//! Phase 5 exit criterion, as an executable matrix (R2.3).
//!
//! The review requires:
//!
//! > Device/integration test matrix proves permission denial, cancellation,
//! > backgrounding, app restart, and out-of-order callbacks cannot bypass
//! > authorization or corrupt an intent.
//!
//! # Why this is not simply "device work"
//!
//! Four of those five are **state questions**, not hardware questions. What a
//! device adds is confidence that Android really does deliver the callback
//! sequence being modelled. What it cannot add is any guarantee about how the
//! domain reacts — that is decided by the state machine, and a device test
//! would only observe it indirectly, slowly, and flakily.
//!
//! So the matrix is written here, against the real `PaymentCoordinator` and
//! `AuthorizationAttempt`, with the platform faked at its documented
//! boundary. Two things follow:
//!
//! - every scenario runs on every commit, not when a phone is free;
//! - a regression names the invariant it broke, rather than surfacing as a
//!   payment that behaved oddly on someone's handset.
//!
//! # What still needs a device
//!
//! That Android emits these sequences at all — permission dialogs, process
//! death timing, callback ordering under memory pressure. This file asserts
//! the *response* is correct for each sequence; a device confirms the
//! *sequences* are the real ones. Both are needed and they are different
//! claims. Recorded in the plan as R2.3b.
//!
//! # The single invariant
//!
//! Across every row: **money never moves without a live, unspent grant, and
//! no lifecycle event settles an intent.**

use nigig_pay_domain::{
    AuthorizationAttempt, AuthorizationSignal, CoordinatorError, CreatePayment, GatewayError,
    Money, PaymentCoordinator, PaymentIntent, PaymentIntentRepository, PaymentState,
    ScriptedBiometric, ScriptedGateway,
};

/// Repository that records every persisted snapshot, so a "restart" can be
/// modelled by replaying what was durably written.
#[derive(Default)]
struct RecordingRepository {
    saved: Vec<PaymentIntent>,
}

impl PaymentIntentRepository for RecordingRepository {
    type Error = String;
    fn save(&mut self, intent: &PaymentIntent) -> Result<(), Self::Error> {
        self.saved.push(intent.clone());
        Ok(())
    }
}

impl RecordingRepository {
    /// The last durable state for an intent — what a restart would recover.
    fn last(&self, id: &str) -> Option<&PaymentIntent> {
        self.saved.iter().rev().find(|i| i.id.as_str() == id)
    }
}

fn command(requires_biometric: bool) -> CreatePayment {
    CreatePayment {
        amount: Money::from_major(1_000),
        estimated_fee: Money::from_major(23),
        recipient_phone: "0712345678".into(),
        recipient_name: "Ada".into(),
        kind: "Send Money".into(),
        category: None,
        note: None,
        requires_biometric,
    }
}

type Coordinator = PaymentCoordinator<ScriptedGateway, ScriptedBiometric, RecordingRepository>;

/// A coordinator whose gateway would succeed if it were ever reached.
fn coordinator() -> Coordinator {
    PaymentCoordinator::new(
        ScriptedGateway::always_ok("session-1"),
        // Deliberately permissive: the matrix must show that dispatch is
        // gated by the *attempt*, not by this.
        ScriptedBiometric::succeeds(),
        RecordingRepository::default(),
    )
}

// ── Row 1: permission denial ────────────────────────────────────────────────

/// Android returns `KeyPermanentlyInvalidated`/no-enrolment/permission-denied
/// before any prompt is shown. Nothing may dispatch.
#[test]
fn permission_denial_cannot_dispatch() {
    let mut coordinator = coordinator();
    let id = coordinator.create(command(true)).expect("intent created");

    let mut attempt = AuthorizationAttempt::unavailable(id.as_str(), "no enrolled fingerprint");
    let result = coordinator.dispatch_with_authorization(&id, &mut attempt);

    assert!(
        matches!(result, Err(CoordinatorError::NotAuthorized { .. })),
        "a permission denial dispatched: {result:?}"
    );
    assert_eq!(coordinator.dispatch_count(&id), 0, "money left the device");
    assert!(matches!(
        coordinator.intent(&id).map(|i| &i.state),
        Some(PaymentState::Failed { .. })
    ));
}

// ── Row 2: cancellation ─────────────────────────────────────────────────────

#[test]
fn cancellation_cannot_dispatch() {
    let mut coordinator = coordinator();
    let id = coordinator.create(command(true)).expect("intent created");

    let mut attempt = AuthorizationAttempt::new(id.as_str());
    attempt.apply(id.as_str(), AuthorizationSignal::PromptShown);
    attempt.apply(id.as_str(), AuthorizationSignal::Cancelled);

    assert!(coordinator
        .dispatch_with_authorization(&id, &mut attempt)
        .is_err());
    assert_eq!(coordinator.dispatch_count(&id), 0);
}

/// A success arriving *after* the user cancelled must not revive the payment.
/// On a real device this is an in-flight callback racing the dismissal.
#[test]
fn a_success_racing_a_cancellation_cannot_dispatch() {
    let mut coordinator = coordinator();
    let id = coordinator.create(command(true)).expect("intent created");

    let mut attempt = AuthorizationAttempt::new(id.as_str());
    attempt.apply(id.as_str(), AuthorizationSignal::Cancelled);
    // The late success.
    attempt.apply(id.as_str(), AuthorizationSignal::Succeeded);

    assert!(coordinator
        .dispatch_with_authorization(&id, &mut attempt)
        .is_err());
    assert_eq!(coordinator.dispatch_count(&id), 0);
}

// ── Row 3: backgrounding ────────────────────────────────────────────────────

/// The app is backgrounded while the prompt is up. The OS tears the prompt
/// down without a terminal callback, so the attempt is abandoned.
#[test]
fn backgrounding_mid_prompt_cannot_dispatch() {
    let mut coordinator = coordinator();
    let id = coordinator.create(command(true)).expect("intent created");

    let mut attempt = AuthorizationAttempt::new(id.as_str());
    attempt.apply(id.as_str(), AuthorizationSignal::PromptShown);
    attempt.apply(id.as_str(), AuthorizationSignal::SensorEngaged);
    attempt.abandon(); // backgrounded

    let result = coordinator.dispatch_with_authorization(&id, &mut attempt);
    assert!(
        matches!(result, Err(CoordinatorError::NotAuthorized { .. })),
        "an abandoned prompt dispatched: {result:?}"
    );
    assert_eq!(coordinator.dispatch_count(&id), 0);
}

/// Backgrounding *after* a grant must not revoke it: the user did authorise,
/// and the payment may legitimately continue when the app resumes.
#[test]
fn backgrounding_after_a_grant_preserves_the_authorization() {
    let mut coordinator = coordinator();
    let id = coordinator.create(command(true)).expect("intent created");

    let mut attempt = AuthorizationAttempt::new(id.as_str());
    attempt.apply(id.as_str(), AuthorizationSignal::Succeeded);
    attempt.abandon(); // backgrounded after authorising

    coordinator
        .dispatch_with_authorization(&id, &mut attempt)
        .expect("a granted payment survives backgrounding");
    assert_eq!(coordinator.dispatch_count(&id), 1);
}

// ── Row 4: app restart ──────────────────────────────────────────────────────

/// Process death after dispatch. The intent is recovered from storage as
/// `Submitted`; it must not be dispatchable again, because the provider may
/// already hold it (review defect B3).
#[test]
fn a_restart_after_dispatch_cannot_redispatch() {
    let mut coordinator = coordinator();
    let id = coordinator.create(command(false)).expect("intent created");
    coordinator
        .dispatch_without_biometric(&id)
        .expect("first dispatch");
    assert_eq!(coordinator.dispatch_count(&id), 1);

    // What a restart would recover.
    let recovered = coordinator
        .repository()
        .last(id.as_str())
        .expect("a durable snapshot exists")
        .clone();
    assert_eq!(
        recovered.state,
        PaymentState::Submitted,
        "an in-flight payment must be recovered as Submitted"
    );
    assert!(
        recovered.provider_operation_id.is_some(),
        "the correlation id must survive a restart, or the callback is orphaned"
    );

    // Re-dispatch is refused. Note *which* guard does it: the state machine
    // rejects `Submitted -> Dispatching` before the budget is consulted, so
    // this assertion alone does not prove the budget works.
    let again = coordinator.dispatch_without_biometric(&id);
    assert!(
        again.is_err(),
        "a recovered in-flight payment was dispatched twice"
    );
    assert_eq!(coordinator.dispatch_count(&id), 1);
}

/// The duplicate-dispatch budget, exercised directly (review defect B3).
///
/// The test above passes even with the budget removed, because the state
/// machine refuses `Submitted -> Dispatching` first. That is good defence in
/// depth and bad test coverage: it hides whether the budget still works.
///
/// Here the intent is walked back to `Dispatching` — the situation a buggy
/// recovery path or a state-machine change could produce — so the budget is
/// the only thing left standing between a restart and a second dispatch.
#[cfg(feature = "test-hooks")]
#[test]
fn the_dispatch_budget_survives_a_state_machine_walk_back() {
    let mut coordinator = coordinator();
    let id = coordinator.create(command(false)).expect("intent created");
    coordinator
        .dispatch_without_biometric(&id)
        .expect("first dispatch");
    assert_eq!(coordinator.dispatch_count(&id), 1);

    // Force the intent back to a dispatchable state, bypassing the state
    // machine exactly as a faulty recovery would.
    coordinator
        .force_state_for_test(&id, PaymentState::Dispatching)
        .expect("intent exists");

    let again = coordinator.dispatch_without_biometric(&id);
    assert!(
        matches!(again, Err(CoordinatorError::DuplicateDispatchBlocked(_))),
        "the dispatch budget did not block a second send: {again:?}"
    );
    assert_eq!(
        coordinator.dispatch_count(&id),
        1,
        "money was dispatched twice"
    );
}

/// Process death *before* dispatch leaves an intent that never reached the
/// provider. It must not be silently settled, and must still require a grant.
#[test]
fn a_restart_before_dispatch_still_requires_authorization() {
    let mut coordinator = coordinator();
    let id = coordinator.create(command(true)).expect("intent created");

    let recovered = coordinator
        .repository()
        .last(id.as_str())
        .expect("a durable snapshot exists")
        .clone();
    assert_eq!(recovered.state, PaymentState::AwaitingUserAuthorization);

    // A fresh attempt after the restart, never answered.
    let mut attempt = AuthorizationAttempt::new(id.as_str());
    attempt.apply(id.as_str(), AuthorizationSignal::PromptShown);

    assert!(coordinator
        .dispatch_with_authorization(&id, &mut attempt)
        .is_err());
    assert_eq!(coordinator.dispatch_count(&id), 0);
}

// ── Row 5: out-of-order callbacks ───────────────────────────────────────────

/// A grant issued for one payment must not authorise another. On a device
/// this is a callback arriving after the user moved to a different payment.
#[test]
fn a_grant_from_another_payment_cannot_dispatch() {
    let mut coordinator = coordinator();
    let victim = coordinator.create(command(true)).expect("intent created");

    let mut foreign = AuthorizationAttempt::new("some-other-intent");
    foreign.apply("some-other-intent", AuthorizationSignal::Succeeded);

    let result = coordinator.dispatch_with_authorization(&victim, &mut foreign);
    assert!(
        matches!(result, Err(CoordinatorError::NotAuthorized { .. })),
        "a foreign grant dispatched: {result:?}"
    );
    assert_eq!(coordinator.dispatch_count(&victim), 0);
    // The victim is untouched — not even failed by a stranger's callback.
    assert_eq!(
        coordinator.intent(&victim).map(|i| &i.state),
        Some(&PaymentState::AwaitingUserAuthorization)
    );
}

/// One grant, one dispatch — a replayed success cannot spend it twice.
#[test]
fn a_replayed_grant_cannot_dispatch_twice() {
    let mut coordinator = coordinator();
    let id = coordinator.create(command(true)).expect("intent created");

    let mut attempt = AuthorizationAttempt::new(id.as_str());
    attempt.apply(id.as_str(), AuthorizationSignal::Succeeded);

    coordinator
        .dispatch_with_authorization(&id, &mut attempt)
        .expect("first dispatch");
    // The callback is redelivered.
    attempt.apply(id.as_str(), AuthorizationSignal::Succeeded);

    assert!(coordinator
        .dispatch_with_authorization(&id, &mut attempt)
        .is_err());
    assert_eq!(coordinator.dispatch_count(&id), 1);
}

// ── The invariant, over the whole matrix ────────────────────────────────────

/// Every lifecycle interruption, checked in one place: none of them may
/// produce a dispatch, and none may settle an intent.
///
/// Written as a loop so a new lifecycle event added later has to be
/// classified deliberately rather than silently omitted.
#[test]
fn no_lifecycle_interruption_dispatches_or_settles() {
    #[allow(clippy::type_complexity)]
    let interruptions: Vec<(&str, Box<dyn Fn(&str) -> AuthorizationAttempt>)> = vec![
        (
            "permission denied",
            Box::new(|id: &str| AuthorizationAttempt::unavailable(id, "no hardware")),
        ),
        (
            "cancelled",
            Box::new(|id: &str| {
                let mut a = AuthorizationAttempt::new(id);
                a.apply(id, AuthorizationSignal::Cancelled);
                a
            }),
        ),
        (
            "backgrounded mid-prompt",
            Box::new(|id: &str| {
                let mut a = AuthorizationAttempt::new(id);
                a.apply(id, AuthorizationSignal::PromptShown);
                a.abandon();
                a
            }),
        ),
        (
            "prompt never answered",
            Box::new(|id: &str| {
                let mut a = AuthorizationAttempt::new(id);
                a.apply(id, AuthorizationSignal::PromptShown);
                a
            }),
        ),
        (
            "hard error",
            Box::new(|id: &str| {
                let mut a = AuthorizationAttempt::new(id);
                a.apply(
                    id,
                    AuthorizationSignal::Errored {
                        reason: "lockout".into(),
                    },
                );
                a
            }),
        ),
        (
            "not recognised, then abandoned",
            Box::new(|id: &str| {
                let mut a = AuthorizationAttempt::new(id);
                a.apply(id, AuthorizationSignal::PromptShown);
                a.apply(id, AuthorizationSignal::NotRecognized);
                a.abandon();
                a
            }),
        ),
    ];

    for (name, build) in interruptions {
        let mut coordinator = coordinator();
        let id = coordinator.create(command(true)).expect("intent created");
        let mut attempt = build(id.as_str());

        let result = coordinator.dispatch_with_authorization(&id, &mut attempt);
        assert!(result.is_err(), "{name}: dispatched");
        assert_eq!(coordinator.dispatch_count(&id), 0, "{name}: money moved");

        let state = coordinator.intent(&id).map(|i| i.state.clone());
        assert!(
            !matches!(state, Some(PaymentState::Confirmed)),
            "{name}: settled an intent"
        );
    }
}

/// The counterpart: the one path that *should* work still does, so the matrix
/// is not passing by refusing everything.
#[test]
fn a_clean_authorization_still_dispatches() {
    let mut coordinator = coordinator();
    let id = coordinator.create(command(true)).expect("intent created");

    let mut attempt = AuthorizationAttempt::new(id.as_str());
    attempt.apply(id.as_str(), AuthorizationSignal::PromptShown);
    attempt.apply(id.as_str(), AuthorizationSignal::SensorEngaged);
    attempt.apply(id.as_str(), AuthorizationSignal::Succeeded);

    coordinator
        .dispatch_with_authorization(&id, &mut attempt)
        .expect("a clean authorisation must dispatch");
    assert_eq!(coordinator.dispatch_count(&id), 1);
    assert_eq!(
        coordinator.intent(&id).map(|i| &i.state),
        Some(&PaymentState::Submitted)
    );
}

/// A gateway failure must not be mistaken for an authorization failure: the
/// grant was spent, so a retry needs a *new* authorisation.
#[test]
fn a_gateway_failure_still_consumes_the_grant() {
    let mut coordinator = PaymentCoordinator::new(
        ScriptedGateway::always_err(GatewayError::SessionTimeout {
            reason: "no answer".into(),
        }),
        ScriptedBiometric::succeeds(),
        RecordingRepository::default(),
    );
    let id = coordinator.create(command(true)).expect("intent created");

    let mut attempt = AuthorizationAttempt::new(id.as_str());
    attempt.apply(id.as_str(), AuthorizationSignal::Succeeded);

    let result = coordinator.dispatch_with_authorization(&id, &mut attempt);
    assert!(
        result.is_err(),
        "an ambiguous gateway result reported success"
    );
    assert!(
        attempt.is_consumed(),
        "the grant must be spent even on failure"
    );

    // And the ambiguous outcome is not retryable on the same grant.
    assert!(coordinator
        .dispatch_with_authorization(&id, &mut attempt)
        .is_err());
}