using SQLInsight.Core.Data;
using SQLInsight.Core.Findings;
using SQLInsight.Rules.Engine;
using SQLInsight.Rules.Performance;
using static SQLInsight.Rules.Tests.TestInstances;

namespace SQLInsight.Rules.Tests;

public class PlanRuleTests
{
    private static RuleResult Run(IRule rule, RuleContext context) => Assert.Single(new RuleEngine([rule]).Evaluate(context));

    private static AnalyzedStatement Statement(PlanWarnings? warnings = null, long execs = 1000, long workerUs = 120_000_000, long? spills = null, long? grantKb = null, long? usedKb = null) => new()
    {
        QueryHash = "0x1234ABCD",
        DatabaseName = "Sales",
        StatementText = "SELECT * FROM dbo.Customers WHERE Code = @code",
        Executions = execs,
        TotalWorkerTimeUs = workerUs,
        TotalElapsedTimeUs = workerUs,
        TotalLogicalReads = execs * 1000,
        TotalSpills = spills,
        TotalGrantKb = grantKb,
        TotalUsedGrantKb = usedKb,
        Warnings = warnings ?? new PlanWarnings(),
    };

    private static RuleContext Plans(params AnalyzedStatement[] statements) => With(new PlanAnalysisSnapshot { CapturedAt = Now, Statements = statements });

    [Fact]
    public void Clean_plan_passes_all_plan_rules()
    {
        foreach (var rule in new IRule[] { new ImplicitConversionRule(), new NoJoinPredicateRule(), new ScalarUdfRule(), new SpillRule(), new ExcessiveGrantRule() })
        {
            Assert.Equal(RuleOutcome.Passed, Run(rule, Plans(Statement(spills: 0, grantKb: 1000, usedKb: 900))).Outcome);
        }
    }

    [Fact]
    public void Implicit_conversion_lists_the_expression()
    {
        var statement = Statement(new PlanWarnings { SeekPreventingConversions = ["CONVERT_IMPLICIT(nvarchar(20),[Sales].[dbo].[Customers].[Code],0)=[@code]"] });

        var finding = Assert.Single(Run(new ImplicitConversionRule(), Plans(statement)).Findings);

        Assert.Equal("statement: 0x1234ABCD", finding.Subject);
        Assert.Contains(finding.Evidence, e => e.Value.StartsWith("CONVERT_IMPLICIT", StringComparison.Ordinal));
        Assert.Contains("AnsiString", finding.Recommendation, StringComparison.Ordinal);
    }

    [Fact]
    public void Missing_join_predicate_is_high()
    {
        Assert.Equal(Severity.High, Assert.Single(Run(new NoJoinPredicateRule(), Plans(Statement(new PlanWarnings { NoJoinPredicate = true }))).Findings).Severity);
    }

    [Fact]
    public void Deliberate_cross_join_is_not_reported()
    {
        var statement = Statement(new PlanWarnings { NoJoinPredicate = true }) with { StatementText = "SELECT * FROM dbo.Sizes s CROSS JOIN dbo.Colors c" };

        Assert.Equal(RuleOutcome.Passed, Run(new NoJoinPredicateRule(), Plans(statement)).Outcome);
    }

    [Fact]
    public void Scalar_udf_only_matters_in_heavy_statements()
    {
        var udf = new PlanWarnings { ScalarUdfs = ["[Sales].[dbo].[fn_Price]"] };

        Assert.Equal(RuleOutcome.Findings, Run(new ScalarUdfRule(), Plans(Statement(udf))).Outcome);
        Assert.Equal(RuleOutcome.Passed, Run(new ScalarUdfRule(), Plans(Statement(udf, workerUs: 5_000_000))).Outcome);
    }

    [Fact]
    public void Spills_per_execution_above_threshold()
    {
        Assert.Equal(RuleOutcome.Findings, Run(new SpillRule(), Plans(Statement(execs: 100, spills: 500_000))).Outcome);
        Assert.Equal(RuleOutcome.Passed, Run(new SpillRule(), Plans(Statement(execs: 100, spills: 5_000))).Outcome);
    }

    [Fact]
    public void Oversized_grant_used_under_ten_percent()
    {
        Assert.Equal(RuleOutcome.Findings, Run(new ExcessiveGrantRule(), Plans(Statement(execs: 10, grantKb: 10 * 500 * 1024, usedKb: 10 * 20 * 1024))).Outcome);
        Assert.Equal(RuleOutcome.Passed, Run(new ExcessiveGrantRule(), Plans(Statement(execs: 10, grantKb: 10 * 500 * 1024, usedKb: 10 * 300 * 1024))).Outcome);
    }

    [Fact]
    public void Memory_rules_must_be_checked_by_hand_without_the_columns()
    {
        Assert.Equal(RuleOutcome.ManualCheck, Run(new SpillRule(), WithVersion("14.0.1000.169", new PlanAnalysisSnapshot { CapturedAt = Now, Statements = [] })).Outcome);
    }

    [Fact]
    public void Findings_are_capped_and_heaviest_first()
    {
        var statements = Enumerable.Range(1, 30).Select(i => Statement(new PlanWarnings { NoJoinPredicate = true }, workerUs: i * 1_000_000) with { QueryHash = $"0x{i:X4}" }).ToArray();

        var findings = Run(new NoJoinPredicateRule(), Plans(statements)).Findings;

        Assert.Equal(PlanRule.MaxFindingsPerRule, findings.Count);
        Assert.Equal("statement: 0x001E", findings[0].Subject);
    }
}