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

using Strata.SqlTools.Breakdowns.Snowflake;

namespace Strata.SqlTools.SqlBreakdown.Tests.Snowflake;

[TestFixture]
public class QueryBreakdownTests
{
    #region Constructor Tests

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

        // Assert
        Assert.That(queryBreakdown.SelectClause.Clause, Is.EqualTo(string.Empty));
        Assert.That(queryBreakdown.FromClause.Clause, Is.EqualTo(string.Empty));
        Assert.That(queryBreakdown.WhereClause.Clause, Is.EqualTo(string.Empty));
        Assert.That(queryBreakdown.OrderByClause.Clause, Is.EqualTo(string.Empty));
        Assert.That(queryBreakdown.GroupByClause.Clause, Is.EqualTo(string.Empty));
        Assert.That(queryBreakdown.HavingClause.Clause, Is.EqualTo(string.Empty));
    }

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

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

        // Assert
        Assert.That(queryBreakdown.SelectClause.Clause, Is.EqualTo(selectClause));
        Assert.That(queryBreakdown.FromClause.Clause, Is.EqualTo(fromClause));
    }

    [Test]
    public void Constructor_WithSelectFromAndWhere_SetsProperties()
    {
        // Arrange
        var selectClause = "ID, NAME";
        var fromClause = "USERS";
        var whereClause = "ACTIVE = 1";

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

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

    #endregion

    #region GetSql Tests - Snowflake Formatting

    [Test]
    public void GetSql_SimpleSelect_UsesSnowflakeFormatting()
    {
        // Arrange
        var queryBreakdown = new QueryBreakdown("ID, NAME", "USERS");

        // Act
        var sql = queryBreakdown.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"));
        // Verify 4-space indentation (Snowflake style)
        Assert.That(sql, Does.Contain("    "));
    }

    [Test]
    public void GetSql_WithAllClauses_GeneratesCorrectSnowflakeSql()
    {
        // Arrange
        var queryBreakdown = new QueryBreakdown("DEPARTMENT, COUNT(*) AS EMP_COUNT", "EMPLOYEES");
        queryBreakdown.WhereClause.Clause = "ACTIVE = 1";
        queryBreakdown.GroupByClause.Clause = "DEPARTMENT";
        queryBreakdown.HavingClause.Clause = "COUNT(*) > 5";
        queryBreakdown.OrderByClause.Clause = "DEPARTMENT ASC";

        // Act
        var sql = queryBreakdown.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"));
    }

    private static readonly char[] separator = new[] { '\r', '\n' };

    [Test]
    public void GetSql_WithSingleWithClause_UsesSnowflakeIndentation()
    {
        // Arrange
        var mainQueryBreakdown = new QueryBreakdown("P.*, PS.TOTAL_QTY", "PRODUCTS P INNER JOIN PRODUCT_SUMMARY PS ON P.PRODUCT_ID = PS.PRODUCT_ID");
        var cte = new QueryBreakdown("PRODUCT_ID, SUM(QUANTITY) AS TOTAL_QTY", "ORDER_DETAILS");
        cte.GroupByClause.Clause = "PRODUCT_ID";
        mainQueryBreakdown.AddWithClause("PRODUCT_SUMMARY", cte);

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

        // Assert
        Assert.That(sql, Does.Contain("WITH"));
        Assert.That(sql, Does.Contain("PRODUCT_SUMMARY AS ("));
        // Verify 4-space Snowflake indentation
        var lines = sql.Split(separator, StringSplitOptions.RemoveEmptyEntries);
        var indentedLines = lines.Where(l => l.StartsWith("    ")).ToList();
        Assert.That(indentedLines.Count, Is.GreaterThan(0));
    }

    [Test]
    public void GetSql_WithMultipleWithClauses_GeneratesCorrectSnowflakeSql()
    {
        // Arrange
        var mainQueryBreakdown = new QueryBreakdown("*", "CTE3");
        var cte1 = new QueryBreakdown("COL1", "TABLE1");
        var cte2 = new QueryBreakdown("COL2", "TABLE2");
        var cte3 = new QueryBreakdown("COL3", "TABLE3");

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

        // Act
        var sql = mainQueryBreakdown.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");
    }

    #endregion

    #region AddWithClause Tests - Snowflake Specific

    [Test]
    public void AddWithClause_WithSnowflakeSql_DefaultsToSnowflakeParsing()
    {
        // Arrange
        var mainQueryBreakdown = new QueryBreakdown("*", "PRODUCTS P INNER JOIN PRODUCT_ORDERS PO ON P.PRODUCT_ID = PO.PRODUCT_ID");
        var cteSql = "SELECT PRODUCT_ID, COUNT(*) AS ORDER_COUNT FROM ORDERS GROUP BY PRODUCT_ID";

        // Act - should default to isMicrosoftSql = false
        mainQueryBreakdown.AddWithClause("PRODUCT_ORDERS", cteSql);

        // Assert
        Assert.That(mainQueryBreakdown.WithClauses.Count, Is.EqualTo(1));
        Assert.That(mainQueryBreakdown.WithClauses[0].TableName, Is.EqualTo("PRODUCT_ORDERS"));
    }

    [Test]
    public void AddWithClause_WithMicrosoftSqlTrue_UsesTSqlParsing()
    {
        // Arrange
        var mainQueryBreakdown = new QueryBreakdown("*", "Products");
        var cteSql = "SELECT ProductID, COUNT(*) AS OrderCount FROM Orders GROUP BY ProductID";

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

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

    [Test]
    public void AddWithClause_WithQueryBreakdown_AddsToInheritedList()
    {
        // Arrange
        var mainQueryBreakdown = new QueryBreakdown("*", "PRODUCTS");
        var cteQuery = new QueryBreakdown("PRODUCT_ID, COUNT(*) AS ORDER_COUNT", "ORDERS");
        cteQuery.GroupByClause.Clause = "PRODUCT_ID";

        // Act
        mainQueryBreakdown.AddWithClause("PRODUCT_ORDERS", cteQuery);

        // Assert
        Assert.That(mainQueryBreakdown.WithClauses.Count, Is.EqualTo(1));
        Assert.That(mainQueryBreakdown.WithClauses[0].Query, Is.EqualTo(cteQuery));
    }

    #endregion

    #region CTE Integration Tests - Snowflake Specific

    [Test]
    public void CTE_NestedCTEs_WithParameterFlow()
    {
        // Arrange: Create inner CTE with Snowflake parameters
        var innerCte = new QueryBreakdown("ID, NAME, CREATED_DATE", "USERS", "CREATED_DATE >= :start_date");
        innerCte.AddParameter(":start_date", DateTime.Today.AddDays(-30));

        // Arrange: Create middle CTE that references inner CTE
        var middleCte = new QueryBreakdown("ID, NAME", "RECENT_USERS", "ID > :min_user_id");
        middleCte.AddParameter(":min_user_id", 100);

        // Arrange: Create main query that references middle CTE
        var mainQuery = new QueryBreakdown("COUNT(*) AS ACTIVE_USER_COUNT", "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 (uppercase for Snowflake style)
        var activeCte = new QueryBreakdown("ID, EMAIL, STATUS", "USERS", "STATUS = 'active'");

        // Arrange: Create CTE 2 - Recent orders with aggregation
        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("PRODUCT_ID, SUM(QUANTITY) AS TOTAL_QUANTITY", "ORDER_DETAILS");
        cteQuery.GroupByClause.Clause = "PRODUCT_ID";

        var mainQuery = new QueryBreakdown("P.PRODUCT_NAME, PT.TOTAL_QUANTITY",
            "PRODUCTS P INNER JOIN PRODUCT_TOTALS PT ON P.PRODUCT_ID = PT.PRODUCT_ID");
        mainQuery.AddWithClause("PRODUCT_TOTALS", 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("PRODUCT_TOTALS"));
        Assert.That(sql, Does.Contain("AS"));
        Assert.That(sql, Does.Contain("PRODUCT_ID"));
        Assert.That(sql, Does.Contain("TOTAL_QUANTITY"));
    }

    [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.Count, Is.EqualTo(1));
    }

    #endregion

    #region CTE Parameter Inheritance Tests - Snowflake

    [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
        // Snowflake stores parameters in both @ and : formats, so count is doubled
        Assert.That(merged.Count, Is.GreaterThanOrEqualTo(2));
        Assert.That(merged.ContainsKey("@UserId") || merged.ContainsKey(":UserId"), Is.True);
        Assert.That(merged.ContainsKey("@ActiveStatus") || merged.ContainsKey(":ActiveStatus"), Is.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("ResultLimit", 100);
        mainQuery.AddWithClause("ACTIVE_USERS", cte);

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

        // Assert
        // Should have parameters from both CTE and main query
        var keys = merged.Keys.ToList();
        Assert.That(keys.Any(k => k.Contains("MinDate")));
        Assert.That(keys.Any(k => k.Contains("ResultLimit")));
    }

    [Test]
    public void GetMergedParameters_WithMultipleCTEs_MergesAllParameters()
    {
        // Arrange
        var cte1 = new QueryBreakdown("ID, STATUS", "USERS", "STATUS = 'active'");
        cte1.AddParameter("Status1", "active");

        var cte2 = new QueryBreakdown("USER_ID, CREATED", "ORDERS", "CREATED >= :DATE");
        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
        var keys = merged.Keys.ToList();
        Assert.That(keys.Any(k => k.Contains("Status1")));
        Assert.That(keys.Any(k => k.Contains("MinDate")));
        Assert.That(keys.Any(k => k.Contains("ResultLimit")));
    }

    [Test]
    public void GetMergedParameters_WithParameterConflict_MainQueryTakesPrecedence()
    {
        // Arrange
        var cte = new QueryBreakdown("ID", "USERS");
        cte.AddParameter("QueryLimit", 10); // CTE sets to 10

        var mainQuery = new QueryBreakdown("*", "FINAL_RESULT");
        mainQuery.AddParameter("QueryLimit", 100); // Main query sets to 100
        mainQuery.AddWithClause("BASE_DATA", cte);

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

        // Assert
        // Main query value should win
        var keys = merged.Keys.Where(k => k.Contains("QueryLimit")).ToList();
        Assert.That(keys.Count, Is.GreaterThan(0));
        // All QueryLimit entries should be 100 (main query's value)
        foreach (var key in keys)
        {
            Assert.That(merged[key], Is.EqualTo(100));
        }
    }

    [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
        var keys = merged.Keys.ToList();
        Assert.That(keys.Any(k => k.Contains("InnerParam")));
        Assert.That(keys.Any(k => k.Contains("MiddleParam")));
        Assert.That(keys.Any(k => k.Contains("MainParam")));
    }

    [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
        // Verify all values are present and types are preserved
        var intValues = merged.Values.OfType<int>().Count();
        var stringValues = merged.Values.OfType<string>().Count();
        var dateValues = merged.Values.OfType<DateTime>().Count();
        var decimalValues = merged.Values.OfType<decimal>().Count();

        Assert.That(intValues, Is.GreaterThan(0), "Should have at least one int value");
        Assert.That(stringValues, Is.GreaterThan(0), "Should have at least one string value");
        Assert.That(dateValues, Is.GreaterThan(0), "Should have at least one DateTime value");
        Assert.That(decimalValues, Is.GreaterThan(0), "Should have at least one decimal value");
    }

    #endregion

    #region Parse Tests - Snowflake Specific

    [Test]
    public void Parse_SimpleSnowflakeSelect_ParsesCorrectly()
    {
        // Arrange
        var sql = "SELECT ID, NAME FROM USERS";

        // Act
        var queryBreakdown = QueryBreakdown.Parse(sql, false);

        // Assert
        Assert.That(queryBreakdown.SelectClause.Clause?.Trim(), Does.Contain("ID, NAME"));
        Assert.That(queryBreakdown.FromClause.Clause?.Trim(), Does.Contain("USERS"));
    }

    [Test]
    public void Parse_WithLimitClause_ParsesCorrectly()
    {
        // Arrange
        var sql = "SELECT ID, NAME FROM USERS ORDER BY NAME LIMIT 10";

        // Act
        var queryBreakdown = QueryBreakdown.Parse(sql, false);

        // Assert
        Assert.That(queryBreakdown.OrderByClause.Clause?.Trim(), Does.Contain("NAME"));
        Assert.That(queryBreakdown.OrderByClause.Clause?.Trim(), Does.Contain("LIMIT 10"));
    }

    [Test]
    public void Parse_WithQualifyClause_ParsesCorrectly()
    {
        // Arrange
        var sql = @"SELECT ID, NAME, ROW_NUMBER() OVER (PARTITION BY DEPT ORDER BY SALARY DESC) AS RN
                        FROM EMPLOYEES
                        QUALIFY RN = 1";

        // Act
        var queryBreakdown = QueryBreakdown.Parse(sql, false);

        // Assert
        Assert.That(queryBreakdown.SelectClause.Clause?.Trim(), Does.Contain("ROW_NUMBER()"));
        // QUALIFY is typically parsed as part of WHERE or as a separate extension in Snowflake
    }

    [Test]
    public void Parse_WithColonParameters_ExtractsSnowflakeParameters()
    {
        // Arrange
        var sql = "SELECT ID, NAME FROM USERS WHERE USER_ID = :userId AND STATUS = :status";

        // Act
        var queryBreakdown = QueryBreakdown.Parse(sql, false);

        // Assert
        Assert.That(queryBreakdown.Parameters, Does.ContainKey(":userId"));
        Assert.That(queryBreakdown.Parameters, Does.ContainKey(":status"));
    }

    [Test]
    public void Parse_WithAtParameters_ExtractsAndNormalizesParameters()
    {
        // Arrange
        var sql = "SELECT ID, NAME FROM USERS WHERE USER_ID = :userId AND STATUS = @status";

        // Act
        var queryBreakdown = QueryBreakdown.Parse(sql, false);

        // Assert
        Assert.That(queryBreakdown.Parameters, Does.ContainKey(":userId"));
        Assert.That(queryBreakdown.Parameters, Does.Not.ContainKey("@status"));
    }

    [Test]
    public void Parse_WithMixedParameters_ExtractsBothFormats()
    {
        // Arrange
        var sql = "SELECT ID, NAME FROM USERS WHERE USER_ID = :userId AND STATUS = @status";

        // Act
        var queryBreakdown = QueryBreakdown.Parse(sql, false);

        // Assert
        Assert.That(queryBreakdown.Parameters.Count, Is.GreaterThan(0));
    }

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

        // Act
        var queryBreakdown = QueryBreakdown.Parse(sql, true);

        // Assert
        Assert.That(queryBreakdown, Is.Not.Null);
        Assert.That(queryBreakdown, Is.InstanceOf<QueryBreakdown>());
        Assert.That(queryBreakdown.Parameters, Does.ContainKey("@UserId"));
    }

    [Test]
    public void Parse_WithSnowflakeWithClause_ParsesCorrectly()
    {
        // Arrange
        var sql = @"WITH PRODUCT_SUMMARY AS (
                SELECT PRODUCT_ID, SUM(QUANTITY) AS TOTAL_QTY
                FROM ORDER_DETAILS
                GROUP BY PRODUCT_ID
            )
            SELECT P.*, PS.TOTAL_QTY
            FROM PRODUCTS P
            INNER JOIN PRODUCT_SUMMARY PS ON P.PRODUCT_ID = PS.PRODUCT_ID";

        // Act
        var queryBreakdown = QueryBreakdown.Parse(sql, false);

        // Assert
        Assert.That(queryBreakdown.IsUsingWithClause, Is.True);
        Assert.That(queryBreakdown.SelectClause.Clause?.Trim(), Does.Contain("P.*, PS.TOTAL_QTY"));
    }

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

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

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

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

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

        // Assert
        Assert.That(success, Is.True);
        Assert.That(queryBreakdown, Is.Not.Null);
        Assert.That(queryBreakdown, Is.InstanceOf<QueryBreakdown>());
    }

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

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

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

    #endregion

    #region Inheritance Tests

    [Test]
    public void InheritsFromQueryBreakdown_CanUseBaseClassMethods()
    {
        // Arrange
        var queryBreakdown = new QueryBreakdown("*", "USERS");

        // Act
        queryBreakdown.AddParameter("UserId", 123);
        queryBreakdown.AddWhereClause("ACTIVE = 1");

        // Assert
        Assert.That(queryBreakdown.Parameters, Does.ContainKey("@UserId"));
        Assert.That(queryBreakdown.WhereClause.Clause, Does.Contain("ACTIVE = 1"));
    }

    [Test]
    public void InheritsWithClauses_SharesSameStorage()
    {
        // Arrange
        var queryBreakdown = new QueryBreakdown("*", "PRODUCTS");
        var cte = new QueryBreakdown("*", "ORDERS");

        // Act
        queryBreakdown.AddWithClause("ORDER_CTE", cte);

        // Assert
        Assert.That(queryBreakdown.WithClauses.Count, Is.EqualTo(1));
        Assert.That(queryBreakdown.IsUsingWithClause, Is.True);
    }

    [Test]
    public void Clone_CreatesSnowflakeInstance()
    {
        // Arrange
        var original = new QueryBreakdown("*", "USERS");
        original.WhereClause.Clause = "ACTIVE = 1";

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

        // Assert
        Assert.That(clone, Is.InstanceOf<QueryBreakdown>());
        Assert.That(clone.SelectClause.Clause, Is.EqualTo(original.SelectClause.Clause));
    }

    #endregion

    #region Integration Tests

    [Test]
    public void ComplexQuery_WithMultipleCTEsAndAllClauses_WorksCorrectly()
    {
        // Arrange
        var mainQueryBreakdown = new QueryBreakdown("*", "FINAL_DATA FD");
        mainQueryBreakdown.WhereClause.Clause = "FD.TOTAL_SALES > :minSales";
        mainQueryBreakdown.OrderByClause.Clause = "FD.TOTAL_SALES DESC LIMIT 100";

        var salesCte = new QueryBreakdown(
            "REGION_ID, SUM(AMOUNT) AS TOTAL_SALES",
            "SALES");
        salesCte.WhereClause.Clause = "SALE_DATE >= :startDate";
        salesCte.GroupByClause.Clause = "REGION_ID";

        var productCte = new QueryBreakdown("*", "PRODUCTS");
        productCte.WhereClause.Clause = "ACTIVE = 1";

        // Act
        mainQueryBreakdown.AddWithClause("SALES_SUMMARY", salesCte);
        mainQueryBreakdown.AddWithClause("ACTIVE_PRODUCTS", productCte);
        mainQueryBreakdown.AddParameter("minSales", 10000);
        mainQueryBreakdown.AddParameter("startDate", new DateTime(2025, 1, 1, 0, 0, 0, DateTimeKind.Utc));

        var sql = mainQueryBreakdown.GetSql();

        // Assert
        Assert.That(sql, Does.Contain("WITH"));
        Assert.That(sql, Does.Contain("SALES_SUMMARY AS ("));
        Assert.That(sql, Does.Contain("ACTIVE_PRODUCTS AS ("));
        Assert.That(sql, Does.Contain("LIMIT 100"));
        Assert.That(mainQueryBreakdown.Parameters, Does.ContainKey(":minSales"));
        Assert.That(mainQueryBreakdown.Parameters, Does.ContainKey(":startDate"));
    }

    [Test]
    public void NestedCTEs_ParseAndGenerate_WorksCorrectly()
    {
        // Arrange - Create nested WITH clause structure
        var innerCte = new QueryBreakdown("ORDER_ID, CUSTOMER_ID", "ORDERS");
        var middleCte = new QueryBreakdown("CUSTOMER_ID, COUNT(*) AS ORDER_COUNT", "INNER_CTE");
        middleCte.GroupByClause.Clause = "CUSTOMER_ID";
        middleCte.AddWithClause("INNER_CTE", innerCte);

        var mainQueryBreakdown = new QueryBreakdown("*", "MIDDLE_CTE");
        mainQueryBreakdown.AddWithClause("MIDDLE_CTE", middleCte);

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

        // Assert
        Assert.That(sql, Does.Contain("WITH"));
        Assert.That(sql, Does.Contain("MIDDLE_CTE AS ("));
        Assert.That(mainQueryBreakdown.WithClauses.Count, Is.EqualTo(1));
    }

    [Test]
    public void RoundTrip_ParseAndGetSql_ProducesSimilarSql()
    {
        // Arrange
        var originalSql = @"SELECT ID, NAME, EMAIL
                                FROM USERS
                                WHERE ACTIVE = 1
                                ORDER BY NAME ASC";

        // Act
        var parsed = QueryBreakdown.Parse(originalSql, false);
        var generatedSql = parsed.GetSql();

        // Assert
        Assert.That(generatedSql, Does.Contain("SELECT"));
        Assert.That(generatedSql, Does.Contain("ID, NAME, EMAIL"));
        Assert.That(generatedSql, Does.Contain("FROM"));
        Assert.That(generatedSql, Does.Contain("USERS"));
        Assert.That(generatedSql, Does.Contain("WHERE"));
        Assert.That(generatedSql, Does.Contain("ACTIVE = 1"));
        Assert.That(generatedSql, Does.Contain("ORDER BY"));
        Assert.That(generatedSql, Does.Contain("NAME ASC"));
    }

    #endregion

    #region Edge Cases

    [Test]
    public void Parse_WithComplexSubqueries_HandlesCorrectly()
    {
        // Arrange
        var sql = @"SELECT U.ID, U.NAME,
                        (SELECT COUNT(*) FROM ORDERS O WHERE O.USER_ID = U.ID) AS ORDER_COUNT
                        FROM USERS U
                        WHERE U.ID IN (SELECT DISTINCT USER_ID FROM ORDERS WHERE AMOUNT > 100)";

        // Act
        var queryBreakdown = QueryBreakdown.Parse(sql, false);

        // Assert
        Assert.That(queryBreakdown, Is.Not.Null);
        Assert.That(queryBreakdown.SelectClause.Clause, Does.Contain("(SELECT COUNT(*)"));
    }

    [Test]
    public void GetSql_EmptyQuery_GeneratesMinimalSql()
    {
        // Arrange
        var queryBreakdown = new QueryBreakdown();

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

        // Assert
        Assert.That(sql, Does.Contain("SELECT"));
        // Should have minimal structure even when empty
    }

    [Test]
    public void Parse_WithCommentsInSql_HandlesGracefully()
    {
        // Arrange
        var sql = @"-- This is a comment
                        SELECT ID, NAME -- inline comment
                        FROM USERS
                        /* Multi-line
                           comment */
                        WHERE ACTIVE = 1";

        // Act & Assert
        // May throw or handle comments - test should verify behavior
        Assert.DoesNotThrow(() =>
        {
            _ = QueryBreakdown.Parse(sql, false);
        });
    }

    #endregion

    #region Outlier Conditions - Snowflake-Specific Edge Cases

    [Test]
    public void Parse_WithDoubleColonCast_ParsesCorrectly()
    {
        // Arrange - Snowflake uses :: for casting
        var sql = "SELECT ID::VARCHAR, AMOUNT::DECIMAL(10,2) FROM ORDERS";

        // Act
        var queryBreakdown = QueryBreakdown.Parse(sql, false);

        // Assert
        Assert.That(queryBreakdown.SelectClause.Clause, Does.Contain("::"));
    }

    [Test]
    public void Parse_WithVariantDataType_ParsesCorrectly()
    {
        // Arrange
        var sql = "SELECT JSON_DATA:name::STRING, JSON_DATA:age::NUMBER FROM JSON_TABLE";

        // Act
        var queryBreakdown = QueryBreakdown.Parse(sql, false);

        // Assert
        Assert.That(queryBreakdown.SelectClause.Clause, Does.Contain("JSON_DATA:name"));
    }

    [Test]
    public void Parse_WithFlattenFunction_ParsesCorrectly()
    {
        // Arrange
        var sql = @"SELECT
                        F.VALUE:id::NUMBER AS ID,
                        F.VALUE:name::STRING AS NAME
                        FROM JSON_TABLE,
                        LATERAL FLATTEN(input => JSON_DATA:items) F";

        // Act
        var queryBreakdown = QueryBreakdown.Parse(sql, false);

        // Assert
        Assert.That(queryBreakdown.SelectClause.Clause, Does.Contain("F.VALUE"));
        Assert.That(queryBreakdown.FromClause.Clause, Does.Contain("FLATTEN"));
    }

    [Test]
    public void Parse_WithSampleClause_ParsesCorrectly()
    {
        // Arrange
        var sql = "SELECT * FROM LARGE_TABLE SAMPLE (10 ROWS)";

        // Act
        var queryBreakdown = QueryBreakdown.Parse(sql, false);

        // Assert
        Assert.That(queryBreakdown.FromClause.Clause, Does.Contain("SAMPLE"));
    }

    [Test]
    public void Parse_WithAtTimestamp_ParsesCorrectly()
    {
        // Arrange - Snowflake Time Travel
        var sql = "SELECT * FROM USERS AT(TIMESTAMP => '2024-01-01 00:00:00'::TIMESTAMP)";

        // Act
        var queryBreakdown = QueryBreakdown.Parse(sql, false);

        // Assert
        Assert.That(queryBreakdown.FromClause.Clause, Does.Contain("AT(TIMESTAMP"));
    }

    [Test]
    public void Parse_WithMatchRecognize_HandlesGracefully()
    {
        // Arrange - Complex Snowflake pattern matching
        var sql = @"SELECT * FROM EVENTS
                        MATCH_RECOGNIZE(
                            PARTITION BY USER_ID
                            ORDER BY EVENT_TIME
                            MEASURES A.EVENT_TIME AS START_TIME
                            PATTERN (A B+ C)
                            DEFINE B AS B.EVENT_TYPE = 'CLICK'
                        )";

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

    [Test]
    public void Parse_WithWindowFunctionAndQualify_ParsesCorrectly()
    {
        // Arrange
        var sql = @"SELECT
                        ID,
                        NAME,
                        ROW_NUMBER() OVER (PARTITION BY DEPARTMENT ORDER BY SALARY DESC) AS RN
                        FROM EMPLOYEES
                        QUALIFY ROW_NUMBER() OVER (PARTITION BY DEPARTMENT ORDER BY SALARY DESC) = 1";

        // Act
        var queryBreakdown = QueryBreakdown.Parse(sql, false);

        // Assert
        Assert.That(queryBreakdown.SelectClause.Clause, Does.Contain("ROW_NUMBER()"));
    }

    #endregion

    #region Outlier Conditions - Parameter Formats

    [Test]
    public void Parse_WithManyColonParameters_ExtractsAll()
    {
        // Arrange
        var sql = @"SELECT * FROM ORDERS
                        WHERE USER_ID = :userId
                        AND ORDER_DATE >= :startDate
                        AND ORDER_DATE <= :endDate
                        AND STATUS = :status
                        AND AMOUNT > :minAmount";

        // Act
        var queryBreakdown = QueryBreakdown.Parse(sql, false);

        // Assert
        Assert.That(queryBreakdown.Parameters.Count, Is.GreaterThanOrEqualTo(5));
        Assert.That(queryBreakdown.Parameters, Does.ContainKey(":userId"));
        Assert.That(queryBreakdown.Parameters, Does.ContainKey(":startDate"));
        Assert.That(queryBreakdown.Parameters, Does.ContainKey(":endDate"));
        Assert.That(queryBreakdown.Parameters, Does.ContainKey(":status"));
        Assert.That(queryBreakdown.Parameters, Does.ContainKey(":minAmount"));
    }

    [Test]
    public void Parse_WithParameterInJsonPath_DoesNotExtractAsParameter()
    {
        // Arrange - Colon in JSON path should not be treated as parameter
        var sql = "SELECT JSON_DATA:user:name FROM JSON_TABLE";

        // Act
        var queryBreakdown = QueryBreakdown.Parse(sql, false);

        // Assert - Should not extract 'user' or 'name' as parameters
        Assert.That(queryBreakdown.SelectClause.Clause, Does.Contain("JSON_DATA:user:name"));
    }

    [Test]
    public void AddParameter_WithColonPrefix_StoresWithColon()
    {
        // Arrange
        var queryBreakdown = new QueryBreakdown();

        // Act
        queryBreakdown.AddParameter(":snowflakeParam", 123);

        // Assert
        // Base class normalizes to @, but Snowflake might handle differently
        Assert.That(queryBreakdown.Parameters.Count, Is.GreaterThan(0));
    }

    #endregion

    #region Outlier Conditions - Snowflake String Handling

    [Test]
    public void Parse_WithDollarQuotedString_HandlesGracefully()
    {
        // Arrange - Snowflake supports $$ for string literals
        var sql = "SELECT $$This is a 'quoted' string$$ AS TEXT FROM DUAL";

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

    [Test]
    public void Parse_WithEscapedSingleQuotes_ParsesCorrectly()
    {
        // Arrange
        var sql = "SELECT NAME FROM USERS WHERE NAME = 'O''Brien'";

        // Act
        var queryBreakdown = QueryBreakdown.Parse(sql, false);

        // Assert
        Assert.That(queryBreakdown.WhereClause.Clause, Does.Contain("O''Brien"));
    }

    #endregion

    #region Outlier Conditions - Complex Snowflake Queries

    [Test]
    public void Parse_WithMultipleSetOperators_HandlesGracefully()
    {
        // Arrange
        var sql = @"SELECT ID, NAME FROM USERS_A
                        UNION ALL
                        SELECT ID, NAME FROM USERS_B
                        EXCEPT
                        SELECT ID, NAME FROM USERS_C
                        INTERSECT
                        SELECT ID, NAME FROM USERS_D";

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

    [Test]
    public void Parse_WithPivotClause_HandlesGracefully()
    {
        // Arrange
        var sql = @"SELECT * FROM SALES
                        PIVOT(SUM(AMOUNT) FOR MONTH IN ('JAN', 'FEB', 'MAR'))";

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

    [Test]
    public void GetSql_WithVeryLongSnowflakeQuery_GeneratesCorrectly()
    {
        // Arrange - Build a complex query with many CTEs
        var mainQueryBreakdown = new QueryBreakdown("*", "FINAL_RESULT");

        for (int i = 0; i < 15; i++)
        {
            var cte = new QueryBreakdown(
                $"COL{i}, COUNT(*) AS CNT{i}",
                $"TABLE_{i}");
            cte.WhereClause.Clause = $"ACTIVE = 1 AND TYPE = {i}";
            cte.GroupByClause.Clause = $"COL{i}";
            mainQueryBreakdown.AddWithClause($"CTE_{i}", cte);
        }

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

        // Assert
        Assert.That(sql, Does.Contain("CTE_0 AS ("));
        Assert.That(sql, Does.Contain("CTE_14 AS ("));
        Assert.That(sql.Length, Is.GreaterThan(1000));
    }

    #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 queryBreakdown = QueryBreakdown.Parse(sql, false);

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

    [Test]
    public void GetSql_ComparesIndentationToBaseClass_UsesFourSpaces()
    {
        // Arrange
        var QueryBreakdown = new QueryBreakdown("ID", "USERS");
        var baseQueryBreakdown = new QueryBreakdown("ID", "USERS");

        // Act
        var snowflakeSql = QueryBreakdown.GetSql();
        _ = baseQueryBreakdown.GetSql();

        // Assert - Snowflake should use 4-space indent, base uses 5-space
        var snowflakeLines = snowflakeSql.Split(separator, StringSplitOptions.RemoveEmptyEntries);
        var snowflakeIndentedLines = snowflakeLines.Where(l => l.StartsWith("    ") && !l.StartsWith("     ")).ToList();
        Assert.That(snowflakeIndentedLines.Count, Is.GreaterThan(0), "Snowflake should use 4-space indentation");
    }

    #endregion

    #region Outlier Conditions - Boundary and Error Cases

    [Test]
    public void Parse_WithOnlySelectNoFrom_HandlesGracefully()
    {
        // Arrange - Snowflake allows SELECT without FROM using DUAL or for constants
        var sql = "SELECT 1 AS ONE, CURRENT_TIMESTAMP() AS NOW";

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

    [Test]
    public void TryParse_WithMalformedSnowflakeSQL_ReturnsFalseWithError()
    {
        // Arrange
        var sql = "SELET * FORM USERS WERE ID = 1"; // Intentional typos

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

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

    [Test]
    public void Parse_WithVeryLongTableName_ParsesCorrectly()
    {
        // Arrange
        var longTableName = "VERY_LONG_TABLE_NAME_" + new string('X', 200);
        var sql = $"SELECT ID FROM {longTableName}";

        // Act
        var queryBreakdown = QueryBreakdown.Parse(sql, false);

        // Assert
        Assert.That(queryBreakdown.FromClause.Clause, Does.Contain(longTableName));
    }

    [Test]
    public void MergeWith_SnowflakeQueryWithBaseQuery_WorksCorrectly()
    {
        // Arrange
        var QueryBreakdown = new QueryBreakdown("*", "USERS U");
        var baseQuery = new QueryBreakdown();
        baseQuery.FromClause.Clause = "INNER JOIN ORDERS O ON U.ID = O.USER_ID";

        // Act
        QueryBreakdown.MergeWith(baseQuery);

        // Assert
        Assert.That(QueryBreakdown.FromClause.Clause, Does.Contain("USERS U"));
        Assert.That(QueryBreakdown.FromClause.Clause, Does.Contain("INNER JOIN ORDERS"));
    }

    #endregion

    #region Outlier Conditions - Real-World Snowflake Scenarios

    [Test]
    public void Parse_WithSnowflakeStageReference_ParsesCorrectly()
    {
        // Arrange
        var sql = "SELECT $1, $2, $3 FROM @MY_STAGE/data/file.csv";

        // Act
        var queryBreakdown = QueryBreakdown.Parse(sql, false);

        // Assert
        Assert.That(queryBreakdown.SelectClause.Clause, Does.Contain("$1"));
        Assert.That(queryBreakdown.FromClause.Clause, Does.Contain("@MY_STAGE"));
    }

    [Test]
    public void Parse_WithSequenceNextval_ParsesCorrectly()
    {
        // Arrange
        var sql = "SELECT MY_SEQUENCE.NEXTVAL, NAME FROM USERS";

        // Act
        var queryBreakdown = QueryBreakdown.Parse(sql, false);

        // Assert
        Assert.That(queryBreakdown.SelectClause.Clause, Does.Contain("NEXTVAL"));
    }

    [Test]
    public void ComplexRealWorldQuery_WithAllSnowflakeFeatures_ParsesAndGenerates()
    {
        // Arrange - Realistic complex Snowflake query
        var salesCte = new QueryBreakdown(
            "REGION_ID, PRODUCT_ID, SUM(AMOUNT::DECIMAL(18,2)) AS TOTAL_SALES",
            "SALES_DATA");
        salesCte.WhereClause.Clause = "SALE_DATE >= :startDate AND SALE_DATE < :endDate";
        salesCte.GroupByClause.Clause = "REGION_ID, PRODUCT_ID";

        var topProductsCte = new QueryBreakdown(
            "REGION_ID, PRODUCT_ID, TOTAL_SALES, ROW_NUMBER() OVER (PARTITION BY REGION_ID ORDER BY TOTAL_SALES DESC) AS RN",
            "SALES_SUMMARY");

        var mainQueryBreakdown = new QueryBreakdown("R.REGION_NAME, T.PRODUCT_ID, T.TOTAL_SALES", "REGIONS R INNER JOIN TOP_PRODUCTS T ON R.REGION_ID = T.REGION_ID");
        mainQueryBreakdown.WhereClause.Clause = "T.RN <= 10";
        mainQueryBreakdown.OrderByClause.Clause = "R.REGION_NAME, T.TOTAL_SALES DESC LIMIT 100";

        mainQueryBreakdown.AddWithClause("SALES_SUMMARY", salesCte);
        mainQueryBreakdown.AddWithClause("TOP_PRODUCTS", topProductsCte);
        mainQueryBreakdown.AddParameter("startDate", "2024-01-01");
        mainQueryBreakdown.AddParameter("endDate", "2024-12-31");

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

        // Assert
        Assert.That(sql, Does.Contain("WITH"));
        Assert.That(sql, Does.Contain("SALES_SUMMARY AS ("));
        Assert.That(sql, Does.Contain("TOP_PRODUCTS AS ("));
        Assert.That(sql, Does.Contain("ROW_NUMBER()"));
        Assert.That(sql, Does.Contain("LIMIT 100"));
        Assert.That(mainQueryBreakdown.Parameters.Count, Is.GreaterThanOrEqualTo(2));
    }

    #endregion

    #region Microsoft SQL Server Compatibility Tests

    [Test]
    public void Parse_MicrosoftSqlQuery_ReturnsQueryBreakdown()
    {
        // Arrange
        var tsqlQuery = "SELECT Id, Name FROM Users WHERE Active = 1";

        // Act
        var result = QueryBreakdown.Parse(tsqlQuery, isMicrosoftSql: true);

        // Assert
        Assert.That(result, Is.Not.Null);
        Assert.That(result, Is.InstanceOf<QueryBreakdown>(), "Should return Snowflake QueryBreakdown instance");
        Assert.That(result.SelectClause.Clause?.Trim(), Does.Contain("Id, Name"));
        Assert.That(result.FromClause.Clause?.Trim(), Does.Contain("Users"));
        Assert.That(result.WhereClause.Clause?.Trim(), Does.Contain("Active = 1"));
    }

    [Test]
    public void Parse_MicrosoftSqlWithParameters_ExtractsParameters()
    {
        // Arrange
        var tsqlQuery = "SELECT ProductId, ProductName FROM Products WHERE CategoryId = @categoryId AND Price > @minPrice";

        // Act
        var result = QueryBreakdown.Parse(tsqlQuery, isMicrosoftSql: true);

        // Assert
        Assert.That(result.Parameters, Does.ContainKey("@categoryId"));
        Assert.That(result.Parameters, Does.ContainKey("@minPrice"));
    }

    [Test]
    public void Parse_MicrosoftSqlWithAllClauses_ParsesAllComponents()
    {
        // Arrange
        var tsqlQuery = @"SELECT DepartmentId, COUNT(*) AS EmployeeCount, AVG(Salary) AS AvgSalary
                             FROM Employees
                             WHERE Active = 1
                             GROUP BY DepartmentId
                             HAVING COUNT(*) > 5
                             ORDER BY EmployeeCount DESC";

        // Act
        var result = QueryBreakdown.Parse(tsqlQuery, isMicrosoftSql: true);

        // Assert
        Assert.That(result.SelectClause.Clause?.Trim(), Does.Contain("DepartmentId"));
        Assert.That(result.SelectClause.Clause?.Trim(), Does.Contain("COUNT(*)"));
        Assert.That(result.FromClause.Clause?.Trim(), Does.Contain("Employees"));
        Assert.That(result.WhereClause.Clause?.Trim(), Does.Contain("Active = 1"));
        Assert.That(result.GroupByClause.Clause?.Trim(), Does.Contain("DepartmentId"));
        Assert.That(result.HavingClause.Clause?.Trim(), Does.Contain("COUNT(*) > 5"));
        Assert.That(result.OrderByClause.Clause?.Trim(), Does.Contain("EmployeeCount DESC"));
    }

    [Test]
    public void GetSql_FromMicrosoftSqlParsedQuery_GeneratesSnowflakeSyntax()
    {
        // Arrange
        var tsqlQuery = "SELECT Id, Name FROM Users WHERE Active = 1 ORDER BY Name";
        var result = QueryBreakdown.Parse(tsqlQuery, isMicrosoftSql: true);

        // Act
        var snowflakeSql = result.GetSql();

        // Assert
        Assert.That(snowflakeSql, Does.Contain("SELECT"));
        Assert.That(snowflakeSql, Does.Contain("FROM"));
        Assert.That(snowflakeSql, Does.Contain("WHERE"));
        Assert.That(snowflakeSql, Does.Contain("ORDER BY"));
        // Verify Snowflake-style formatting (4-space indentation)
        var lines = snowflakeSql.Split(separator, StringSplitOptions.RemoveEmptyEntries);
        var indentedLines = lines.Where(l => l.StartsWith("    ")).ToList();
        Assert.That(indentedLines.Count, Is.GreaterThan(0), "Should have Snowflake-style indentation");
    }

    [Test]
    public void Parse_MicrosoftSqlWithJoins_ParsesCorrectly()
    {
        // Arrange
        var tsqlQuery = @"SELECT o.OrderId, c.CustomerName, p.ProductName
                             FROM Orders o
                             INNER JOIN Customers c ON o.CustomerId = c.CustomerId
                             LEFT JOIN OrderDetails od ON o.OrderId = od.OrderId
                             LEFT JOIN Products p ON od.ProductId = p.ProductId
                             WHERE o.OrderDate >= @startDate";

        // Act
        var result = QueryBreakdown.Parse(tsqlQuery, isMicrosoftSql: true);

        // Assert
        Assert.That(result.SelectClause.Clause?.Trim(), Does.Contain("o.OrderId"));
        Assert.That(result.FromClause.Clause?.Trim(), Does.Contain("INNER JOIN"));
        Assert.That(result.FromClause.Clause?.Trim(), Does.Contain("LEFT JOIN"));
        Assert.That(result.WhereClause.Clause?.Trim(), Does.Contain("OrderDate"));
    }

    [Test]
    public void Parse_MicrosoftSqlWithSubquery_ParsesCorrectly()
    {
        // Arrange
        var tsqlQuery = @"SELECT CustomerId, CustomerName
                             FROM Customers
                             WHERE CustomerId IN (SELECT CustomerId FROM Orders WHERE OrderDate >= @startDate)";

        // Act
        var result = QueryBreakdown.Parse(tsqlQuery, isMicrosoftSql: true);

        // Assert
        Assert.That(result.SelectClause.Clause?.Trim(), Does.Contain("CustomerId, CustomerName"));
        Assert.That(result.WhereClause.Clause?.Trim(), Does.Contain("IN"));
        Assert.That(result.WhereClause.Clause?.Trim(), Does.Contain("SELECT"));
    }

    [Test]
    public void TryParse_MicrosoftSqlValidQuery_ReturnsTrue()
    {
        // Arrange
        var tsqlQuery = "SELECT TOP 100 Id, Name FROM Users ORDER BY Name";

        // Act
        var success = QueryBreakdown.TryParse(tsqlQuery, out var result, isMicrosoftSql: true);

        // Assert
        Assert.That(success, Is.True);
        Assert.That(result, Is.Not.Null);
        Assert.That(result, Is.InstanceOf<QueryBreakdown>());
    }

    [Test]
    public void TryParse_MicrosoftSqlInvalidQuery_ReturnsFalse()
    {
        // Arrange
        var invalidQuery = "INVALID T-SQL QUERY";

        // Act
        var success = QueryBreakdown.TryParse(invalidQuery, out var result, out var errorMessage, isMicrosoftSql: true);

        // Assert
        Assert.That(success, Is.False);
        Assert.That(result, Is.Null);
        Assert.That(errorMessage, Is.Not.Null.And.Not.Empty);
    }

    [Test]
    public void Parse_MicrosoftSqlWithBracketedIdentifiers_ParsesCorrectly()
    {
        // Arrange
        var tsqlQuery = "SELECT [Order Id], [Customer Name] FROM [Order Details] WHERE [Active] = 1";

        // Act
        var result = QueryBreakdown.Parse(tsqlQuery, isMicrosoftSql: true);

        // Assert
        Assert.That(result.SelectClause.Clause?.Trim(), Does.Contain("[Order Id]"));
        Assert.That(result.FromClause.Clause?.Trim(), Does.Contain("[Order Details]"));
        Assert.That(result.WhereClause.Clause?.Trim(), Does.Contain("[Active]"));
    }

    [Test]
    public void Parse_MicrosoftSqlWithCTE_ParsesCorrectly()
    {
        // Arrange
        var tsqlQuery = @"WITH EmployeeCTE AS (
                                 SELECT DepartmentId, COUNT(*) AS EmployeeCount
                                 FROM Employees
                                 GROUP BY DepartmentId
                             )
                             SELECT d.DepartmentName, e.EmployeeCount
                             FROM Departments d
                             INNER JOIN EmployeeCTE e ON d.DepartmentId = e.DepartmentId";

        // Act
        var result = QueryBreakdown.Parse(tsqlQuery, isMicrosoftSql: true);

        // Assert
        Assert.That(result.IsUsingWithClause, Is.True);
        Assert.That(result.SelectClause.Clause?.Trim(), Does.Contain("DepartmentName"));
    }

    [Test]
    public void GetSql_MicrosoftSqlWithCTE_GeneratesSnowflakeFormattedOutput()
    {
        // Arrange
        var tsqlQuery = @"WITH SalesSummary AS (
                                 SELECT ProductId, SUM(Quantity) AS TotalQty
                                 FROM OrderDetails
                                 GROUP BY ProductId
                             )
                             SELECT p.ProductName, s.TotalQty
                             FROM Products p
                             INNER JOIN SalesSummary s ON p.ProductId = s.ProductId";
        var result = QueryBreakdown.Parse(tsqlQuery, isMicrosoftSql: true);

        // Act
        var snowflakeSql = result.GetSql();

        // Assert
        Assert.That(snowflakeSql, Does.Contain("WITH"));
        Assert.That(snowflakeSql, Does.Contain("SELECT"));
        Assert.That(result.IsUsingWithClause, Is.True, "Should have WITH clause parsed");
        // Note: WITH clause content is stored in WithClause property when parsed via isMicrosoftSql
        // The GetSql() will output it if WithClauses collection is populated or if we manually add it
    }

    [Test]
    public void Parse_MicrosoftSqlComplexQuery_ParsesAndConvertsToSnowflake()
    {
        // Arrange
        var tsqlQuery = @"SELECT
                                 YEAR(o.OrderDate) AS OrderYear,
                                 MONTH(o.OrderDate) AS OrderMonth,
                                 c.Region,
                                 COUNT(DISTINCT o.OrderId) AS OrderCount,
                                 SUM(od.Quantity * od.UnitPrice) AS TotalRevenue
                             FROM Orders o
                             INNER JOIN OrderDetails od ON o.OrderId = od.OrderId
                             INNER JOIN Customers c ON o.CustomerId = c.CustomerId
                             WHERE o.OrderDate >= @startDate AND o.OrderDate < @endDate
                             GROUP BY YEAR(o.OrderDate), MONTH(o.OrderDate), c.Region
                             HAVING COUNT(DISTINCT o.OrderId) > 10
                             ORDER BY OrderYear DESC, OrderMonth DESC, TotalRevenue DESC";

        // Act
        var result = QueryBreakdown.Parse(tsqlQuery, isMicrosoftSql: true);
        var snowflakeSql = result.GetSql();

        // Assert - Verify parsing
        Assert.That(result, Is.InstanceOf<QueryBreakdown>());
        Assert.That(result.SelectClause.Clause?.Trim(), Does.Contain("YEAR"));
        Assert.That(result.GroupByClause.Clause?.Trim(), Does.Contain("YEAR"));
        Assert.That(result.HavingClause.Clause?.Trim(), Does.Contain("COUNT"));
        Assert.That(result.Parameters, Does.ContainKey("@startDate"));
        Assert.That(result.Parameters, Does.ContainKey("@endDate"));

        // Assert - Verify Snowflake SQL generation
        Assert.That(snowflakeSql, Does.Contain("SELECT"));
        Assert.That(snowflakeSql, Does.Contain("FROM"));
        Assert.That(snowflakeSql, Does.Contain("WHERE"));
        Assert.That(snowflakeSql, Does.Contain("GROUP BY"));
        Assert.That(snowflakeSql, Does.Contain("HAVING"));
        Assert.That(snowflakeSql, Does.Contain("ORDER BY"));
    }

    [Test]
    public void AddWithClause_ToMicrosoftSqlParsedQuery_WorksCorrectly()
    {
        // Arrange
        var mainQuery = "SELECT * FROM ProductSummary";
        var result = QueryBreakdown.Parse(mainQuery, isMicrosoftSql: true);
        var cteQuery = new QueryBreakdown("ProductId, COUNT(*) AS OrderCount", "Orders");
        cteQuery.GroupByClause.Clause = "ProductId";

        // Act
        result.AddWithClause("ProductSummary", cteQuery);
        var snowflakeSql = result.GetSql();

        // Assert
        Assert.That(result.WithClauses.Count, Is.EqualTo(1));
        Assert.That(snowflakeSql, Does.Contain("WITH"));
        Assert.That(snowflakeSql, Does.Contain("ProductSummary AS ("));
    }

    [Test]
    public void Clone_MicrosoftSqlParsedQuery_CreatesSnowflakeInstance()
    {
        // Arrange
        var tsqlQuery = "SELECT Id, Name FROM Users WHERE Active = 1";
        var original = QueryBreakdown.Parse(tsqlQuery, isMicrosoftSql: true);

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

        // Assert
        Assert.That(clone, Is.InstanceOf<QueryBreakdown>());
        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));
    }

    #endregion

    #region AddSelectExpression Tests

    [Test]
    public void AddSelectExpression_WithSnowflakeSyntax_GeneratesCorrectSql()
    {
        // Arrange
        var query = new QueryBreakdown();
        var expr = new Strata.SqlTools.SqlBreakdown.Expressions.GenericColumnExpression("CUSTOMER_ID", "CUSTOMERS");

        // Act
        query.AddSelectExpression(expr, null, isMicrosoftSql: false);

        // Assert
        // Snowflake doesn't use brackets
        Assert.That(query.SelectClause.Clause, Is.EqualTo("CUSTOMERS.CUSTOMER_ID"));
    }

    [Test]
    public void AddSelectExpression_WithSqlServerSyntax_GeneratesCorrectSql()
    {
        // Arrange
        var query = new QueryBreakdown();
        var expr = new Strata.SqlTools.SqlBreakdown.Expressions.GenericColumnExpression("CustomerID", "Customers");

        // Act
        query.AddSelectExpression(expr, null, isMicrosoftSql: true);

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

    [Test]
    public void AddSelectExpression_DefaultBehavior_UsesSnowflakeSyntax()
    {
        // Arrange
        var query = new QueryBreakdown();
        var expr = new Strata.SqlTools.SqlBreakdown.Expressions.GenericColumnExpression("CUSTOMER_ID", "CUSTOMERS");

        // Act
        query.AddSelectExpression(expr); // Default should be Snowflake

        // Assert
        Assert.That(query.SelectClause.Clause, Is.EqualTo("CUSTOMERS.CUSTOMER_ID"));
        Assert.That(query.SelectClause.Clause, Does.Not.Contain("["));
    }

    [Test]
    public void AddSelectExpression_WithMultipleExpressions_AppendsWithComma()
    {
        // Arrange
        var query = new QueryBreakdown();
        var expr1 = new Strata.SqlTools.SqlBreakdown.Expressions.GenericColumnExpression("CUSTOMER_ID", "CUSTOMERS");
        var expr2 = new Strata.SqlTools.SqlBreakdown.Expressions.GenericColumnExpression("CUSTOMER_NAME", "CUSTOMERS");

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

        // Assert
        Assert.That(query.SelectClause.Clause, Is.EqualTo("CUSTOMERS.CUSTOMER_ID, CUSTOMERS.CUSTOMER_NAME"));
    }

    [Test]
    public void AddSelectExpression_WithComment_AddsCommentToSelectClause()
    {
        // Arrange
        var query = new QueryBreakdown();
        var expr = new Strata.SqlTools.SqlBreakdown.Expressions.GenericColumnExpression("CUSTOMER_ID", "CUSTOMERS");

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

        // Assert
        Assert.That(query.SelectClause.Clause, Is.EqualTo("CUSTOMERS.CUSTOMER_ID"));
        Assert.That(query.SelectClause.Comment, Is.EqualTo("/* Primary key */"));
    }

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

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

    [Test]
    public void AddSelectExpression_WithBooleanLiteral_UsesSnowflakeSyntax()
    {
        // Arrange
        var query = new QueryBreakdown();
        var expr = new Strata.SqlTools.SqlBreakdown.Expressions.Literals.BooleanLiteralExpression(true);

        // Act
        query.AddSelectExpression(expr, null, isMicrosoftSql: false);

        // Assert
        // Snowflake uses TRUE/FALSE
        Assert.That(query.SelectClause.Clause, Is.EqualTo("TRUE"));
    }

    [Test]
    public void AddSelectExpression_WithBooleanLiteral_UsesSqlServerSyntax()
    {
        // Arrange
        var query = new QueryBreakdown();
        var expr = new Strata.SqlTools.SqlBreakdown.Expressions.Literals.BooleanLiteralExpression(true);

        // Act
        query.AddSelectExpression(expr, null, isMicrosoftSql: true);

        // Assert
        // SQL Server uses 1/0
        Assert.That(query.SelectClause.Clause, Is.EqualTo("1"));
    }

    #endregion

    #region AddWhereExpression Tests

    [Test]
    public void AddWhereExpression_WithSnowflakeSyntax_GeneratesCorrectSql()
    {
        // Arrange
        var query = new QueryBreakdown();
        var col = new Strata.SqlTools.SqlBreakdown.Expressions.GenericColumnExpression("ACTIVE", "USERS");
        var expr = col == 1;

        // Act
        query.AddWhereExpression(expr, null, "and", isMicrosoftSql: false);

        // Assert
        Assert.That(query.WhereClause.Clause, Does.Contain("USERS.ACTIVE"));
        Assert.That(query.WhereClause.Clause, Does.Not.Contain("["));
    }

    [Test]
    public void AddWhereExpression_WithSqlServerSyntax_GeneratesCorrectSql()
    {
        // Arrange
        var query = new QueryBreakdown();
        var col = new Strata.SqlTools.SqlBreakdown.Expressions.GenericColumnExpression("Active", "Users");
        var expr = col == 1;

        // Act
        query.AddWhereExpression(expr, null, "and", isMicrosoftSql: true);

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

    [Test]
    public void AddWhereExpression_DefaultBehavior_UsesSnowflakeSyntax()
    {
        // Arrange
        var query = new QueryBreakdown();
        var col = new Strata.SqlTools.SqlBreakdown.Expressions.GenericColumnExpression("ACTIVE", "USERS");
        var expr = col == 1;

        // Act
        query.AddWhereExpression(expr); // Default should be Snowflake

        // Assert
        Assert.That(query.WhereClause.Clause, Does.Contain("USERS.ACTIVE"));
        Assert.That(query.WhereClause.Clause, Does.Not.Contain("["));
    }

    [Test]
    public void AddWhereExpression_WithMultipleExpressions_AppendsWithAnd()
    {
        // Arrange
        var query = new QueryBreakdown();
        var col1 = new Strata.SqlTools.SqlBreakdown.Expressions.GenericColumnExpression("ACTIVE", "USERS");
        var col2 = new Strata.SqlTools.SqlBreakdown.Expressions.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 Strata.SqlTools.SqlBreakdown.Expressions.GenericColumnExpression("STATUS", "ORDERS");
        var col2 = new Strata.SqlTools.SqlBreakdown.Expressions.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 Strata.SqlTools.SqlBreakdown.Expressions.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 Strata.SqlTools.SqlBreakdown.Expressions.GenericColumnExpression("ACTIVE", "USERS");
        var col2 = new Strata.SqlTools.SqlBreakdown.Expressions.GenericColumnExpression("VERIFIED", "USERS");
        var expr1 = col1 == 1;
        var expr2 = col2 == new Strata.SqlTools.SqlBreakdown.Expressions.Literals.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_UsesCorrectQuotes()
    {
        // Arrange
        var query = new QueryBreakdown();
        var col = new Strata.SqlTools.SqlBreakdown.Expressions.GenericColumnExpression("NAME", "USERS");
        var expr = col == "John";

        // Act
        query.AddWhereExpression(expr);

        // Assert
        Assert.That(query.WhereClause.Clause, Does.Contain("USERS.NAME"));
        Assert.That(query.WhereClause.Clause, Does.Contain("'John'"));
    }

    [Test]
    public void AddWhereExpression_MixingSyntaxModes_AllowsBothInSameQuery()
    {
        // Arrange
        var query = new QueryBreakdown();
        var col1 = new Strata.SqlTools.SqlBreakdown.Expressions.GenericColumnExpression("ACTIVE", "USERS");
        var col2 = new Strata.SqlTools.SqlBreakdown.Expressions.GenericColumnExpression("Status", "Users");
        var expr1 = col1 == 1;
        var expr2 = col2 == "Active";

        // Act
        query.AddWhereExpression(expr1, null, "and", isMicrosoftSql: false); // Snowflake
        query.AddWhereExpression(expr2, null, "and", isMicrosoftSql: true);  // SQL Server

        // Assert
        // Should contain both syntaxes
        Assert.That(query.WhereClause.Clause, Does.Contain("USERS.ACTIVE")); // Snowflake style
        Assert.That(query.WhereClause.Clause, Does.Contain("[Users].[Status]")); // SQL Server style
    }

    [Test]
    public void AddWhereExpression_WithComplexExpression_GeneratesCorrectSql()
    {
        // Arrange
        var query = new QueryBreakdown();
        var col1 = new Strata.SqlTools.SqlBreakdown.Expressions.GenericColumnExpression("PRICE", "PRODUCTS");
        var col2 = new Strata.SqlTools.SqlBreakdown.Expressions.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(">"));
    }

    [Test]
    public void AddSelectExpression_ToExistingClause_PreservesExistingContent()
    {
        // Arrange
        var query = new QueryBreakdown();
        query.SelectClause.Clause = "ID";
        var expr = new Strata.SqlTools.SqlBreakdown.Expressions.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 Strata.SqlTools.SqlBreakdown.Expressions.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 AddWhereClause Parameter Extraction Tests

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

        // Act - Use Snowflake :param syntax
        query.AddWhereClause("USER_ID = :UserId AND STATUS = :Status", false);

        // Assert
        Assert.That(query.WhereClause.Clause, Is.EqualTo("USER_ID = :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_WithMicrosoftParameters_ExtractsParametersAutomatically()
    {
        // Arrange
        var query = new QueryBreakdown();

        // Act - Use Microsoft @param syntax with isMicrosoftSql=true
        query.AddWhereClause("USER_ID = @UserId AND STATUS = @Status", "and", true);

        // Assert
        Assert.That(query.WhereClause.Clause, Is.EqualTo("USER_ID = @UserId AND STATUS = @Status"));
        Assert.That(query.Parameters, Does.ContainKey("@UserId"));
        Assert.That(query.Parameters, Does.ContainKey("@Status"));
    }

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

        // Act - Add where clause with same parameter
        query.AddWhereClause("USER_ID = :UserId", false);

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

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

        // Act
        query.AddWhereClause("USER_ID = :UserId", false);
        query.AddWhereClause("STATUS = :Status", "and", false);
        query.AddWhereClause("CREATED_DATE > :StartDate", "and", false);

        // Assert
        Assert.That(query.Parameters.Count, Is.GreaterThanOrEqualTo(3));
        Assert.That(query.Parameters, Does.ContainKey(":UserId"));
        Assert.That(query.Parameters, Does.ContainKey(":Status"));
        Assert.That(query.Parameters, Does.ContainKey(":StartDate"));
    }

    #endregion
}