using System.Net.Http.Headers;
using System.Text;
using Microsoft.Extensions.Diagnostics.HealthChecks;
using Microsoft.Extensions.Options;
using EmailMicroservice.Models;

namespace EmailMicroservice.Services
{
	public class ExchangeHealthCheck : IHealthCheck
	{
		private readonly MailSettings _mailSettings;
		private readonly IHttpClientFactory _httpClientFactory;

		public ExchangeHealthCheck(IOptions<MailSettings> options, IHttpClientFactory httpClientFactory)
		{
			_mailSettings = options.Value;
			_httpClientFactory = httpClientFactory;
		}

		public async Task<HealthCheckResult> CheckHealthAsync(HealthCheckContext context, CancellationToken cancellationToken = default)
		{
			try
			{
				var client = _httpClientFactory.CreateClient("ExchangeClient");


				// Si Exchange se "traba" y no responde en 10 segundos, cortamos la llamada.
				// Esto evita que tu microservicio se quede congelado esperando.
				client.Timeout = TimeSpan.FromSeconds(10);

				// Usamos las mismas credenciales que el servicio principal para asegurar consistencia

				client.DefaultRequestHeaders.Authorization = GetBasicAuthHeader();

				string? url = _mailSettings.EwsUrl;
				if (string.IsNullOrEmpty(url))
				{
					return HealthCheckResult.Degraded("URL de Exchange no configurada.");
				}

				// Intentamos conectar. Si Exchange no responde, aquí saltará el error a los 10 seg.
				var response = await client.GetAsync(url, cancellationToken);

				if (response.IsSuccessStatusCode)
				{
					return HealthCheckResult.Healthy("Conexión a Exchange operativa.");
				}

				return HealthCheckResult.Unhealthy($"Exchange respondió error: {response.StatusCode}");
			}
			// TIMEOUT
			catch (TaskCanceledException)
			{
				return HealthCheckResult.Unhealthy("Sin respuesta del servicio Exchange: posible caída o latencia excesiva (>10s).");
			}
			catch (Exception ex)
			{
				return HealthCheckResult.Unhealthy("Fallo crítico de conexión.", ex);
			}
		}

		private AuthenticationHeaderValue GetBasicAuthHeader()
		{
			var emailAddress = string.IsNullOrEmpty(Environment.GetEnvironmentVariable("EMAIL_ADDRESS")) ? _mailSettings.EmailAddress : Environment.GetEnvironmentVariable("EMAIL_ADDRESS");
			var pass = string.IsNullOrEmpty(Environment.GetEnvironmentVariable("EMAIL_PASS")) ? _mailSettings.Password : Environment.GetEnvironmentVariable("EMAIL_PASS");
			var byteArray = Encoding.ASCII.GetBytes($"{emailAddress}:{pass}");
			return new AuthenticationHeaderValue("Basic", Convert.ToBase64String(byteArray));
		}
	}
}