using Microsoft.Extensions.Options;
using MongoDB.Driver;

namespace StellaOps.Concelier.Storage.Mongo;

public interface IMongoSessionProvider
{
    Task<IClientSessionHandle> StartSessionAsync(CancellationToken cancellationToken = default);
}

internal sealed class MongoSessionProvider : IMongoSessionProvider
{
    private readonly IMongoClient _client;
    private readonly MongoStorageOptions _options;

    public MongoSessionProvider(IMongoClient client, IOptions<MongoStorageOptions> options)
    {
        _client = client ?? throw new ArgumentNullException(nameof(client));
        _options = options?.Value ?? throw new ArgumentNullException(nameof(options));
    }

    public Task<IClientSessionHandle> StartSessionAsync(CancellationToken cancellationToken = default)
    {
        var sessionOptions = new ClientSessionOptions
        {
            DefaultTransactionOptions = new TransactionOptions(
                readPreference: ReadPreference.Primary,
                readConcern: ReadConcern.Majority,
                writeConcern: WriteConcern.WMajority.With(wTimeout: _options.CommandTimeout))
        };

        return _client.StartSessionAsync(sessionOptions, cancellationToken);
    }
}