using MiaoJiZhang.Infrastructure.Persistence;
using Microsoft.EntityFrameworkCore;

namespace MiaoJiZhang.Api.Services;

public class AccountClosureCleanupService(
    IServiceScopeFactory scopeFactory,
    ILogger<AccountClosureCleanupService> logger) : BackgroundService
{
    protected override async Task ExecuteAsync(
        CancellationToken stoppingToken)
    {
        await Cleanup(stoppingToken);
        using var timer = new PeriodicTimer(TimeSpan.FromHours(1));
        while (await timer.WaitForNextTickAsync(stoppingToken))
            await Cleanup(stoppingToken);
    }

    private async Task Cleanup(CancellationToken ct)
    {
        try
        {
            using var scope = scopeFactory.CreateScope();
            var db = scope.ServiceProvider.GetRequiredService<AppDbContext>();
            var eraser =
                scope.ServiceProvider.GetRequiredService<AccountDataEraser>();
            var ids = await db.Users
                .Where(user =>
                    user.AccountClosureScheduledAt.HasValue &&
                    user.AccountClosureScheduledAt <= DateTime.UtcNow)
                .Select(user => user.Id)
                .ToListAsync(ct);
            foreach (var userId in ids)
            {
                await eraser.EraseAsync(userId, ct);
                logger.LogInformation(
                    "Permanently removed account {UserId} after closure grace period",
                    userId);
            }
        }
        catch (OperationCanceledException) when (ct.IsCancellationRequested)
        {
        }
        catch (Exception exception)
        {
            logger.LogError(exception, "Account closure cleanup failed");
        }
    }
}