using Microsoft.Extensions.Options;
using MongoDB.Driver;
using Supercell.GUT.Server.Database.Document;
using Supercell.GUT.Server.Database.Options;

namespace Supercell.GUT.Server.Database;

public class DatabaseManager
{
    private const string IdentifierCounterCollection = "t_id_counter";
    private static readonly FindOneAndUpdateOptions<IdentifierCounterDocument> s_counterUpdateOptions = new() { ReturnDocument = ReturnDocument.After };

    private readonly DatabaseOptions _options;

    private readonly MongoClient _client;
    private readonly IMongoDatabase _database;

    private readonly IMongoCollection<IdentifierCounterDocument> _idCounters;

    public DatabaseManager(IOptions<DatabaseOptions> options)
    {
        _options = options.Value;

        _client = new MongoClient(_options.MongoConnectionString);
        _database = _client.GetDatabase(_options.DatabaseName);

        _idCounters = _database.GetCollection<IdentifierCounterDocument>(IdentifierCounterCollection);
    }

    public IMongoCollection<TDatabaseDocument> GetCollection<TDatabaseDocument>(string collectionName) where TDatabaseDocument : IDatabaseDocument
    {
        return _database.GetCollection<TDatabaseDocument>(collectionName);
    }

    public async Task<int> GetNextLowIdAsync(string counterName)
    {
        var cursor = await _idCounters.FindAsync(doc => doc.CounterName == counterName);
        if (!cursor.Any())
        {
            await _idCounters.InsertOneAsync(new IdentifierCounterDocument
            {
                CounterName = counterName,
                CurrentLowId = 0
            });
        }

        IdentifierCounterDocument? document = await _idCounters.FindOneAndUpdateAsync<IdentifierCounterDocument>(
            x => x.CounterName == counterName,
            Builders<IdentifierCounterDocument>.Update.Inc(nameof(IdentifierCounterDocument.CurrentLowId), 1),
            s_counterUpdateOptions);

        return document.CurrentLowId;
    }
}