using Strata.SqlTools.Interfaces;
using System.Linq;
using System.Text;

namespace Strata.SqlTools.SqlBreakdown.Tests;

/// <summary>
/// Unit tests for the SqlBreakdownCollection class.
/// </summary>
[TestFixture]
public class SqlBreakdownCollectionTests
{
    [Test]
    public void Constructor_WithNoArguments_CreatesEmptyCollection()
    {
        // Arrange & Act
        var collection = new SqlBreakdownCollection();

        // Assert
        Assert.That(collection.Count, Is.EqualTo(0));
        Assert.That(collection.IsEmpty, Is.True);
        Assert.That(collection.Breakdowns, Is.Empty);
        Assert.That(collection.RawStatements, Is.Empty);
    }

    [Test]
    public void Constructor_WithBreakdownList_InitializesCollection()
    {
        // Arrange
        var mockBreakdowns = new List<ISqlBreakdown>
        {
            new MockSqlBreakdown("SELECT * FROM Table1"),
            new MockSqlBreakdown("SELECT * FROM Table2")
        };

        // Act
        var collection = new SqlBreakdownCollection(mockBreakdowns);

        // Assert
        Assert.That(collection.Count, Is.EqualTo(2));
        Assert.That(collection.IsEmpty, Is.False);
    }

    [Test]
    public void Add_WithValidBreakdown_AddsToCollection()
    {
        // Arrange
        var collection = new SqlBreakdownCollection();
        var breakdown = new MockSqlBreakdown("SELECT * FROM Table1");

        // Act
        collection.Add(breakdown);

        // Assert
        Assert.That(collection.Count, Is.EqualTo(1));
        Assert.That(collection.GetAt(0), Is.EqualTo(breakdown));
    }

    [Test]
    public void Add_WithNullBreakdown_ThrowsArgumentNullException()
    {
        // Arrange
        var collection = new SqlBreakdownCollection();

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

    [Test]
    public void AddRange_WithMultipleBreakdowns_AddsAllItems()
    {
        // Arrange
        var collection = new SqlBreakdownCollection();
        var breakdowns = new List<ISqlBreakdown>
        {
            new MockSqlBreakdown("SELECT * FROM Table1"),
            new MockSqlBreakdown("SELECT * FROM Table2"),
            new MockSqlBreakdown("SELECT * FROM Table3")
        };

        // Act
        collection.AddRange(breakdowns);

        // Assert
        Assert.That(collection.Count, Is.EqualTo(3));
    }

    [Test]
    public void AddRange_WithNullCollection_ThrowsArgumentNullException()
    {
        // Arrange
        var collection = new SqlBreakdownCollection();

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

    [Test]
    public void Remove_WithExistingBreakdown_RemovesItem()
    {
        // Arrange
        var breakdown = new MockSqlBreakdown("SELECT * FROM Table1");
        var collection = new SqlBreakdownCollection(new[] { breakdown });

        // Act
        var result = collection.Remove(breakdown);

        // Assert
        Assert.That(result, Is.True);
        Assert.That(collection.Count, Is.EqualTo(0));
    }

    [Test]
    public void Remove_WithNonExistingBreakdown_ReturnsFalse()
    {
        // Arrange
        var collection = new SqlBreakdownCollection(new[] { new MockSqlBreakdown("SELECT * FROM Table1") });
        var otherBreakdown = new MockSqlBreakdown("SELECT * FROM Table2");

        // Act
        var result = collection.Remove(otherBreakdown);

        // Assert
        Assert.That(result, Is.False);
        Assert.That(collection.Count, Is.EqualTo(1));
    }

    [Test]
    public void Clear_WithMultipleItems_RemovesAll()
    {
        // Arrange
        var collection = new SqlBreakdownCollection(new[]
        {
            new MockSqlBreakdown("SELECT * FROM Table1"),
            new MockSqlBreakdown("SELECT * FROM Table2")
        });

        // Act
        collection.Clear();

        // Assert
        Assert.That(collection.Count, Is.EqualTo(0));
        Assert.That(collection.IsEmpty, Is.True);
    }

    [Test]
    public void ParseBatch_WithGoSeparators_ParsesStatements()
    {
        // Arrange
        var collection = new SqlBreakdownCollection();
        var batchSql = @"
            SELECT * FROM Table1
            GO
            SELECT * FROM Table2
            GO
            SELECT * FROM Table3
            ";

        // Act
        collection.ParseBatch(batchSql);

        // Assert
        Assert.That(collection.RawStatements.Count, Is.EqualTo(3));
        Assert.That(collection.RawStatements[0], Does.Contain("Table1"));
        Assert.That(collection.RawStatements[1], Does.Contain("Table2"));
        Assert.That(collection.RawStatements[2], Does.Contain("Table3"));
    }

    [Test]
    public void ParseBatch_WithMixedCaseGO_ParsesCorrectly()
    {
        // Arrange
        var collection = new SqlBreakdownCollection();
        var batchSql = @"
            SELECT * FROM Table1
            go
            SELECT * FROM Table2
            GO
            SELECT * FROM Table3
            ";

        // Act
        collection.ParseBatch(batchSql);

        // Assert
        Assert.That(collection.RawStatements.Count, Is.EqualTo(3));
    }

    [Test]
    public void ParseBatch_WithGoAndWhitespace_ParsesCorrectly()
    {
        // Arrange
        var collection = new SqlBreakdownCollection();
        var batchSql = @"
            SELECT * FROM Table1
               GO
            SELECT * FROM Table2
            	GO
            SELECT * FROM Table3
            ";

        // Act
        collection.ParseBatch(batchSql);

        // Assert
        Assert.That(collection.RawStatements.Count, Is.EqualTo(3));
    }

    [Test]
    public void ParseBatch_WithEmptyStatements_FiltersOutEmptyValues()
    {
        // Arrange
        var collection = new SqlBreakdownCollection();
        var batchSql = @"
            SELECT * FROM Table1
            GO
            GO

            SELECT * FROM Table2
            ";

        // Act
        collection.ParseBatch(batchSql);

        // Assert
        Assert.That(collection.RawStatements.Count, Is.EqualTo(2));
        Assert.That(collection.RawStatements[0], Does.Contain("Table1"));
        Assert.That(collection.RawStatements[1], Does.Contain("Table2"));
    }

    [Test]
    public void ParseBatch_WithNullInput_ThrowsArgumentNullException()
    {
        // Arrange
        var collection = new SqlBreakdownCollection();

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

    [Test]
    public void GetCombinedSql_WithMultipleBreakdowns_CombinesSqlWithSeparator()
    {
        // Arrange
        var breakdowns = new[]
        {
            new MockSqlBreakdown("SELECT * FROM Table1"),
            new MockSqlBreakdown("SELECT * FROM Table2")
        };
        var collection = new SqlBreakdownCollection(breakdowns);

        // Act
        var result = collection.GetCombinedSql();

        // Assert
        Assert.That(result, Does.Contain("Table1"));
        Assert.That(result, Does.Contain("Table2"));
        Assert.That(result, Does.Contain("GO"));
    }

    [Test]
    public void GetCombinedSql_WithEmptyCollection_ReturnsEmpty()
    {
        // Arrange
        var collection = new SqlBreakdownCollection();

        // Act
        var result = collection.GetCombinedSql();

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

    [Test]
    public void GetCombinedSql_WithCustomSeparator_UsesCustomSeparator()
    {
        // Arrange
        var breakdowns = new[]
        {
            new MockSqlBreakdown("SELECT * FROM Table1"),
            new MockSqlBreakdown("SELECT * FROM Table2")
        };
        var collection = new SqlBreakdownCollection(breakdowns);

        // Act
        var result = collection.GetCombinedSql(true, ";");

        // Assert
        Assert.That(result, Does.Contain(";"));
        Assert.That(result, Does.Not.Contain("GO"));
    }

    [Test]
    public void GetBatchSql_WithRawStatements_CombinesWithGO()
    {
        // Arrange
        var collection = new SqlBreakdownCollection();
        collection.ParseBatch(@"
            SELECT * FROM Table1
            GO
            SELECT * FROM Table2
            ");

        // Act
        var result = collection.GetBatchSql();

        // Assert
        Assert.That(result, Does.Contain("Table1"));
        Assert.That(result, Does.Contain("GO"));
        Assert.That(result, Does.Contain("Table2"));
    }

    [Test]
    public void GetBatchSql_WithEmptyCollection_ReturnsEmpty()
    {
        // Arrange
        var collection = new SqlBreakdownCollection();

        // Act
        var result = collection.GetBatchSql();

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

    [Test]
    public void Where_WithValidPredicate_FiltersBreakdowns()
    {
        // Arrange
        var breakdowns = new[]
        {
            new MockSqlBreakdown("SELECT * FROM Table1"),
            new MockSqlBreakdown("SELECT * FROM Table2"),
            new MockSqlBreakdown("SELECT * FROM Table3")
        };
        var collection = new SqlBreakdownCollection(breakdowns);

        // Act
        var filtered = collection.Where(b => b.ToString()!.Contains("Table2")).ToList();

        // Assert
        Assert.That(filtered.Count, Is.EqualTo(1));
        Assert.That(filtered[0].ToString()!, Does.Contain("Table2"));
    }

    [Test]
    public void Select_WithValidSelector_ProjectsBreakdowns()
    {
        // Arrange
        var breakdowns = new[]
        {
            new MockSqlBreakdown("SELECT * FROM Table1"),
            new MockSqlBreakdown("SELECT * FROM Table2")
        };
        var collection = new SqlBreakdownCollection(breakdowns);

        // Act
        var projected = collection.Select(b => b.ToString()!.Length).ToList();

        // Assert
        Assert.That(projected.Count, Is.EqualTo(2));
        Assert.That(projected[0], Is.GreaterThan(0));
    }

    [Test]
    public void GetAt_WithValidIndex_ReturnsBreakdown()
    {
        // Arrange
        var breakdown1 = new MockSqlBreakdown("SELECT * FROM Table1");
        var breakdown2 = new MockSqlBreakdown("SELECT * FROM Table2");
        var collection = new SqlBreakdownCollection(new[] { breakdown1, breakdown2 });

        // Act
        var result = collection.GetAt(1);

        // Assert
        Assert.That(result, Is.EqualTo(breakdown2));
    }

    [Test]
    public void GetAt_WithInvalidIndex_ThrowsIndexOutOfRangeException()
    {
        // Arrange
        var collection = new SqlBreakdownCollection(new[] { new MockSqlBreakdown("SELECT * FROM Table1") });

        // Act & Assert
        Assert.Throws<IndexOutOfRangeException>(() => collection.GetAt(5));
    }

    [Test]
    public void FirstOrDefault_WithMatchingPredicate_ReturnsBreakdown()
    {
        // Arrange
        var breakdowns = new[]
        {
            new MockSqlBreakdown("SELECT * FROM Table1"),
            new MockSqlBreakdown("SELECT * FROM Table2")
        };
        var collection = new SqlBreakdownCollection(breakdowns);

        // Act
        var result = collection.FirstOrDefault(b => b.ToString()!.Contains("Table2"));

        // Assert
        Assert.That(result, Is.Not.Null);
        Assert.That(result!.ToString(), Does.Contain("Table2"));
    }

    [Test]
    public void FirstOrDefault_WithNoMatch_ReturnsNull()
    {
        // Arrange
        var collection = new SqlBreakdownCollection(new[] { new MockSqlBreakdown("SELECT * FROM Table1") });

        // Act
        var result = collection.FirstOrDefault(b => b.ToString()!.Contains("NonExistent"));

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

    [Test]
    public void GetRawStatementAt_WithValidIndex_ReturnsStatement()
    {
        // Arrange
        var collection = new SqlBreakdownCollection();
        collection.ParseBatch(@"
            SELECT * FROM Table1
            GO
            SELECT * FROM Table2
            ");

        // Act
        var result = collection.GetRawStatementAt(1);

        // Assert
        Assert.That(result, Does.Contain("Table2"));
    }

    [Test]
    public void GetRawStatementAt_WithInvalidIndex_ThrowsIndexOutOfRangeException()
    {
        // Arrange
        var collection = new SqlBreakdownCollection();
        collection.ParseBatch("SELECT * FROM Table1");

        // Act & Assert
        Assert.Throws<IndexOutOfRangeException>(() => collection.GetRawStatementAt(5));
    }

    [Test]
    public void ToString_ReturnsFormattedSql()
    {
        // Arrange
        var breakdowns = new[]
        {
            new MockSqlBreakdown("SELECT * FROM Table1"),
            new MockSqlBreakdown("SELECT * FROM Table2")
        };
        var collection = new SqlBreakdownCollection(breakdowns);

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

        // Assert
        Assert.That(result, Does.Contain("Table1"));
        Assert.That(result, Does.Contain("Table2"));
        Assert.That(result, Does.Contain("GO"));
    }

    // ============================================================
    // CRUD Tests - Complete SQL Statement Coverage
    // ============================================================

    #region CREATE Tests

    [Test]
    public void ParseBatch_WithCreateTableStatements_ParsesSuccessfully()
    {
        // Arrange
        var collection = new SqlBreakdownCollection();
        var batchSql = @"
            CREATE TABLE Users (
                Id INT PRIMARY KEY,
                Name NVARCHAR(100),
                Email NVARCHAR(100)
            )
            GO
            CREATE TABLE Orders (
                OrderId INT PRIMARY KEY,
                UserId INT FOREIGN KEY REFERENCES Users(Id),
                OrderDate DATETIME
            )
            ";

        // Act
        collection.ParseBatch(batchSql);

        // Assert
        Assert.That(collection.Count, Is.EqualTo(2));
        Assert.That(collection.GetRawStatementAt(0), Does.Contain("CREATE TABLE Users"));
        Assert.That(collection.GetRawStatementAt(1), Does.Contain("CREATE TABLE Orders"));
    }

    [Test]
    public void ParseBatch_WithCreateIndexStatements_ParsesSuccessfully()
    {
        // Arrange
        var collection = new SqlBreakdownCollection();
        var batchSql = @"
            CREATE INDEX idx_Users_Email ON Users(Email)
            GO
            CREATE UNIQUE INDEX idx_Orders_OrderDate ON Orders(OrderDate)
            ";

        // Act
        collection.ParseBatch(batchSql);

        // Assert
        Assert.That(collection.Count, Is.EqualTo(2));
        Assert.That(collection.GetRawStatementAt(0), Does.Contain("CREATE INDEX"));
        Assert.That(collection.GetRawStatementAt(1), Does.Contain("UNIQUE"));
    }

    [Test]
    public void ParseBatch_WithCreateProcedureStatement_ParsesSuccessfully()
    {
        // Arrange
        var collection = new SqlBreakdownCollection();
        var batchSql = @"
            CREATE PROCEDURE sp_GetUserById
                @UserId INT
            AS
            BEGIN
                SELECT * FROM Users WHERE Id = @UserId
            END
            ";

        // Act
        collection.ParseBatch(batchSql);

        // Assert
        Assert.That(collection.Count, Is.GreaterThanOrEqualTo(1));
        Assert.That(collection.GetRawStatementAt(0), Does.Contain("CREATE PROCEDURE"));
    }

    #endregion

    #region INSERT (CREATE Data) Tests

    [Test]
    public void ParseBatch_WithInsertStatements_ParsesSuccessfully()
    {
        // Arrange
        var collection = new SqlBreakdownCollection();
        var batchSql = @"
            INSERT INTO Users (Id, Name, Email) VALUES (1, 'John Doe', 'john@example.com')
            GO
            INSERT INTO Users (Id, Name, Email) VALUES (2, 'Jane Smith', 'jane@example.com')
            GO
            INSERT INTO Users (Id, Name, Email) VALUES (3, 'Bob Johnson', 'bob@example.com')
            ";

        // Act
        collection.ParseBatch(batchSql);

        // Assert
        Assert.That(collection.Count, Is.EqualTo(3));
        Assert.That(collection.GetRawStatementAt(0), Does.Contain("INSERT INTO Users"));
        Assert.That(collection.GetRawStatementAt(1), Does.Contain("Jane Smith"));
        Assert.That(collection.GetRawStatementAt(2), Does.Contain("Bob Johnson"));
    }

    [Test]
    public void ParseBatch_WithInsertSelectStatements_ParsesSuccessfully()
    {
        // Arrange
        var collection = new SqlBreakdownCollection();
        var batchSql = @"
            INSERT INTO UsersArchive
            SELECT Id, Name, Email FROM Users WHERE CreatedDate < '2020-01-01'
            GO
            INSERT INTO OrdersBackup
            SELECT OrderId, UserId, OrderDate FROM Orders WHERE OrderDate < DATEADD(year, -1, GETDATE())
            ";

        // Act
        collection.ParseBatch(batchSql);

        // Assert
        Assert.That(collection.Count, Is.EqualTo(2));
        Assert.That(collection.GetRawStatementAt(0), Does.Contain("INSERT INTO UsersArchive"));
        Assert.That(collection.GetRawStatementAt(0), Does.Contain("SELECT"));
    }

    [Test]
    public void ParseBatch_WithBulkInsertStatements_ParsesSuccessfully()
    {
        // Arrange
        var collection = new SqlBreakdownCollection();
        var batchSql = @"
            BULK INSERT Users FROM 'C:\data\users.csv'
            WITH (FIELDTERMINATOR=',', ROWTERMINATOR='\n')
            GO
            BULK INSERT Orders FROM 'C:\data\orders.csv'
            WITH (FIELDTERMINATOR=',', ROWTERMINATOR='\n')
            ";

        // Act
        collection.ParseBatch(batchSql);

        // Assert
        Assert.That(collection.Count, Is.EqualTo(2));
        Assert.That(collection.GetRawStatementAt(0), Does.Contain("BULK INSERT"));
    }

    #endregion

    #region SELECT (READ) Tests

    [Test]
    public void ParseBatch_WithComplexSelectStatements_ParsesSuccessfully()
    {
        // Arrange
        var collection = new SqlBreakdownCollection();
        var batchSql = @"
            SELECT u.Id, u.Name, COUNT(o.OrderId) AS OrderCount
            FROM Users u
            LEFT JOIN Orders o ON u.Id = o.UserId
            WHERE u.CreatedDate > '2020-01-01'
            GROUP BY u.Id, u.Name
            HAVING COUNT(o.OrderId) > 0
            ORDER BY OrderCount DESC
            GO
            SELECT * FROM Orders WHERE OrderDate BETWEEN '2020-01-01' AND '2021-12-31'
            ";

        // Act
        collection.ParseBatch(batchSql);

        // Assert
        Assert.That(collection.Count, Is.EqualTo(2));
        Assert.That(collection.GetRawStatementAt(0), Does.Contain("LEFT JOIN"));
        Assert.That(collection.GetRawStatementAt(0), Does.Contain("GROUP BY"));
        Assert.That(collection.GetRawStatementAt(1), Does.Contain("BETWEEN"));
    }

    [Test]
    public void ParseBatch_WithSelectWithCommonTableExpression_ParsesSuccessfully()
    {
        // Arrange
        var collection = new SqlBreakdownCollection();
        var batchSql = @"
            WITH UserOrders AS (
                SELECT UserId, OrderId, OrderDate
                FROM Orders
                WHERE OrderDate > '2020-01-01'
            )
            SELECT u.Id, u.Name, uo.OrderId
            FROM Users u
            INNER JOIN UserOrders uo ON u.Id = uo.UserId
            ";

        // Act
        collection.ParseBatch(batchSql);

        // Assert
        Assert.That(collection.Count, Is.GreaterThanOrEqualTo(1));
        Assert.That(collection.GetRawStatementAt(0), Does.Contain("WITH UserOrders AS"));
    }

    [Test]
    public void ParseBatch_WithSelectFromMultipleTables_ParsesSuccessfully()
    {
        // Arrange
        var collection = new SqlBreakdownCollection();
        var batchSql = @"
            SELECT u.Id, u.Name, o.OrderId, p.ProductName
            FROM Users u
            JOIN Orders o ON u.Id = o.UserId
            JOIN OrderItems oi ON o.OrderId = oi.OrderId
            JOIN Products p ON oi.ProductId = p.Id
            WHERE u.Country = 'USA'
            GO
            SELECT * FROM UserProfiles WHERE UserId IN (SELECT Id FROM Users)
            ";

        // Act
        collection.ParseBatch(batchSql);

        // Assert
        Assert.That(collection.Count, Is.EqualTo(2));
        Assert.That(collection.GetRawStatementAt(0), Does.Contain("JOIN"));
        Assert.That(collection.GetRawStatementAt(1), Does.Contain("IN"));
    }

    #endregion

    #region UPDATE Tests

    [Test]
    public void ParseBatch_WithUpdateStatements_ParsesSuccessfully()
    {
        // Arrange
        var collection = new SqlBreakdownCollection();
        var batchSql = @"
            UPDATE Users SET Name = 'John Updated', ModifiedDate = GETDATE() WHERE Id = 1
            GO
            UPDATE Orders SET Status = 'Shipped' WHERE OrderDate < DATEADD(day, -30, GETDATE())
            GO
            UPDATE Products SET Price = Price * 1.1 WHERE Category = 'Electronics'
            ";

        // Act
        collection.ParseBatch(batchSql);

        // Assert
        Assert.That(collection.Count, Is.EqualTo(3));
        Assert.That(collection.GetRawStatementAt(0), Does.Contain("UPDATE Users"));
        Assert.That(collection.GetRawStatementAt(1), Does.Contain("Status"));
        Assert.That(collection.GetRawStatementAt(2), Does.Contain("Price * 1.1"));
    }

    [Test]
    public void ParseBatch_WithUpdateFromSelectStatements_ParsesSuccessfully()
    {
        // Arrange
        var collection = new SqlBreakdownCollection();
        var batchSql = @"
            UPDATE u
            SET u.LastOrderDate = (SELECT MAX(OrderDate) FROM Orders WHERE UserId = u.Id)
            FROM Users u
            WHERE u.Id IN (SELECT DISTINCT UserId FROM Orders)
            GO
            UPDATE Products
            SET Quantity = Quantity - 1
            FROM OrderItems oi
            WHERE Products.Id = oi.ProductId AND oi.OrderId = 100
            ";

        // Act
        collection.ParseBatch(batchSql);

        // Assert
        Assert.That(collection.Count, Is.EqualTo(2));
        Assert.That(collection.GetRawStatementAt(0), Does.Contain("UPDATE u"));
        Assert.That(collection.GetRawStatementAt(1), Does.Contain("Quantity - 1"));
    }

    [Test]
    public void ParseBatch_WithUpdateWithJoinStatements_ParsesSuccessfully()
    {
        // Arrange
        var collection = new SqlBreakdownCollection();
        var batchSql = @"
            UPDATE Orders
            SET OrderStatus = 'Processed'
            FROM Orders o
            JOIN OrderItems oi ON o.OrderId = oi.OrderId
            WHERE oi.Quantity > 50
            ";

        // Act
        collection.ParseBatch(batchSql);

        // Assert
        Assert.That(collection.Count, Is.GreaterThanOrEqualTo(1));
        Assert.That(collection.GetRawStatementAt(0), Does.Contain("UPDATE Orders"));
        Assert.That(collection.GetRawStatementAt(0), Does.Contain("JOIN"));
    }

    #endregion

    #region DELETE Tests

    [Test]
    public void ParseBatch_WithDeleteStatements_ParsesSuccessfully()
    {
        // Arrange
        var collection = new SqlBreakdownCollection();
        var batchSql = @"
            DELETE FROM Orders WHERE OrderDate < '2019-01-01'
            GO
            DELETE FROM UserProfiles WHERE UserId NOT IN (SELECT Id FROM Users)
            GO
            DELETE FROM AuditLog WHERE LogDate < DATEADD(year, -2, GETDATE())
            ";

        // Act
        collection.ParseBatch(batchSql);

        // Assert
        Assert.That(collection.Count, Is.EqualTo(3));
        Assert.That(collection.GetRawStatementAt(0), Does.Contain("DELETE FROM Orders"));
        Assert.That(collection.GetRawStatementAt(1), Does.Contain("NOT IN"));
        Assert.That(collection.GetRawStatementAt(2), Does.Contain("DATEADD"));
    }

    [Test]
    public void ParseBatch_WithDeleteFromSelectStatements_ParsesSuccessfully()
    {
        // Arrange
        var collection = new SqlBreakdownCollection();
        var batchSql = @"
            DELETE o FROM Orders o
            WHERE NOT EXISTS (SELECT 1 FROM OrderItems oi WHERE oi.OrderId = o.OrderId)
            GO
            DELETE FROM Users
            WHERE Id IN (SELECT UserId FROM Orders WHERE OrderStatus = 'Cancelled')
            ";

        // Act
        collection.ParseBatch(batchSql);

        // Assert
        Assert.That(collection.Count, Is.EqualTo(2));
        Assert.That(collection.GetRawStatementAt(0), Does.Contain("EXISTS"));
    }

    [Test]
    public void ParseBatch_WithDeleteWithJoinStatements_ParsesSuccessfully()
    {
        // Arrange
        var collection = new SqlBreakdownCollection();
        var batchSql = @"
            DELETE Orders
            FROM Orders o
            INNER JOIN OrderStatuses os ON o.StatusId = os.Id
            WHERE os.StatusName = 'Archived'
            ";

        // Act
        collection.ParseBatch(batchSql);

        // Assert
        Assert.That(collection.Count, Is.GreaterThanOrEqualTo(1));
        Assert.That(collection.GetRawStatementAt(0), Does.Contain("DELETE Orders"));
        Assert.That(collection.GetRawStatementAt(0), Does.Contain("INNER JOIN"));
    }

    #endregion

    #region DROP Tests

    [Test]
    public void ParseBatch_WithDropTableStatements_ParsesSuccessfully()
    {
        // Arrange
        var collection = new SqlBreakdownCollection();
        var batchSql = @"
            DROP TABLE IF EXISTS OrderItems
            GO
            DROP TABLE IF EXISTS Orders
            GO
            DROP TABLE IF EXISTS Users
            ";

        // Act
        collection.ParseBatch(batchSql);

        // Assert
        Assert.That(collection.Count, Is.EqualTo(3));
        Assert.That(collection.GetRawStatementAt(0), Does.Contain("DROP TABLE"));
        Assert.That(collection.GetRawStatementAt(1), Does.Contain("DROP TABLE"));
    }

    [Test]
    public void ParseBatch_WithDropIndexAndProcedureStatements_ParsesSuccessfully()
    {
        // Arrange
        var collection = new SqlBreakdownCollection();
        var batchSql = @"
            DROP INDEX IF EXISTS idx_Users_Email ON Users
            GO
            DROP PROCEDURE IF EXISTS sp_GetUserById
            GO
            DROP VIEW IF EXISTS vw_UserOrders
            ";

        // Act
        collection.ParseBatch(batchSql);

        // Assert
        Assert.That(collection.Count, Is.EqualTo(3));
        Assert.That(collection.GetRawStatementAt(0), Does.Contain("DROP INDEX"));
        Assert.That(collection.GetRawStatementAt(1), Does.Contain("PROCEDURE"));
        Assert.That(collection.GetRawStatementAt(2), Does.Contain("VIEW"));
    }

    #endregion

    #region Mixed CRUD Operations Tests

    [Test]
    public void ParseBatch_WithMixedCrudOperations_ParsesSuccessfully()
    {
        // Arrange
        var collection = new SqlBreakdownCollection();
        var batchSql = @"
            CREATE TABLE Users (
                Id INT PRIMARY KEY,
                Name NVARCHAR(100),
                Email NVARCHAR(100)
            )
            GO
            INSERT INTO Users (Id, Name, Email) VALUES (1, 'John Doe', 'john@example.com')
            GO
            INSERT INTO Users (Id, Name, Email) VALUES (2, 'Jane Smith', 'jane@example.com')
            GO
            SELECT * FROM Users WHERE Id = 1
            GO
            UPDATE Users SET Name = 'John Updated' WHERE Id = 1
            GO
            DELETE FROM Users WHERE Id = 2
            GO
            DROP TABLE Users
            ";

        // Act
        collection.ParseBatch(batchSql);

        // Assert
        Assert.That(collection.Count, Is.EqualTo(7));
        Assert.That(collection.GetRawStatementAt(0), Does.Contain("CREATE TABLE"));
        Assert.That(collection.GetRawStatementAt(1), Does.Contain("INSERT"));
        Assert.That(collection.GetRawStatementAt(3), Does.Contain("SELECT"));
        Assert.That(collection.GetRawStatementAt(4), Does.Contain("UPDATE"));
        Assert.That(collection.GetRawStatementAt(5), Does.Contain("DELETE"));
        Assert.That(collection.GetRawStatementAt(6), Does.Contain("DROP"));
    }

    [Test]
    public void ParseBatch_WithComplexMultipleStatements_ParsesAllStatements()
    {
        // Arrange
        var collection = new SqlBreakdownCollection();
        var batchSql = @"
            CREATE TABLE Products (
                Id INT PRIMARY KEY,
                Name NVARCHAR(100),
                Price DECIMAL(10, 2),
                Quantity INT
            )
            GO
            INSERT INTO Products (Id, Name, Price, Quantity)
            SELECT Id, ProductName, BasePrice, StockQuantity
            FROM StagingProducts
            WHERE IsActive = 1
            GO
            UPDATE Products SET Price = Price * 1.1 WHERE Quantity < 10
            GO
            SELECT p.Name,
                   COUNT(oi.Id) AS OrderCount,
                   SUM(oi.Quantity) AS TotalSold
            FROM Products p
            LEFT JOIN OrderItems oi ON p.Id = oi.ProductId
            GROUP BY p.Id, p.Name
            HAVING SUM(oi.Quantity) > 100
            GO
            DELETE FROM Products WHERE Quantity = 0 AND LastUpdated < DATEADD(month, -6, GETDATE())
            ";

        // Act
        collection.ParseBatch(batchSql);

        // Assert
        Assert.That(collection.Count, Is.EqualTo(5));
        Assert.That(collection.RawStatements.Count, Is.EqualTo(5));
        foreach (var statement in collection.RawStatements)
        {
            Assert.That(statement, Is.Not.Empty);
        }
    }

    #endregion

    #region Transaction Tests

    [Test]
    public void ParseBatch_WithTransactionStatements_ParsesSuccessfully()
    {
        // Arrange
        var collection = new SqlBreakdownCollection();
        var batchSql = @"
            BEGIN TRANSACTION UpdatePrices
            UPDATE Products SET Price = Price * 1.1 WHERE Category = 'Electronics'
            UPDATE ProductPriceHistory SET NewPrice = Price FROM Products WHERE Products.Id = ProductPriceHistory.ProductId
            COMMIT TRANSACTION UpdatePrices
            GO
            BEGIN TRANSACTION DeleteOldOrders
            DELETE FROM OrderItems WHERE OrderId IN (SELECT OrderId FROM Orders WHERE OrderDate < '2018-01-01')
            DELETE FROM Orders WHERE OrderDate < '2018-01-01'
            COMMIT TRANSACTION DeleteOldOrders
            ";

        // Act
        collection.ParseBatch(batchSql);

        // Assert
        Assert.That(collection.Count, Is.GreaterThanOrEqualTo(1));
        var statement = collection.GetRawStatementAt(0);
        Assert.That(statement, Does.Contain("BEGIN TRANSACTION"));
        Assert.That(statement, Does.Contain("COMMIT"));
    }

    #endregion

    #region Custom Separator Tests

    [Test]
    public void ParseBatch_WithSemicolonSeparator_ParsesSuccessfully()
    {
        // Arrange
        var collection = new SqlBreakdownCollection();
        var batchSql = @"
            SELECT * FROM Users
            ;
            SELECT * FROM Orders
            ;
            SELECT * FROM Products
            ";

        // Act
        collection.ParseBatch(batchSql, ";");

        // Assert
        Assert.That(collection.Count, Is.EqualTo(3));
        Assert.That(collection.GetRawStatementAt(0), Does.Contain("Users"));
        Assert.That(collection.GetRawStatementAt(1), Does.Contain("Orders"));
        Assert.That(collection.GetRawStatementAt(2), Does.Contain("Products"));
    }

    [Test]
    public void ParseBatch_WithCustomSeparator_ParsesSuccessfully()
    {
        // Arrange
        var collection = new SqlBreakdownCollection();
        var batchSql = @"
            INSERT INTO Users VALUES (1, 'John')
            ~~~
            INSERT INTO Users VALUES (2, 'Jane')
            ~~~
            INSERT INTO Users VALUES (3, 'Bob')
            ";

        // Act
        collection.ParseBatch(batchSql, "~~~");

        // Assert
        Assert.That(collection.Count, Is.EqualTo(3));
        Assert.That(collection.RawStatements.Count, Is.EqualTo(3));
    }

    #endregion

    #region Parameter Tests with CRUD

    [Test]
    public void ParseBatch_WithParameterizedInsertStatements_PreservesParameters()
    {
        // Arrange
        var collection = new SqlBreakdownCollection();
        var batchSql = @"
            INSERT INTO Users (Id, Name, Email) VALUES (@UserId, @UserName, @UserEmail)
            GO
            INSERT INTO Orders (OrderId, UserId, OrderDate) VALUES (@OrderId, @UserId, @OrderDate)
            ";

        // Act
        collection.ParseBatch(batchSql);

        // Assert
        Assert.That(collection.Count, Is.EqualTo(2));
        Assert.That(collection.GetRawStatementAt(0), Does.Contain("@UserId"));
        Assert.That(collection.GetRawStatementAt(0), Does.Contain("@UserEmail"));
    }

    [Test]
    public void ParseBatch_WithParameterizedUpdateStatements_PreservesParameters()
    {
        // Arrange
        var collection = new SqlBreakdownCollection();
        var batchSql = @"
            UPDATE Users SET Name = @Name, Email = @Email WHERE Id = @UserId
            GO
            UPDATE Orders SET Status = @Status, ModifiedDate = @ModifiedDate WHERE OrderId = @OrderId
            ";

        // Act
        collection.ParseBatch(batchSql);

        // Assert
        Assert.That(collection.Count, Is.EqualTo(2));
        Assert.That(collection.GetRawStatementAt(0), Does.Contain("@Name"));
        Assert.That(collection.GetRawStatementAt(1), Does.Contain("@Status"));
    }

    [Test]
    public void GetCombinedSql_WithMixedCrudOperations_CombinesCorrectly()
    {
        // Arrange
        var collection = new SqlBreakdownCollection();
        collection.ParseBatch(@"
            INSERT INTO Users (Id, Name) VALUES (1, 'John')
            GO
            UPDATE Users SET Name = 'Jane' WHERE Id = 1
            GO
            DELETE FROM Users WHERE Id = 1
            ");

        // Act
        var combined = collection.GetCombinedSql();

        // Assert
        Assert.That(combined, Does.Contain("INSERT"));
        Assert.That(combined, Does.Contain("UPDATE"));
        Assert.That(combined, Does.Contain("DELETE"));
        Assert.That(combined, Does.Contain("GO"));
    }

    #endregion

    /// <summary>
    /// Mock implementation of ISqlBreakdown for testing purposes.
    /// </summary>
    public class MockSqlBreakdown : ISqlBreakdown
    {
        private readonly string _sql;

        public MockSqlBreakdown(string sql)
        {
            _sql = sql;
            SetupClauses = new List<string>();
            FinishClauses = new System.Collections.ArrayList();
        }

        public string? RawSql { get; set; }
        public List<string> SetupClauses { get; set; }
        public bool IsUsingSetupClause => SetupClauses.Count > 0;
        public System.Collections.ArrayList FinishClauses { get; set; }
        public bool IsUsingFinishClause => FinishClauses.Count > 0;

        public string GetSql(bool includeSetupFinish = true)
        {
            var sb = new StringBuilder();

            if (includeSetupFinish)
            {
                foreach (string setup in SetupClauses)
                {
                    sb.AppendLine(setup);
                }
            }

            sb.Append(_sql);

            if (includeSetupFinish)
            {
                foreach (string finish in FinishClauses)
                {
                    sb.AppendLine(finish);
                }
            }

            return sb.ToString();
        }

        public override string ToString() => GetSql();

        public object Clone()
        {
            var clone = (MockSqlBreakdown)MemberwiseClone();
            clone.SetupClauses = new List<string>(SetupClauses);
            clone.FinishClauses = new System.Collections.ArrayList(FinishClauses);
            return clone;
        }
    }
}