using Microsoft.EntityFrameworkCore;
using PnvPanel.Application.Auth;
using PnvPanel.Application.Common.Interfaces;
using PnvPanel.Application.Common.Messaging;
using PnvPanel.Application.Common.Models;
using PnvPanel.Domain.Configs;

namespace PnvPanel.Application.Configs.Rotate;

public sealed class RotateVpnConfigCommandHandler(
    IAppDbContext dbContext,
    IXuiPanelGateway gateway,
    IIdentityService identityService,
    ICurrentUser currentUser
) : ICommandHandler<RotateVpnConfigCommand, Result<VpnConfigDto>>
{
    public async Task<Result<VpnConfigDto>> Handle(
        RotateVpnConfigCommand command,
        CancellationToken cancellationToken
    )
    {
        if (currentUser.UserId is not { } userId)
            return Result.Failure<VpnConfigDto>(AuthErrors.Unauthorized);

        var config = await dbContext.VpnConfigs.FirstOrDefaultAsync(
            c => c.Id == command.ConfigId && c.UserId == userId,
            cancellationToken
        );
        if (config is null)
            return Result.Failure<VpnConfigDto>(ConfigErrors.NotFound);

        if (config.Status != ConfigStatus.Active)
            return Result.Failure<VpnConfigDto>(ConfigErrors.NotFound);

        var inbound = await dbContext
            .Inbounds.AsNoTracking()
            .FirstOrDefaultAsync(i => i.Id == config.InboundId, cancellationToken);
        if (inbound is null)
            return Result.Failure<VpnConfigDto>(ConfigErrors.InboundNotAvailable);

        var node = await dbContext
            .Nodes.AsNoTracking()
            .FirstOrDefaultAsync(n => n.Id == inbound.NodeId, cancellationToken);
        if (node is null)
            return Result.Failure<VpnConfigDto>(ConfigErrors.NodeDisabled);

        var profile = await identityService.GetProfileAsync(userId, cancellationToken);
        if (profile is null)
            return Result.Failure<VpnConfigDto>(AuthErrors.Unauthorized);

        var newClientEmail = VpnConfig.GenerateClientEmail(userId);
        var addResult = await gateway.AddClientAsync(
            node,
            inbound.RemoteInboundId,
            config.Protocol,
            newClientEmail,
            config.Label ?? newClientEmail,
            profile.MaxIpLimit,
            cancellationToken
        );

        if (!addResult.IsSuccess)
            return Result.Failure<VpnConfigDto>(addResult.Error);

        var oldClientExternalId = config.ClientExternalId;
        config.Rotate(newClientEmail, addResult.Value);
        await dbContext.SaveChangesAsync(cancellationToken);

        // Старого клиента удаляем ПОСЛЕ коммита нового состояния: если удаление не выйдет,
        // у пользователя просто останется лишний нерабочий-для-него клиент в панели — не критично.
        await gateway.RemoveClientAsync(
            node,
            inbound.RemoteInboundId,
            oldClientExternalId,
            config.Protocol,
            cancellationToken
        );

        return Result.Success(VpnConfigDto.FromDomain(config, inbound));
    }
}