EnvelopeGenerator/EnvelopeGenerator.Application/Notifications/SendMailHandler.cs

using DigitalData.Core.Abstraction.Application.Repository;
using DigitalData.EmailProfilerDispatcher.Abstraction.Entities;
using EnvelopeGenerator.Application.Configurations;
using EnvelopeGenerator.Domain.Constants;
using EnvelopeGenerator.Domain.Entities;
using MediatR;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Options;
using Newtonsoft.Json;

namespace EnvelopeGenerator.Application.Notifications;

/// <summary>
/// 
/// </summary>
public interface ISendMailNotification : INotification
{
    /// <summary>
    /// 
    /// </summary>
    public EmailTemplateType TemplateType { get; }

    /// <summary>
    /// 
    /// </summary>
    public string EmailAddress { get; }
}

/// <summary>
/// 
/// </summary>
public abstract class SendMailHandler<TNotification> : INotificationHandler<TNotification>
    where TNotification : ISendMailNotification
{
    /// <summary>
    /// 
    /// </summary>
    protected readonly IRepository<EmailTemplate> TempRepo;

    /// <summary>
    /// 
    /// </summary>
    protected readonly IRepository<EmailOut> EmailOutRepo;

    /// <summary>
    /// 
    /// </summary>
    protected virtual Dictionary<string, string> BodyPlaceHolders { get; } = new();

    /// <summary>
    /// 
    /// </summary>
    protected readonly MailParams MailParams;

    /// <summary>
    /// 
    /// </summary>
    protected readonly DispatcherParams DispatcherParams;

    /// <summary>
    /// 
    /// </summary>
    protected virtual Dictionary<string, string> SubjectPlaceHolders { get; } = new();

    /// <summary>
    /// ReferenceString = Envelope.Uuid
    /// </summary>
    /// <param name="emailOut"></param>
    /// <returns></returns>
    protected abstract void ConfigEmailOut(EmailOut emailOut);

    /// <summary>
    /// 
    /// </summary>
    /// <param name="tempRepo"></param>
    /// <param name="emailOutRepo"></param>
    /// <param name="mailParamsOptions"></param>
    /// <param name="dispatcherParamsOptions"></param>
    protected SendMailHandler(IRepository<EmailTemplate> tempRepo, IRepository<EmailOut> emailOutRepo, IOptions<MailParams> mailParamsOptions, IOptions<DispatcherParams> dispatcherParamsOptions)
    {
        TempRepo = tempRepo;
        EmailOutRepo = emailOutRepo;
        MailParams = mailParamsOptions.Value;
        DispatcherParams = dispatcherParamsOptions.Value;
    }

    /// <summary>
    /// 
    /// </summary>
    /// <param name="notification"></param>
    /// <param name="cancel"></param>
    /// <returns></returns>
    /// <exception cref="NotImplementedException"></exception>
    public async Task Handle(TNotification notification, CancellationToken cancel)
    {
        var temp = await TempRepo
            .ReadOnly()
            .SingleOrDefaultAsync(x => x.Name == notification.TemplateType.ToString(), cancel)
                ?? throw new InvalidOperationException($"Receiver information is missing in the notification." +
                $"{typeof(TNotification)}:\n {JsonConvert.SerializeObject(notification, Format.Json.ForDiagnostics)}");

        temp.Subject = ReplacePlaceHolders(temp.Subject, SubjectPlaceHolders, MailParams.Placeholders);

        temp.Body = ReplacePlaceHolders(temp.Body, BodyPlaceHolders, MailParams.Placeholders);

        var emailOut = new EmailOut
        {
            EmailAddress = notification.EmailAddress,
            EmailBody = temp.Body,
            EmailSubj = temp.Subject,
            AddedWhen = DateTime.UtcNow,
            AddedWho = DispatcherParams.AddedWho,
            SendingProfile = DispatcherParams.SendingProfile,
            ReminderTypeId = DispatcherParams.ReminderTypeId,
            EmailAttmt1 = DispatcherParams.EmailAttmt1,
            WfId = (int)EnvelopeStatus.MessageConfirmationSent,
            
        };
        ConfigEmailOut(emailOut);
        await EmailOutRepo.CreateAsync(emailOut, cancel);
    }

    private static string ReplacePlaceHolders(string text, params Dictionary<string, string>[] placeHoldersList)
    {
        foreach (var placeHolders in placeHoldersList)
            foreach (var ph in placeHolders)
                text = text.Replace(ph.Key, ph.Value);
        return text;
    }

    private static string TextToHtml(string input)
    {
        if (string.IsNullOrEmpty(input)) return "";

        // HTML encoding special characters
        string encoded = System.Net.WebUtility.HtmlEncode(input);

        // Convert tabs to &nbsp; (4 non-breaking spaces)
        encoded = encoded.Replace("\t", "&nbsp;&nbsp;&nbsp;&nbsp;");

        // Convert line breaks to <br />
        encoded = encoded.Replace("\r\n", "<br />"); // Windows
        encoded = encoded.Replace("\r", "<br />");   // Mac old
        encoded = encoded.Replace("\n", "<br />");   // Unix/Linux

        return encoded;
    }
}