sql-utilities/tests/Strata.SqlTools.SqlServer.Tests/SqlServer/QueryBreakdownTests.cs

using Strata.SqlTools.Breakdowns.SqlServer;
using Strata.SqlTools.SqlBreakdown.Expressions;
using Strata.SqlTools.SqlBreakdown.Expressions.Literals;
using Strata.SqlTools.SqlServer.Exceptions;

namespace Strata.SqlTools.SqlBreakdown.Tests.SqlServer;

[TestFixture]
public class QueryBreakdownTests
{
    #region Constructor Tests

    [Test]
    public void Constructor_Default_InitializesEmptyProperties()
    {
        // Arrange & Act
        var query = new QueryBreakdown();

        // Assert
        Assert.That(query.SelectClause.Clause, Is.EqualTo(string.Empty));
        Assert.That(query.FromClause.Clause, Is.EqualTo(string.Empty));
        Assert.That(query.WhereClause.Clause, Is.EqualTo(string.Empty));
        Assert.That(query.OrderByClause.Clause, Is.EqualTo(string.Empty));
        Assert.That(query.GroupByClause.Clause, Is.EqualTo(string.Empty));
        Assert.That(query.HavingClause.Clause, Is.EqualTo(string.Empty));
        Assert.That(query.SetupClauses, Is.Not.Null);
        Assert.That(query.FinishClauses, Is.Not.Null);
        Assert.That(query.WithClauses, Is.Not.Null);
        Assert.That(query.WithClauses, Is.Empty);
        Assert.That(query.Parameters, Is.Not.Null);
        Assert.That(query.ParameterList, Is.Not.Null);
    }

    [Test]
    public void Constructor_WithSelectAndFrom_SetsProperties()
    {
        // Arrange
        var selectClause = "ID, Name";
        var fromClause = "Users";

        // Act
        var query = new QueryBreakdown(selectClause, fromClause);

        // Assert
        Assert.That(query.SelectClause.Clause, Is.EqualTo(selectClause));
        Assert.That(query.FromClause.Clause, Is.EqualTo(fromClause));
        Assert.That(query.WhereClause.Clause, Is.EqualTo(string.Empty));
    }

    [Test]
    public void Constructor_WithSelectFromAndWhere_SetsProperties()
    {
        // Arrange
        var selectClause = "ID, Name";
        var fromClause = "Users";
        var whereClause = "Active = 1";

        // Act
        var query = new QueryBreakdown(selectClause, fromClause, whereClause);

        // Assert
        Assert.That(query.SelectClause.Clause, Is.EqualTo(selectClause));
        Assert.That(query.FromClause.Clause, Is.EqualTo(fromClause));
        Assert.That(query.WhereClause.Clause, Is.EqualTo(whereClause));
        Assert.That(query.OrderByClause.Clause, Is.EqualTo(string.Empty));
    }

    [Test]
    public void Constructor_WithAllClauses_SetsProperties()
    {
        // Arrange
        var selectClause = "ID, Name";
        var fromClause = "Users";
        var whereClause = "Active = 1";
        var orderByClause = "Name ASC";

        // Act
        var query = new QueryBreakdown(selectClause, fromClause, whereClause, orderByClause);

        // Assert
        Assert.That(query.SelectClause.Clause, Is.EqualTo(selectClause));
        Assert.That(query.FromClause.Clause, Is.EqualTo(fromClause));
        Assert.That(query.WhereClause.Clause, Is.EqualTo(whereClause));
        Assert.That(query.OrderByClause.Clause, Is.EqualTo(orderByClause));
    }

    #endregion

    #region Property Tests

    [Test]
    public void IsUsingFromClause_WhenFromIsEmpty_ReturnsFalse()
    {
        // Arrange
        var query = new QueryBreakdown();
        query.FromClause.Clause = string.Empty;

        // Act & Assert
        Assert.That(query.IsUsingFromClause, Is.False);
    }

    [Test]
    public void IsUsingFromClause_WhenFromHasValue_ReturnsTrue()
    {
        // Arrange
        var query = new QueryBreakdown();
        query.FromClause.Clause = "Users";

        // Act & Assert
        Assert.That(query.IsUsingFromClause, Is.True);
    }

    [Test]
    public void IsUsingWithClause_WhenNoWithClauses_ReturnsFalse()
    {
        // Arrange
        var query = new QueryBreakdown();

        // Act & Assert
        Assert.That(query.IsUsingWithClause, Is.False);
    }

    [Test]
    public void IsUsingWithClause_WhenWithClausesAdded_ReturnsTrue()
    {
        // Arrange
        var query = new QueryBreakdown("*", "Products");
        var cteQuery = new QueryBreakdown("ProductID, SUM(Quantity) AS Total", "OrderDetails");

        // Act
        query.AddWithClause("ProductSummary", cteQuery);

        // Assert
        Assert.That(query.IsUsingWithClause, Is.True);
    }

    #endregion

    #region Parameter Tests

    [Test]
    public void AddParameter_WithNameAndValue_AddsToParameterList()
    {
        // Arrange
        var query = new QueryBreakdown();

        // Act
        query.AddParameter("UserId", 123);

        // Assert
        Assert.That(query.ParameterList.Count(), Is.EqualTo(1));
        Assert.That(query.Parameters["@UserId"], Is.EqualTo(123));
    }

    [Test]
    public void AddParameter_WithAtSymbol_AddsCorrectly()
    {
        // Arrange
        var query = new QueryBreakdown();

        // Act
        query.AddParameter("@UserId", 456);

        // Assert
        Assert.That(query.Parameters["@UserId"], Is.EqualTo(456));
    }

    [Test]
    public void SetParameterValue_UpdatesExistingParameter()
    {
        // Arrange
        var query = new QueryBreakdown();
        query.AddParameter("UserId", 123);

        // Act
        query.SetParameterValue("UserId", 789);

        // Assert
        Assert.That(query.GetParameterValue("UserId"), Is.EqualTo(789));
    }

    [Test]
    public void GetParameterValue_ForNonExistentParameter_ReturnsNull()
    {
        // Arrange
        var query = new QueryBreakdown();

        // Act
        var value = query.GetParameterValue("NonExistent");

        // Assert
        Assert.That(value, Is.Null);
    }

    #endregion

    #region CTE Parameter Inheritance Tests

    [Test]
    public void GetMergedParameters_WithNoCTEs_ReturnsMainQueryParameters()
    {
        // Arrange
        var query = new QueryBreakdown("*", "users");
        query.AddParameter("@UserId", 123);
        query.AddParameter("@ActiveStatus", true);

        // Act
        var merged = query.GetMergedParameters();

        // Assert
        Assert.That(merged, Has.Count.EqualTo(2));
        Assert.That(merged["@UserId"], Is.EqualTo(123));
        Assert.That(merged["@ActiveStatus"], Is.EqualTo(true));
    }

    [Test]
    public void GetMergedParameters_WithSingleCTE_MergesParameters()
    {
        // Arrange
        var cte = new QueryBreakdown("id, name", "base_users", "active = 1");
        cte.AddParameter("@MinDate", DateTime.Today.AddDays(-30));

        var mainQuery = new QueryBreakdown("*", "active_users");
        mainQuery.AddParameter("@Limit", 100);
        mainQuery.AddWithClause("active_users", cte);

        // Act
        var merged = mainQuery.GetMergedParameters();

        // Assert
        Assert.That(merged, Has.Count.EqualTo(2));
        Assert.That(merged["@MinDate"], Is.EqualTo(DateTime.Today.AddDays(-30)));
        Assert.That(merged["@Limit"], Is.EqualTo(100));
    }

    [Test]
    public void GetMergedParameters_WithMultipleCTEs_MergesAllParameters()
    {
        // Arrange
        var cte1 = new QueryBreakdown("id, status", "users", "status = @Status1");
        cte1.AddParameter("@Status1", "active");

        var cte2 = new QueryBreakdown("user_id, created", "orders", "created >= @MinDate");
        cte2.AddParameter("@MinDate", DateTime.Today.AddDays(-30));

        var mainQuery = new QueryBreakdown("*", "results");
        mainQuery.AddParameter("@ResultLimit", 50);
        mainQuery.AddWithClause("active_users", cte1);
        mainQuery.AddWithClause("recent_orders", cte2);

        // Act
        var merged = mainQuery.GetMergedParameters();

        // Assert
        Assert.That(merged, Has.Count.EqualTo(3));
        Assert.That(merged["@Status1"], Is.EqualTo("active"));
        Assert.That(merged["@MinDate"], Is.EqualTo(DateTime.Today.AddDays(-30)));
        Assert.That(merged["@ResultLimit"], Is.EqualTo(50));
    }

    [Test]
    public void GetMergedParameters_WithParameterConflict_MainQueryTakesPrecedence()
    {
        // Arrange
        var cte = new QueryBreakdown("id", "users");
        cte.AddParameter("@Limit", 10); // CTE sets Limit to 10

        var mainQuery = new QueryBreakdown("*", "final_result");
        mainQuery.AddParameter("@Limit", 100); // Main query sets Limit to 100
        mainQuery.AddWithClause("base_data", cte);

        // Act
        var merged = mainQuery.GetMergedParameters();

        // Assert
        Assert.That(merged, Has.Count.EqualTo(1));
        Assert.That(merged["@Limit"], Is.EqualTo(100)); // Main query value wins
    }

    [Test]
    public void GetMergedParameters_WithNestedCTEs_CollectsAllParameters()
    {
        // Arrange: Create deeply nested CTEs
        var innerCte = new QueryBreakdown("id", "base_table");
        innerCte.AddParameter("@InnerParam", "inner_value");

        var middleCte = new QueryBreakdown("id, name", "layer1");
        middleCte.AddParameter("@MiddleParam", "middle_value");
        middleCte.AddWithClause("layer1_source", innerCte);

        var mainQuery = new QueryBreakdown("id, name, status", "layer2");
        mainQuery.AddParameter("@MainParam", "main_value");
        mainQuery.AddWithClause("layer2_source", middleCte);

        // Act
        var merged = mainQuery.GetMergedParameters();

        // Assert - All parameters from all levels should be present
        Assert.That(merged, Has.Count.EqualTo(3));
        Assert.That(merged["@InnerParam"], Is.EqualTo("inner_value"));
        Assert.That(merged["@MiddleParam"], Is.EqualTo("middle_value"));
        Assert.That(merged["@MainParam"], Is.EqualTo("main_value"));
    }

    [Test]
    public void GetMergedParameters_WithEmptyParameters_ReturnsEmpty()
    {
        // Arrange
        var cte = new QueryBreakdown("id", "table1");
        // No parameters added

        var mainQuery = new QueryBreakdown("*", "table2");
        // No parameters added
        mainQuery.AddWithClause("source", cte);

        // Act
        var merged = mainQuery.GetMergedParameters();

        // Assert
        Assert.That(merged, Is.Empty);
    }

    [Test]
    public void GetMergedParameters_PreservesParameterTypes()
    {
        // Arrange
        var cte = new QueryBreakdown("id", "users");
        cte.AddParameter("@IntValue", 123);
        cte.AddParameter("@StringValue", "test");
        cte.AddParameter("@DateValue", DateTime.Today);
        cte.AddParameter("@DecimalValue", 99.99m);

        var mainQuery = new QueryBreakdown("*", "results");
        mainQuery.AddWithClause("source", cte);

        // Act
        var merged = mainQuery.GetMergedParameters();

        // Assert
        Assert.That(merged["@IntValue"], Is.TypeOf<int>());
        Assert.That(merged["@StringValue"], Is.TypeOf<string>());
        Assert.That(merged["@DateValue"], Is.TypeOf<DateTime>());
        Assert.That(merged["@DecimalValue"], Is.TypeOf<decimal>());
    }

    #endregion

    #region AddWhereClause Tests

    [Test]
    public void AddWhereClause_WhenEmpty_SetsWhereClause()
    {
        // Arrange
        var query = new QueryBreakdown();

        // Act
        query.AddWhereClause("Active = 1");

        // Assert
        Assert.That(query.WhereClause.Clause, Is.EqualTo("Active = 1"));
    }

    [Test]
    public void AddWhereClause_WhenExists_AppendsWithAnd()
    {
        // Arrange
        var query = new QueryBreakdown();
        query.WhereClause.Clause = "Active = 1";

        // Act
        query.AddWhereClause("Status = 'Open'");

        // Assert
        Assert.That(query.WhereClause.Clause, Is.EqualTo("Active = 1 and Status = 'Open'"));
    }

    [Test]
    public void AddWhereClause_WithOrOperation_AppendsWithOr()
    {
        // Arrange
        var query = new QueryBreakdown();
        query.WhereClause.Clause = "Active = 1";

        // Act
        query.AddWhereClause("Status = 'Closed'", "or");

        // Assert
        Assert.That(query.WhereClause.Clause, Is.EqualTo("Active = 1 or Status = 'Closed'"));
    }

    [Test]
    public void AddWhereClause_WithNullOrEmpty_DoesNothing()
    {
        // Arrange
        var query = new QueryBreakdown();
        query.WhereClause.Clause = "Active = 1";

        // Act
        query.AddWhereClause(null!);
        query.AddWhereClause(string.Empty);
        query.AddWhereClause("  ");

        // Assert
        Assert.That(query.WhereClause.Clause, Is.EqualTo("Active = 1"));
    }

    [Test]
    public void AddWhereClause_WithParameters_ExtractsParametersAutomatically()
    {
        // Arrange
        var query = new QueryBreakdown();

        // Act
        query.AddWhereClause("UserID = @UserId AND Status = @Status");

        // Assert
        Assert.That(query.WhereClause.Clause, Is.EqualTo("UserID = @UserId AND Status = @Status"));
        Assert.That(query.Parameters, Does.ContainKey("@UserId"));
        Assert.That(query.Parameters, Does.ContainKey("@Status"));
        Assert.That(query.Parameters["@UserId"], Is.Null);
        Assert.That(query.Parameters["@Status"], Is.Null);
    }

    [Test]
    public void AddWhereClause_WithExistingParameter_KeepsExistingValue()
    {
        // Arrange
        var query = new QueryBreakdown();
        query.Parameters["@UserId"] = 123;

        // Act - Add where clause with same parameter
        query.AddWhereClause("UserID = @UserId");

        // Assert - Original value should be preserved
        Assert.That(query.Parameters["@UserId"], Is.EqualTo(123));
    }

    [Test]
    public void AddWhereClause_WithExistingNullParameter_SetsValue()
    {
        // Arrange
        var query = new QueryBreakdown();
        query.Parameters["@UserId"] = null!;

        // Act - Try to set it via direct method (simulating manual set)
        query.SetParameterValue("@UserId", 456);

        // Add where clause with same parameter - should keep the set value
        query.AddWhereClause("UserID = @UserId");

        // Assert - Value should be set
        Assert.That(query.Parameters["@UserId"], Is.EqualTo(456));
    }

    [Test]
    public void AddWhereClause_WithMultipleCalls_AccumulatesParameters()
    {
        // Arrange
        var query = new QueryBreakdown();

        // Act
        query.AddWhereClause("UserID = @UserId");
        query.AddWhereClause("Status = @Status", "and");
        query.AddWhereClause("CreatedDate > @StartDate", "and");

        // Assert
        Assert.That(query.Parameters, Has.Count.EqualTo(3));
        Assert.That(query.Parameters, Does.ContainKey("@UserId"));
        Assert.That(query.Parameters, Does.ContainKey("@Status"));
        Assert.That(query.Parameters, Does.ContainKey("@StartDate"));
    }

    [Test]
    public void AddWhereClause_AfterSettingParameterValue_PreservesValue()
    {
        // Arrange
        var query = new QueryBreakdown();
        query.SetParameterValue("@UserId", 123);
        query.SetParameterValue("@Status", "Active");

        // Act - AddWhereClause should not overwrite existing non-null values
        query.AddWhereClause("UserID = @UserId AND Status = @Status");

        // Assert - Values should be preserved
        Assert.That(query.Parameters["@UserId"], Is.EqualTo(123));
        Assert.That(query.Parameters["@Status"], Is.EqualTo("Active"));
    }

    #endregion

    #region Parameter Management Tests

    [Test]
    public void AddOrUpdateParameter_NewParameter_AddsToParameters()
    {
        // Arrange
        var query = new QueryBreakdown();

        // Act - Use AddWhereClause which internally calls AddOrUpdateParameter
        query.AddWhereClause("UserID = @NewParam");

        // Assert
        Assert.That(query.Parameters, Does.ContainKey("@NewParam"));
    }

    [Test]
    public void AddOrUpdateParameter_ExistingParameterWithNull_SetsValue()
    {
        // Arrange
        var query = new QueryBreakdown();
        query.AddWhereClause("UserID = @UserId"); // Creates parameter with null
        Assert.That(query.Parameters["@UserId"], Is.Null);

        // Act - Set value
        query.SetParameterValue("@UserId", 789);

        // Assert
        Assert.That(query.Parameters["@UserId"], Is.EqualTo(789));
    }

    [Test]
    public void SetParameterValue_ExistingParameterSameType_UpdatesValue()
    {
        // Arrange
        var query = new QueryBreakdown();
        query.SetParameterValue("@UserId", 100);

        // Act
        query.SetParameterValue("@UserId", 200);

        // Assert
        Assert.That(query.Parameters["@UserId"], Is.EqualTo(200));
    }

    [Test]
    public void Parameters_ManuallySettingDifferentType_CanBeDetectedOnNextAddWhereClause()
    {
        // Arrange
        var query = new QueryBreakdown();
        query.SetParameterValue("@UserId", 100); // Set as int

        // Manually change to different type (simulating external manipulation)
        query.Parameters["@UserId"] = "StringValue";

        // Act - AddWhereClause with same parameter should work since extraction creates null values
        // This demonstrates the parameters dictionary can hold different types if manually set
        query.AddWhereClause("UserID = @UserId");

        // Assert - The manual string value is preserved because extracted value is null
        Assert.That(query.Parameters["@UserId"], Is.EqualTo("StringValue"));
    }

    #endregion

    #region AddWithClause Tests

    [Test]
    public void AddWithClause_WithQueryBreakdown_AddsToList()
    {
        // Arrange
        var mainQuery = new QueryBreakdown("*", "Products");
        var cteQuery = new QueryBreakdown("ProductID, COUNT(*) AS OrderCount", "Orders");
        cteQuery.GroupByClause.Clause = "ProductID";

        // Act
        mainQuery.AddWithClause("ProductOrders", cteQuery);

        // Assert
        Assert.That(mainQuery.WithClauses, Has.Count.EqualTo(1));
        Assert.That(mainQuery.WithClauses[0].TableName, Is.EqualTo("ProductOrders"));
        Assert.That(mainQuery.WithClauses[0].Query, Is.EqualTo(cteQuery));
    }

    [Test]
    public void AddWithClause_WithMultipleCTEs_MaintainsOrder()
    {
        // Arrange
        var mainQuery = new QueryBreakdown("*", "FinalData");
        var cte1 = new QueryBreakdown("*", "Table1");
        var cte2 = new QueryBreakdown("*", "Table2");
        var cte3 = new QueryBreakdown("*", "Table3");

        // Act
        mainQuery.AddWithClause("CTE1", cte1);
        mainQuery.AddWithClause("CTE2", cte2);
        mainQuery.AddWithClause("CTE3", cte3);

        // Assert
        Assert.That(mainQuery.WithClauses, Has.Count.EqualTo(3));
        Assert.That(mainQuery.WithClauses[0].TableName, Is.EqualTo("CTE1"));
        Assert.That(mainQuery.WithClauses[1].TableName, Is.EqualTo("CTE2"));
        Assert.That(mainQuery.WithClauses[2].TableName, Is.EqualTo("CTE3"));
    }

    [Test]
    public void AddWithClause_WithSqlString_ParsesAndAdds()
    {
        // Arrange
        var mainQuery = new QueryBreakdown("*", "Products p INNER JOIN ProductOrders po ON p.ProductID = po.ProductID");
        var cteSql = "SELECT ProductID, COUNT(*) AS OrderCount FROM Orders GROUP BY ProductID";

        // Act
        mainQuery.AddWithClause("ProductOrders", cteSql, isMicrosoftSql: true);

        // Assert
        Assert.That(mainQuery.WithClauses, Has.Count.EqualTo(1));
        Assert.That(mainQuery.WithClauses[0].TableName, Is.EqualTo("ProductOrders"));
        Assert.That(mainQuery.WithClauses[0].Query!.SelectClause.Clause, Does.Contain("ProductID"));
        Assert.That(mainQuery.WithClauses[0].Query!.GroupByClause.Clause, Does.Contain("ProductID"));
    }

    [Test]
    public void AddWithClause_WithNullName_ThrowsCteValidationException()
    {
        // Arrange
        var mainQuery = new QueryBreakdown("*", "Products");
        var cteQuery = new QueryBreakdown("*", "Orders");

        // Act & Assert
        Assert.Throws<CteValidationException>(() => mainQuery.AddWithClause(null!, cteQuery));
    }

    [Test]
    public void AddWithClause_WithNullQuery_ThrowsCteValidationException()
    {
        // Arrange
        var mainQuery = new QueryBreakdown("*", "Products");

        // Act & Assert
        Assert.Throws<CteValidationException>(() => mainQuery.AddWithClause("ProductOrders", (QueryBreakdown)null!));
    }

    [Test]
    public void AddWithClause_WithNullSql_ThrowsCteValidationException()
    {
        // Arrange
        var mainQuery = new QueryBreakdown("*", "Products");

        // Act & Assert
        Assert.Throws<CteValidationException>(() => mainQuery.AddWithClause("ProductOrders", (string)null!));
    }

    #endregion

    #region CTE Integration Tests

    [Test]
    public void CTE_NestedCTEs_WithParameterFlow()
    {
        // Arrange: Create inner CTE with parameters
        var innerCte = new QueryBreakdown("id, name, created_date", "users", "created_date >= @StartDate");
        innerCte.AddParameter("@StartDate", DateTime.Today.AddDays(-30));

        // Arrange: Create middle CTE that references inner CTE
        var middleCte = new QueryBreakdown("id, name", "recent_users", "id > @MinUserId");
        middleCte.AddParameter("@MinUserId", 100);

        // Arrange: Create main query that references middle CTE
        var mainQuery = new QueryBreakdown("COUNT(*) AS ActiveUserCount", "filtered_users");
        mainQuery.AddWithClause("recent_users", innerCte);
        mainQuery.AddWithClause("filtered_users", middleCte);

        // Act
        var sql = mainQuery.GetSql();
        var innerParams = innerCte.ParameterList.Count();
        var middleParams = middleCte.ParameterList.Count();

        // Assert - Each CTE maintains its own parameters
        Assert.That(innerParams, Is.EqualTo(1));
        Assert.That(middleParams, Is.EqualTo(1));
        // SQL should contain both WITH clauses
        Assert.That(sql, Does.Contain("WITH"));
        Assert.That(sql, Does.Contain("recent_users"));
        Assert.That(sql, Does.Contain("filtered_users"));
    }

    [Test]
    public void CTE_MultipleCTEs_WithComplexQueries()
    {
        // Arrange: Create CTE 1 - Active users
        var activeCte = new QueryBreakdown("id, email, status", "users", "status = 'active'");

        // Arrange: Create CTE 2 - Recent orders
        var ordersCte = new QueryBreakdown("user_id, COUNT(*) AS order_count, SUM(total) AS total_spent", "orders");
        ordersCte.GroupByClause.Clause = "user_id";
        ordersCte.HavingClause.Clause = "COUNT(*) > 0";

        // Arrange: Create main query combining both CTEs
        var mainQuery = new QueryBreakdown("a.id, a.email, o.order_count, o.total_spent",
            "active_users a LEFT JOIN user_orders o ON a.id = o.user_id");
        mainQuery.OrderByClause.Clause = "o.total_spent DESC";

        mainQuery.AddWithClause("active_users", activeCte);
        mainQuery.AddWithClause("user_orders", ordersCte);

        // Act
        var sql = mainQuery.GetSql();

        // Assert
        Assert.That(sql, Does.Contain("WITH"));
        Assert.That(sql, Does.Contain("active_users"));
        Assert.That(sql, Does.Contain("user_orders"));
        Assert.That(sql, Does.Contain("GROUP BY"));
        Assert.That(sql, Does.Contain("HAVING"));
        Assert.That(sql, Does.Contain("LEFT JOIN"));
        Assert.That(sql, Does.Contain("ORDER BY"));
    }

    [Test]
    public void CTE_GetSql_GeneratesProperCTESyntax()
    {
        // Arrange
        var cteQuery = new QueryBreakdown("ProductID, SUM(Quantity) AS TotalQuantity", "OrderDetails");
        cteQuery.GroupByClause.Clause = "ProductID";

        var mainQuery = new QueryBreakdown("p.ProductName, pt.TotalQuantity", "Products p INNER JOIN ProductTotals pt ON p.ProductID = pt.ProductID");
        mainQuery.AddWithClause("ProductTotals", cteQuery);

        // Act
        var sql = mainQuery.GetSql();

        // Assert - Verify WITH clause appears before main SELECT
        var withIndex = sql.IndexOf("WITH");
        var mainSelectIndex = sql.LastIndexOf("SELECT");
        Assert.That(withIndex, Is.GreaterThan(-1));
        Assert.That(mainSelectIndex, Is.GreaterThan(-1));
        Assert.That(withIndex, Is.LessThan(mainSelectIndex));

        // Assert - Verify CTE definition
        Assert.That(sql, Does.Contain("ProductTotals"));
        Assert.That(sql, Does.Contain("AS"));
        Assert.That(sql, Does.Contain("ProductID"));
        Assert.That(sql, Does.Contain("TotalQuantity"));
    }

    [Test]
    public void CTE_WithClauseProperties_RoundTrip()
    {
        // Arrange: Create original query
        var cteQuery = new QueryBreakdown("id, name", "employees", "department = 'Sales'");
        var mainQuery = new QueryBreakdown("*", "sales_team");
        mainQuery.AddWithClause("sales_team", cteQuery);

        // Act: Get SQL and verify CTE is properly included
        var sql = mainQuery.GetSql();
        var withClause = mainQuery.WithClauses[0];

        // Assert: Verify WithClause properties
        Assert.That(withClause.TableName, Is.EqualTo("sales_team"));
        Assert.That(withClause.Query, Is.Not.Null);
        Assert.That(withClause.Sql, Is.Not.Null);
        Assert.That(withClause.Sql?.SelectClause?.Clause, Contains.Substring("id, name"));
        Assert.That(withClause.Sql?.FromClause?.Clause, Contains.Substring("employees"));
        Assert.That(withClause.Sql?.WhereClause?.Clause, Contains.Substring("department = 'Sales'"));
    }

    [Test]
    public void CTE_IsUsingWithClause_ReturnsCorrectStatus()
    {
        // Arrange
        var query = new QueryBreakdown("*", "data");

        // Act & Assert - No WITH clauses yet
        Assert.That(query.IsUsingWithClause, Is.False);

        // Act - Add a CTE
        var cte = new QueryBreakdown("id, name", "source_table");
        query.AddWithClause("source_cte", cte);

        // Assert - Now using WITH clause
        Assert.That(query.IsUsingWithClause, Is.True);
        Assert.That(query.WithClauses, Has.Count.EqualTo(1));
    }

    #endregion

    #region GetSql Tests

    [Test]
    public void GetSql_SimpleSelectFrom_GeneratesCorrectSql()
    {
        // Arrange
        var query = new QueryBreakdown("ID, Name", "Users");

        // Act
        var sql = query.GetSql();

        // Assert
        Assert.That(sql, Does.Contain("SELECT"));
        Assert.That(sql, Does.Contain("ID, Name"));
        Assert.That(sql, Does.Contain("FROM"));
        Assert.That(sql, Does.Contain("Users"));
    }

    [Test]
    public void GetSql_WithAllClauses_GeneratesCorrectSql()
    {
        // Arrange
        var query = new QueryBreakdown("Department, COUNT(*) AS EmpCount", "Employees");
        query.WhereClause.Clause = "Active = 1";
        query.GroupByClause.Clause = "Department";
        query.HavingClause.Clause = "COUNT(*) > 5";
        query.OrderByClause.Clause = "Department ASC";

        // Act
        var sql = query.GetSql();

        // Assert
        Assert.That(sql, Does.Contain("SELECT"));
        Assert.That(sql, Does.Contain("FROM"));
        Assert.That(sql, Does.Contain("WHERE"));
        Assert.That(sql, Does.Contain("GROUP BY"));
        Assert.That(sql, Does.Contain("HAVING"));
        Assert.That(sql, Does.Contain("ORDER BY"));
    }

    [Test]
    public void GetSql_WithSingleWithClause_GeneratesCorrectSql()
    {
        // Arrange
        var mainQuery = new QueryBreakdown("p.*, ps.TotalQty", "Products p INNER JOIN ProductSummary ps ON p.ProductID = ps.ProductID");
        var cte = new QueryBreakdown("ProductID, SUM(Quantity) AS TotalQty", "OrderDetails");
        cte.GroupByClause.Clause = "ProductID";
        mainQuery.AddWithClause("ProductSummary", cte);

        // Act
        var sql = mainQuery.GetSql();

        // Assert
        Assert.That(sql, Does.Contain("WITH"));
        Assert.That(sql, Does.Contain("ProductSummary AS ("));
        Assert.That(sql, Does.Contain("SUM(Quantity) AS TotalQty"));
        Assert.That(sql, Does.Contain("GROUP BY"));
    }

    [Test]
    public void GetSql_WithMultipleWithClauses_GeneratesCorrectSqlWithCommas()
    {
        // Arrange
        var mainQuery = new QueryBreakdown("*", "CTE3");
        var cte1 = new QueryBreakdown("Col1", "Table1");
        var cte2 = new QueryBreakdown("Col2", "Table2");
        var cte3 = new QueryBreakdown("Col3", "Table3");

        mainQuery.AddWithClause("CTE1", cte1);
        mainQuery.AddWithClause("CTE2", cte2);
        mainQuery.AddWithClause("CTE3", cte3);

        // Act
        var sql = mainQuery.GetSql();

        // Assert
        Assert.That(sql, Does.Contain("WITH"));
        Assert.That(sql, Does.Contain("CTE1 AS ("));
        Assert.That(sql, Does.Contain("CTE2 AS ("));
        Assert.That(sql, Does.Contain("CTE3 AS ("));

        // Verify commas between CTEs by checking the pattern
        // CTE1 should be followed by ), then comma, then CTE2
        var cte1Index = sql.IndexOf("CTE1 AS (");
        var cte2Index = sql.IndexOf("CTE2 AS (", cte1Index);
        var betweenCtes = sql.Substring(cte1Index, cte2Index - cte1Index);
        Assert.That(betweenCtes, Does.Contain("),"), "CTE1 should be followed by a comma before CTE2");

        // Verify comma between CTE2 and CTE3
        var cte3Index = sql.IndexOf("CTE3 AS (", cte2Index);
        var betweenCte2And3 = sql.Substring(cte2Index, cte3Index - cte2Index);
        Assert.That(betweenCte2And3, Does.Contain("),"), "CTE2 should be followed by a comma before CTE3");
    }

    [Test]
    public void GetSql_WithSetupClauses_IncludesSetup()
    {
        // Arrange
        var query = new QueryBreakdown("*", "Users");
        query.SetupClauses.Add("DECLARE @Status INT = 1");

        // Act
        var sql = query.GetSql(includeSetupFinish: true);

        // Assert
        Assert.That(sql, Does.Contain("DECLARE @Status INT = 1"));
    }

    [Test]
    public void GetSql_WithFinishClauses_IncludesFinish()
    {
        // Arrange
        var query = new QueryBreakdown("*", "Users");
        query.FinishClauses.Add("DROP TABLE #TempUsers");

        // Act
        var sql = query.GetSql(includeSetupFinish: true);

        // Assert
        Assert.That(sql, Does.Contain("DROP TABLE #TempUsers"));
    }

    [Test]
    public void GetSql_WithIncludeSetupFinishFalse_ExcludesSetupAndFinish()
    {
        // Arrange
        var query = new QueryBreakdown("*", "Users");
        query.SetupClauses.Add("DECLARE @Status INT = 1");
        query.FinishClauses.Add("DROP TABLE #TempUsers");

        // Act
        var sql = query.GetSql(includeSetupFinish: false);

        // Assert
        Assert.That(sql, Does.Not.Contain("DECLARE"));
        Assert.That(sql, Does.Not.Contain("DROP TABLE"));
    }

    #endregion

    #region Parse Tests

    [Test]
    public void Parse_SimpleSelectStatement_ParsesCorrectly()
    {
        // Arrange
        var sql = "SELECT ID, Name FROM Users";

        // Act
        var query = QueryBreakdown.Parse(sql);

        // Assert
        Assert.That(query.SelectClause.Clause?.Trim(), Does.Contain("ID, Name"));
        Assert.That(query.FromClause.Clause?.Trim(), Does.Contain("Users"));
    }

    [Test]
    public void Parse_WithWhereClause_ParsesCorrectly()
    {
        // Arrange
        var sql = "SELECT ID, Name FROM Users WHERE Active = 1";

        // Act
        var query = QueryBreakdown.Parse(sql);

        // Assert
        Assert.That(query.SelectClause.Clause?.Trim(), Does.Contain("ID, Name"));
        Assert.That(query.FromClause.Clause?.Trim(), Does.Contain("Users"));
        Assert.That(query.WhereClause.Clause?.Trim(), Does.Contain("Active = 1"));
    }

    [Test]
    public void Parse_WithGroupByAndHaving_ParsesCorrectly()
    {
        // Arrange
        var sql = "SELECT Department, COUNT(*) AS EmpCount FROM Employees GROUP BY Department HAVING COUNT(*) > 5";

        // Act
        var query = QueryBreakdown.Parse(sql);

        // Assert
        Assert.That(query.SelectClause.Clause?.Trim(), Does.Contain("Department"));
        Assert.That(query.GroupByClause.Clause?.Trim(), Does.Contain("Department"));
        Assert.That(query.HavingClause.Clause?.Trim(), Does.Contain("COUNT(*) > 5"));
    }

    [Test]
    public void Parse_WithOrderBy_ParsesCorrectly()
    {
        // Arrange
        var sql = "SELECT ID, Name FROM Users ORDER BY Name ASC";

        // Act
        var query = QueryBreakdown.Parse(sql);

        // Assert
        Assert.That(query.OrderByClause.Clause?.Trim(), Does.Contain("Name ASC"));
    }

    [Test]
    public void Parse_WithParameters_ExtractsParameters()
    {
        // Arrange
        var sql = "SELECT ID, Name FROM Users WHERE UserID = @UserId AND Status = @Status";

        // Act
        var query = QueryBreakdown.Parse(sql);

        // Assert
        Assert.That(query.Parameters, Does.ContainKey("@UserId"));
        Assert.That(query.Parameters, Does.ContainKey("@Status"));
    }

    [Test]
    public void Parse_WithWithClause_ParsesCorrectly()
    {
        // Arrange
        var sql = @"WITH ProductSummary AS (
                SELECT ProductID, SUM(Quantity) AS TotalQty
                FROM OrderDetails
                GROUP BY ProductID
            )
            SELECT p.*, ps.TotalQty
            FROM Products p
            INNER JOIN ProductSummary ps ON p.ProductID = ps.ProductID";

        // Act
        var query = QueryBreakdown.Parse(sql);

        // Assert
        Assert.That(query.IsUsingWithClause, Is.True);
        Assert.That(query.SelectClause.Clause?.Trim(), Does.Contain("p.*, ps.TotalQty"));
        Assert.That(query.FromClause.Clause?.Trim(), Does.Contain("Products p"));
    }

    [Test]
    public void Parse_WithNullSql_ThrowsArgumentNullException()
    {
        // Act & Assert
        Assert.Throws<ArgumentNullException>(() => QueryBreakdown.Parse(null!));
    }

    [Test]
    public void Parse_WithEmptySql_ThrowsArgumentNullException()
    {
        // Act & Assert
        Assert.Throws<ArgumentNullException>(() => QueryBreakdown.Parse(string.Empty));
    }

    [Test]
    public void Parse_WithInvalidSql_ThrowsSqlParseException()
    {
        // Arrange
        var sql = "INVALID SQL STATEMENT";

        // Act & Assert
        Assert.Throws<SqlParseException>(() => QueryBreakdown.Parse(sql));
    }

    [Test]
    public void TryParse_WithValidSql_ReturnsTrue()
    {
        // Arrange
        var sql = "SELECT ID FROM Users";

        // Act
        var success = QueryBreakdown.TryParse(sql, out var query);

        // Assert
        Assert.That(success, Is.True);
        Assert.That(query, Is.Not.Null);
    }

    [Test]
    public void TryParse_WithInvalidSql_ReturnsFalse()
    {
        // Arrange
        var sql = "INVALID SQL";

        // Act
        var success = QueryBreakdown.TryParse(sql, out var query, out var error);

        // Assert
        Assert.That(success, Is.False);
        Assert.That(query, Is.Null);
        Assert.That(error, Is.Not.Null);
    }

    #endregion

    #region MergeWith Tests

    [Test]
    public void MergeWith_AnotherQuery_MergesFromClauses()
    {
        // Arrange
        var query1 = new QueryBreakdown("*", "Users u");
        var query2 = new QueryBreakdown();
        query2.FromClause.Clause = "INNER JOIN Orders o ON u.UserID = o.UserID";

        // Act
        query1.MergeWith(query2);

        // Assert
        Assert.That(query1.FromClause.Clause, Does.Contain("Users u"));
        Assert.That(query1.FromClause.Clause, Does.Contain("INNER JOIN Orders"));
    }

    [Test]
    public void MergeWith_WithWhereClauses_MergesWithAnd()
    {
        // Arrange
        var query1 = new QueryBreakdown();
        query1.WhereClause.Clause = "Active = 1";
        var query2 = new QueryBreakdown();
        query2.WhereClause.Clause = "Status = 'Open'";

        // Act
        query1.MergeWith(query2);

        // Assert
        Assert.That(query1.WhereClause.Clause, Does.Contain("Active = 1"));
        Assert.That(query1.WhereClause.Clause, Does.Contain("AND"));
        Assert.That(query1.WhereClause.Clause, Does.Contain("Status = 'Open'"));
    }

    [Test]
    public void MergeWith_Parameters_MergesParameters()
    {
        // Arrange
        var query1 = new QueryBreakdown();
        query1.AddParameter("Param1", 123);

        var query2 = new QueryBreakdown();
        query2.AddParameter("Param2", 456);

        // Act
        query1.MergeWith(query2);

        // Assert
        Assert.That(query1.Parameters, Does.ContainKey("@Param1"));
        Assert.That(query1.Parameters, Does.ContainKey("@Param2"));
    }

    #endregion

    #region Clone Tests

    [Test]
    public void Clone_CreatesDeepCopy()
    {
        // Arrange
        var original = new QueryBreakdown("*", "Employees", "Active = 1", "Name ASC");
        original.AddParameter("UserId", 123);

        // Act
        var clone = (QueryBreakdown)original.Clone();

        // Assert
        Assert.That(clone, Is.Not.SameAs(original));
        Assert.That(clone.SelectClause.Clause, Is.EqualTo(original.SelectClause.Clause));
        Assert.That(clone.FromClause.Clause, Is.EqualTo(original.FromClause.Clause));
        Assert.That(clone.WhereClause.Clause, Is.EqualTo(original.WhereClause.Clause));
        Assert.That(clone.OrderByClause.Clause, Is.EqualTo(original.OrderByClause.Clause));
    }

    [Test]
    public void Clone_ModifyingClone_DoesNotAffectOriginal()
    {
        // Arrange
        var original = new QueryBreakdown("*", "Users");
        var clone = (QueryBreakdown)original.Clone();

        // Act
        clone.WhereClause.Clause = "Active = 1";

        // Assert
        Assert.That(original.WhereClause.Clause, Is.EqualTo(string.Empty));
        Assert.That(clone.WhereClause.Clause, Is.EqualTo("Active = 1"));
    }

    #endregion

    #region ToString Tests

    [Test]
    public void ToString_ReturnsSqlString()
    {
        // Arrange
        var query = new QueryBreakdown("ID, Name", "Users");

        // Act
        var result = query.ToString();

        // Assert
        Assert.That(result, Does.Contain("SELECT"));
        Assert.That(result, Does.Contain("ID, Name"));
        Assert.That(result, Does.Contain("FROM"));
        Assert.That(result, Does.Contain("Users"));
    }

    #endregion

    #region Outlier Conditions - SQL Injection & Malformed SQL

    [Test]
    public void Parse_WithSingleQuotesInString_ParsesCorrectly()
    {
        // Arrange
        var sql = "SELECT Name FROM Users WHERE Name = 'O''Brien'";

        // Act
        var query = QueryBreakdown.Parse(sql);

        // Assert
        Assert.That(query, Is.Not.Null);
        Assert.That(query.WhereClause.Clause, Does.Contain("O''Brien"));
    }

    [Test]
    public void Parse_WithDoubleQuotesInIdentifiers_ParsesCorrectly()
    {
        // Arrange
        var sql = "SELECT \"User Name\", \"User ID\" FROM \"User Table\"";

        // Act
        var query = QueryBreakdown.Parse(sql);

        // Assert
        Assert.That(query.SelectClause.Clause, Does.Contain("\"User Name\""));
        Assert.That(query.FromClause.Clause, Does.Contain("\"User Table\""));
    }

    [Test]
    public void Parse_WithSemicolonInString_DoesNotSplitStatement()
    {
        // Arrange
        var sql = "SELECT Description FROM Products WHERE Description = 'Price: $10; Quantity: 5'";

        // Act
        var query = QueryBreakdown.Parse(sql);

        // Assert
        Assert.That(query.WhereClause.Clause, Does.Contain("Price: $10; Quantity: 5"));
    }

    [Test]
    public void Parse_WithCommentedOutClause_IgnoresComment()
    {
        // Arrange
        var sql = @"SELECT ID, Name
                        FROM Users
                        -- WHERE Active = 1
                        ORDER BY Name";

        // Act & Assert
        // Parser may or may not handle comments - test gracefully
        Assert.DoesNotThrow(() => QueryBreakdown.Parse(sql));
    }

    [Test]
    public void Parse_WithMultiLineComment_HandlesGracefully()
    {
        // Arrange
        var sql = @"SELECT ID /* This is the user ID */, Name /* User's full name */
                        FROM Users";

        // Act & Assert
        Assert.DoesNotThrow(() => QueryBreakdown.Parse(sql));
    }

    [Test]
    public void Parse_WithUnbalancedParenthesesInString_ParsesCorrectly()
    {
        // Arrange
        var sql = "SELECT Description FROM Products WHERE Description = 'Test (unbalanced'";

        // Act & Assert
        Assert.DoesNotThrow(() => QueryBreakdown.Parse(sql));
    }

    [Test]
    public void AddParameter_WithSqlInjectionAttempt_StoresAsParameter()
    {
        // Arrange
        var query = new QueryBreakdown("*", "Users");
        var maliciousValue = "1' OR '1'='1";

        // Act
        query.AddParameter("UserId", maliciousValue);

        // Assert
        Assert.That(query.Parameters["@UserId"], Is.EqualTo(maliciousValue));
    }

    #endregion

    #region Outlier Conditions - Whitespace and Formatting

    [Test]
    public void Parse_WithExcessiveWhitespace_NormalizesCorrectly()
    {
        // Arrange
        var sql = "SELECT    ID,     Name     FROM      Users      WHERE     Active=1";

        // Act
        var query = QueryBreakdown.Parse(sql);

        // Assert
        Assert.That(query, Is.Not.Null);
        Assert.That(query.SelectClause.Clause, Does.Contain("ID"));
    }

    [Test]
    public void Parse_WithTabsAndNewlines_ParsesCorrectly()
    {
        // Arrange
        var sql = "SELECT\tID,\nName\r\nFROM\tUsers\r\nWHERE\tActive=1";

        // Act
        var query = QueryBreakdown.Parse(sql);

        // Assert
        Assert.That(query, Is.Not.Null);
    }

    [Test]
    public void Parse_WithMixedLineEndings_HandlesCorrectly()
    {
        // Arrange
        var sql = "SELECT ID\rFROM Users\nWHERE Active=1\r\nORDER BY Name";

        // Act
        var query = QueryBreakdown.Parse(sql);

        // Assert
        Assert.That(query, Is.Not.Null);
    }

    [Test]
    public void GetSql_WithVeryLongClause_GeneratesCorrectly()
    {
        // Arrange
        var longSelectClause = string.Join(", ", Enumerable.Range(1, 100).Select(i => $"Column{i}"));
        var query = new QueryBreakdown(longSelectClause, "LargeTable");

        // Act
        var sql = query.GetSql();

        // Assert
        Assert.That(sql, Does.Contain("Column1"));
        Assert.That(sql, Does.Contain("Column100"));
    }

    #endregion

    #region Outlier Conditions - Special Characters and Unicode

    [Test]
    public void Parse_WithUnicodeCharacters_ParsesCorrectly()
    {
        // Arrange
        var sql = "SELECT Name, Description FROM Products WHERE Name = '日本語テスト'";

        // Act
        var query = QueryBreakdown.Parse(sql);

        // Assert
        Assert.That(query, Is.Not.Null);
        Assert.That(query.WhereClause.Clause, Does.Contain("日本語テスト"));
    }

    [Test]
    public void AddParameter_WithUnicodeValue_StoresCorrectly()
    {
        // Arrange
        var query = new QueryBreakdown();
        var unicodeValue = "Müller über größer äöü";

        // Act
        query.AddParameter("Name", unicodeValue);

        // Assert
        Assert.That(query.Parameters["@Name"], Is.EqualTo(unicodeValue));
    }

    [Test]
    public void Parse_WithSpecialSqlCharacters_HandlesCorrectly()
    {
        // Arrange
        var sql = "SELECT Price FROM Products WHERE Price >= 10.50 AND Discount <= 25%";

        // Act
        var query = QueryBreakdown.Parse(sql);

        // Assert
        Assert.That(query.WhereClause.Clause, Does.Contain(">="));
        Assert.That(query.WhereClause.Clause, Does.Contain("<="));
    }

    #endregion

    #region Outlier Conditions - Nested Queries and Complex Structures

    [Test]
    public void Parse_WithDeeplyNestedSubqueries_ParsesCorrectly()
    {
        // Arrange
        var sql = @"SELECT ID FROM Users
                        WHERE ID IN (
                            SELECT UserID FROM Orders
                            WHERE OrderID IN (
                                SELECT OrderID FROM OrderDetails
                                WHERE ProductID IN (SELECT ID FROM Products)
                            )
                        )";

        // Act
        var query = QueryBreakdown.Parse(sql);

        // Assert
        Assert.That(query, Is.Not.Null);
        Assert.That(query.WhereClause.Clause, Does.Contain("SELECT UserID FROM Orders"));
    }

    [Test]
    public void Parse_WithCorrelatedSubquery_ParsesCorrectly()
    {
        // Arrange
        var sql = @"SELECT u.Name,
                        (SELECT COUNT(*) FROM Orders o WHERE o.UserID = u.ID) AS OrderCount
                        FROM Users u";

        // Act
        var query = QueryBreakdown.Parse(sql);

        // Assert
        Assert.That(query.SelectClause.Clause, Does.Contain("SELECT COUNT(*)"));
    }

    [Test]
    public void Parse_WithCaseExpression_ParsesCorrectly()
    {
        // Arrange
        var sql = @"SELECT
                        CASE
                            WHEN Status = 1 THEN 'Active'
                            WHEN Status = 0 THEN 'Inactive'
                            ELSE 'Unknown'
                        END AS StatusText
                        FROM Users";

        // Act
        var query = QueryBreakdown.Parse(sql);

        // Assert
        Assert.That(query.SelectClause.Clause, Does.Contain("CASE"));
        Assert.That(query.SelectClause.Clause, Does.Contain("WHEN"));
    }

    [Test]
    public void Parse_WithMultipleJoins_ParsesCorrectly()
    {
        // Arrange
        var sql = @"SELECT u.Name, o.OrderDate, p.ProductName
                        FROM Users u
                        INNER JOIN Orders o ON u.ID = o.UserID
                        LEFT JOIN OrderDetails od ON o.ID = od.OrderID
                        RIGHT JOIN Products p ON od.ProductID = p.ID";

        // Act
        var query = QueryBreakdown.Parse(sql);

        // Assert
        Assert.That(query.FromClause.Clause, Does.Contain("INNER JOIN"));
        Assert.That(query.FromClause.Clause, Does.Contain("LEFT JOIN"));
        Assert.That(query.FromClause.Clause, Does.Contain("RIGHT JOIN"));
    }

    #endregion

    #region Outlier Conditions - Reserved Words and Keywords

    [Test]
    public void Parse_WithReservedWordsAsIdentifiers_ParsesCorrectly()
    {
        // Arrange
        var sql = "SELECT [Select], [From], [Where] FROM [Order]";

        // Act
        var query = QueryBreakdown.Parse(sql);

        // Assert
        Assert.That(query.SelectClause.Clause, Does.Contain("[Select]"));
        Assert.That(query.SelectClause.Clause, Does.Contain("[From]"));
        Assert.That(query.SelectClause.Clause, Does.Contain("[Where]"));
        Assert.That(query.FromClause.Clause, Does.Contain("[Order]"));
    }

    [Test]
    public void Parse_WithKeywordInColumnAlias_ParsesCorrectly()
    {
        // Arrange
        var sql = "SELECT ID AS [Select], Name AS [From] FROM Users";

        // Act
        var query = QueryBreakdown.Parse(sql);

        // Assert
        Assert.That(query.SelectClause.Clause, Does.Contain("AS [Select]"));
    }

    #endregion

    #region Outlier Conditions - Parameter Edge Cases

    [Test]
    public void Parse_WithDuplicateParameters_ExtractsBoth()
    {
        // Arrange
        var sql = "SELECT * FROM Users WHERE ID = @UserId OR ParentID = @UserId";

        // Act
        var query = QueryBreakdown.Parse(sql);

        // Assert
        Assert.That(query.Parameters, Does.ContainKey("@UserId"));
    }

    [Test]
    public void AddParameter_WithNullValue_StoresNull()
    {
        // Arrange
        var query = new QueryBreakdown();

        // Act
        query.AddParameter("NullParam", null!);

        // Assert
        Assert.That(query.Parameters, Does.ContainKey("@NullParam"));
        Assert.That(query.Parameters["@NullParam"], Is.Null);
    }

    [Test]
    public void AddParameter_WithDBNull_StoresCorrectly()
    {
        // Arrange
        var query = new QueryBreakdown();

        // Act
        query.AddParameter("DbNullParam", DBNull.Value);

        // Assert
        Assert.That(query.Parameters["@DbNullParam"], Is.EqualTo(DBNull.Value));
    }

    [Test]
    public void AddParameter_WithVeryLongParameterName_StoresCorrectly()
    {
        // Arrange
        var query = new QueryBreakdown();
        var longName = "VeryLongParameterName" + new string('X', 100);

        // Act
        query.AddParameter(longName, 123);

        // Assert
        Assert.That(query.Parameters, Does.ContainKey($"@{longName}"));
    }

    [Test]
    public void AddParameter_WithSpecialCharactersInName_StoresCorrectly()
    {
        // Arrange
        var query = new QueryBreakdown();

        // Act
        query.AddParameter("Param_With_Underscores", 123);
        query.AddParameter("Param123WithNumbers", 456);

        // Assert
        Assert.That(query.Parameters, Does.ContainKey("@Param_With_Underscores"));
        Assert.That(query.Parameters, Does.ContainKey("@Param123WithNumbers"));
    }

    [Test]
    public void SetParameterValue_WithComplexObject_StoresCorrectly()
    {
        // Arrange
        var query = new QueryBreakdown();
        var complexObj = new { Id = 1, Name = "Test", Values = new[] { 1, 2, 3 } };

        // Act
        query.SetParameterValue("ComplexParam", complexObj);

        // Assert
        Assert.That(query.GetParameterValue("ComplexParam"), Is.EqualTo(complexObj));
    }

    #endregion

    #region Outlier Conditions - WITH Clause Edge Cases

    [Test]
    public void AddWithClause_WithEmptyTableName_ThrowsCteValidationException()
    {
        // Arrange
        var query = new QueryBreakdown("*", "Users");
        var cte = new QueryBreakdown("*", "Orders");

        // Act & Assert
        Assert.Throws<CteValidationException>(() => query.AddWithClause("", cte));
        Assert.Throws<CteValidationException>(() => query.AddWithClause("   ", cte));
    }

    [Test]
    public void AddWithClause_WithVeryLongCTEName_AddsCorrectly()
    {
        // Arrange
        var query = new QueryBreakdown("*", "FinalTable");
        var cte = new QueryBreakdown("*", "SourceTable");
        var longName = "CTE_" + new string('X', 200);

        // Act
        query.AddWithClause(longName, cte);

        // Assert
        Assert.That(query.WithClauses[0].TableName, Is.EqualTo(longName));
    }

    [Test]
    public void AddWithClause_WithSpecialCharactersInName_AddsCorrectly()
    {
        // Arrange
        var query = new QueryBreakdown("*", "FinalTable");
        var cte = new QueryBreakdown("*", "SourceTable");

        // Act
        query.AddWithClause("CTE_With_Underscores_123", cte);

        // Assert
        Assert.That(query.WithClauses[0].TableName, Is.EqualTo("CTE_With_Underscores_123"));
    }

    [Test]
    public void GetSql_WithVeryManyCTEs_GeneratesCorrectly()
    {
        // Arrange
        var query = new QueryBreakdown("*", "FinalCTE");
        for (int i = 0; i < 20; i++)
        {
            var cte = new QueryBreakdown($"Col{i}", $"Table{i}");
            query.AddWithClause($"CTE{i}", cte);
        }

        // Act
        var sql = query.GetSql();

        // Assert
        Assert.That(sql, Does.Contain("CTE0 AS ("));
        Assert.That(sql, Does.Contain("CTE19 AS ("));
    }

    #endregion

    #region Outlier Conditions - Empty and Boundary Cases

    [Test]
    public void GetSql_WithAllEmptyClauses_GeneratesMinimalSql()
    {
        // Arrange
        var query = new QueryBreakdown();

        // Act
        var sql = query.GetSql();

        // Assert
        Assert.That(sql, Does.Contain("SELECT"));
    }

    [Test]
    public void MergeWith_WithEmptyQuery_HandlesGracefully()
    {
        // Arrange
        var query1 = new QueryBreakdown("*", "Users");
        var query2 = new QueryBreakdown();

        // Act
        query1.MergeWith(query2);

        // Assert
        Assert.That(query1.FromClause.Clause, Does.Contain("Users"));
    }

    [Test]
    public void AddWhereClause_WithOnlyWhitespace_DoesNotAdd()
    {
        // Arrange
        var query = new QueryBreakdown("*", "Users");

        // Act
        query.AddWhereClause("   \t\n   ");

        // Assert
        Assert.That(query.WhereClause.Clause, Is.EqualTo(string.Empty));
    }

    [Test]
    public void Parse_WithOnlySelectNoFrom_HandlesGracefully()
    {
        // Arrange - SQL Server allows SELECT without FROM for constants
        var sql = "SELECT 1 AS One, 'Test' AS TestValue";

        // Act & Assert
        Assert.DoesNotThrow(() => QueryBreakdown.Parse(sql));
    }

    #endregion

    #region Outlier Conditions - Complex WHERE Clauses

    [Test]
    public void Parse_WithComplexBooleanLogic_ParsesCorrectly()
    {
        // Arrange
        var sql = @"SELECT * FROM Users
                        WHERE (Active = 1 AND Status = 'Valid')
                        OR (Active = 0 AND Status = 'Pending' AND CreateDate > '2024-01-01')";

        // Act
        var query = QueryBreakdown.Parse(sql);

        // Assert
        Assert.That(query.WhereClause.Clause, Does.Contain("Active = 1"));
        Assert.That(query.WhereClause.Clause, Does.Contain("AND"));
        Assert.That(query.WhereClause.Clause, Does.Contain("OR"));
    }

    [Test]
    public void Parse_WithInClauseWithMultipleValues_ParsesCorrectly()
    {
        // Arrange
        var sql = "SELECT * FROM Users WHERE ID IN (1, 2, 3, 4, 5)";

        // Act
        var query = QueryBreakdown.Parse(sql);

        // Assert
        Assert.That(query.WhereClause.Clause, Does.Contain("IN (1, 2, 3, 4, 5)"));
    }

    [Test]
    public void Parse_WithBetweenClause_ParsesCorrectly()
    {
        // Arrange
        var sql = "SELECT * FROM Orders WHERE OrderDate BETWEEN '2024-01-01' AND '2024-12-31'";

        // Act
        var query = QueryBreakdown.Parse(sql);

        // Assert
        Assert.That(query.WhereClause.Clause, Does.Contain("BETWEEN"));
    }

    [Test]
    public void Parse_WithLikePattern_ParsesCorrectly()
    {
        // Arrange
        var sql = "SELECT * FROM Users WHERE Name LIKE '%Smith%' OR Email LIKE 'test@%'";

        // Act
        var query = QueryBreakdown.Parse(sql);

        // Assert
        Assert.That(query.WhereClause.Clause, Does.Contain("LIKE"));
        Assert.That(query.WhereClause.Clause, Does.Contain("%Smith%"));
    }

    [Test]
    public void Parse_WithIsNullCheck_ParsesCorrectly()
    {
        // Arrange
        var sql = "SELECT * FROM Users WHERE DeletedDate IS NULL AND Email IS NOT NULL";

        // Act
        var query = QueryBreakdown.Parse(sql);

        // Assert
        Assert.That(query.WhereClause.Clause, Does.Contain("IS NULL"));
        Assert.That(query.WhereClause.Clause, Does.Contain("IS NOT NULL"));
    }

    #endregion

    #region Outlier Conditions - Aggregate Functions

    [Test]
    public void Parse_WithMultipleAggregateFunctions_ParsesCorrectly()
    {
        // Arrange
        var sql = @"SELECT
                        COUNT(*) AS TotalCount,
                        SUM(Amount) AS TotalAmount,
                        AVG(Price) AS AvgPrice,
                        MIN(CreateDate) AS FirstDate,
                        MAX(UpdateDate) AS LastDate
                        FROM Orders";

        // Act
        var query = QueryBreakdown.Parse(sql);

        // Assert
        Assert.That(query.SelectClause.Clause, Does.Contain("COUNT(*)"));
        Assert.That(query.SelectClause.Clause, Does.Contain("SUM(Amount)"));
        Assert.That(query.SelectClause.Clause, Does.Contain("AVG(Price)"));
        Assert.That(query.SelectClause.Clause, Does.Contain("MIN(CreateDate)"));
        Assert.That(query.SelectClause.Clause, Does.Contain("MAX(UpdateDate)"));
    }

    [Test]
    public void Parse_WithDistinct_ParsesCorrectly()
    {
        // Arrange
        var sql = "SELECT DISTINCT Country, City FROM Customers";

        // Act
        var query = QueryBreakdown.Parse(sql);

        // Assert
        Assert.That(query.SelectClause.Clause, Does.Contain("DISTINCT"));
    }

    [Test]
    public void Parse_WithTop_ParsesCorrectly()
    {
        // Arrange
        var sql = "SELECT TOP 10 Name FROM Users ORDER BY CreateDate DESC";

        // Act
        var query = QueryBreakdown.Parse(sql);

        // Assert
        Assert.That(query.SelectClause.Clause, Does.Contain("TOP 10"));
    }

    #endregion

    #region AddSelectExpression Tests

    [Test]
    public void AddSelectExpression_WhenEmpty_SetsSelectClause()
    {
        // Arrange
        var query = new QueryBreakdown();
        var expr = new GenericColumnExpression("CustomerID", "Customers");

        // Act
        query.AddSelectExpression(expr);

        // Assert
        Assert.That(query.SelectClause.Clause, Is.EqualTo("[Customers].[CustomerID]"));
    }

    [Test]
    public void AddSelectExpression_WithMultipleExpressions_AppendsWithComma()
    {
        // Arrange
        var query = new QueryBreakdown();
        var expr1 = new GenericColumnExpression("CustomerID", "Customers");
        var expr2 = new GenericColumnExpression("CustomerName", "Customers");

        // Act
        query.AddSelectExpression(expr1);
        query.AddSelectExpression(expr2);

        // Assert
        Assert.That(query.SelectClause.Clause, Is.EqualTo("[Customers].[CustomerID], [Customers].[CustomerName]"));
    }

    [Test]
    public void AddSelectExpression_WithComment_AddsCommentToSelectClause()
    {
        // Arrange
        var query = new QueryBreakdown();
        var expr = new GenericColumnExpression("CustomerID", "Customers");

        // Act
        query.AddSelectExpression(expr, "/* Primary key */");

        // Assert
        Assert.That(query.SelectClause.Clause, Is.EqualTo("[Customers].[CustomerID]"));
        Assert.That(query.SelectClause.Comment, Is.EqualTo("/* Primary key */"));
    }

    [Test]
    public void AddSelectExpression_WithMultipleComments_AppendsComments()
    {
        // Arrange
        var query = new QueryBreakdown();
        var expr1 = new GenericColumnExpression("CustomerID", "Customers");
        var expr2 = new GenericColumnExpression("CustomerName", "Customers");

        // Act
        query.AddSelectExpression(expr1, "/* Primary key */");
        query.AddSelectExpression(expr2, "/* Display name */");

        // Assert
        Assert.That(query.SelectClause.Comment, Is.EqualTo("/* Primary key */ /* Display name */"));
    }

    [Test]
    public void AddSelectExpression_WithNullExpression_ThrowsArgumentNullException()
    {
        // Arrange
        var query = new QueryBreakdown();

        // Act & Assert
        Assert.Throws<ArgumentNullException>(() => query.AddSelectExpression(null!));
    }

    [Test]
    public void AddSelectExpression_WithLiteralExpression_GeneratesCorrectSql()
    {
        // Arrange
        var query = new QueryBreakdown();
        var expr = new Strata.SqlTools.SqlBreakdown.Expressions.Literals.NumberLiteralExpression(100);

        // Act
        query.AddSelectExpression(expr);

        // Assert
        Assert.That(query.SelectClause.Clause, Is.EqualTo("100"));
    }

    [Test]
    public void AddSelectExpression_WithComparisonExpression_GeneratesCorrectSql()
    {
        // Arrange
        var query = new QueryBreakdown();
        var col = new GenericColumnExpression("Age", "Users");
        var expr = col > 18;

        // Act
        query.AddSelectExpression(expr);

        // Assert
        Assert.That(query.SelectClause.Clause, Does.Contain("[Users].[Age]"));
        Assert.That(query.SelectClause.Clause, Does.Contain(">"));
        Assert.That(query.SelectClause.Clause, Does.Contain("18"));
    }

    #endregion

    #region AddWhereExpression Tests

    [Test]
    public void AddWhereExpression_WhenEmpty_SetsWhereClause()
    {
        // Arrange
        var query = new QueryBreakdown();
        var col = new GenericColumnExpression("Active", "Users");
        var expr = col == 1;

        // Act
        query.AddWhereExpression(expr);

        // Assert
        Assert.That(query.WhereClause.Clause, Does.Contain("[Users].[Active]"));
        Assert.That(query.WhereClause.Clause, Does.Contain("="));
        Assert.That(query.WhereClause.Clause, Does.Contain("1"));
    }

    [Test]
    public void AddWhereExpression_WithMultipleExpressions_AppendsWithAnd()
    {
        // Arrange
        var query = new QueryBreakdown();
        var col1 = new GenericColumnExpression("Active", "Users");
        var col2 = new GenericColumnExpression("Age", "Users");
        var expr1 = col1 == 1;
        var expr2 = col2 >= 18;

        // Act
        query.AddWhereExpression(expr1);
        query.AddWhereExpression(expr2);

        // Assert
        Assert.That(query.WhereClause.Clause, Does.Contain("[Users].[Active]"));
        Assert.That(query.WhereClause.Clause, Does.Contain(" and "));
        Assert.That(query.WhereClause.Clause, Does.Contain("[Users].[Age]"));
    }

    [Test]
    public void AddWhereExpression_WithOrOperation_AppendsWithOr()
    {
        // Arrange
        var query = new QueryBreakdown();
        var col1 = new GenericColumnExpression("Status", "Orders");
        var col2 = new GenericColumnExpression("Priority", "Orders");
        var expr1 = col1 == "Urgent";
        var expr2 = col2 > 5;

        // Act
        query.AddWhereExpression(expr1);
        query.AddWhereExpression(expr2, null, "or");

        // Assert
        Assert.That(query.WhereClause.Clause, Does.Contain("[Orders].[Status]"));
        Assert.That(query.WhereClause.Clause, Does.Contain(" or "));
        Assert.That(query.WhereClause.Clause, Does.Contain("[Orders].[Priority]"));
    }

    [Test]
    public void AddWhereExpression_WithComment_AddsCommentToWhereClause()
    {
        // Arrange
        var query = new QueryBreakdown();
        var col = new GenericColumnExpression("Active", "Users");
        var expr = col == 1;

        // Act
        query.AddWhereExpression(expr, "/* Filter active users */");

        // Assert
        Assert.That(query.WhereClause.Comment, Is.EqualTo("/* Filter active users */"));
    }

    [Test]
    public void AddWhereExpression_WithMultipleComments_AppendsComments()
    {
        // Arrange
        var query = new QueryBreakdown();
        var col1 = new GenericColumnExpression("Active", "Users");
        var col2 = new GenericColumnExpression("Verified", "Users");
        var expr1 = col1 == 1;
        var expr2 = col2 == new BooleanLiteralExpression(true);

        // Act
        query.AddWhereExpression(expr1, "/* Active users */");
        query.AddWhereExpression(expr2, "/* Verified only */");

        // Assert
        Assert.That(query.WhereClause.Comment, Is.EqualTo("/* Active users */ /* Verified only */"));
    }

    [Test]
    public void AddWhereExpression_WithNullExpression_ThrowsArgumentNullException()
    {
        // Arrange
        var query = new QueryBreakdown();

        // Act & Assert
        Assert.Throws<ArgumentNullException>(() => query.AddWhereExpression(null!));
    }

    [Test]
    public void AddWhereExpression_WithStringComparison_GeneratesCorrectSql()
    {
        // Arrange
        var query = new QueryBreakdown();
        var col = new GenericColumnExpression("Name", "Users");
        var expr = col == "John";

        // Act
        query.AddWhereExpression(expr);

        // Assert
        Assert.That(query.WhereClause.Clause, Is.EqualTo("[Users].[Name] = 'John'"));
    }

    [Test]
    public void AddWhereExpression_WithComplexExpression_GeneratesCorrectSql()
    {
        // Arrange
        var query = new QueryBreakdown();
        var col1 = new GenericColumnExpression("Price", "Products");
        var col2 = new GenericColumnExpression("Discount", "Products");
        var expr = (col1 - col2) > 100;

        // Act
        query.AddWhereExpression(expr);

        // Assert
        Assert.That(query.WhereClause.Clause, Does.Contain("[Products].[Price]"));
        Assert.That(query.WhereClause.Clause, Does.Contain("-"));
        Assert.That(query.WhereClause.Clause, Does.Contain("[Products].[Discount]"));
        Assert.That(query.WhereClause.Clause, Does.Contain(">"));
        Assert.That(query.WhereClause.Clause, Does.Contain("100"));
    }

    [Test]
    public void AddSelectExpression_ToExistingClause_PreservesExistingContent()
    {
        // Arrange
        var query = new QueryBreakdown();
        query.SelectClause.Clause = "ID";
        var expr = new GenericColumnExpression("Name", "Users");

        // Act
        query.AddSelectExpression(expr);

        // Assert
        Assert.That(query.SelectClause.Clause, Does.StartWith("ID, "));
        Assert.That(query.SelectClause.Clause, Does.Contain("[Users].[Name]"));
    }

    [Test]
    public void AddWhereExpression_ToExistingClause_PreservesExistingContent()
    {
        // Arrange
        var query = new QueryBreakdown();
        query.WhereClause.Clause = "Status = 'Active'";
        var col = new GenericColumnExpression("Age", "Users");
        var expr = col > 18;

        // Act
        query.AddWhereExpression(expr);

        // Assert
        Assert.That(query.WhereClause.Clause, Does.StartWith("Status = 'Active' and "));
        Assert.That(query.WhereClause.Clause, Does.Contain("[Users].[Age]"));
    }

    #endregion

    #region Type Mismatch Tests

    [Test]
    public void AddOrUpdateParameter_WithTypeMismatch_ThrowsException()
    {
        // Arrange
        var helper = new QueryBreakdownTestHelper();
        helper.SetParameterValue("@TestParam", 123); // Set as int

        // Act & Assert
        var ex = Assert.Throws<InvalidOperationException>(() =>
        {
            helper.TestAddOrUpdateParameter("@TestParam", "StringValue"); // Try to set as string
        });

        Assert.That(ex.Message, Does.Contain("@TestParam"));
        Assert.That(ex.Message, Does.Contain("Int32"));
        Assert.That(ex.Message, Does.Contain("String"));
    }

    [Test]
    public void AddOrUpdateParameter_WithSameType_KeepsExistingValue()
    {
        // Arrange
        var helper = new QueryBreakdownTestHelper();
        helper.SetParameterValue("@TestParam", 123); // Set as int

        // Act - Try to update with another int value
        helper.TestAddOrUpdateParameter("@TestParam", 456);

        // Assert - Should keep the original value (123), not update to 456
        // This is the expected behavior for AddWhereClause where we don't overwrite existing values
        Assert.That(helper.Parameters["@TestParam"], Is.EqualTo(123));
    }

    [Test]
    public void AddOrUpdateParameter_NullToValue_SetsValue()
    {
        // Arrange
        var helper = new QueryBreakdownTestHelper();
        helper.Parameters["@TestParam"] = null!;

        // Act
        helper.TestAddOrUpdateParameter("@TestParam", 999);

        // Assert
        Assert.That(helper.Parameters["@TestParam"], Is.EqualTo(999));
    }

    #endregion
}

/// <summary>
/// Test helper class to expose protected members of QueryBreakdown for testing.
/// </summary>
internal class QueryBreakdownTestHelper : QueryBreakdown
{
    public void TestAddOrUpdateParameter(string parameterName, object? value)
    {
        AddOrUpdateParameter(parameterName, value);
    }

    public void TestExtractAndAddParameters(string sql)
    {
        ExtractAndAddParameters(sql);
    }
}