Mastering the Bridge Design Pattern: A Complete Guide for Software Developers

				
					// Implementation hierarchy - How notifications are sent
public interface INotificationChannel
{
    Task SendAsync(string recipient, string subject, string message);
}

public class EmailChannel : INotificationChannel
{
    public async Task SendAsync(string recipient, string subject, string message)
    {
        // Email-specific implementation
        await Task.Delay(100); // Simulate email sending
        Console.WriteLine($"Email sent to {recipient}");
        Console.WriteLine($"Subject: {subject}");
        Console.WriteLine($"Message: {message}");
    }
}

public class SMSChannel : INotificationChannel
{
    public async Task SendAsync(string recipient, string subject, string message)
    {
        // SMS-specific implementation
        await Task.Delay(50); // Simulate SMS sending
        Console.WriteLine($"SMS sent to {recipient}");
        Console.WriteLine($"Message: {message}"); // SMS doesn't use subject
    }
}

public class SlackChannel : INotificationChannel
{
    public async Task SendAsync(string recipient, string subject, string message)
    {
        // Slack-specific implementation
        await Task.Delay(30); // Simulate Slack API call
        Console.WriteLine($"Slack message sent to #{recipient}");
        Console.WriteLine($"**{subject}**\n{message}");
    }
}

// Abstraction hierarchy - What notifications are sent
public abstract class Notification
{
    protected INotificationChannel channel; // THE BRIDGE!

    protected Notification(INotificationChannel channel)
    {
        this.channel = channel;
    }

    public abstract Task SendAsync(string recipient);

    // Template method for common functionality
    protected virtual string FormatMessage(string content)
    {
        return $"[{DateTime.Now:yyyy-MM-dd HH:mm}] {content}";
    }
}

public class OrderConfirmation : Notification
{
    private readonly string orderNumber;
    private readonly decimal totalAmount;

    public OrderConfirmation(INotificationChannel channel, string orderNumber, decimal totalAmount) 
        : base(channel)
    {
        this.orderNumber = orderNumber;
        this.totalAmount = totalAmount;
    }

    public override async Task SendAsync(string recipient)
    {
        var subject = $"Order Confirmation - #{orderNumber}";
        var message = FormatMessage(
            $"Thank you for your order #{orderNumber}. " +
            $"Total amount: ${totalAmount:F2}. " +
            $"We'll notify you when it ships!"
        );

        await channel.SendAsync(recipient, subject, message);
    }
}

public class ShippingUpdate : Notification
{
    private readonly string orderNumber;
    private readonly string trackingNumber;
    private readonly string carrier;

    public ShippingUpdate(INotificationChannel channel, string orderNumber, 
                         string trackingNumber, string carrier) : base(channel)
    {
        this.orderNumber = orderNumber;
        this.trackingNumber = trackingNumber;
        this.carrier = carrier;
    }

    public override async Task SendAsync(string recipient)
    {
        var subject = $"Your Order #{orderNumber} Has Shipped";
        var message = FormatMessage(
            $"Great news! Your order #{orderNumber} is on its way. " +
            $"Tracking number: {trackingNumber} via {carrier}."
        );

        await channel.SendAsync(recipient, subject, message);
    }
}

public class PromotionalOffer : Notification
{
    private readonly string offerTitle;
    private readonly int discountPercent;
    private readonly DateTime validUntil;

    public PromotionalOffer(INotificationChannel channel, string offerTitle, 
                           int discountPercent, DateTime validUntil) : base(channel)
    {
        this.offerTitle = offerTitle;
        this.discountPercent = discountPercent;
        this.validUntil = validUntil;
    }

    public override async Task SendAsync(string recipient)
    {
        var subject = $"Special Offer: {offerTitle}";
        var message = FormatMessage(
            $"Don't miss out! {offerTitle} - Save {discountPercent}% " +
            $"on your next purchase. Valid until {validUntil:MMM dd, yyyy}."
        );

        await channel.SendAsync(recipient, subject, message);
    }
}