//! AZ-650 acceptance criteria — Pre-flight Built-In Test (F9).
//!
//! Tests the controller via its public surface using mock
//! [`BitEvaluator`]s. The FSM integration ("machine transitions to
//! BIT_OK") is one watch-channel hop away — the controller publishes
//! `bit_ok` and the composition root pipes that into the telemetry
//! projection. We assert the controller side (`bit_ok = true` exactly
//! when state == Pass) which is the test seam the composition root
//! consumes.

use std::sync::Arc;
use std::time::{Duration, Instant as StdInstant};

use mission_executor::{
    BitController, BitControllerConfig, BitDegradedAck, BitEvaluator, BitItemStatus, BitOverall,
    BitState,
};
use tokio::sync::{mpsc, watch};

/// Static-status evaluator for tests.
struct StaticEvaluator {
    name: &'static str,
    status: std::sync::Mutex<BitItemStatus>,
}
impl StaticEvaluator {
    fn new(name: &'static str, status: BitItemStatus) -> Arc<Self> {
        Arc::new(Self {
            name,
            status: std::sync::Mutex::new(status),
        })
    }
    #[allow(dead_code)]
    fn set(&self, status: BitItemStatus) {
        *self.status.lock().unwrap() = status;
    }
}
impl BitEvaluator for StaticEvaluator {
    fn name(&self) -> &'static str {
        self.name
    }
    fn evaluate(&self) -> BitItemStatus {
        self.status.lock().unwrap().clone()
    }
}

fn fast_config(ack_timeout: Duration) -> BitControllerConfig {
    BitControllerConfig {
        evaluation_interval: Duration::from_millis(20),
        ack_timeout,
    }
}

/// Wait until `predicate` returns `true`, polling every 10 ms. Panics
/// on `deadline`.
async fn wait_for<F>(label: &str, deadline: StdInstant, mut predicate: F)
where
    F: FnMut() -> bool,
{
    loop {
        if predicate() {
            return;
        }
        if StdInstant::now() >= deadline {
            panic!("timed out waiting for {label}");
        }
        tokio::time::sleep(Duration::from_millis(10)).await;
    }
}

/// AC-1 — every dependency healthy → controller transitions to Pass
/// and `bit_ok` flips to `true`.
#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
async fn ac1_all_pass_proceeds() {
    // Arrange — three evaluators, all Pass
    let evaluators: Vec<Arc<dyn BitEvaluator>> = vec![
        StaticEvaluator::new("mavlink_link", BitItemStatus::Pass),
        StaticEvaluator::new("mission_loaded", BitItemStatus::Pass),
        StaticEvaluator::new("state_dir_free_space", BitItemStatus::Pass),
    ];
    let (_ack_tx, ack_rx) = mpsc::channel::<BitDegradedAck>(8);
    let controller = BitController::new(fast_config(Duration::from_secs(60)), evaluators, ack_rx);
    let (shutdown_tx, shutdown_rx) = watch::channel(false);
    let (handle, join) = controller.spawn(shutdown_rx);

    // Act — let the controller evaluate at least once
    let mut bit_ok_rx = handle.bit_ok();
    let mut state_rx = handle.state();
    let deadline = StdInstant::now() + Duration::from_secs(2);
    wait_for("bit_ok = true", deadline, || *bit_ok_rx.borrow_and_update()).await;

    // Assert
    assert!(*bit_ok_rx.borrow());
    assert_eq!(*state_rx.borrow_and_update(), BitState::Pass);
    let report = handle.last_report().await.expect("report generated");
    assert_eq!(report.overall, BitOverall::Pass);
    assert_eq!(report.items.len(), 3);

    // Cleanup
    shutdown_tx.send(true).unwrap();
    let _ = join.await;
}

/// AC-2 — `camera_rtsp` reports Fail → `bit_ok = false`; controller
/// stays Failed; FSM (downstream of `bit_ok`) does NOT transition.
#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
async fn ac2_fail_blocks_transition() {
    // Arrange — one Fail evaluator
    let evaluators: Vec<Arc<dyn BitEvaluator>> = vec![
        StaticEvaluator::new("mavlink_link", BitItemStatus::Pass),
        StaticEvaluator::new(
            "camera_rtsp",
            BitItemStatus::Fail {
                detail: "no RTSP peer".into(),
            },
        ),
    ];
    let (_ack_tx, ack_rx) = mpsc::channel::<BitDegradedAck>(8);
    let controller = BitController::new(fast_config(Duration::from_secs(60)), evaluators, ack_rx);
    let (shutdown_tx, shutdown_rx) = watch::channel(false);
    let (handle, join) = controller.spawn(shutdown_rx);

    // Act — wait for one evaluation cycle
    let mut state_rx = handle.state();
    let deadline = StdInstant::now() + Duration::from_secs(2);
    wait_for("state != Idle", deadline, || {
        !matches!(*state_rx.borrow_and_update(), BitState::Idle)
    })
    .await;

    // Assert — bit_ok is false; state is Failed; report is observable
    let bit_ok = *handle.bit_ok().borrow();
    assert!(!bit_ok, "bit_ok must remain false on Fail");
    match state_rx.borrow().clone() {
        BitState::Failed { reason } => assert!(reason.contains("camera_rtsp")),
        other => panic!("expected Failed, got {other:?}"),
    }
    let report = handle.last_report().await.unwrap();
    assert_eq!(report.overall, BitOverall::Fail);

    // Cleanup
    shutdown_tx.send(true).unwrap();
    let _ = join.await;
}

/// AC-3 — Degraded → controller enters AwaitingAck → signed ack with
/// matching report_id flips to Pass and `bit_ok = true`.
#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
async fn ac3_degraded_requires_signed_ack() {
    // Arrange — Degraded evaluator (e.g. mapobjects on cached fallback)
    let evaluators: Vec<Arc<dyn BitEvaluator>> = vec![
        StaticEvaluator::new("mavlink_link", BitItemStatus::Pass),
        StaticEvaluator::new(
            "mapobjects_synced_or_cached_acked",
            BitItemStatus::Degraded {
                detail: "operating on cached fallback".into(),
            },
        ),
    ];
    let (ack_tx, ack_rx) = mpsc::channel::<BitDegradedAck>(8);
    let controller = BitController::new(fast_config(Duration::from_secs(60)), evaluators, ack_rx);
    let (shutdown_tx, shutdown_rx) = watch::channel(false);
    let (handle, join) = controller.spawn(shutdown_rx);

    // Act — wait for AwaitingAck state
    let mut state_rx = handle.state();
    let deadline = StdInstant::now() + Duration::from_secs(2);
    wait_for("state == AwaitingAck", deadline, || {
        matches!(*state_rx.borrow_and_update(), BitState::AwaitingAck { .. })
    })
    .await;

    let report_id = match state_rx.borrow().clone() {
        BitState::AwaitingAck { report_id } => report_id,
        other => panic!("expected AwaitingAck, got {other:?}"),
    };

    // `bit_ok` is still false while awaiting ack
    assert!(!*handle.bit_ok().borrow());

    // Act — send a matching signed ack
    ack_tx
        .send(BitDegradedAck {
            report_id,
            operator_id: Some("op-A".into()),
        })
        .await
        .unwrap();

    // Wait for state → Pass
    let mut bit_ok_rx = handle.bit_ok();
    let deadline = StdInstant::now() + Duration::from_secs(2);
    wait_for("bit_ok = true after ack", deadline, || {
        *bit_ok_rx.borrow_and_update()
    })
    .await;

    // Assert
    assert!(*bit_ok_rx.borrow());
    assert_eq!(*state_rx.borrow_and_update(), BitState::Pass);

    // Cleanup
    shutdown_tx.send(true).unwrap();
    let _ = join.await;
}

/// AC-3 supplement — an ack with a *different* report_id is ignored;
/// controller stays AwaitingAck.
#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
async fn ac3_mismatched_ack_is_ignored() {
    // Arrange
    let evaluators: Vec<Arc<dyn BitEvaluator>> = vec![StaticEvaluator::new(
        "mapobjects_synced_or_cached_acked",
        BitItemStatus::Degraded {
            detail: "cached fallback".into(),
        },
    )];
    let (ack_tx, ack_rx) = mpsc::channel::<BitDegradedAck>(8);
    let controller = BitController::new(fast_config(Duration::from_secs(60)), evaluators, ack_rx);
    let (shutdown_tx, shutdown_rx) = watch::channel(false);
    let (handle, join) = controller.spawn(shutdown_rx);

    let mut state_rx = handle.state();
    let deadline = StdInstant::now() + Duration::from_secs(2);
    wait_for("state == AwaitingAck", deadline, || {
        matches!(*state_rx.borrow_and_update(), BitState::AwaitingAck { .. })
    })
    .await;

    // Act — send an ack with a bogus report_id
    ack_tx
        .send(BitDegradedAck {
            report_id: uuid::Uuid::nil(),
            operator_id: Some("op-A".into()),
        })
        .await
        .unwrap();

    // Give the controller time to process the mismatch
    tokio::time::sleep(Duration::from_millis(100)).await;

    // Assert — still AwaitingAck; bit_ok still false
    assert!(matches!(
        *state_rx.borrow_and_update(),
        BitState::AwaitingAck { .. }
    ));
    assert!(!*handle.bit_ok().borrow());

    // Cleanup
    shutdown_tx.send(true).unwrap();
    let _ = join.await;
}

/// AC-4 — Degraded ack timeout transitions to Failed; `bit_ok` stays
/// false.
#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
async fn ac4_degraded_ack_timeout_fails_the_bit() {
    // Arrange — short ack timeout
    let evaluators: Vec<Arc<dyn BitEvaluator>> = vec![StaticEvaluator::new(
        "mapobjects_synced_or_cached_acked",
        BitItemStatus::Degraded {
            detail: "cached fallback".into(),
        },
    )];
    let (_ack_tx, ack_rx) = mpsc::channel::<BitDegradedAck>(8);
    let controller =
        BitController::new(fast_config(Duration::from_millis(200)), evaluators, ack_rx);
    let (shutdown_tx, shutdown_rx) = watch::channel(false);
    let (handle, join) = controller.spawn(shutdown_rx);

    // Wait for AwaitingAck
    let mut state_rx = handle.state();
    let deadline = StdInstant::now() + Duration::from_secs(2);
    wait_for("state == AwaitingAck", deadline, || {
        matches!(*state_rx.borrow_and_update(), BitState::AwaitingAck { .. })
    })
    .await;

    // Act — don't ack; let the timeout fire (200 ms ack_timeout + slack)
    let deadline = StdInstant::now() + Duration::from_secs(2);
    wait_for("state == Failed", deadline, || {
        matches!(*state_rx.borrow_and_update(), BitState::Failed { .. })
    })
    .await;

    // Assert
    match state_rx.borrow().clone() {
        BitState::Failed { reason } => assert!(
            reason.contains("ack_timeout"),
            "Failed reason should mention ack_timeout, got {reason}"
        ),
        other => panic!("expected Failed, got {other:?}"),
    }
    assert!(!*handle.bit_ok().borrow());

    // Cleanup
    shutdown_tx.send(true).unwrap();
    let _ = join.await;
}