.Male;

                return true;

            }

            if (s == "F")

            {

                dto.Gender = Gender.Female;

                return true;

            }

            return false;

        }

        private bool ParseRefNum(string line, DocumentMetadata dto)

        {

            if (!line.StartsWith("RefNum:")) return false;

            dto.RefNum = line.Substring(7);

            return true;

        }

    }

    public class Application

    {

        protected readonly IDocumentParser _parser; // injected

        public Application(IDocumentParser parser)

        {

            _parser = parser;

        }

        public void Run()

        {

            var input = new string[]

            {

                "DOB:1/1/2018",

                "Sex:Male",

                "RefNum:1234"

            };

            var result = _parser.Parse(input);

            Console.WriteLine(result);

        }

    }

    public class Program

    {

        public static void Main()

        {

            var application = new Application(new DocumentParser());

            application.Run();

        }

    }

}