/*
 * DynamORM - Dynamic Object-Relational Mapping library.
 * Copyright (c) 2012-2026, Grzegorz Russek (grzegorz.russek@gmail.com)
 * All rights reserved.
 */

using System;
using System.Data;
using System.Threading;
using System.Threading.Tasks;
using NUnit.Framework;

namespace DynamORM.Tests.Helpers
{
    [TestFixture]
    public class ConnectionPoolingAndLockingTests
    {
        private FakeProviderState _state;
        private DynamicDatabase _db;

        [TearDown]
        public void TearDown()
        {
            if (_db != null)
                _db.Dispose();
        }

        [Test]
        public void TestConnectionPoolingReusesIdleConnection()
        {
            CreateDatabase(DynamicDatabaseOptions.ConnectionPooling);

            using (_db.Open()) { }
            using (_db.Open()) { }

            Assert.AreEqual(1, _state.CreatedConnections);
            Assert.AreEqual(1, _state.OpenCalls);
            Assert.AreEqual(0, _state.CloseCalls);
        }

        [Test]
        public void TestConnectionPoolingWaitsForReleasedConnectionWhenAtMaximum()
        {
            CreateDatabase(DynamicDatabaseOptions.ConnectionPooling);
            _db.ConnectionPoolingKeepOpenCount = 1;
            _db.ConnectionPoolingMaximumOpenCount = 1;

            var first = _db.Open();
            var started = new ManualResetEventSlim(false);
            var completed = new ManualResetEventSlim(false);

            var task = Task.Run(() =>
            {
                started.Set();
                using (_db.Open()) { }
                completed.Set();
            });

            Assert.IsTrue(started.Wait(TimeSpan.FromSeconds(2)));
            Assert.IsFalse(completed.Wait(TimeSpan.FromMilliseconds(200)));

            first.Dispose();

            Assert.IsTrue(completed.Wait(TimeSpan.FromSeconds(2)));
            task.Wait(TimeSpan.FromSeconds(2));
            Assert.AreEqual(1, _state.CreatedConnections);
        }

        [Test]
        public void TestConnectionPoolingClosesExpiredIdleConnections()
        {
            CreateDatabase(DynamicDatabaseOptions.ConnectionPooling);
            _db.ConnectionPoolingConnectionLifetime = TimeSpan.Zero;

            using (_db.Open()) { }
            using (_db.Open()) { }

            Assert.AreEqual(2, _state.CreatedConnections);
            Assert.GreaterOrEqual(_state.CloseCalls, 1);
            Assert.GreaterOrEqual(_state.DisposeCalls, 1);
        }

        [Test]
        public void TestConnectionPoolingTrimsIdleConnectionsAbovePreferredLimit()
        {
            CreateDatabase(DynamicDatabaseOptions.ConnectionPooling);
            _db.ConnectionPoolingKeepOpenCount = 1;
            _db.ConnectionPoolingMaximumOpenCount = 3;

            var c1 = _db.Open();
            var c2 = _db.Open();
            var c3 = _db.Open();

            c1.Dispose();
            c2.Dispose();
            c3.Dispose();

            Assert.AreEqual(3, _state.CreatedConnections);
            Assert.AreEqual(2, _state.CloseCalls);
            Assert.AreEqual(2, _state.DisposeCalls);
        }

        [Test]
        public void TestDirectTransactionUsesSameThreadConnectionAndSeparateThreadGetsDifferentOne()
        {
            CreateDatabase(DynamicDatabaseOptions.ConnectionPooling);

            using (var trans = _db.BeginTransaction())
            {
                IDbConnection threadLocalA = _db.Open();
                IDbConnection threadLocalB = _db.Open();

                try
                {
                    Assert.AreSame(((DynamicConnection)threadLocalA).Connection, ((DynamicConnection)threadLocalB).Connection);

                    IDbConnection otherThreadConnection = null;
                    var task = Task.Run(() =>
                    {
                        using (var other = _db.Open())
                            otherThreadConnection = ((DynamicConnection)other).Connection;
                    });

                    Assert.IsTrue(task.Wait(TimeSpan.FromSeconds(2)));
                    Assert.AreNotSame(((DynamicConnection)threadLocalA).Connection, otherThreadConnection);
                }
                finally
                {
                    threadLocalA.Dispose();
                    threadLocalB.Dispose();
                }
            }
        }

        [Test]
        public void TestDirectTransactionUsesTransactionOnlyOnOwningThread()
        {
            CreateDatabase(DynamicDatabaseOptions.ConnectionPooling);

            using (var transaction = _db.BeginTransaction())
            {
                ExecuteFakeCommand();

                var otherThread = Task.Run(() => ExecuteFakeCommand());
                Assert.IsTrue(otherThread.Wait(TimeSpan.FromSeconds(2)));

                transaction.Commit();
            }

            lock (_state.SeenTransactions)
            {
                Assert.AreEqual(2, _state.SeenTransactions.Count);
                Assert.NotNull(_state.SeenTransactions[0]);
                Assert.IsNull(_state.SeenTransactions[1]);
            }
        }

        [TestCase(DynamicDatabaseOptions.SingleConnection)]
        [TestCase(DynamicDatabaseOptions.SingleTransaction)]
        public void TestSingleModesSerializeCommandExecution(DynamicDatabaseOptions option)
        {
            CreateDatabase(option);
            _state.BlockFirstExecution = true;
            _state.AllowExecution.Reset();

            Task task1 = Task.Run(() => ExecuteFakeCommand());
            Assert.IsTrue(_state.FirstExecutionEntered.Wait(TimeSpan.FromSeconds(2)));

            Task task2 = Task.Run(() => ExecuteFakeCommand());
            Thread.Sleep(200);

            Assert.AreEqual(1, _state.MaxConcurrentExecutions);

            _state.AllowExecution.Set();

            Assert.IsTrue(Task.WaitAll(new[] { task1, task2 }, TimeSpan.FromSeconds(5)));
            Assert.AreEqual(1, _state.MaxConcurrentExecutions);
        }

        [TestCase(DynamicDatabaseOptions.SingleConnection)]
        [TestCase(DynamicDatabaseOptions.SingleTransaction)]
        public void TestSingleModesSerializeReaderLifetime(DynamicDatabaseOptions option)
        {
            CreateDatabase(option);
            _state.BlockFirstReader = true;
            _state.AllowReader.Reset();

            IDataReader reader = null;
            var task1 = Task.Run(() =>
            {
                using (var connection = _db.Open())
                using (var command = connection.CreateCommand())
                {
                    command.SetCommand("SELECT 1;");
                    reader = command.ExecuteReader();
                }
            });

            Assert.IsTrue(_state.FirstReaderEntered.Wait(TimeSpan.FromSeconds(2)));

            var secondCompleted = new ManualResetEventSlim(false);
            var task2 = Task.Run(() =>
            {
                ExecuteFakeCommand();
                secondCompleted.Set();
            });

            Assert.IsFalse(secondCompleted.Wait(TimeSpan.FromMilliseconds(200)));

            _state.AllowReader.Set();
            SpinWait.SpinUntil(() => reader != null, TimeSpan.FromSeconds(2));
            reader.Dispose();

            Assert.IsTrue(Task.WaitAll(new[] { task1, task2 }, TimeSpan.FromSeconds(5)));
            Assert.AreEqual(1, _state.MaxConcurrentExecutions);
        }

        private void ExecuteFakeCommand()
        {
            using (var connection = _db.Open())
            using (var command = connection.CreateCommand())
            {
                command.SetCommand("SELECT 1;");
                command.ExecuteNonQuery();
            }
        }

        private void CreateDatabase(DynamicDatabaseOptions options)
        {
            _state = new FakeProviderState();
            _db = new DynamicDatabase(new FakeProviderFactory(_state), "fake", options);
        }
    }
}