using Host.Application.Stories;
using Knot.Shared.Kernel;
using Knot.Shared.Kernel.Configuration;
using Knot.Shared.Kernel.Constants;
using System;
using System.Linq;
using System.Security.Cryptography;
using System.Threading;
using System.Threading.Tasks;
using MediatR;

namespace Host.Application.Federation.Commands;

public record HandshakeRequest(string Domain, string PublicKey);
public record HandshakeResponse(string Domain, string PublicKey, string Status);

public record HandshakeFederationCommand(HandshakeRequest Request) : ICommand<HandshakeResponse>;

internal sealed class HandshakeFederationCommandHandler : ICommandHandler<HandshakeFederationCommand, HandshakeResponse>
{
    private readonly ISettingsService _settings;

    public HandshakeFederationCommandHandler(ISettingsService settings)
    {
        _settings = settings;
    }

    public Task<Result<HandshakeResponse>> Handle(HandshakeFederationCommand request, CancellationToken cancellationToken)
    {
        var conf = _settings.Current;
        if (!conf.EnableConfederation)
            return Task.FromResult(Result.Failure<HandshakeResponse>(new Error(Errors.DisabledByAdmin, "Federation is disabled")));

        if (string.IsNullOrEmpty(request.Request.Domain) || string.IsNullOrEmpty(request.Request.PublicKey))
            return Task.FromResult(Result.Failure<HandshakeResponse>(DomainErrors.RequestInvalid));

        var allowedList = conf.AllowedDomains?.Select(d => d.Trim().ToLower()).ToList() ?? new System.Collections.Generic.List<string>();
        if (!allowedList.Contains(request.Request.Domain.ToLowerInvariant()))
            return Task.FromResult(Result.Failure<HandshakeResponse>(StoryErrors.Unauthorized));

        using var rsa = RSA.Create(2048);
        var selfPublicKey = Convert.ToBase64String(rsa.ExportRSAPublicKey());

        var response = new HandshakeResponse(
            Environment.GetEnvironmentVariable("DOMAIN") ?? "knot.local",
            selfPublicKey,
            "Accepted"
        );
        
        return Task.FromResult(Result.Success(response));
    }
}