sql-utilities/tests/Strata.SqlTools.LinqToSql.Tests/QueryCollectionAnalyzerTests.cs

using NUnit.Framework;
using Strata.SqlTools.Analyzers.LinqToSql;
using Strata.SqlTools.Builders.LinqToSql;

namespace Strata.SqlTools.LinqToSql.Tests;

[TestFixture]
public class QueryCollectionAnalyzerTests
{
    #region Basic Analysis Tests

    [Test]
    public void Analyze_WithEmptyCollection_ReturnsZeroStatistics()
    {
        // Arrange
        var queries = new List<Strata.SqlTools.Breakdowns.LinqToSql.LinqQueryBreakdown>();
        var analyzer = QueryCollectionAnalyzer.Analyze(queries);

        // Act
        var stats = analyzer.Analyze();

        // Assert
        Assert.That(stats.TotalQueries, Is.EqualTo(0));
        Assert.That(stats.UniqueQueries, Is.EqualTo(0));
        Assert.That(stats.DuplicateQueries, Is.Empty);
    }

    [Test]
    public void Analyze_WithSingleQuery_ReturnsCorrectStatistics()
    {
        // Arrange
        var queries = new List<Strata.SqlTools.Breakdowns.LinqToSql.LinqQueryBreakdown>
        {
            LinqQueryBreakdownBuilder
                .Create()
                .SelectColumns("Id", "Name")
                .FromTable("Users")
                .Where("IsActive = true")
                .Build()
        };
        var analyzer = QueryCollectionAnalyzer.Analyze(queries);

        // Act
        var stats = analyzer.Analyze();

        // Assert
        Assert.That(stats.TotalQueries, Is.EqualTo(1));
        Assert.That(stats.UniqueQueries, Is.EqualTo(1));
        Assert.That(stats.DuplicateQueries, Is.Empty);
    }

    [Test]
    public void Analyze_WithIdenticalQueries_IdentifiesDuplicates()
    {
        // Arrange
        var query1 = LinqQueryBreakdownBuilder
            .Create()
            .SelectColumns("Id", "Name")
            .FromTable("Users")
            .Build();

        var query2 = LinqQueryBreakdownBuilder
            .Create()
            .SelectColumns("Id", "Name")
            .FromTable("Users")
            .Build();

        var query3 = LinqQueryBreakdownBuilder
            .Create()
            .SelectColumns("Id", "Name")
            .FromTable("Users")
            .Build();

        var queries = new List<Strata.SqlTools.Breakdowns.LinqToSql.LinqQueryBreakdown> { query1, query2, query3 };
        var analyzer = QueryCollectionAnalyzer.Analyze(queries);

        // Act
        var stats = analyzer.Analyze();

        // Assert
        Assert.That(stats.TotalQueries, Is.EqualTo(3));
        Assert.That(stats.UniqueQueries, Is.EqualTo(1));
        Assert.That(stats.DuplicateQueries, Has.Count.EqualTo(2));
    }

    #endregion

    #region Deduplication Rate Tests

    [Test]
    public void DeduplicationRate_WithAllUnique_ReturnsOne()
    {
        // Arrange
        var queries = new List<Strata.SqlTools.Breakdowns.LinqToSql.LinqQueryBreakdown>
        {
            LinqQueryBreakdownBuilder.Create().SelectAll().FromTable("Users").Build(),
            LinqQueryBreakdownBuilder.Create().SelectAll().FromTable("Orders").Build(),
            LinqQueryBreakdownBuilder.Create().SelectAll().FromTable("Products").Build()
        };
        var analyzer = QueryCollectionAnalyzer.Analyze(queries);

        // Act
        var stats = analyzer.Analyze();

        // Assert
        Assert.That(stats.DeduplicationRate, Is.EqualTo(1.0));
    }

    [Test]
    public void DeduplicationRate_WithSomeDuplicates_ReturnsCorrectRatio()
    {
        // Arrange
        var query = LinqQueryBreakdownBuilder.Create().SelectAll().FromTable("Users").Build();
        var queries = new List<Strata.SqlTools.Breakdowns.LinqToSql.LinqQueryBreakdown>
        {
            query,
            LinqQueryBreakdownBuilder.Create().SelectAll().FromTable("Users").Build(), // Duplicate
            LinqQueryBreakdownBuilder.Create().SelectAll().FromTable("Orders").Build()
        };
        var analyzer = QueryCollectionAnalyzer.Analyze(queries);

        // Act
        var stats = analyzer.Analyze();

        // Assert
        Assert.That(stats.DeduplicationRate, Is.EqualTo(2.0 / 3.0).Within(0.01));
    }

    #endregion

    #region Query Characteristics Tests

    [Test]
    public void Analyze_CountsQueriesWithoutWhere()
    {
        // Arrange
        var queries = new List<Strata.SqlTools.Breakdowns.LinqToSql.LinqQueryBreakdown>
        {
            LinqQueryBreakdownBuilder.Create().SelectAll().FromTable("Users").Build(),
            LinqQueryBreakdownBuilder.Create().SelectAll().FromTable("Orders").Where("Amount > 100").Build(),
            LinqQueryBreakdownBuilder.Create().SelectAll().FromTable("Products").Build()
        };
        var analyzer = QueryCollectionAnalyzer.Analyze(queries);

        // Act
        var stats = analyzer.Analyze();

        // Assert
        Assert.That(stats.QueriesWithoutWhere, Is.EqualTo(2));
    }

    [Test]
    public void Analyze_CountsQueriesWithoutOrderBy()
    {
        // Arrange
        var queries = new List<Strata.SqlTools.Breakdowns.LinqToSql.LinqQueryBreakdown>
        {
            LinqQueryBreakdownBuilder.Create().SelectAll().FromTable("Users").OrderByAscending("Name").Build(),
            LinqQueryBreakdownBuilder.Create().SelectAll().FromTable("Orders").Build(),
            LinqQueryBreakdownBuilder.Create().SelectAll().FromTable("Products").Build()
        };
        var analyzer = QueryCollectionAnalyzer.Analyze(queries);

        // Act
        var stats = analyzer.Analyze();

        // Assert
        Assert.That(stats.QueriesWithoutOrderBy, Is.EqualTo(2));
    }

    [Test]
    public void Analyze_CountsQueriesWithSelectAll()
    {
        // Arrange
        var queries = new List<Strata.SqlTools.Breakdowns.LinqToSql.LinqQueryBreakdown>
        {
            LinqQueryBreakdownBuilder.Create().SelectAll().FromTable("Users").Build(),
            LinqQueryBreakdownBuilder.Create().SelectColumns("Id", "Name").FromTable("Orders").Build(),
            LinqQueryBreakdownBuilder.Create().SelectAll().FromTable("Products").Build()
        };
        var analyzer = QueryCollectionAnalyzer.Analyze(queries);

        // Act
        var stats = analyzer.Analyze();

        // Assert
        Assert.That(stats.QueriesWithSelectAll, Is.EqualTo(2));
    }

    #endregion

    #region Table Usage Analysis Tests

    [Test]
    public void Analyze_AnalyzesTableUsageFrequency()
    {
        // Arrange
        var queries = new List<Strata.SqlTools.Breakdowns.LinqToSql.LinqQueryBreakdown>
        {
            LinqQueryBreakdownBuilder.Create().SelectAll().FromTable("Users").Build(),
            LinqQueryBreakdownBuilder.Create().SelectAll().FromTable("Users").Build(),
            LinqQueryBreakdownBuilder.Create().SelectAll().FromTable("Orders").Build(),
            LinqQueryBreakdownBuilder.Create().SelectAll().FromTable("Users").Build()
        };
        var analyzer = QueryCollectionAnalyzer.Analyze(queries);

        // Act
        var stats = analyzer.Analyze();

        // Assert
        Assert.That(stats.TableUsageFrequency["Users"], Is.EqualTo(3));
        Assert.That(stats.TableUsageFrequency["Orders"], Is.EqualTo(1));
    }

    [Test]
    public void Analyze_IgnoresNullTableNames()
    {
        // Arrange
        var query = LinqQueryBreakdownBuilder.Create().SelectAll().FromTable("Users").Build();
        var queries = new List<Strata.SqlTools.Breakdowns.LinqToSql.LinqQueryBreakdown> { query };
        var analyzer = QueryCollectionAnalyzer.Analyze(queries);

        // Act
        var stats = analyzer.Analyze();

        // Assert
        Assert.That(stats.TableUsageFrequency.ContainsKey("Users"), Is.True);
    }

    #endregion

    #region Column Usage Analysis Tests

    [Test]
    public void Analyze_AnalyzesColumnSelectionFrequency()
    {
        // Arrange
        var queries = new List<Strata.SqlTools.Breakdowns.LinqToSql.LinqQueryBreakdown>
        {
            LinqQueryBreakdownBuilder.Create().SelectColumns("Id", "Name", "Email").FromTable("Users").Build(),
            LinqQueryBreakdownBuilder.Create().SelectColumns("Id", "Name").FromTable("Users").Build(),
            LinqQueryBreakdownBuilder.Create().SelectColumns("Id").FromTable("Users").Build()
        };
        var analyzer = QueryCollectionAnalyzer.Analyze(queries);

        // Act
        var stats = analyzer.Analyze();

        // Assert
        Assert.That(stats.ColumnSelectionFrequency.ContainsKey("Id"), Is.True);
        Assert.That(stats.ColumnSelectionFrequency["Id"], Is.EqualTo(3));
        Assert.That(stats.ColumnSelectionFrequency["Name"], Is.EqualTo(2));
        Assert.That(stats.ColumnSelectionFrequency["Email"], Is.EqualTo(1));
    }

    [Test]
    public void Analyze_IgnoresSelectAll_InColumnUsage()
    {
        // Arrange
        var queries = new List<Strata.SqlTools.Breakdowns.LinqToSql.LinqQueryBreakdown>
        {
            LinqQueryBreakdownBuilder.Create().SelectAll().FromTable("Users").Build(),
            LinqQueryBreakdownBuilder.Create().SelectColumns("Id").FromTable("Users").Build()
        };
        var analyzer = QueryCollectionAnalyzer.Analyze(queries);

        // Act
        var stats = analyzer.Analyze();

        // Assert
        Assert.That(stats.ColumnSelectionFrequency.ContainsKey("*"), Is.False);
        Assert.That(stats.ColumnSelectionFrequency["Id"], Is.EqualTo(1));
    }

    #endregion

    #region Complexity Analysis Tests

    [Test]
    public void Analyze_CalculatesAverageComplexity()
    {
        // Arrange
        var simpleQuery = LinqQueryBreakdownBuilder.Create().SelectAll().FromTable("Users").Build();
        var complexQuery = LinqQueryBreakdownBuilder
            .Create()
            .SelectColumns("Department", "COUNT(*)")
            .FromTable("Employees")
            .Where("Salary > 50000 AND Department IN ('IT', 'HR')")
            .GroupBy("Department")
            .Having("COUNT(*) > 5")
            .OrderByDescending("COUNT(*)")
            .Build();

        var queries = new List<Strata.SqlTools.Breakdowns.LinqToSql.LinqQueryBreakdown> { simpleQuery, complexQuery };
        var analyzer = QueryCollectionAnalyzer.Analyze(queries);

        // Act
        var stats = analyzer.Analyze();

        // Assert
        Assert.That(stats.AverageComplexity, Is.GreaterThan(0));
        Assert.That(stats.AverageComplexity, Is.LessThanOrEqualTo(10));
    }

    [Test]
    public void Analyze_CountsComplexQueries()
    {
        // Arrange
        var simpleQuery = LinqQueryBreakdownBuilder.Create().SelectAll().FromTable("Users").Build();
        var complexQuery = LinqQueryBreakdownBuilder
            .Create()
            .SelectColumns("Dept", "COUNT(*)")
            .FromTable("Emp")
            .Where("Salary > 50000 AND Department IN ('IT', 'HR')")
            .GroupBy("Dept")
            .Having("COUNT(*) > 5")
            .Build();

        var queries = new List<Strata.SqlTools.Breakdowns.LinqToSql.LinqQueryBreakdown> { simpleQuery, complexQuery };
        var analyzer = QueryCollectionAnalyzer.Analyze(queries);

        // Act
        var stats = analyzer.Analyze();

        // Assert
        Assert.That(stats.ComplexQueriesCount, Is.GreaterThan(0));
    }

    #endregion

    #region FindDuplicates Tests

    [Test]
    public void FindDuplicates_WithNoDuplicates_ReturnsEmptyList()
    {
        // Arrange
        var queries = new List<Strata.SqlTools.Breakdowns.LinqToSql.LinqQueryBreakdown>
        {
            LinqQueryBreakdownBuilder.Create().SelectAll().FromTable("Users").Build(),
            LinqQueryBreakdownBuilder.Create().SelectAll().FromTable("Orders").Build()
        };
        var analyzer = QueryCollectionAnalyzer.Analyze(queries);

        // Act
        var duplicates = analyzer.FindDuplicates();

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

    [Test]
    public void FindDuplicates_WithDuplicates_ReturnsDuplicateQueries()
    {
        // Arrange
        var query = LinqQueryBreakdownBuilder.Create().SelectAll().FromTable("Users").Build();
        var queries = new List<Strata.SqlTools.Breakdowns.LinqToSql.LinqQueryBreakdown>
        {
            query,
            LinqQueryBreakdownBuilder.Create().SelectAll().FromTable("Users").Build(),
            LinqQueryBreakdownBuilder.Create().SelectAll().FromTable("Users").Build()
        };
        var analyzer = QueryCollectionAnalyzer.Analyze(queries);

        // Act
        var duplicates = analyzer.FindDuplicates();

        // Assert
        Assert.That(duplicates, Has.Count.EqualTo(2));
    }

    #endregion

    #region FindSimilarQueries Tests

    [Test]
    public void FindSimilarQueries_WithSimilarQueries_ReturnsSimilarPairs()
    {
        // Arrange
        var queries = new List<Strata.SqlTools.Breakdowns.LinqToSql.LinqQueryBreakdown>
        {
            LinqQueryBreakdownBuilder.Create().SelectColumns("Id", "Name").FromTable("Users").Build(),
            LinqQueryBreakdownBuilder.Create().SelectColumns("Id", "Name", "Email").FromTable("Users").Build(),
            LinqQueryBreakdownBuilder.Create().SelectAll().FromTable("Orders").Build()
        };
        var analyzer = QueryCollectionAnalyzer.Analyze(queries);

        // Act
        var similar = analyzer.FindSimilarQueries(0.5); // Lower threshold for testing

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

    [Test]
    public void FindSimilarQueries_SimilarityScoresBounded()
    {
        // Arrange
        var queries = new List<Strata.SqlTools.Breakdowns.LinqToSql.LinqQueryBreakdown>
        {
            LinqQueryBreakdownBuilder.Create().SelectColumns("Id").FromTable("Users").Build(),
            LinqQueryBreakdownBuilder.Create().SelectColumns("Id", "Name").FromTable("Users").Build()
        };
        var analyzer = QueryCollectionAnalyzer.Analyze(queries);

        // Act
        var similar = analyzer.FindSimilarQueries(0.5);

        // Assert
        foreach (var pair in similar)
        {
            Assert.That(pair.Similarity, Is.GreaterThanOrEqualTo(0.5));
            Assert.That(pair.Similarity, Is.LessThan(1.0));
        }
    }

    #endregion

    #region Report Generation Tests

    [Test]
    public void GetReport_IncludesBasicStatistics()
    {
        // Arrange
        var queries = new List<Strata.SqlTools.Breakdowns.LinqToSql.LinqQueryBreakdown>
        {
            LinqQueryBreakdownBuilder.Create().SelectAll().FromTable("Users").Build()
        };
        var analyzer = QueryCollectionAnalyzer.Analyze(queries);

        // Act
        var report = analyzer.GetReport();

        // Assert
        Assert.That(report, Contains.Substring("Query Collection Analysis Report"));
        Assert.That(report, Contains.Substring("Total Queries: 1"));
        Assert.That(report, Contains.Substring("Unique Queries: 1"));
    }

    [Test]
    public void GetReport_IncludesTableUsage()
    {
        // Arrange
        var queries = new List<Strata.SqlTools.Breakdowns.LinqToSql.LinqQueryBreakdown>
        {
            LinqQueryBreakdownBuilder.Create().SelectAll().FromTable("Users").Build(),
            LinqQueryBreakdownBuilder.Create().SelectAll().FromTable("Users").Build(),
            LinqQueryBreakdownBuilder.Create().SelectAll().FromTable("Orders").Build()
        };
        var analyzer = QueryCollectionAnalyzer.Analyze(queries);

        // Act
        var report = analyzer.GetReport();

        // Assert
        Assert.That(report, Contains.Substring("Most Frequently Used Tables"));
    }

    #endregion

    #region Null Handling Tests

    [Test]
    public void Constructor_WithNullQueries_ThrowsArgumentNullException()
    {
        // Act & Assert
        Assert.Throws<ArgumentNullException>(() => new QueryCollectionAnalyzer(null!));
    }

    #endregion

    #region Edge Cases

    [Test]
    public void Analyze_WithLargeCollection_PerformsAnalysis()
    {
        // Arrange
        var queries = new List<Strata.SqlTools.Breakdowns.LinqToSql.LinqQueryBreakdown>();
        for (int i = 0; i < 100; i++)
        {
            queries.Add(LinqQueryBreakdownBuilder
                .Create()
                .SelectColumns("Id", "Name")
                .FromTable("Users")
                .Build());
        }
        var analyzer = QueryCollectionAnalyzer.Analyze(queries);

        // Act
        var stats = analyzer.Analyze();

        // Assert
        Assert.That(stats.TotalQueries, Is.EqualTo(100));
        Assert.That(stats.UniqueQueries, Is.EqualTo(1));
    }

    #endregion
}