sql-utilities/tests/Strata.SqlTools.Markdown.Tests/PostgreSql/QueryBreakdownGeneratorTests.cs

using Strata.SqlTools.Breakdowns.PostgreSql;
using Strata.SqlTools.Markdown.PostgreSql;

namespace Strata.SqlTools.Markdown.Tests.PostgreSql;

[TestFixture]
public class QueryBreakdownGeneratorTests
{
    [Test]
    public void GenerateMermaidDiagram_SimplePostgreSqlQuery_GeneratesValidMermaid()
    {
        // Arrange - Using PostgreSQL syntax with lowercase identifiers
        var query = new QueryBreakdown("user_id, user_name", "users");

        // Act
        var result = QueryBreakdownGenerator.GenerateMermaidDiagram(query, "Simple User Query");

        // Assert
        Assert.That(result, Does.Contain("```mermaid"));
        Assert.That(result, Does.Contain("flowchart TD"));
        Assert.That(result, Does.Contain("### Simple User Query"));
        Assert.That(result, Does.Contain("SELECT"));
        Assert.That(result, Does.Contain("FROM"));
        Assert.That(result, Does.Contain("```"));
    }

    [Test]
    public void GenerateMermaidDiagram_WithPositionalParameters_HandlesParameters()
    {
        // Arrange - PostgreSQL uses $1, $2 syntax for positional parameters
        var query = QueryBreakdown.Parse(@"
            SELECT user_id, user_name, status
            FROM users
            WHERE user_id = $1
              AND status = $2
        ");

        // Act
        var result = QueryBreakdownGenerator.GenerateMermaidDiagram(query);

        // Assert
        Assert.That(result, Does.Contain("WHERE"));
        Assert.That(result, Does.Contain("```mermaid"));
        Assert.That(result, Does.Contain("flowchart TD"));
    }

    [Test]
    public void GenerateMermaidDiagram_WithNamedParameters_HandlesColonSyntax()
    {
        // Arrange - PostgreSQL also supports :parameter syntax
        var query = QueryBreakdown.Parse(@"
            SELECT user_id, user_name, email
            FROM users
            WHERE user_id = :userId
              AND status = :status
        ");

        // Act
        var result = QueryBreakdownGenerator.GenerateMermaidDiagram(query);

        // Assert
        Assert.That(result, Does.Contain("WHERE"));
        Assert.That(result, Does.Contain("```mermaid"));
        Assert.That(result, Does.Contain("flowchart TD"));
    }

    [Test]
    public void GenerateMermaidDiagram_WithPostgreSqlCTE_ShowsWithClause()
    {
        // Arrange - PostgreSQL CTE with lowercase naming
        var query = QueryBreakdown.Parse(@"
            WITH active_users AS (
                SELECT user_id, user_name
                FROM users
                WHERE status = 'ACTIVE'
            )
            SELECT u.user_id, u.user_name, COUNT(o.order_id) AS order_count
            FROM active_users u
            JOIN orders o ON u.user_id = o.user_id
            GROUP BY u.user_id, u.user_name
        ");

        // Act
        var result = QueryBreakdownGenerator.GenerateMermaidDiagram(query, "Users with Orders");

        // Assert
        Assert.That(result, Does.Contain("### Users with Orders"));
        Assert.That(result, Does.Contain("```mermaid"));
        Assert.That(result, Does.Contain("flowchart TD"));
        Assert.That(result, Does.Contain("GROUP BY"));
    }

    [Test]
    public void GenerateMermaidDiagram_WithLimit_HandlesLimitClause()
    {
        // Arrange - PostgreSQL LIMIT clause
        var query = QueryBreakdown.Parse(@"
            SELECT user_id, user_name, created_at
            FROM users
            ORDER BY created_at DESC
            LIMIT 10
        ");

        // Act
        var result = QueryBreakdownGenerator.GenerateMermaidDiagram(query, "Recent Users");

        // Assert
        Assert.That(result, Does.Contain("SELECT"));
        Assert.That(result, Does.Contain("FROM"));
        Assert.That(result, Does.Contain("ORDER BY"));
        Assert.That(result, Does.Contain("```mermaid"));
    }

    [Test]
    public void GenerateMermaidDiagram_WithLimitOffset_HandlesPagination()
    {
        // Arrange - PostgreSQL LIMIT/OFFSET for pagination
        var query = QueryBreakdown.Parse(@"
            SELECT product_id, product_name, price
            FROM products
            ORDER BY product_name
            LIMIT 20 OFFSET 40
        ");

        // Act
        var result = QueryBreakdownGenerator.GenerateMermaidDiagram(query);

        // Assert
        Assert.That(result, Does.Contain("SELECT"));
        Assert.That(result, Does.Contain("ORDER BY"));
        Assert.That(result, Does.Contain("FROM"));
    }

    [Test]
    public void GenerateMermaidDiagram_WithDoubleQuotedIdentifiers_HandlesPostgreSqlQuoting()
    {
        // Arrange - PostgreSQL uses "identifier" for case-sensitive names
        var query = QueryBreakdown.Parse(@"
            SELECT ""userId"", ""userName"", ""emailAddress""
            FROM ""Users""
            WHERE ""status"" = 'ACTIVE'
        ");

        // Act
        var result = QueryBreakdownGenerator.GenerateMermaidDiagram(query);

        // Assert
        Assert.That(result, Does.Contain("SELECT"));
        Assert.That(result, Does.Contain("WHERE"));
        Assert.That(result, Does.Contain("FROM"));
    }

    [Test]
    public void GenerateMermaidDiagram_ComplexPostgreSqlQuery_GeneratesCompleteDiagram()
    {
        // Arrange - Complex PostgreSQL query with multiple clauses
        var query = QueryBreakdown.Parse(@"
            WITH sales_data AS (
                SELECT
                    region,
                    product_id,
                    SUM(sales_amount) AS total_sales,
                    COUNT(*) AS order_count
                FROM sales
                WHERE sale_date >= $1 AND sale_date <= $2
                GROUP BY region, product_id
            )
            SELECT
                sd.region,
                p.product_name,
                sd.total_sales,
                sd.order_count
            FROM sales_data sd
            JOIN products p ON sd.product_id = p.product_id
            WHERE sd.total_sales > $3
            ORDER BY sd.total_sales DESC
        ");

        // Act
        var result = QueryBreakdownGenerator.GenerateMermaidDiagram(query, "Regional Sales Analysis");

        // Assert
        Assert.That(result, Does.Contain("### Regional Sales Analysis"));
        Assert.That(result, Does.Contain("```mermaid"));
        Assert.That(result, Does.Contain("flowchart TD"));
        Assert.That(result, Does.Contain("SELECT"));
        Assert.That(result, Does.Contain("FROM"));
        Assert.That(result, Does.Contain("WHERE"));
        Assert.That(result, Does.Contain("ORDER BY"));
    }

    [Test]
    public void GenerateMermaidDiagram_WithGroupByAndHaving_IncludesBothClauses()
    {
        // Arrange
        var query = QueryBreakdown.Parse(@"
            SELECT category, COUNT(*) AS product_count, AVG(price) AS avg_price
            FROM products
            GROUP BY category
            HAVING COUNT(*) > 10 AND AVG(price) < 100
        ");

        // Act
        var result = QueryBreakdownGenerator.GenerateMermaidDiagram(query);

        // Assert
        Assert.That(result, Does.Contain("GROUP BY"));
        Assert.That(result, Does.Contain("HAVING"));
    }

    [Test]
    public void GenerateMermaidDiagram_NullTitle_GeneratesWithoutTitle()
    {
        // Arrange
        var query = new QueryBreakdown("id", "orders");

        // Act
        var result = QueryBreakdownGenerator.GenerateMermaidDiagram(query, null);

        // Assert
        Assert.That(result, Does.Not.Contain("###"));
        Assert.That(result, Does.Contain("```mermaid"));
        Assert.That(result, Does.Contain("flowchart TD"));
    }

    [Test]
    public void GenerateMermaidDiagram_EmptyTitle_GeneratesWithoutTitle()
    {
        // Arrange
        var query = new QueryBreakdown("order_id", "orders");

        // Act
        var result = QueryBreakdownGenerator.GenerateMermaidDiagram(query, "");

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

    [Test]
    public void GenerateMermaidDiagram_PostgreSqlTypeCasting_PreservesSyntax()
    {
        // Arrange - PostgreSQL :: casting syntax
        var query = QueryBreakdown.Parse(@"
            SELECT
                order_id::VARCHAR AS order_code,
                amount::DECIMAL(10,2) AS formatted_amount,
                create_date::TIMESTAMP AS created_at
            FROM orders
        ");

        // Act
        var result = QueryBreakdownGenerator.GenerateMermaidDiagram(query, "Type Cast Example");

        // Assert
        Assert.That(result, Does.Contain("SELECT"));
        Assert.That(result, Does.Contain("FROM"));
        Assert.That(result, Does.Contain("### Type Cast Example"));
    }

    [Test]
    public void GenerateMermaidDiagram_PostgreSqlJsonOperators_HandlesJsonNotation()
    {
        // Arrange - PostgreSQL JSON operators (-> for JSON object, ->> for text)
        var query = QueryBreakdown.Parse(@"
            SELECT
                json_data->>'name' AS name,
                json_data->'address'->>'city' AS city,
                (json_data->>'age')::INTEGER AS age
            FROM user_json
        ");

        // Act
        var result = QueryBreakdownGenerator.GenerateMermaidDiagram(query, "JSON Data");

        // Assert
        Assert.That(result, Does.Contain("SELECT"));
        Assert.That(result, Does.Contain("FROM"));
        Assert.That(result, Does.Contain("```mermaid"));
    }

    [Test]
    public void GenerateMermaidDiagram_WithDistinct_HandlesDistinctClause()
    {
        // Arrange - PostgreSQL DISTINCT
        var query = QueryBreakdown.Parse(@"
            SELECT DISTINCT region, product_category
            FROM sales
            ORDER BY region, product_category
        ");

        // Act
        var result = QueryBreakdownGenerator.GenerateMermaidDiagram(query);

        // Assert
        Assert.That(result, Does.Contain("SELECT"));
        Assert.That(result, Does.Contain("FROM"));
        Assert.That(result, Does.Contain("ORDER BY"));
    }
}