using FluentResults;
using MediatR;
using Microsoft.AspNetCore.SignalR;
using Microsoft.EntityFrameworkCore;
using NexusReader.Application.Commands.Sync;
using NexusReader.Domain.Entities;
using NexusReader.Infrastructure.Persistence;
using NexusReader.Infrastructure.RealTime;

namespace NexusReader.Infrastructure.Handlers;

public class UpdateReadingProgressCommandHandler : IRequestHandler<UpdateReadingProgressCommand, Result>
{
    private readonly AppDbContext _context;
    private readonly IHubContext<SyncHub> _hubContext;

    public UpdateReadingProgressCommandHandler(
        AppDbContext context, 
        IHubContext<SyncHub> hubContext)
    {
        _context = context;
        _hubContext = hubContext;
    }

    public async Task<Result> Handle(UpdateReadingProgressCommand request, CancellationToken cancellationToken)
    {
        var user = await _context.Users.FirstOrDefaultAsync(u => u.Id == request.UserId, cancellationToken);
        if (user == null)
        {
            return Result.Fail("User not found.");
        }

        var now = DateTime.UtcNow;
        user.LastReadPageId = request.PageId;
        user.LastReadAt = now;

        await _context.SaveChangesAsync(cancellationToken);

        // Broadcast to other devices
        await _hubContext.Clients
            .Group($"User_{request.UserId}")
            .SendAsync("ProgressUpdated", request.PageId, now, cancellationToken);

        return Result.Ok();
    }
}