using System;
using System.Net.Http;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.Extensions.Logging;
using StellaOps.AirGap.Policy;

namespace StellaOps.Cli.Configuration;

internal sealed class EgressPolicyHttpMessageHandler : DelegatingHandler
{
    private readonly IEgressPolicy? _policy;
    private readonly ILogger _logger;
    private readonly string _component;
    private readonly string _intent;

    public EgressPolicyHttpMessageHandler(IEgressPolicy? policy, ILogger logger, string component, string intent)
    {
        _policy = policy;
        _logger = logger ?? throw new ArgumentNullException(nameof(logger));
        _component = string.IsNullOrWhiteSpace(component) ? "stellaops-cli" : component;
        _intent = string.IsNullOrWhiteSpace(intent) ? "cli-http" : intent;
    }

    protected override Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
    {
        if (_policy is null || request.RequestUri is not { IsAbsoluteUri: true } uri)
        {
            return base.SendAsync(request, cancellationToken);
        }

        try
        {
            var egressRequest = new EgressRequest(
                _component,
                uri,
                _intent,
                operation: request.Method.Method);

            _policy.EnsureAllowed(egressRequest);
        }
        catch (AirGapEgressBlockedException ex)
        {
            _logger.LogWarning(ex, "Egress blocked for {Component} when contacting {Destination}", _component, request.RequestUri);

            throw;
        }

        return base.SendAsync(request, cancellationToken);
    }
}