sql-utilities/tests/Strata.SqlTools.SqlBreakdown.Tests/Extensions/QueryBreakdownExtensionsTests.cs

using Strata.SqlTools.Breakdowns.SqlServer;
using Strata.SqlTools.Extensions;

namespace Strata.SqlTools.SqlBreakdown.Tests.Extensions;

[TestFixture]
public class QueryBreakdownExtensionsTests
{
    #region Basic Clause Tests

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

        // Act
        var result = query.Select("id, name");

        // Assert
        Assert.That(result, Is.SameAs(query));
        Assert.That(query.SelectClause.Clause, Is.EqualTo("id, name"));
    }

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

        // Act
        var result = query.From("users");

        // Assert
        Assert.That(result, Is.SameAs(query));
        Assert.That(query.FromClause.Clause, Is.EqualTo("users"));
    }

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

        // Act
        var result = query.Where("active = 1");

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

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

        // Act
        var result = query.GroupBy("department");

        // Assert
        Assert.That(result, Is.SameAs(query));
        Assert.That(query.GroupByClause.Clause, Is.EqualTo("department"));
    }

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

        // Act
        var result = query.Having("COUNT(*) > 5");

        // Assert
        Assert.That(result, Is.SameAs(query));
        Assert.That(query.HavingClause.Clause, Is.EqualTo("COUNT(*) > 5"));
    }

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

        // Act
        var result = query.OrderBy("name ASC");

        // Assert
        Assert.That(result, Is.SameAs(query));
        Assert.That(query.OrderByClause.Clause, Is.EqualTo("name ASC"));
    }

    [Test]
    public void AddWhere_AppendsToWhereClause()
    {
        // Arrange
        var query = new QueryBreakdown().Where("active = 1");

        // Act
        var result = query.AddWhere("AND age > 18");

        // Assert
        Assert.That(result, Is.SameAs(query));
        Assert.That(query.WhereClause.Clause, Does.Contain("active = 1"));
        Assert.That(query.WhereClause.Clause, Does.Contain("AND age > 18"));
    }

    #endregion

    #region Method Chaining Tests

    [Test]
    public void FluentAPI_CanChainSelectFromWhere()
    {
        // Act
        var query = new QueryBreakdown()
            .Select("id, name")
            .From("users")
            .Where("active = 1");

        // Assert
        Assert.That(query.SelectClause.Clause, Is.EqualTo("id, name"));
        Assert.That(query.FromClause.Clause, Is.EqualTo("users"));
        Assert.That(query.WhereClause.Clause, Is.EqualTo("active = 1"));
    }

    [Test]
    public void FluentAPI_CanChainAllClauses()
    {
        // Act
        var query = new QueryBreakdown()
            .Select("department, COUNT(*) as employee_count")
            .From("employees")
            .Where("salary > 50000")
            .GroupBy("department")
            .Having("COUNT(*) > 5")
            .OrderBy("employee_count DESC");

        // Assert
        Assert.That(query.SelectClause.Clause, Is.EqualTo("department, COUNT(*) as employee_count"));
        Assert.That(query.FromClause.Clause, Is.EqualTo("employees"));
        Assert.That(query.WhereClause.Clause, Is.EqualTo("salary > 50000"));
        Assert.That(query.GroupByClause.Clause, Is.EqualTo("department"));
        Assert.That(query.HavingClause.Clause, Is.EqualTo("COUNT(*) > 5"));
        Assert.That(query.OrderByClause.Clause, Is.EqualTo("employee_count DESC"));
    }

    [Test]
    public void FluentAPI_GeneratesCorrectSQL()
    {
        // Arrange & Act
        var query = new QueryBreakdown()
            .Select("id, name, email")
            .From("users")
            .Where("active = 1")
            .OrderBy("name ASC");

        var sql = query.GetSql();

        // Assert
        Assert.That(sql, Does.Contain("SELECT"));
        Assert.That(sql, Does.Contain("id, name, email"));
        Assert.That(sql, Does.Contain("FROM"));
        Assert.That(sql, Does.Contain("users"));
        Assert.That(sql, Does.Contain("WHERE"));
        Assert.That(sql, Does.Contain("active = 1"));
        Assert.That(sql, Does.Contain("ORDER BY"));
        Assert.That(sql, Does.Contain("name ASC"));
    }

    #endregion

    #region WithCte Tests

    [Test]
    public void WithCte_WithConfigureAction_AddsCtesToQuery()
    {
        // Arrange & Act
        var query = new QueryBreakdown()
            .WithCte("active_users", cte => cte
                .Select("id, name")
                .From("users")
                .Where("active = 1"))
            .Select("*")
            .From("active_users");

        // Assert
        Assert.That(query.IsUsingWithClause, Is.True);
        Assert.That(query.WithClauses, Has.Count.EqualTo(1));
        Assert.That(query.WithClauses[0].TableName, Is.EqualTo("active_users"));
        Assert.That(query.SelectClause.Clause, Is.EqualTo("*"));
        Assert.That(query.FromClause.Clause, Is.EqualTo("active_users"));
    }

    [Test]
    public void WithCte_GeneratesCorrectSQL()
    {
        // Arrange & Act
        var query = new QueryBreakdown()
            .WithCte("active_users", cte => cte
                .Select("id, name")
                .From("users")
                .Where("active = 1"))
            .Select("*")
            .From("active_users");

        var sql = query.GetSql();

        // Assert
        Assert.That(sql, Does.Contain("WITH"));
        Assert.That(sql, Does.Contain("active_users AS"));
        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"));
        Assert.That(sql, Does.Contain("WHERE"));
        Assert.That(sql, Does.Contain("active = 1"));
    }

    [Test]
    public void WithCte_SupportsMultipleCTEs()
    {
        // Arrange & Act
        var query = new QueryBreakdown()
            .WithCte("active_users", cte => cte
                .Select("id, name")
                .From("users")
                .Where("active = 1"))
            .WithCte("recent_orders", cte => cte
                .Select("order_id, user_id, total")
                .From("orders")
                .Where("created_date > '2024-01-01'"))
            .Select("u.name, COUNT(o.order_id) as order_count")
            .From("active_users u LEFT JOIN recent_orders o ON u.id = o.user_id")
            .GroupBy("u.id, u.name");

        // Assert
        Assert.That(query.IsUsingWithClause, Is.True);
        Assert.That(query.WithClauses, Has.Count.EqualTo(2));
        Assert.That(query.WithClauses[0].TableName, Is.EqualTo("active_users"));
        Assert.That(query.WithClauses[1].TableName, Is.EqualTo("recent_orders"));
    }

    private static readonly string[] columns = new[] { "id", "name", "email" };

    [Test]
    public void WithCte_WithColumnList_AddsCtesWithColumns()
    {
        // Arrange & Act
        var query = new QueryBreakdown()
            .WithCte("active_users", columns, cte => cte
                .Select("user_id, user_name, user_email")
                .From("users")
                .Where("status = 'active'"))
            .Select("*")
            .From("active_users");

        var sql = query.GetSql();

        // Assert
        Assert.That(query.IsUsingWithClause, Is.True);
        Assert.That(query.WithClauses, Has.Count.EqualTo(1));
        Assert.That(sql, Does.Contain("active_users (id, name, email)"));
    }

    [Test]
    public void WithCte_WithIQueryBreakdown_AddsCte()
    {
        // Arrange
        var cteQuery = new QueryBreakdown()
            .Select("id, name")
            .From("users")
            .Where("active = 1");

        // Act
        var query = new QueryBreakdown()
            .WithCte("active_users", cteQuery)
            .Select("*")
            .From("active_users");

        // Assert
        Assert.That(query.IsUsingWithClause, Is.True);
        Assert.That(query.WithClauses, Has.Count.EqualTo(1));
        Assert.That(query.WithClauses[0].TableName, Is.EqualTo("active_users"));
    }

    #endregion

    #region Complex Query Tests

    [Test]
    public void FluentAPI_ComplexQueryWithGrouping()
    {
        // Arrange & Act
        var query = new QueryBreakdown()
            .Select("department, AVG(salary) as avg_salary, COUNT(*) as emp_count")
            .From("employees")
            .Where("hire_date >= '2020-01-01'")
            .GroupBy("department")
            .Having("COUNT(*) >= 10")
            .OrderBy("avg_salary DESC");

        var sql = query.GetSql();

        // Assert
        Assert.That(sql, Does.Contain("SELECT"));
        Assert.That(sql, Does.Contain("department, AVG(salary) as avg_salary, COUNT(*) as emp_count"));
        Assert.That(sql, Does.Contain("GROUP BY"));
        Assert.That(sql, Does.Contain("HAVING"));
        Assert.That(sql, Does.Contain("COUNT(*) >= 10"));
    }

    [Test]
    public void FluentAPI_RealWorldExample_SalesSummaryReport()
    {
        // Arrange & Act - Build a sales summary report with CTE
        var query = new QueryBreakdown()
            .WithCte("monthly_sales", cte => cte
                .Select("YEAR(order_date) as year, MONTH(order_date) as month, SUM(total_amount) as total_sales")
                .From("orders")
                .Where("status = 'completed'")
                .GroupBy("YEAR(order_date), MONTH(order_date)"))
            .Select("year, month, total_sales, LAG(total_sales) OVER (ORDER BY year, month) as prev_month_sales")
            .From("monthly_sales")
            .OrderBy("year DESC, month DESC");

        var sql = query.GetSql();

        // Assert
        Assert.That(sql, Does.Contain("WITH"));
        Assert.That(sql, Does.Contain("monthly_sales AS"));
        Assert.That(sql, Does.Contain("LAG(total_sales)"));
        Assert.That(query.IsUsingWithClause, Is.True);
    }

    [Test]
    public void FluentAPI_RealWorldExample_ActiveUserHierarchy()
    {
        // Arrange & Act - Build a hierarchical user/order report
        var query = new QueryBreakdown()
            .WithCte("active_users", cte => cte
                .Select("id, name, email")
                .From("users")
                .Where("active = 1 AND last_login > DATEADD(month, -3, GETDATE())"))
            .WithCte("user_orders", cte => cte
                .Select("u.id as user_id, u.name, COUNT(o.id) as order_count, SUM(o.total) as total_spent")
                .From("active_users u LEFT JOIN orders o ON u.id = o.user_id")
                .GroupBy("u.id, u.name"))
            .Select("name, order_count, total_spent, CASE WHEN total_spent > 1000 THEN 'VIP' ELSE 'Regular' END as customer_tier")
            .From("user_orders")
            .Where("order_count > 0")
            .OrderBy("total_spent DESC");

        var sql = query.GetSql();

        // Assert
        Assert.That(query.WithClauses, Has.Count.EqualTo(2));
        Assert.That(sql, Does.Contain("active_users AS"));
        Assert.That(sql, Does.Contain("user_orders AS"));
        Assert.That(sql, Does.Contain("customer_tier"));
    }

    #endregion

    #region Validation Tests

    [Test]
    public void Select_WithNullQuery_ThrowsArgumentNullException()
    {
        // Arrange
        QueryBreakdown? query = null;

        // Act & Assert
        Assert.Throws<ArgumentNullException>(() => query!.Select("*"));
    }

    [Test]
    public void From_WithNullQuery_ThrowsArgumentNullException()
    {
        // Arrange
        QueryBreakdown? query = null;

        // Act & Assert
        Assert.Throws<ArgumentNullException>(() => query!.From("users"));
    }

    [Test]
    public void Where_WithNullQuery_ThrowsArgumentNullException()
    {
        // Arrange
        QueryBreakdown? query = null;

        // Act & Assert
        Assert.Throws<ArgumentNullException>(() => query!.Where("active = 1"));
    }

    [Test]
    public void WithCte_WithNullQuery_ThrowsArgumentNullException()
    {
        // Arrange
        QueryBreakdown? query = null;

        // Act & Assert
        Assert.Throws<ArgumentNullException>(() =>
            query!.WithCte("test", cte => cte.Select("*").From("users")));
    }

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

        // Act & Assert
        Assert.Throws<ArgumentException>(() =>
            query.WithCte("", cte => cte.Select("*").From("users")));
    }

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

        // Act & Assert
        Assert.Throws<ArgumentNullException>(() =>
            query.WithCte("test", (Action<QueryBreakdown>)null!));
    }

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

        // Act & Assert
        Assert.Throws<ArgumentException>(() =>
            query.WithCte("test", Array.Empty<string>(), cte => cte.Select("*").From("users")));
    }

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

        // Act & Assert
        Assert.Throws<ArgumentNullException>(() =>
            query.WithCte("test", (QueryBreakdown)null!));
    }

    #endregion

    #region Edge Case Tests

    [Test]
    public void FluentAPI_CanOverwriteClauses()
    {
        // Arrange
        var query = new QueryBreakdown()
            .Select("*")
            .From("users")
            .Where("active = 1");

        // Act - Overwrite clauses
        query.Select("id, name").Where("active = 0");

        // Assert
        Assert.That(query.SelectClause.Clause, Is.EqualTo("id, name"));
        Assert.That(query.WhereClause.Clause, Is.EqualTo("active = 0"));
    }

    [Test]
    public void FluentAPI_HandlesEmptyStrings()
    {
        // Arrange & Act
        var query = new QueryBreakdown()
            .Select("")
            .From("")
            .Where("");

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

    [Test]
    public void FluentAPI_PreservesWhitespace()
    {
        // Arrange & Act
        var query = new QueryBreakdown()
            .Select("  id,  name  ")
            .From("  users  ");

        // Assert
        Assert.That(query.SelectClause.Clause, Is.EqualTo("  id,  name  "));
        Assert.That(query.FromClause.Clause, Is.EqualTo("  users  "));
    }

    #endregion
}