using SlackNet.WebApi;

//using System;

using System.Collections.Generic;

using System.Linq;

public class Program

{

    public static void Main()

    {

        MessageBuilder

            .New()

            .To("")

            .WithMetadata("", "")

            .WithMetadata("", "")

            .WithMarkdown("")

            .Build();

    }

}

​

public class MessageBuilder : IMessageBuilder, IMessageHeader, IMessageBody, IMessageComplete

{

    private readonly Message message;

​

    private MessageBuilder()

    {

        this.message = new Message();

    }

    public static IMessageBuilder New()

    {

        return new MessageBuilder();

    }

    public IMessageHeader To(params string[] recipients)

    {

        return this;

    }

    public IMessageHeader WithTitle(string title)

    {

        return this;

    }

    public IMessageBody WithMetadata(string key, string value)

    {

        return this;

    }

    public IMessageBody WithDivider()

    {

        return this;

    }

    public IMessageComplete WithMarkdown(string message)

    {

        return this;

    }

    public Message Build() => this.message;

}

​

public interface IMessageBuilder 

{

    IMessageHeader To(params string[] recipients);

}

​

public interface IMessageHeader

{

    IMessageHeader WithTitle(string title);

    IMessageBody WithMetadata(string key, string value);

}

​

public interface IMessageBody

{

    IMessageBody WithMetadata(string key, string value);

    IMessageBody WithDivider();

    IMessageComplete WithMarkdown(string message);

}

​

public interface IMessageComplete

{

    Message Build();

}

​

public static class SlackMarkdown

{

    public static string ToLink(string url, string text) => $"<{url}|{text}>";

    public static string ToList(IList<string> items) => string.Join("\\n", items.Select(item => ToListItem(item)));

    public static string ToListItem(string item) => string.IsNullOrEmpty(item) ? item : $"* {item}";

    // bold             - *text*

    // italic           - _text_

    // strikethrough    - ~text~

    // inline code      - `text`

    // blockquote       - > text

    // ordered list     - 1. text

    // unordered list   - * text

    // link             - <{url}|{text}>

}