//! AZ-679 — POI surface event mapping + dequeue emission.
//!
//! `PoiSurfaceMapper::map(poi)` produces the
//! [`OperatorPoiEvent`](shared::models::operator_event::OperatorPoiEvent)
//! that the operator UI consumes (per `architecture.md §7.10` and the
//! task spec's field list). On queue rotation / age-out / completion
//! `emit_dequeued` produces a `PoiDequeued` event.
//!
//! Both events are pushed through `TelemetrySink::push_operator_event`
//! — composition root supplies the sink (in production, the
//! `telemetry_stream::TelemetryStreamHandle`).
//!
//! `pois_surfaced_per_min` counter exposed via [`PoiSurfaceMetrics`].

use std::sync::atomic::{AtomicU64, Ordering};
use std::sync::Arc;

use chrono::Utc;
use parking_lot::Mutex;

use shared::contracts::TelemetrySink;
use shared::error::{AutopilotError, Result};
use shared::models::operator_event::{
    DequeueReason, OperatorEvent, OperatorPoiEvent, PhotoMetadata, PoiDequeued,
    Tier2EvidenceSummary,
};
use shared::models::poi::{Poi, VlmPipelineStatus};
use uuid::Uuid;

/// Sliding 60 s window over POI-surfaced timestamps. Used by the
/// `pois_surfaced_per_min` health metric.
#[derive(Default)]
struct SurfaceRateWindow {
    timestamps: Mutex<std::collections::VecDeque<std::time::Instant>>,
}

impl SurfaceRateWindow {
    fn record_and_count(&self) -> usize {
        let now = std::time::Instant::now();
        let mut w = self.timestamps.lock();
        w.push_back(now);
        while let Some(&t) = w.front() {
            if now.duration_since(t) > std::time::Duration::from_secs(60) {
                w.pop_front();
            } else {
                break;
            }
        }
        w.len()
    }

    fn current_rate(&self) -> usize {
        let now = std::time::Instant::now();
        let mut w = self.timestamps.lock();
        while let Some(&t) = w.front() {
            if now.duration_since(t) > std::time::Duration::from_secs(60) {
                w.pop_front();
            } else {
                break;
            }
        }
        w.len()
    }
}

#[derive(Debug, Clone)]
pub struct PoiSurfaceMetrics {
    pub pois_surfaced_per_min: usize,
    pub pois_surfaced_total: u64,
    pub pois_dequeued_total: u64,
}

pub struct PoiSurfaceMapper {
    sink: Arc<dyn TelemetrySink>,
    pois_surfaced_total: AtomicU64,
    pois_dequeued_total: AtomicU64,
    rate: SurfaceRateWindow,
}

impl PoiSurfaceMapper {
    pub fn new(sink: Arc<dyn TelemetrySink>) -> Self {
        Self {
            sink,
            pois_surfaced_total: AtomicU64::new(0),
            pois_dequeued_total: AtomicU64::new(0),
            rate: SurfaceRateWindow::default(),
        }
    }

    /// Pure mapping — produces the wire-format event. Used by tests
    /// and by [`surface`] (which also pushes through the sink).
    /// Photo metadata is optional and may be supplied by the caller
    /// when the POI's source detection has a captured ROI snapshot;
    /// the `Poi` model itself does not carry photo bytes.
    pub fn map(poi: &Poi, photo_metadata: Option<PhotoMetadata>) -> OperatorPoiEvent {
        let tier2_evidence_summary = poi.tier2_evidence.as_ref().map(|t| Tier2EvidenceSummary {
            path_freshness: t.path_freshness,
            endpoint_score: t.endpoint_score,
            concealment_score: t.concealment_score,
            recommended_next_action: t.recommended_next_action,
            status: t.status,
        });

        let vlm_label = match poi.vlm_status {
            // The Poi model does not carry the VLM label string — only
            // the pipeline status. The label is attached upstream
            // when the assessment lands in scan_controller; for now
            // we surface None and let scan_controller pass the label
            // through a richer overload once AZ-684 wires it.
            VlmPipelineStatus::Ok => None,
            _ => None,
        };

        OperatorPoiEvent {
            poi_id: poi.id,
            mgrs: poi.mgrs.clone(),
            class_group: poi.class_group.clone(),
            confidence: poi.confidence,
            vlm_status: poi.vlm_status,
            vlm_label,
            tier2_evidence_summary,
            photo_metadata,
            deadline_unix_ms: poi.deadline.timestamp_millis(),
        }
    }

    /// Map + push. Returns the wire event so the caller can also
    /// attach it to the audit log if needed.
    pub async fn surface(
        &self,
        poi: &Poi,
        photo_metadata: Option<PhotoMetadata>,
    ) -> Result<OperatorPoiEvent> {
        let event = Self::map(poi, photo_metadata);
        self.sink
            .push_operator_event(OperatorEvent::PoiSurfaced(event.clone()))
            .await
            .map_err(|e| AutopilotError::Internal(format!("push_operator_event(poi): {e}")))?;
        self.pois_surfaced_total.fetch_add(1, Ordering::Relaxed);
        self.rate.record_and_count();
        Ok(event)
    }

    /// Emit a `PoiDequeued` event. Called by `scan_controller` (via
    /// `operator_bridge`) when a POI is rotated, ages out, or
    /// completes (operator decided).
    pub async fn emit_dequeued(&self, poi_id: Uuid, reason: DequeueReason) -> Result<()> {
        let event = PoiDequeued {
            poi_id,
            reason,
            dequeued_at: Utc::now(),
        };
        self.sink
            .push_operator_event(OperatorEvent::PoiDequeued(event))
            .await
            .map_err(|e| AutopilotError::Internal(format!("push_operator_event(dequeue): {e}")))?;
        self.pois_dequeued_total.fetch_add(1, Ordering::Relaxed);
        Ok(())
    }

    pub fn metrics(&self) -> PoiSurfaceMetrics {
        PoiSurfaceMetrics {
            pois_surfaced_per_min: self.rate.current_rate(),
            pois_surfaced_total: self.pois_surfaced_total.load(Ordering::Relaxed),
            pois_dequeued_total: self.pois_dequeued_total.load(Ordering::Relaxed),
        }
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use async_trait::async_trait;
    use chrono::{Duration, Utc};
    use shared::models::detection::DetectionBatch;
    use shared::models::frame::Frame;
    use shared::models::tier2::{RecommendedNextAction, Tier2Evidence, Tier2Status};

    /// Recording sink that captures every operator event pushed to it.
    /// Lets tests assert on the exact wire content without spinning
    /// up a real gRPC server.
    #[derive(Default, Clone)]
    struct RecordingSink {
        events: Arc<Mutex<Vec<OperatorEvent>>>,
    }

    #[async_trait]
    impl TelemetrySink for RecordingSink {
        async fn push_frame(&self, _frame: Frame) -> Result<()> {
            Ok(())
        }
        async fn push_detections(&self, _batch: DetectionBatch) -> Result<()> {
            Ok(())
        }
        async fn push_operator_event(&self, event: OperatorEvent) -> Result<()> {
            self.events.lock().push(event);
            Ok(())
        }
    }

    fn poi_with_full_evidence() -> Poi {
        Poi {
            id: Uuid::new_v4(),
            confidence: 0.92,
            mgrs: "33UWP05".to_string(),
            class: "tank".to_string(),
            class_group: "vehicle".to_string(),
            source_detection_ids: vec![Uuid::new_v4()],
            enqueued_at: Utc::now(),
            priority: 0.92,
            decline_suppressed: false,
            vlm_status: VlmPipelineStatus::Ok,
            tier2_evidence: Some(Tier2Evidence {
                roi_id: Uuid::new_v4(),
                path_freshness: Some(0.7),
                endpoint_score: Some(0.5),
                concealment_score: Some(0.3),
                recommended_next_action: RecommendedNextAction::HoldEndpoint,
                source_detections: vec![],
                status: Tier2Status::Ok,
            }),
            deadline: Utc::now() + Duration::seconds(120),
        }
    }

    fn poi_vlm_disabled() -> Poi {
        Poi {
            vlm_status: VlmPipelineStatus::Disabled,
            tier2_evidence: None,
            ..poi_with_full_evidence()
        }
    }

    /// AC-1 — full POI maps with every required field populated; the
    /// optional `tier2_evidence_summary` is present when input has it.
    #[test]
    fn ac1_full_poi_maps_all_required_fields() {
        // Arrange
        let poi = poi_with_full_evidence();
        let meta = PhotoMetadata {
            photo_ref: "snap/123.jpg".to_string(),
            width: 1920,
            height: 1080,
            captured_at_unix_ms: 1_700_000_000_000,
        };

        // Act
        let evt = PoiSurfaceMapper::map(&poi, Some(meta.clone()));

        // Assert
        assert_eq!(evt.poi_id, poi.id);
        assert_eq!(evt.mgrs, "33UWP05");
        assert_eq!(evt.class_group, "vehicle");
        assert!((evt.confidence - 0.92).abs() < 1e-6);
        assert_eq!(evt.vlm_status, VlmPipelineStatus::Ok);
        let tier2 = evt
            .tier2_evidence_summary
            .as_ref()
            .expect("Tier2 evidence should be carried through");
        assert_eq!(
            tier2.recommended_next_action,
            RecommendedNextAction::HoldEndpoint
        );
        assert_eq!(tier2.status, Tier2Status::Ok);
        assert_eq!(
            evt.photo_metadata.as_ref().map(|p| &p.photo_ref),
            Some(&meta.photo_ref)
        );
        assert_eq!(evt.deadline_unix_ms, poi.deadline.timestamp_millis());
    }

    /// AC-2 — VLM-disabled POIs map to vlm_status = Disabled and
    /// vlm_label = None.
    #[test]
    fn ac2_vlm_disabled_carries_explicit_status() {
        // Arrange
        let poi = poi_vlm_disabled();

        // Act
        let evt = PoiSurfaceMapper::map(&poi, None);

        // Assert
        assert_eq!(evt.vlm_status, VlmPipelineStatus::Disabled);
        assert!(evt.vlm_label.is_none());
        // tier2 absence preserved.
        assert!(evt.tier2_evidence_summary.is_none());
        assert!(evt.photo_metadata.is_none());
    }

    /// AC-3 — Dequeue path emits a PoiDequeued event with the
    /// configured reason and the supplied poi_id.
    #[tokio::test]
    async fn ac3_dequeue_emits_event_through_sink() {
        // Arrange
        let sink = RecordingSink::default();
        let captured = Arc::clone(&sink.events);
        let mapper = PoiSurfaceMapper::new(Arc::new(sink));
        let poi = poi_with_full_evidence();

        // Act — surface, then dequeue.
        mapper.surface(&poi, None).await.unwrap();
        mapper
            .emit_dequeued(poi.id, DequeueReason::Rotated)
            .await
            .unwrap();

        // Assert — sink saw both events in order.
        let events = captured.lock().clone();
        assert_eq!(events.len(), 2);
        assert!(matches!(events[0], OperatorEvent::PoiSurfaced(_)));
        match &events[1] {
            OperatorEvent::PoiDequeued(d) => {
                assert_eq!(d.poi_id, poi.id);
                assert_eq!(d.reason, DequeueReason::Rotated);
            }
            _ => panic!("second event must be PoiDequeued"),
        }
        let m = mapper.metrics();
        assert_eq!(m.pois_surfaced_total, 1);
        assert_eq!(m.pois_dequeued_total, 1);
        assert_eq!(m.pois_surfaced_per_min, 1);
    }
}