myAi/Apis/email-api/Services/SmtpEmailDispatcher.cs

using EmailApi.Data.Services;
using EmailApi.Models.Requests;
using MailKit.Net.Smtp;
using MailKit.Security;
using Microsoft.Extensions.Options;
using MimeKit;
using Models.Settings;

namespace EmailApi.Services;

/// <summary>
/// Wraps an HTML body fragment in the branded HTML shell and sends the resulting email via SMTP using MailKit.
/// Attaches files from the shared file-storage volume when an attachment path is provided.
/// </summary>
public sealed class SmtpEmailDispatcher
{
    private readonly SmtpSettings _smtp;
    private readonly FileStorageSettings _fileStorage;
    private readonly IEmailTemplateService _templates;
    private readonly ILogger<SmtpEmailDispatcher> _log;
    private readonly string _environmentName;

    public SmtpEmailDispatcher(
        IOptions<SmtpSettings> smtp,
        IOptions<FileStorageSettings> fileStorage,
        IEmailTemplateService templates,
        ILogger<SmtpEmailDispatcher> log)
    {
        _smtp = smtp.Value;
        _fileStorage = fileStorage.Value;
        _templates = templates;
        _log = log;
        _environmentName = Environment.GetEnvironmentVariable("APP_ENVIRONMENT_NAME") ?? "Development";
    }

    /// <summary>
    /// Builds a <see cref="MimeMessage"/> from <paramref name="req"/>, wraps the body in the HTML shell,
    /// optionally attaches a file, and sends via the configured SMTP server.
    /// Logs a warning and returns without throwing when the SMTP host is not configured.
    /// </summary>
    /// <param name="req">Email payload containing recipients, subject, HTML body, and optional attachment path.</param>
    /// <param name="ct">Cancellation token.</param>
    public async Task SendAsync(SendEmailRequest req, CancellationToken ct)
    {
        if (string.IsNullOrWhiteSpace(_smtp.Host))
        {
            _log.LogWarning("SMTP host not configured — email skipped (to: {To})", string.Join(", ", req.To));
            return;
        }

        var msg = new MimeMessage();
        msg.From.Add(MailboxAddress.Parse(_smtp.Username));

        foreach (var to in req.To)
            msg.To.Add(MailboxAddress.Parse(to));

        if (!string.IsNullOrWhiteSpace(req.ReplyTo))
            msg.ReplyTo.Add(MailboxAddress.Parse(req.ReplyTo));

        msg.Subject = $"[{_environmentName}] {req.Subject}".Trim();

        var shellStart = _templates.Get("email.html-shell.start", "*");
        var shellEnd = _templates.Get("email.html-shell.end", "*");

        var builder = new BodyBuilder
        {
            HtmlBody = shellStart + req.HtmlBody + shellEnd
        };

        if (!string.IsNullOrWhiteSpace(req.AttachmentPath))
        {
            var fullPath = Path.Combine(_fileStorage.Path, req.AttachmentPath);
            if (File.Exists(fullPath))
            {
                builder.Attachments.Add(fullPath);
                _log.LogDebug("Attachment added: {Path}", fullPath);
            }
            else
            {
                _log.LogWarning("Attachment not found, skipping: {Path}", fullPath);
            }
        }

        msg.Body = builder.ToMessageBody();

        _log.LogInformation("Sending email to {Recipients} subject {Subject}",
            string.Join(", ", req.To), req.Subject);

        using var client = new SmtpClient();
        var tls = _smtp.UseStartTls ? SecureSocketOptions.StartTls : SecureSocketOptions.Auto;
        await client.ConnectAsync(_smtp.Host, _smtp.Port, tls, ct);

        if (!string.IsNullOrWhiteSpace(_smtp.Username))
            await client.AuthenticateAsync(_smtp.Username, _smtp.Password, ct);

        await client.SendAsync(msg, ct);
        await client.DisconnectAsync(true, ct);

        _log.LogInformation("Email sent successfully to {Recipients}", string.Join(", ", req.To));
    }
}