using System;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Logging;

namespace Svrnty.CQRS.Events.PostgreSQL.Migration;

/// <summary>
/// Hosted service that runs database migrations on application startup.
/// </summary>
internal class MigrationHostedService : IHostedService
{
    private readonly DatabaseMigrator _migrator;
    private readonly ILogger<MigrationHostedService> _logger;

    public MigrationHostedService(
        DatabaseMigrator migrator,
        ILogger<MigrationHostedService> logger)
    {
        _migrator = migrator ?? throw new ArgumentNullException(nameof(migrator));
        _logger = logger ?? throw new ArgumentNullException(nameof(logger));
    }

    public async Task StartAsync(CancellationToken cancellationToken)
    {
        _logger.LogInformation("Running database migrations...");

        try
        {
            await _migrator.MigrateAsync(cancellationToken);
            _logger.LogInformation("Database migrations completed successfully");
        }
        catch (Exception ex)
        {
            _logger.LogError(ex, "Failed to run database migrations");
            throw; // Fail application startup if migrations fail
        }
    }

    public Task StopAsync(CancellationToken cancellationToken)
    {
        // No cleanup needed
        return Task.CompletedTask;
    }
}