using System.Diagnostics.Metrics;
using System.Linq.Expressions;
using System.Runtime.CompilerServices;
using JdeScoping.Core.Interfaces;
using JdeScoping.Core.Models.Enums;
using JdeScoping.DataAccess.Interfaces;
using JdeScoping.DataSync.Options;
using JdeScoping.DataSync.Contracts;
using JdeScoping.DataSync.IntegrationTests.Infrastructure;
using JdeScoping.DataSync.Models;
using JdeScoping.DataSync.Services;
using JdeScoping.DataSync.Telemetry;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Logging.Abstractions;
using Microsoft.Extensions.Options;
using NSubstitute;

namespace JdeScoping.DataSync.IntegrationTests;

/// <summary>
/// Integration tests for TableSyncOperation.
/// Tests end-to-end sync paths (incremental and mass) against real SQL Server.
/// </summary>
[Collection("Database")]
public class TableSyncOperationTests : IAsyncLifetime
{
    private readonly SqlServerFixture _fixture;
    private SqlConnection _connection = null!;

    public TableSyncOperationTests(SqlServerFixture fixture)
    {
        _fixture = fixture;
    }

    public async Task InitializeAsync()
    {
        _connection = await _fixture.CreateConnectionAsync();
        await _fixture.CleanupTablesAsync();
    }

    public async Task DisposeAsync()
    {
        await _connection.DisposeAsync();
    }

    #region Daily Update (Incremental Path) Tests

    [Fact]
    public async Task ExecuteAsync_DailyUpdate_UsesStagingAndMerge()
    {
        // Arrange
        var baseTime = DateTime.UtcNow;

        // Pre-populate with some existing records
        var existingRecords = new List<WorkOrderTestEntity>
        {
            new() { OrderNumber = 1, Status = "Old", Description = "Existing 1", Quantity = 10, LastUpdateDT = baseTime.AddHours(-2) },
            new() { OrderNumber = 2, Status = "Old", Description = "Existing 2", Quantity = 20, LastUpdateDT = baseTime.AddHours(-2) }
        };
        await InsertWorkOrdersDirectly(existingRecords);

        // New records to sync (one update, one insert)
        var syncRecords = new List<WorkOrderTestEntity>
        {
            new() { OrderNumber = 1, Status = "Updated", Description = "Updated 1", Quantity = 100, LastUpdateDT = baseTime },
            new() { OrderNumber = 3, Status = "New", Description = "New 3", Quantity = 30, LastUpdateDT = baseTime }
        };

        var sut = CreateTableSyncOperation(syncRecords);
        var task = CreateTask("WorkOrder_Test", UpdateTypes.Daily, minimumDt: baseTime.AddDays(-1));

        // Act
        await sut.ExecuteAsync(task);

        // Assert
        var results = (await _connection.QueryAsync<WorkOrderTestEntity>(
            "SELECT * FROM WorkOrder_Test ORDER BY OrderNumber")).ToList();

        results.Count.ShouldBe(3);

        // Record 1 should be updated
        results[0].OrderNumber.ShouldBe(1);
        results[0].Status.ShouldBe("Updated");
        results[0].Quantity.ShouldBe(100);

        // Record 2 should be unchanged (not in sync batch)
        results[1].OrderNumber.ShouldBe(2);
        results[1].Status.ShouldBe("Old");

        // Record 3 should be inserted
        results[2].OrderNumber.ShouldBe(3);
        results[2].Status.ShouldBe("New");
    }

    [Fact]
    public async Task ExecuteAsync_HourlyUpdate_UsesStagingAndMerge()
    {
        // Arrange
        var syncRecords = TestDataGenerator.GenerateWorkOrders(15);
        var sut = CreateTableSyncOperation(syncRecords);
        var task = CreateTask("WorkOrder_Test", UpdateTypes.Hourly, minimumDt: DateTime.UtcNow.AddHours(-1));

        // Act
        await sut.ExecuteAsync(task);

        // Assert
        var count = await _connection.ExecuteScalarAsync<int>("SELECT COUNT(*) FROM WorkOrder_Test");
        count.ShouldBe(15);
    }

    #endregion

    #region Mass Update (Truncate Path) Tests

    [Fact]
    public async Task ExecuteAsync_MassUpdate_UsesTruncatePath()
    {
        // Arrange: Pre-populate table
        var existingRecords = TestDataGenerator.GenerateWorkOrders(50);
        await InsertWorkOrdersDirectly(existingRecords);

        var initialCount = await _connection.ExecuteScalarAsync<int>("SELECT COUNT(*) FROM WorkOrder_Test");
        initialCount.ShouldBe(50);

        // New mass sync with different records
        var massRecords = TestDataGenerator.GenerateWorkOrders(30);
        var sut = CreateTableSyncOperation(massRecords);
        var task = CreateTask("WorkOrder_Test", UpdateTypes.Mass, prepurge: true);

        // Act
        await sut.ExecuteAsync(task);

        // Assert: Table should be truncated and reloaded
        var finalCount = await _connection.ExecuteScalarAsync<int>("SELECT COUNT(*) FROM WorkOrder_Test");
        finalCount.ShouldBe(30);
    }

    [Fact]
    public async Task ExecuteAsync_MassUpdate_WithEmptyRecords_TruncatesTable()
    {
        // Arrange: Pre-populate table
        var existingRecords = TestDataGenerator.GenerateWorkOrders(25);
        await InsertWorkOrdersDirectly(existingRecords);

        var sut = CreateTableSyncOperation(new List<WorkOrderTestEntity>());
        var task = CreateTask("WorkOrder_Test", UpdateTypes.Mass, prepurge: true);

        // Act
        await sut.ExecuteAsync(task);

        // Assert: Table should be empty
        var count = await _connection.ExecuteScalarAsync<int>("SELECT COUNT(*) FROM WorkOrder_Test");
        count.ShouldBe(0);
    }

    #endregion

    #region Temp Table Cleanup Tests

    [Fact]
    public async Task ExecuteAsync_OnSuccess_CleansTempTable()
    {
        // Arrange
        var syncRecords = TestDataGenerator.GenerateWorkOrders(10);
        var sut = CreateTableSyncOperation(syncRecords);
        var task = CreateTask("WorkOrder_Test", UpdateTypes.Daily, minimumDt: DateTime.UtcNow.AddDays(-1));

        // Act
        await sut.ExecuteAsync(task);

        // Assert: No temp tables should remain (BulkMergeHelper uses #TEMP_* naming)
        var tempTableCount = await _connection.ExecuteScalarAsync<int>(@"
            SELECT COUNT(*)
            FROM tempdb.sys.tables
            WHERE name LIKE '#TEMP[_]%'");

        tempTableCount.ShouldBe(0);
    }

    [Fact]
    public async Task ExecuteAsync_OnFetcherError_CleansTempTable()
    {
        // Arrange: Create a fetcher that throws after yielding some records
        var failingFetcher = new FailingFetcher(failAfterCount: 5);

        var sut = CreateTableSyncOperationWithFetcher(failingFetcher);
        var task = CreateTask("WorkOrder_Test", UpdateTypes.Daily, minimumDt: DateTime.UtcNow.AddDays(-1), fetcherTypeName: nameof(FailingFetcher));

        // Act & Assert
        await Should.ThrowAsync<InvalidOperationException>(() => sut.ExecuteAsync(task));

        // Temp tables should still be cleaned up
        var tempTableCount = await _connection.ExecuteScalarAsync<int>(@"
            SELECT COUNT(*)
            FROM tempdb.sys.tables
            WHERE name LIKE '#TEMP[_]%'");

        tempTableCount.ShouldBe(0);
    }

    #endregion

    #region Helper Methods

    private TableSyncOperation CreateTableSyncOperation(List<WorkOrderTestEntity> records)
    {
        var fetcher = new TestFetcher(records);
        return CreateTableSyncOperationWithFetcher(fetcher);
    }

    private TableSyncOperation CreateTableSyncOperationWithFetcher(IDataFetcher<WorkOrderTestEntity> fetcher)
    {
        var services = new ServiceCollection();
        services.AddMetrics();
        services.AddSingleton(fetcher);
        var provider = services.BuildServiceProvider();

        var connectionFactory = Substitute.For<IDbConnectionFactory>();
        connectionFactory.CreateLotFinderConnectionAsync(Arg.Any<CancellationToken>())
            .Returns(async _ =>
            {
                var conn = new SqlConnection(_fixture.ConnectionString);
                await conn.OpenAsync();
                return conn;
            });

        var updateRepository = Substitute.For<IDataUpdateRepository>();
        updateRepository.StartUpdateAsync(
            Arg.Any<string>(), Arg.Any<string>(), Arg.Any<string>(),
            Arg.Any<UpdateTypes>(), Arg.Any<CancellationToken>())
            .Returns(1);

        // Setup mock BulkMergeHelper for integration tests - return appropriate results
        var bulkMergeHelper = Substitute.For<IBulkMergeHelper>();

        // Setup mock merge configuration registry
        var configRegistry = Substitute.For<IMergeConfigurationRegistry>();
        var mockConfig = Substitute.For<IMergeConfiguration<WorkOrderTestEntity>>();
        mockConfig.TableName.Returns("WorkOrder_Test");
        mockConfig.MatchOn.Returns(x => x.OrderNumber);
        mockConfig.UpdateColumns.Returns(x => new { x.Status, x.Description, x.Quantity, x.LastUpdateDT });
        mockConfig.UpdateWhen.Returns((src, tgt) => src.LastUpdateDT > tgt.LastUpdateDT);
        mockConfig.InsertColumns.Returns((Expression<Func<WorkOrderTestEntity, object>>?)null);
        configRegistry.GetConfiguration<WorkOrderTestEntity>().Returns(mockConfig);

        // Setup BulkMergeHelper to return results based on actual data processing
        bulkMergeHelper.MergeAsync(
            Arg.Any<IAsyncEnumerable<WorkOrderTestEntity>>(),
            Arg.Any<string>(),
            Arg.Any<Expression<Func<WorkOrderTestEntity, object>>>(),
            Arg.Any<Expression<Func<WorkOrderTestEntity, object>>>(),
            Arg.Any<Expression<Func<WorkOrderTestEntity, WorkOrderTestEntity, bool>>>(),
            Arg.Any<Expression<Func<WorkOrderTestEntity, object>>>(),
            Arg.Any<string>(),
            Arg.Any<int>(),
            Arg.Any<bool>(),
            Arg.Any<CancellationToken>())
            .Returns(async callInfo =>
            {
                var data = callInfo.ArgAt<IAsyncEnumerable<WorkOrderTestEntity>>(0);
                var records = await data.ToListAsync();

                // Actually perform the merge against the real database using Dapper
                foreach (var record in records)
                {
                    var exists = await _connection.ExecuteScalarAsync<bool>(
                        "SELECT CASE WHEN EXISTS (SELECT 1 FROM WorkOrder_Test WHERE OrderNumber = @OrderNumber) THEN 1 ELSE 0 END",
                        new { record.OrderNumber });

                    if (exists)
                    {
                        await _connection.ExecuteAsync(@"
                            UPDATE WorkOrder_Test
                            SET Status = @Status, Description = @Description, Quantity = @Quantity, LastUpdateDT = @LastUpdateDT
                            WHERE OrderNumber = @OrderNumber",
                            record);
                    }
                    else
                    {
                        await _connection.ExecuteAsync(@"
                            INSERT INTO WorkOrder_Test (OrderNumber, Status, Description, Quantity, LastUpdateDT)
                            VALUES (@OrderNumber, @Status, @Description, @Quantity, @LastUpdateDT)",
                            record);
                    }
                }

                return new MergeResult(
                    records.Count,
                    records.Count,
                    0,
                    0,
                    TimeSpan.Zero);
            });

        bulkMergeHelper.MassInsertAsync(
            Arg.Any<IAsyncEnumerable<WorkOrderTestEntity>>(),
            Arg.Any<string>(),
            Arg.Any<bool>(),
            Arg.Any<int>(),
            Arg.Any<CancellationToken>())
            .Returns(async callInfo =>
            {
                var data = callInfo.ArgAt<IAsyncEnumerable<WorkOrderTestEntity>>(0);
                var records = await data.ToListAsync();

                // Truncate and insert into real database
                await _connection.ExecuteAsync("TRUNCATE TABLE WorkOrder_Test");
                foreach (var record in records)
                {
                    await _connection.ExecuteAsync(@"
                        INSERT INTO WorkOrder_Test (OrderNumber, Status, Description, Quantity, LastUpdateDT)
                        VALUES (@OrderNumber, @Status, @Description, @Quantity, @LastUpdateDT)",
                        record);
                }

                return new MassInsertResult(records.Count, TimeSpan.Zero, true);
            });

        var options = Microsoft.Extensions.Options.Options.Create(new DataSyncOptions
        {
            BatchSize = 1000,
            BulkCopyBatchSize = 100
        });

        var meterFactory = provider.GetRequiredService<IMeterFactory>();
        var metrics = new DataSyncMetrics(meterFactory);

        // Create a service provider that can resolve our test fetcher
        var testServiceProvider = Substitute.For<IServiceProvider>();
        testServiceProvider.GetService(typeof(TestFetcher)).Returns(fetcher);
        testServiceProvider.GetService(typeof(FailingFetcher)).Returns(fetcher);

        return new TableSyncOperation(
            testServiceProvider,
            connectionFactory,
            updateRepository,
            bulkMergeHelper,
            configRegistry,
            options,
            NullLogger<TableSyncOperation>.Instance,
            metrics);
    }

    private static DataUpdateTask CreateTask(
        string tableName,
        UpdateTypes updateType,
        DateTime? minimumDt = null,
        bool prepurge = false,
        string? fetcherTypeName = null)
    {
        return new DataUpdateTask
        {
            TableName = tableName,
            SourceSystem = "JDE",
            SourceData = tableName.ToUpper(),
            UpdateType = updateType,
            MinimumDt = minimumDt,
            Config = new DataSourceConfig
            {
                TableName = tableName,
                SourceSystem = "JDE",
                SourceData = tableName.ToUpper(),
                FetcherTypeName = fetcherTypeName ?? nameof(TestFetcher),
                IsEnabled = true,
                MassConfig = new ScheduleConfig
                {
                    Enabled = true,
                    IntervalMinutes = 10080,
                    PrepurgeData = prepurge,
                    ReIndexData = false
                },
                DailyConfig = new ScheduleConfig { Enabled = true, IntervalMinutes = 1440 },
                HourlyConfig = new ScheduleConfig { Enabled = true, IntervalMinutes = 60 }
            }
        };
    }

    private async Task InsertWorkOrdersDirectly(List<WorkOrderTestEntity> records)
    {
        const string sql = @"
            INSERT INTO WorkOrder_Test (OrderNumber, Status, Description, Quantity, LastUpdateDT)
            VALUES (@OrderNumber, @Status, @Description, @Quantity, @LastUpdateDT)";

        await _connection.ExecuteAsync(sql, records);
    }

    #endregion
}

#region Test Fetchers

/// <summary>
/// Test fetcher that yields records from an in-memory list.
/// </summary>
public class TestFetcher : IDataFetcher<WorkOrderTestEntity>
{
    private readonly List<WorkOrderTestEntity> _records;

    public TestFetcher(List<WorkOrderTestEntity> records)
    {
        _records = records;
    }

    public async IAsyncEnumerable<WorkOrderTestEntity> FetchAsync(
        DateTime? minimumDt,
        [EnumeratorCancellation] CancellationToken cancellationToken = default)
    {
        foreach (var record in _records)
        {
            if (cancellationToken.IsCancellationRequested)
                yield break;

            await Task.Yield(); // Simulate async behavior
            yield return record;
        }
    }
}

/// <summary>
/// Test fetcher that fails after yielding a specified number of records.
/// </summary>
public class FailingFetcher : IDataFetcher<WorkOrderTestEntity>
{
    private readonly int _failAfterCount;

    public FailingFetcher(int failAfterCount)
    {
        _failAfterCount = failAfterCount;
    }

    public async IAsyncEnumerable<WorkOrderTestEntity> FetchAsync(
        DateTime? minimumDt,
        [EnumeratorCancellation] CancellationToken cancellationToken = default)
    {
        for (var i = 0; i < _failAfterCount; i++)
        {
            await Task.Yield();
            yield return new WorkOrderTestEntity
            {
                OrderNumber = i + 1,
                Status = "Test",
                Description = $"Record {i + 1}",
                Quantity = i * 10,
                LastUpdateDT = DateTime.UtcNow
            };
        }

        throw new InvalidOperationException("Simulated fetcher failure");
    }
}

#endregion