using System.Net;
using System.Net.Mail;

namespace JobTrackerApi.Services;

public interface IAppEmailSender
{
    Task SendAsync(string toEmail, string subject, string bodyText, CancellationToken cancellationToken = default);
}

public sealed class SmtpEmailSender : IAppEmailSender
{
    private readonly IConfiguration _cfg;
    private readonly ILogger<SmtpEmailSender> _logger;

    public SmtpEmailSender(IConfiguration cfg, ILogger<SmtpEmailSender> logger)
    {
        _cfg = cfg;
        _logger = logger;
    }

    public async Task SendAsync(string toEmail, string subject, string bodyText, CancellationToken cancellationToken = default)
    {
        var host = (_cfg["Email:SmtpHost"] ?? "").Trim();
        var user = (_cfg["Email:SmtpUser"] ?? "").Trim();
        var pass = (_cfg["Email:SmtpPassword"] ?? "").Trim();
        var from = (_cfg["Email:From"] ?? user).Trim();
        var fromName = (_cfg["Email:FromName"] ?? "Jobbjakt").Trim();

        var port = _cfg.GetValue("Email:SmtpPort", 587);
        if (port <= 0) port = 587;

        var enableSsl = _cfg.GetValue("Email:SmtpEnableSsl", true);
        var timeoutMs = _cfg.GetValue("Email:SmtpTimeoutMs", 15000);
        if (timeoutMs <= 0) timeoutMs = 15000;

        var enabled = _cfg.GetValue("Email:Enabled", false);
        if (!enabled)
        {
            _logger.LogWarning("Email sending is disabled (Email:Enabled=false). Suppressed email to {To} subject={Subject}", toEmail, subject);
            return;
        }

        if (string.IsNullOrWhiteSpace(host)) throw new InvalidOperationException("Email:SmtpHost is not configured.");
        if (string.IsNullOrWhiteSpace(from)) throw new InvalidOperationException("Email:From is not configured.");

        using var msg = new MailMessage();
        msg.From = new MailAddress(from, string.IsNullOrWhiteSpace(fromName) ? null : fromName);
        msg.To.Add(new MailAddress(toEmail));
        msg.Subject = subject;
        msg.Body = bodyText;
        msg.IsBodyHtml = false;

        using var smtp = new SmtpClient(host, port)
        {
            EnableSsl = enableSsl,
            DeliveryMethod = SmtpDeliveryMethod.Network,
            Timeout = timeoutMs,
        };

        if (!string.IsNullOrWhiteSpace(user))
        {
            smtp.Credentials = new NetworkCredential(user, pass);
        }

        // SmtpClient has no CancellationToken support; run on thread pool.
        await Task.Run(() => smtp.Send(msg), cancellationToken);
    }
}