use cm_domain::GatedCategory;
use cm_tools::{Effect, GateDecision, GatePolicy, TaintSet, TaintSource};

fn policy() -> GatePolicy {
    GatePolicy
}

#[test]
fn effect_free_tools_are_allowed() {
    let decision = policy().classify(&[], &TaintSet::clean());
    assert_eq!(decision, GateDecision::Allow);
}

#[test]
fn read_only_effects_are_allowed() {
    let decision = policy().classify(&[Effect::ReadsWorkspaceData], &TaintSet::clean());
    assert_eq!(decision, GateDecision::Allow);
}

#[test]
fn every_spec_15_category_has_a_triggering_effect() {
    // The six gated categories (§15) and the effect that triggers each.
    let cases = [
        (Effect::SendsExternally, GatedCategory::OutboundMessage),
        (Effect::SharesSecrets, GatedCategory::SecretSharing),
        (Effect::ChangesAccess, GatedCategory::AccessChange),
        (Effect::MovesMoney, GatedCategory::FinancialTransaction),
        (Effect::DeletesData, GatedCategory::FileDeletion),
        (Effect::GrantsInfraAccess, GatedCategory::InfraAccessGrant),
    ];
    for (effect, category) in cases {
        let decision = policy().classify(&[effect], &TaintSet::clean());
        assert_eq!(
            decision,
            GateDecision::RequireApproval(category),
            "{effect:?} must gate as {category:?}"
        );
    }
}

#[test]
fn the_most_severe_effect_wins_for_multi_effect_tools() {
    let decision = policy().classify(
        &[Effect::ReadsWorkspaceData, Effect::MovesMoney],
        &TaintSet::clean(),
    );
    assert_eq!(
        decision,
        GateDecision::RequireApproval(GatedCategory::FinancialTransaction)
    );
}

#[test]
fn undeclared_external_reach_is_gated_by_default() {
    // A tool that reaches outside the workspace but declares nothing
    // specific is still gated (§15 untrusted-by-default).
    let decision = policy().classify(&[Effect::ReachesExternally], &TaintSet::clean());
    assert_eq!(
        decision,
        GateDecision::RequireApproval(GatedCategory::OutboundMessage)
    );
}

#[test]
fn tainted_input_gates_even_benign_external_tools() {
    let taint = TaintSet::from_sources(&[TaintSource::Web]);
    let decision = policy().classify(&[Effect::ReachesExternally], &taint);
    assert!(matches!(decision, GateDecision::RequireApproval(_)));
}

#[test]
fn tainted_input_does_not_gate_purely_internal_reads() {
    // Untrusted content is data, not instructions; reading workspace data
    // with tainted input has no external effect to protect.
    let taint = TaintSet::from_sources(&[TaintSource::InterAgent]);
    let decision = policy().classify(&[Effect::ReadsWorkspaceData], &taint);
    assert_eq!(decision, GateDecision::Allow);
}

mod properties {
    use super::*;
    use proptest::prelude::*;

    fn arb_effect() -> impl Strategy<Value = Effect> {
        prop_oneof![
            Just(Effect::ReadsWorkspaceData),
            Just(Effect::WritesWorkspaceData),
            Just(Effect::ReachesExternally),
            Just(Effect::SendsExternally),
            Just(Effect::SharesSecrets),
            Just(Effect::ChangesAccess),
            Just(Effect::MovesMoney),
            Just(Effect::DeletesData),
            Just(Effect::GrantsInfraAccess),
        ]
    }

    fn arb_taint() -> impl Strategy<Value = TaintSet> {
        proptest::collection::vec(
            prop_oneof![
                Just(TaintSource::Web),
                Just(TaintSource::Email),
                Just(TaintSource::InterAgent),
                Just(TaintSource::ToolResult),
            ],
            0..4,
        )
        .prop_map(|sources| TaintSet::from_sources(&sources))
    }

    proptest! {
        /// §15 invariant: input carrying untrusted taint combined with ANY
        /// externally-visible effect is never auto-allowed.
        #[test]
        fn tainted_external_is_never_allowed(
            effects in proptest::collection::vec(arb_effect(), 1..4),
            taint in arb_taint(),
        ) {
            let has_external = effects.iter().any(|e| e.is_external());
            let decision = GatePolicy.classify(&effects, &taint);
            if !taint.is_clean() && has_external {
                prop_assert!(
                    matches!(decision, GateDecision::RequireApproval(_)),
                    "tainted external effects must require approval, got {decision:?}"
                );
            }
        }

        /// Gated effects require approval regardless of taint.
        #[test]
        fn gated_effects_always_require_approval(
            taint in arb_taint(),
        ) {
            for effect in [
                Effect::SendsExternally,
                Effect::SharesSecrets,
                Effect::ChangesAccess,
                Effect::MovesMoney,
                Effect::DeletesData,
                Effect::GrantsInfraAccess,
            ] {
                let decision = GatePolicy.classify(&[effect], &taint);
                prop_assert!(matches!(decision, GateDecision::RequireApproval(_)));
            }
        }
    }
}