parlov-elicit 0.5.0

//! `DependencyDeleteElicitation` -- probes with DELETE to detect resource dependency differentials.
//!
//! Sends a plain DELETE with no body on both baseline and probe requests. The oracle
//! signal is the server returning 409 (the existing resource has dependents that block
//! deletion) versus 404 (the resource does not exist).

use http::Method;
use parlov_core::{
    Applicability, NormativeStrength, OracleClass, ResponseSurface, SignalSurface, Technique,
    Vector,
};

use crate::strategy::Strategy;
use crate::types::{ProbeSpec, RiskLevel, StrategyMetadata};
use crate::util::build_pair;
use crate::ScanContext;

static METADATA: StrategyMetadata = StrategyMetadata {
    strategy_id: "dependency-delete-elicit",
    strategy_name: "Dependency Delete Elicitation",
    risk: RiskLevel::OperationDestructive,
};

/// Confirms the dependency check ran. `Strong` for 409 (Conflict — referential integrity),
/// 404 (resource missing), or 422 (Unprocessable Entity). `Weak` otherwise.
fn dependency_delete_applicable(
    baseline: &ResponseSurface,
    probe: &ResponseSurface,
) -> Applicability {
    let is_strong = |s: u16| matches!(s, 409 | 404 | 422);
    if is_strong(baseline.status.as_u16()) || is_strong(probe.status.as_u16()) {
        return Applicability::Strong;
    }
    Applicability::Weak
}

static TECHNIQUE: Technique = Technique {
    id: "dependency-delete",
    name: "Dependency-blocked DELETE probe",
    oracle_class: OracleClass::Existence,
    vector: Vector::StatusCodeDiff,
    strength: NormativeStrength::May,
    normalization_weight: Some(0.02),
    inverted_signal_weight: None,
    method_relevant: false,
    parser_relevant: true,
    applicability: dependency_delete_applicable,
    contradiction_surface: SignalSurface::Status,
};

/// Elicits existence differentials via a DELETE that may be blocked by resource dependencies.
pub struct DependencyDeleteElicitation;

impl Strategy for DependencyDeleteElicitation {
    fn metadata(&self) -> &'static StrategyMetadata {
        &METADATA
    }

    fn technique_def(&self) -> &'static Technique {
        &TECHNIQUE
    }

    fn methods(&self) -> &[Method] {
        &[Method::DELETE]
    }

    fn is_applicable(&self, _ctx: &ScanContext) -> bool {
        true
    }

    fn generate(&self, ctx: &ScanContext) -> Vec<ProbeSpec> {
        let pair = build_pair(
            ctx,
            Method::DELETE,
            ctx.headers.clone(),
            ctx.headers.clone(),
            None,
            METADATA.clone(),
            TECHNIQUE,
        );
        vec![ProbeSpec::Pair(pair)]
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::test_utils::ctx_operation_destructive;

    #[test]
    fn risk_is_operation_destructive() {
        assert_eq!(
            DependencyDeleteElicitation.risk(),
            RiskLevel::OperationDestructive
        );
    }

    #[test]
    fn generate_returns_one_item() {
        assert_eq!(
            DependencyDeleteElicitation
                .generate(&ctx_operation_destructive())
                .len(),
            1
        );
    }

    #[test]
    fn item_is_pair_variant() {
        let specs = DependencyDeleteElicitation.generate(&ctx_operation_destructive());
        assert!(matches!(specs[0], ProbeSpec::Pair(_)));
    }

    #[test]
    fn probe_body_is_none() {
        let specs = DependencyDeleteElicitation.generate(&ctx_operation_destructive());
        let ProbeSpec::Pair(pair) = &specs[0] else {
            panic!("expected Pair")
        };
        assert!(pair.probe.body.is_none());
    }

    #[test]
    fn technique_strength_is_may() {
        let specs = DependencyDeleteElicitation.generate(&ctx_operation_destructive());
        assert_eq!(specs[0].technique().strength, NormativeStrength::May);
    }

    #[test]
    fn normalization_weight_is_0_02() {
        assert_eq!(TECHNIQUE.normalization_weight, Some(0.02));
    }

    #[test]
    fn inverted_signal_weight_is_none() {
        assert_eq!(TECHNIQUE.inverted_signal_weight, None);
    }
}