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

namespace PnvPanel.Application.Support.CreateRoleRequest;

/// <summary>Проверка "нет висящей заявки" + создание — под AdvisoryLock (по UserId), см.
/// CreatePaymentRequestCommandHandler для полного обоснования.</summary>
public sealed class CreateRoleRequestTicketCommandHandler(
    IAppDbContext dbContext,
    IRoleService roleService,
    IRealtimeNotifier notifier,
    ITelegramNotifier telegramNotifier,
    ICurrentUser currentUser
) : ICommandHandler<CreateRoleRequestTicketCommand, Result<TicketDetailDto>>
{
    // Совпадает со значением Infrastructure.Identity.RoleNames.Admin — Application не может ссылаться
    // на Infrastructure (направление зависимостей), поэтому системное имя роли продублировано здесь.
    private const string AdminRoleName = "admin";

    public async Task<Result<TicketDetailDto>> Handle(
        CreateRoleRequestTicketCommand command,
        CancellationToken cancellationToken
    )
    {
        if (currentUser.UserId is not { } userId)
            return Result.Failure<TicketDetailDto>(AuthErrors.Unauthorized);

        string? requestedRoleName = null;
        if (command.ExistingRoleId is { } existingRoleId)
        {
            var roles = await roleService.ListRolesAsync(cancellationToken);
            var role = roles.FirstOrDefault(r => r.Id == existingRoleId);
            if (role is null)
                return Result.Failure<TicketDetailDto>(SupportErrors.RoleNotFound);

            if (role.Name.Equals(AdminRoleName, StringComparison.OrdinalIgnoreCase))
                return Result.Failure<TicketDetailDto>(SupportErrors.CannotRequestAdminRole);

            requestedRoleName = role.Name;
        }

        var claimed = await AdvisoryLock.RunAsync(
            dbContext,
            userId,
            async lockedCancellationToken =>
            {
                var hasPending = await dbContext.SupportTickets.AnyAsync(
                    t =>
                        t.UserId == userId
                        && t.Type == TicketType.RoleRequest
                        && t.Status == TicketStatus.Open,
                    lockedCancellationToken
                );
                if (hasPending)
                    return Result.Failure<(SupportTicket, TicketComment)>(
                        SupportErrors.RoleRequestAlreadyPending
                    );

                var newTicket =
                    command.ExistingRoleId is { } roleId
                        ? SupportTicket.CreateRoleRequestForExistingRole(userId, roleId)
                        : SupportTicket.CreateRoleRequestForNewRole(
                            userId,
                            command.NewRoleName!,
                            command.NewRoleMaxConfigs!.Value,
                            command.NewRoleMaxIpLimit!.Value
                        );
                dbContext.SupportTickets.Add(newTicket);
                var newComment = TicketComment.Create(newTicket.Id, userId, command.Justification);
                dbContext.TicketComments.Add(newComment);
                return Result.Success((newTicket, newComment));
            },
            cancellationToken
        );
        if (!claimed.IsSuccess)
            return Result.Failure<TicketDetailDto>(claimed.Error);

        var (ticket, comment) = claimed.Value;
        var userName = currentUser.UserName ?? userId.ToString();
        var roleDescription =
            requestedRoleName
            ?? $"новая роль «{command.NewRoleName}» (конфигов: {command.NewRoleMaxConfigs}, IP: {command.NewRoleMaxIpLimit})";

        await notifier.NotifyTicketCreatedAsync(
            ticket.Id,
            userId,
            userName,
            ticket.Type,
            cancellationToken
        );
        await telegramNotifier.NotifyAdminsRoleRequestCreatedAsync(
            ticket.Id,
            userName,
            roleDescription,
            command.Justification,
            cancellationToken
        );

        var commentDto = new TicketCommentDto(
            comment.Id,
            userId,
            userName,
            comment.Body,
            comment.CreatedAt,
            []
        );

        var dto = new TicketDetailDto(
            ticket.Id,
            ticket.UserId,
            userName,
            ticket.Type,
            ticket.Status,
            ticket.RequestedRoleId,
            requestedRoleName,
            ticket.ProposedRoleName,
            ticket.ProposedMaxConfigs,
            ticket.ProposedMaxIpLimit,
            ticket.RequestedDays,
            ticket.CreatedAt,
            [commentDto]
        );

        return Result.Success(dto);
    }
}