Custom form autoresponder emails

using System;
using System.Collections.Generic;
using System.Threading.Tasks;

using CMS;
using CMS.ContactManagement;
using CMS.OnlineForms;

using CMS.Automation;

// Registers the custom IFormSubmitAutomationEmailProvider implementation
[assembly: RegisterImplementation(typeof(IFormSubmitAutomationEmailProvider), typeof(Custom.CustomFormSubmitAutomationEmailProvider))]

namespace Custom
{
    public class CustomFormSubmitAutomationEmailProvider : IFormSubmitAutomationEmailProvider
    {
        // Stores an instance of the default IFormSubmitAutomationEmailProvider implementation
        private readonly IFormSubmitAutomationEmailProvider defaultAutomationEmailProvider;

        public CustomFormSubmitAutomationEmailProvider(IFormSubmitAutomationEmailProvider defaultAutomationEmailProvider)
        {
            this.defaultAutomationEmailProvider = defaultAutomationEmailProvider;
        }

        // Creates an autoresponder email based on the submitted form
        public Task<AutomationEmail> GetEmail(BizFormInfo form, BizFormItem formData, ContactInfo contact)
        {
            // Gets the email address from the contact's Email attribute
            string recipient = contact.ContactEmail;

            if (string.IsNullOrEmpty(recipient))
            {
                // The user hasn't provided an email address, so no autoresponder email is sent
                return null;
            }

            // Prepares a custom autoresponder email for a form with the 'ContactUs' code name
            if (form.FormName.Equals("ContactUs", StringComparison.InvariantCultureIgnoreCase))
            {
                return Task.FromResult(new AutomationEmail
                {
                    Subject = "Thanks for contacting us",
                    // Builds the email body, including the name of the contact who submitted the form,
                    // and the value of the 'UserMessage' form field
                    Body = $"Hello {contact.ContactFirstName}, <br />" +
                           "thank you for contacting us. You sent us the following message:<br />" +
                           formData.GetStringValue("UserMessage", ""),
                    Sender = "no-reply@company.com",
                    Recipients = new List<string> { recipient }
                });
            }

            // Returns the default form autoresponder email as a fallback
            return defaultAutomationEmailProvider.GetEmail(form, formData, contact);
        }
    }
}