rsigma_eval/

router.rs

//! Multi-engine schema router: classify each event, route it to the detection
//! engine built for its schema's pipeline-set, and feed every detection into
//! one shared correlation store.
//!
//! # Design
//!
//! - One [`Engine`] per deduplicated pipeline-set (index-aligned with
//!   [`RoutingPlan::pipeline_sets`]). The schema's pipeline is applied to the
//!   detection rules in its engine, exactly as a single-pipeline run would.
//! - One shared [`CorrelationEngine`] (present only when the rule set has
//!   correlation rules), built Sigma-native (no pipeline). Detections from any
//!   per-schema engine feed into it via
//!   [`CorrelationEngine::correlate_detections`].
//! - Cross-schema correlation grouping works because the group-by extraction is
//!   schema-aware: each set carries a `Sigma -> event field` map (derived from
//!   its pipelines' field-name mappings), and the event is wrapped in a
//!   [`MappedEvent`] before correlation so the Sigma-native group-by names
//!   resolve to the schema's field names. The window store stays shared, keyed
//!   by the logical correlation plus the extracted group values.
//!
//! This subsumes the single-schema case (one pipeline-set is the degenerate
//! configuration), so there is no separate code path for "routing off".

use std::collections::HashMap;

use rsigma_parser::{LogSource, SigmaCollection, SigmaRule};

use crate::correlation_engine::{
    CorrelationConfig, CorrelationEngine, CorrelationSnapshot, CorrelationStateSnapshot,
    ProcessResult,
};
use crate::engine::Engine;
use crate::error::Result;
use crate::event::{Event, MappedEvent};
use crate::logsource::LogSourceExtractor;
use crate::pipeline::Pipeline;
use crate::pipeline::transformations::Transformation;
use crate::result::EvaluationResult;
use crate::result::MatchDetailLevel;
use crate::schema::{OnUnknown, RouteDecision, RoutingPlan, SchemaClassifier};

/// Per-schema logsource pruning summary: how many rules a schema's events
/// evaluate versus how many are pruned by its implied logsource. A static view
/// (independent of any specific event's field values) for operator visibility.
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct SchemaPruning {
    /// The recognized schema name.
    pub schema: String,
    /// Rules evaluated for this schema (logsource-compatible).
    pub eligible: usize,
    /// Rules pruned for this schema (logsource-conflicting).
    pub pruned: usize,
}

/// What the router did with an event, for reporting and `on_unknown` handling.
#[derive(Debug, Clone, PartialEq, Eq)]
pub enum RouteOutcome {
    /// Evaluated against a bound or known schema's set.
    Evaluated,
    /// Evaluated against the default set because the schema was unrecognized
    /// (`on_unknown: warn` or `passthrough`).
    EvaluatedUnknown,
    /// Dropped without evaluating (`on_unknown: drop`).
    Dropped,
    /// Dropped and flagged as an error (`on_unknown: error`).
    Errored,
}

/// The result of routing one event.
pub struct RouteResult {
    /// Evaluation results (empty when dropped or errored).
    pub results: ProcessResult,
    /// The classified schema name, or `None` when unrecognized.
    pub schema: Option<String>,
    /// What the router did.
    pub outcome: RouteOutcome,
}

/// Collect a combined `Sigma -> [event field]` map from a pipeline-set's
/// field-name mappings, used for schema-aware correlation group-by extraction.
fn collect_field_map(pipelines: &[Pipeline]) -> HashMap<String, Vec<String>> {
    let mut map: HashMap<String, Vec<String>> = HashMap::new();
    for pipeline in pipelines {
        for item in &pipeline.transformations {
            if let Transformation::FieldNameMapping { mapping } = &item.transformation {
                for (from, to) in mapping {
                    map.entry(from.clone())
                        .or_default()
                        .extend(to.iter().cloned());
                }
            }
        }
    }
    map
}

/// Outcome of the stateless phase for one event in [`SchemaRouter::process_batch`].
enum Routed1 {
    /// Dropped or errored (`on_unknown`): no results.
    Skip,
    /// Evaluate detections against the shared correlation store under set `set`.
    Eval {
        set: usize,
        detections: Vec<EvaluationResult>,
    },
}

/// Keep a detection rule when partitioning a per-schema engine: rules with no
/// product apply to every platform; a product-tagged rule is kept only when its
/// product is among the set's allowed products (lowercased).
fn rule_product_kept(rule: &SigmaRule, products: &std::collections::HashSet<String>) -> bool {
    match &rule.logsource.product {
        None => true,
        Some(p) => products.contains(&p.to_ascii_lowercase()),
    }
}

/// Whether a pipeline rewrites a rule's product via `change_logsource`, which
/// makes pre-pipeline product partitioning unsafe (a rule could be re-producted
/// at compile time). Such a set keeps its full ruleset.
fn pipeline_changes_product(pipeline: &Pipeline) -> bool {
    pipeline.transformations.iter().any(|item| {
        matches!(
            &item.transformation,
            Transformation::ChangeLogsource {
                product: Some(_),
                ..
            }
        )
    })
}

/// Resolve an event's logsource for conflict-based pruning: the extractor's
/// value (explicit event fields, then static/format defaults) wins, and the
/// recognized schema's implied logsource fills any dimension left unset. This
/// is what lets a `product`-less event still prune cross-product rules once its
/// schema is known (for example a `sysmon`-classified event implies
/// `product: windows`).
fn resolve_event_logsource<E: Event>(
    extractor: &LogSourceExtractor,
    implied: Option<&LogSource>,
    event: &E,
) -> LogSource {
    let mut ls = extractor.extract(event);
    if let Some(implied) = implied {
        if ls.product.is_none() {
            ls.product = implied.product.clone();
        }
        if ls.service.is_none() {
            ls.service = implied.service.clone();
        }
        if ls.category.is_none() {
            ls.category = implied.category.clone();
        }
        for (key, value) in &implied.custom {
            ls.custom
                .entry(key.clone())
                .or_insert_with(|| value.clone());
        }
    }
    ls
}

/// Stateless detection for one event: classify, decide, evaluate. Borrows only
/// shared state so it can run in parallel across a batch. When a logsource
/// extractor is configured, the event's logsource is resolved (explicit fields
/// plus the schema's implied logsource) and fed into conflict-based pruning.
fn detect_one<E: Event>(
    classifier: &SchemaClassifier,
    plan: &RoutingPlan,
    engines: &[Engine],
    extractor: Option<&LogSourceExtractor>,
    event: &E,
) -> Routed1 {
    let schema = classifier.classify(event).map(|m| m.name);
    match plan.decide(schema.as_deref()) {
        RouteDecision::Drop | RouteDecision::Error => Routed1::Skip,
        RouteDecision::Evaluate { set, .. } => {
            let detections = match extractor {
                Some(ex) => {
                    let implied = schema.as_deref().and_then(|s| plan.schema_logsource(s));
                    let ls = resolve_event_logsource(ex, implied, event);
                    engines[set].evaluate_pruned(event, &ls)
                }
                None => engines[set].evaluate(event),
            };
            Routed1::Eval { set, detections }
        }
    }
}

/// A multi-engine router over a classifier, a [`RoutingPlan`], one detection
/// engine per pipeline-set, and one shared correlation store.
pub struct SchemaRouter {
    classifier: SchemaClassifier,
    plan: RoutingPlan,
    /// One detection engine per pipeline-set (index = set index).
    engines: Vec<Engine>,
    /// `Sigma -> event field` map per pipeline-set, for correlation group-by.
    field_maps: Vec<HashMap<String, Vec<String>>>,
    /// Shared correlation store; `None` when there are no correlation rules.
    correlation: Option<CorrelationEngine>,
    /// Event-logsource extractor for conflict-based pruning; `None` disables
    /// pruning. Resolution happens per event in the router (extractor value
    /// plus the schema's implied logsource), so it is not set on the engines.
    logsource_extractor: Option<LogSourceExtractor>,
}

impl SchemaRouter {
    /// Build a router. `pipeline_sets` must be index-aligned with
    /// `plan.pipeline_sets()` (one resolved pipeline list per set).
    #[allow(clippy::too_many_arguments)]
    pub fn build(
        collection: &SigmaCollection,
        classifier: SchemaClassifier,
        plan: RoutingPlan,
        pipeline_sets: Vec<Vec<Pipeline>>,
        corr_config: CorrelationConfig,
        include_event: bool,
        match_detail: MatchDetailLevel,
        logsource_extractor: Option<LogSourceExtractor>,
        partition_rules: bool,
    ) -> Result<Self> {
        // Optional, gated per-schema rule partitioning: each engine bound only
        // to platform-locked schemas compiles just the rules whose product can
        // apply, cutting the N-copies memory cost. Off by default and disabled
        // for any set whose pipelines rewrite product.
        let partition = if partition_rules {
            plan.set_product_partition()
        } else {
            vec![None; pipeline_sets.len()]
        };

        let mut engines = Vec::with_capacity(pipeline_sets.len());
        let mut field_maps = Vec::with_capacity(pipeline_sets.len());
        for (idx, set) in pipeline_sets.iter().enumerate() {
            let mut engine = Engine::new();
            engine.set_include_event(include_event);
            engine.set_match_detail(match_detail);
            for p in set {
                engine.add_pipeline(p.clone());
            }
            // Partition only when the set has an allowed-product set and no
            // pipeline rewrites product; otherwise compile the full ruleset.
            let partitioned = partition
                .get(idx)
                .and_then(|o| o.as_ref())
                .filter(|_| !set.iter().any(pipeline_changes_product));
            match partitioned {
                Some(products) => {
                    let mut filtered = collection.clone();
                    filtered.rules.retain(|r| rule_product_kept(r, products));
                    engine.add_collection(&filtered)?;
                }
                None => engine.add_collection(collection)?,
            }
            engines.push(engine);
            field_maps.push(collect_field_map(set));
        }

        // The shared correlation store is Sigma-native (no pipeline): group-by
        // names stay logical and are mapped per schema at feed time. Its inner
        // detection engine is unused (routed detection runs in `engines`).
        let correlation = if collection.correlations.is_empty() {
            None
        } else {
            let mut ce = CorrelationEngine::new(corr_config);
            ce.set_include_event(include_event);
            ce.set_match_detail(match_detail);
            ce.add_collection(collection)?;
            Some(ce)
        };

        Ok(SchemaRouter {
            classifier,
            plan,
            engines,
            field_maps,
            correlation,
            logsource_extractor,
        })
    }

    /// The unknown-handling policy this router enforces.
    pub fn on_unknown(&self) -> OnUnknown {
        self.plan.on_unknown()
    }

    /// Whether this router has a correlation store.
    pub fn has_correlations(&self) -> bool {
        self.correlation.is_some()
    }

    /// Number of detection rules (same across every per-schema engine, unless
    /// per-schema rule partitioning is enabled; see [`engine_rule_counts`]).
    ///
    /// [`engine_rule_counts`]: SchemaRouter::engine_rule_counts
    pub fn detection_rule_count(&self) -> usize {
        self.engines.first().map(|e| e.rule_count()).unwrap_or(0)
    }

    /// Per-pipeline-set detection rule counts, in set order. Equal across sets
    /// unless per-schema rule partitioning is enabled, in which case
    /// platform-locked sets carry fewer rules than the default set.
    pub fn engine_rule_counts(&self) -> Vec<usize> {
        self.engines.iter().map(Engine::rule_count).collect()
    }

    /// Total rule candidates pruned by logsource across every per-schema
    /// engine (each event routes to exactly one engine).
    pub fn logsource_pruned_total(&self) -> u64 {
        self.engines
            .iter()
            .map(Engine::logsource_pruned_total)
            .sum()
    }

    /// Total evaluate calls with no extractable event logsource (fail-open)
    /// across every per-schema engine.
    pub fn logsource_absent_total(&self) -> u64 {
        self.engines
            .iter()
            .map(Engine::logsource_absent_total)
            .sum()
    }

    /// Static per-schema pruning summary: for each schema with an implied
    /// logsource, how many rules its events evaluate versus prune. Empty when
    /// logsource routing is disabled (no extractor). Sorted by descending
    /// pruned count, then schema name.
    pub fn schema_pruning_summary(&self) -> Vec<SchemaPruning> {
        if self.logsource_extractor.is_none() {
            return Vec::new();
        }
        let mut out = Vec::new();
        for schema in self.plan.schemas_with_logsource() {
            let Some(implied) = self.plan.schema_logsource(&schema) else {
                continue;
            };
            let set = match self.plan.decide(Some(&schema)) {
                RouteDecision::Evaluate { set, .. } => set,
                RouteDecision::Drop | RouteDecision::Error => 0,
            };
            let (eligible, pruned) = self.engines[set].logsource_eligibility(implied);
            out.push(SchemaPruning {
                schema,
                eligible,
                pruned,
            });
        }
        out.sort_by(|a, b| {
            b.pruned
                .cmp(&a.pruned)
                .then_with(|| a.schema.cmp(&b.schema))
        });
        out
    }

    /// Number of correlation rules in the shared store (0 when none).
    pub fn correlation_rule_count(&self) -> usize {
        self.correlation
            .as_ref()
            .map(|c| c.correlation_rule_count())
            .unwrap_or(0)
    }

    /// Number of live correlation window-state entries (0 when none).
    pub fn state_count(&self) -> usize {
        self.correlation
            .as_ref()
            .map(|c| c.state_count())
            .unwrap_or(0)
    }

    /// Introspect the shared correlation store, if any (id/group filtered).
    pub fn correlation_introspect(
        &self,
        id: Option<&str>,
        group: Option<&str>,
    ) -> Option<CorrelationStateSnapshot> {
        self.correlation
            .as_ref()
            .map(|c| c.introspect_filtered(id, group))
    }

    /// Export the shared correlation state, if any, for hot-reload carry-over.
    pub fn export_state(&self) -> Option<CorrelationSnapshot> {
        self.correlation.as_ref().map(|c| c.export_state())
    }

    /// Import previously exported correlation state into the shared store.
    /// No-op (returns `true`) when there is no correlation store.
    pub fn import_state(&mut self, snapshot: CorrelationSnapshot) -> bool {
        match &mut self.correlation {
            Some(c) => c.import_state(snapshot),
            None => true,
        }
    }

    /// Route a batch of events: parallel classify + detection, then sequential
    /// correlation into the shared store. Mirrors
    /// `CorrelationEngine::process_batch`: the stateless phase runs concurrently
    /// (under the `parallel` feature) and the stateful correlation phase runs
    /// in order. Drop/error outcomes yield empty results for that event.
    pub fn process_batch<E: Event + Sync>(&mut self, events: &[&E]) -> Vec<ProcessResult> {
        // Stateless phase: classify + route + detect. Borrows only `&self`
        // fields, so it parallelizes; correlation state is untouched here.
        let classifier = &self.classifier;
        let plan = &self.plan;
        let engines = &self.engines;
        let extractor = self.logsource_extractor.as_ref();
        let phase1: Vec<Routed1> = {
            #[cfg(feature = "parallel")]
            {
                use rayon::prelude::*;
                events
                    .par_iter()
                    .map(|e| detect_one(classifier, plan, engines, extractor, *e))
                    .collect()
            }
            #[cfg(not(feature = "parallel"))]
            {
                events
                    .iter()
                    .map(|e| detect_one(classifier, plan, engines, extractor, *e))
                    .collect()
            }
        };

        // Stateful phase: feed detections into the shared correlation store in
        // event order. Disjoint field borrows let the field maps and the
        // correlation store be held at once.
        let field_maps = &self.field_maps;
        let correlation = &mut self.correlation;
        phase1
            .into_iter()
            .zip(events)
            .map(|(routed, event)| match routed {
                Routed1::Skip => Vec::new(),
                Routed1::Eval { set, detections } => match correlation {
                    Some(ce) => {
                        let mapped = MappedEvent::new(*event, &field_maps[set]);
                        ce.correlate_detections(&mapped, detections)
                    }
                    None => detections,
                },
            })
            .collect()
    }

    /// Classify and route one event.
    pub fn route(&mut self, event: &impl Event) -> RouteResult {
        let schema = self.classifier.classify(event).map(|m| m.name);
        match self.plan.decide(schema.as_deref()) {
            RouteDecision::Drop => RouteResult {
                results: Vec::new(),
                schema,
                outcome: RouteOutcome::Dropped,
            },
            RouteDecision::Error => RouteResult {
                results: Vec::new(),
                schema,
                outcome: RouteOutcome::Errored,
            },
            RouteDecision::Evaluate { set, unknown } => {
                let detections = match self.logsource_extractor.as_ref() {
                    Some(ex) => {
                        let implied = schema
                            .as_deref()
                            .and_then(|s| self.plan.schema_logsource(s));
                        let ls = resolve_event_logsource(ex, implied, event);
                        self.engines[set].evaluate_pruned(event, &ls)
                    }
                    None => self.engines[set].evaluate(event),
                };
                let results = match &mut self.correlation {
                    Some(ce) => {
                        let mapped = MappedEvent::new(event, &self.field_maps[set]);
                        ce.correlate_detections(&mapped, detections)
                    }
                    None => detections,
                };
                RouteResult {
                    results,
                    schema,
                    outcome: if unknown {
                        RouteOutcome::EvaluatedUnknown
                    } else {
                        RouteOutcome::Evaluated
                    },
                }
            }
        }
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::JsonEvent;
    use crate::pipeline::parse_pipeline;
    use crate::schema::RoutingConfig;
    use rsigma_parser::parse_sigma_yaml;
    use serde_json::json;

    const RULES: &str = r#"
title: Whoami
id: rule-whoami
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        CommandLine|contains: whoami
    condition: selection
level: high
"#;

    const ECS_PIPELINE: &str = r#"
name: ecs_test
priority: 20
transformations:
  - id: map
    type: field_name_mapping
    mapping:
      CommandLine: process.command_line
      User: user.name
"#;

    fn plan(bindings: &[(&str, &[&str])]) -> RoutingPlan {
        let config = RoutingConfig {
            on_unknown: OnUnknown::Warn,
            default_pipelines: vec![],
            aliases: std::collections::HashMap::new(),
            bindings: bindings
                .iter()
                .map(|(s, ps)| crate::schema::SchemaBinding {
                    schema: (*s).to_string(),
                    pipelines: ps.iter().map(|p| (*p).to_string()).collect(),
                    logsource: None,
                })
                .collect(),
        };
        RoutingPlan::from_config(&config)
    }

    #[test]
    fn routes_ecs_event_to_ecs_engine() {
        let collection = parse_sigma_yaml(RULES).unwrap();
        // set 0 = default (no pipeline, Sigma-native fields), set 1 = ECS.
        let ecs = parse_pipeline(ECS_PIPELINE).unwrap();
        let plan = plan(&[("ecs", &["ecs_test"])]);
        let mut router = SchemaRouter::build(
            &collection,
            SchemaClassifier::builtin(),
            plan,
            vec![vec![], vec![ecs]],
            CorrelationConfig::default(),
            false,
            MatchDetailLevel::Off,
            None,
            false,
        )
        .unwrap();

        // ECS event: fields are renamed; only the ECS engine matches it.
        let ecs_event = json!({"ecs.version": "8.0.0", "process.command_line": "cmd /c whoami"});
        let r = router.route(&JsonEvent::borrow(&ecs_event));
        assert_eq!(r.schema.as_deref(), Some("ecs"));
        assert_eq!(r.outcome, RouteOutcome::Evaluated);
        assert_eq!(r.results.len(), 1, "ECS event matches via the ECS engine");

        // A Sigma-native event with the same command is unrecognized here
        // (no ecs.version, no sysmon markers) -> generic_json -> default set,
        // which has no pipeline, so the rule's CommandLine matches it.
        let native = json!({"CommandLine": "cmd /c whoami"});
        let r = router.route(&JsonEvent::borrow(&native));
        assert_eq!(r.schema.as_deref(), Some("generic_json"));
        assert_eq!(r.results.len(), 1);
    }

    #[test]
    fn cross_schema_correlation_groups_the_same_entity() {
        // A detection rule plus an event_count correlation grouped by User.
        // The same user appears once as an ECS event (user.name) and once as a
        // Sigma-native event (User); they must land in the same window and fire.
        let rules = r#"
title: Whoami
id: rule-whoami
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        CommandLine|contains: whoami
    condition: selection
level: high
---
title: Repeated whoami by user
correlation:
    type: event_count
    rules:
        - rule-whoami
    group-by:
        - User
    timespan: 1h
    condition:
        gte: 2
level: high
"#;
        let collection = parse_sigma_yaml(rules).unwrap();
        let ecs = parse_pipeline(ECS_PIPELINE).unwrap();
        // set 0 = default (Sigma-native), set 1 = ECS. ecs schema -> set 1;
        // everything else (incl. the generic event) -> default set 0.
        let plan = plan(&[("ecs", &["ecs_test"])]);

        let config = CorrelationConfig {
            timestamp_fallback: crate::correlation_engine::TimestampFallback::WallClock,
            ..Default::default()
        };

        let mut router = SchemaRouter::build(
            &collection,
            SchemaClassifier::builtin(),
            plan,
            vec![vec![], vec![ecs]],
            config,
            false,
            MatchDetailLevel::Off,
            None,
            false,
        )
        .unwrap();

        // First occurrence: ECS event for user alice.
        let ecs_event = json!({
            "ecs.version": "8.0.0",
            "process.command_line": "cmd /c whoami",
            "user.name": "alice"
        });
        let r1 = router.route(&JsonEvent::borrow(&ecs_event));
        assert_eq!(r1.schema.as_deref(), Some("ecs"));
        assert!(
            !r1.results.iter().any(|r| r.is_correlation()),
            "first event must not fire the count>=2 correlation yet"
        );

        // Second occurrence: Sigma-native event for the SAME user alice.
        let native_event = json!({"CommandLine": "cmd /c whoami", "User": "alice"});
        let r2 = router.route(&JsonEvent::borrow(&native_event));
        assert!(
            r2.results.iter().any(|r| r.is_correlation()),
            "the two events share group User=alice across schemas and must correlate"
        );
    }

    #[test]
    fn drop_policy_skips_unknown_events() {
        let collection = parse_sigma_yaml(RULES).unwrap();
        let config = RoutingConfig {
            on_unknown: OnUnknown::Drop,
            default_pipelines: vec![],
            aliases: std::collections::HashMap::new(),
            // Bind generic_json away so a plain event is truly unknown.
            bindings: vec![],
        };
        let plan = RoutingPlan::from_config(&config);
        let mut router = SchemaRouter::build(
            &collection,
            // Classifier with no generic_json: only ECS recognized, everything
            // else is unknown.
            SchemaClassifier::new(vec![]),
            plan,
            vec![vec![]],
            CorrelationConfig::default(),
            false,
            MatchDetailLevel::Off,
            None,
            false,
        )
        .unwrap();

        let native = json!({"CommandLine": "cmd /c whoami"});
        let r = router.route(&JsonEvent::borrow(&native));
        assert_eq!(r.schema, None);
        assert_eq!(r.outcome, RouteOutcome::Dropped);
        assert!(r.results.is_empty());
    }

    #[test]
    fn schema_derived_logsource_prunes_cross_product_rules() {
        // A Windows rule and a Linux rule that both match the same CommandLine.
        let rules = r#"
title: Win whoami
id: win-whoami
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        CommandLine|contains: whoami
    condition: selection
level: high
---
title: Linux whoami
id: linux-whoami
logsource:
    category: process_creation
    product: linux
detection:
    selection:
        CommandLine|contains: whoami
    condition: selection
level: high
"#;
        let collection = parse_sigma_yaml(rules).unwrap();
        // A flat Sysmon event with no explicit `product` field. It classifies
        // as `sysmon`, whose built-in implied logsource is product: windows.
        let event = json!({
            "EventID": 1,
            "ProcessGuid": "{abc}",
            "Image": "C:/Windows/System32/cmd.exe",
            "CommandLine": "cmd /c whoami"
        });

        // Without an extractor, no pruning: both rules fire.
        let mut plain = SchemaRouter::build(
            &collection,
            SchemaClassifier::builtin(),
            plan(&[]),
            vec![vec![]],
            CorrelationConfig::default(),
            false,
            MatchDetailLevel::Off,
            None,
            false,
        )
        .unwrap();
        let r = plain.route(&JsonEvent::borrow(&event));
        assert_eq!(r.schema.as_deref(), Some("sysmon"));
        assert_eq!(r.results.len(), 2, "no pruning without an extractor");

        // With an extractor, the schema-derived product (windows) prunes the
        // Linux rule while keeping the Windows rule, even though the event
        // carries no explicit product field.
        let mut pruned = SchemaRouter::build(
            &collection,
            SchemaClassifier::builtin(),
            plan(&[]),
            vec![vec![]],
            CorrelationConfig::default(),
            false,
            MatchDetailLevel::Off,
            Some(LogSourceExtractor::new()),
            false,
        )
        .unwrap();
        let r = pruned.route(&JsonEvent::borrow(&event));
        assert_eq!(r.schema.as_deref(), Some("sysmon"));
        assert_eq!(
            r.results.len(),
            1,
            "schema-derived product prunes the Linux rule"
        );
        assert_eq!(pruned.logsource_pruned_total(), 1);

        // The static per-schema summary reflects the same eligibility: for the
        // sysmon schema (product: windows) the Linux rule is pruned and the
        // Windows rule stays eligible. Cross-platform schemas are absent, and
        // the summary is empty without an extractor.
        let summary = pruned.schema_pruning_summary();
        let sysmon = summary
            .iter()
            .find(|s| s.schema == "sysmon")
            .expect("sysmon in summary");
        assert_eq!(sysmon.eligible, 1);
        assert_eq!(sysmon.pruned, 1);
        assert!(!summary.iter().any(|s| s.schema == "ecs"));
        assert!(plain.schema_pruning_summary().is_empty());
    }

    #[test]
    fn partition_rules_compiles_only_applicable_rules_per_set() {
        // Windows, Linux, and a product-less rule that all match `whoami`.
        let rules = r#"
title: Win whoami
id: win-whoami
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        CommandLine|contains: whoami
    condition: selection
level: high
---
title: Linux whoami
id: linux-whoami
logsource:
    category: process_creation
    product: linux
detection:
    selection:
        CommandLine|contains: whoami
    condition: selection
level: high
---
title: Any whoami
id: any-whoami
logsource:
    category: process_creation
detection:
    selection:
        CommandLine|contains: whoami
    condition: selection
level: high
"#;
        let collection = parse_sigma_yaml(rules).unwrap();
        // Bind sysmon (implied product: windows) to a non-default pipeline-set
        // (a no-op field mapping so the set differs from the default set).
        let passthrough = parse_pipeline(
            "name: passthrough\npriority: 10\ntransformations:\n  - id: noop\n    type: field_name_mapping\n    mapping:\n      __unused_a: __unused_b\n",
        )
        .unwrap();
        let plan = plan(&[("sysmon", &["passthrough"])]);

        let router = SchemaRouter::build(
            &collection,
            SchemaClassifier::builtin(),
            plan,
            vec![vec![], vec![passthrough]],
            CorrelationConfig::default(),
            false,
            MatchDetailLevel::Off,
            None,
            true, // partition rules
        )
        .unwrap();

        // Default set keeps all 3; the sysmon set drops the Linux rule and
        // keeps the Windows and product-less rules.
        assert_eq!(router.engine_rule_counts(), vec![3, 2]);
    }

    #[test]
    fn partition_rules_off_keeps_full_ruleset() {
        let rules = r#"
title: Win whoami
id: win-whoami
logsource:
    product: windows
detection:
    selection:
        CommandLine|contains: whoami
    condition: selection
---
title: Linux whoami
id: linux-whoami
logsource:
    product: linux
detection:
    selection:
        CommandLine|contains: whoami
    condition: selection
"#;
        let collection = parse_sigma_yaml(rules).unwrap();
        let passthrough = parse_pipeline(
            "name: passthrough\npriority: 10\ntransformations:\n  - id: noop\n    type: field_name_mapping\n    mapping:\n      __unused_a: __unused_b\n",
        )
        .unwrap();
        let plan = plan(&[("sysmon", &["passthrough"])]);
        let router = SchemaRouter::build(
            &collection,
            SchemaClassifier::builtin(),
            plan,
            vec![vec![], vec![passthrough]],
            CorrelationConfig::default(),
            false,
            MatchDetailLevel::Off,
            None,
            false, // partitioning off
        )
        .unwrap();
        assert_eq!(router.engine_rule_counts(), vec![2, 2]);
    }
}