rustial-engine 0.0.1

//! Interaction and query API primitives.
//!
//! This module provides a small engine-owned query surface for source-feature
//! lookup, rendered-feature picking, and feature-state storage keyed by style
//! sources / feature ids.

use crate::geometry::{Feature, Geometry, PropertyValue};
use rustial_math::{GeoCoord, TileId, WebMercator};
use std::collections::HashMap;

/// Mutable per-feature state payload.
pub type FeatureState = HashMap<String, PropertyValue>;

/// Stable feature-state identifier.
#[derive(Debug, Clone, PartialEq, Eq, Hash)]
pub struct FeatureStateId {
    /// Style source id owning the feature.
    pub source_id: String,
    /// Stable feature id within that source.
    pub feature_id: String,
}

impl FeatureStateId {
    /// Create a new feature-state id.
    pub fn new(source_id: impl Into<String>, feature_id: impl Into<String>) -> Self {
        Self {
            source_id: source_id.into(),
            feature_id: feature_id.into(),
        }
    }
}

/// Query filtering options.
#[derive(Debug, Clone, Default)]
pub struct QueryOptions {
    /// Restrict results to specific style layer ids / runtime layer names.
    pub layers: Vec<String>,
    /// Restrict results to specific source ids.
    pub sources: Vec<String>,
    /// Hit tolerance in meters for point/line picking.
    pub tolerance_meters: f64,
    /// Whether placed-symbol collision boxes participate in rendered queries.
    pub include_symbols: bool,
}

impl QueryOptions {
    /// Create default query options.
    pub fn new() -> Self {
        Self {
            layers: Vec::new(),
            sources: Vec::new(),
            tolerance_meters: 16.0,
            include_symbols: true,
        }
    }
}

/// A feature returned by source or rendered query APIs.
#[derive(Debug, Clone)]
pub struct QueriedFeature {
    /// Style layer id or runtime layer name that produced the feature.
    pub layer_id: Option<String>,
    /// Style source id, when known.
    pub source_id: Option<String>,
    /// Style source-layer id, when known.
    pub source_layer: Option<String>,
    /// Tile that supplied the feature, when known.
    pub source_tile: Option<TileId>,
    /// Stable feature id.
    pub feature_id: String,
    /// Source-local feature index.
    pub feature_index: usize,
    /// Feature geometry.
    pub geometry: Geometry,
    /// Feature properties.
    pub properties: HashMap<String, PropertyValue>,
    /// Mutable feature-state snapshot.
    pub state: FeatureState,
    /// Distance from the query position in meters.
    pub distance_meters: f64,
    /// Whether the hit came from the rendered symbol representation.
    pub from_symbol: bool,
}

/// Derive a stable feature id from properties or source-local index.
pub fn feature_id_for_feature(feature: &Feature, feature_index: usize) -> String {
    if let Some(value) = feature.property("id") {
        return property_value_as_feature_id(value).unwrap_or_else(|| feature_index.to_string());
    }
    if let Some(value) = feature.property("feature_id") {
        return property_value_as_feature_id(value).unwrap_or_else(|| feature_index.to_string());
    }
    feature_index.to_string()
}

/// Geometric hit-testing against a feature geometry.
pub fn geometry_hit_distance(
    geometry: &Geometry,
    coord: &GeoCoord,
    tolerance_meters: f64,
) -> Option<f64> {
    match geometry {
        Geometry::Point(point) => {
            let dist = world_distance(coord, &point.coord);
            (dist <= tolerance_meters).then_some(dist)
        }
        Geometry::LineString(line) => {
            line_distance(&line.coords, coord).filter(|distance| *distance <= tolerance_meters)
        }
        Geometry::Polygon(polygon) => polygon_hit_distance(polygon, coord, tolerance_meters),
        Geometry::MultiPoint(points) => points
            .points
            .iter()
            .filter_map(|point| {
                geometry_hit_distance(&Geometry::Point(point.clone()), coord, tolerance_meters)
            })
            .min_by(f64::total_cmp),
        Geometry::MultiLineString(lines) => lines
            .lines
            .iter()
            .filter_map(|line| {
                geometry_hit_distance(&Geometry::LineString(line.clone()), coord, tolerance_meters)
            })
            .min_by(f64::total_cmp),
        Geometry::MultiPolygon(polygons) => polygons
            .polygons
            .iter()
            .filter_map(|polygon| {
                geometry_hit_distance(&Geometry::Polygon(polygon.clone()), coord, tolerance_meters)
            })
            .min_by(f64::total_cmp),
        Geometry::GeometryCollection(geometries) => geometries
            .iter()
            .filter_map(|geometry| geometry_hit_distance(geometry, coord, tolerance_meters))
            .min_by(f64::total_cmp),
    }
}

fn property_value_as_feature_id(value: &PropertyValue) -> Option<String> {
    match value {
        PropertyValue::Null => None,
        PropertyValue::Bool(value) => Some(value.to_string()),
        PropertyValue::Number(value) => Some(value.to_string()),
        PropertyValue::String(value) => Some(value.clone()),
    }
}

fn polygon_hit_distance(
    polygon: &crate::geometry::Polygon,
    coord: &GeoCoord,
    tolerance_meters: f64,
) -> Option<f64> {
    if point_in_ring(&polygon.exterior, coord)
        && !polygon
            .interiors
            .iter()
            .any(|hole| point_in_ring(hole, coord))
    {
        return Some(0.0);
    }

    let mut min_distance = line_distance(&polygon.exterior, coord);
    for hole in &polygon.interiors {
        let hole_distance = line_distance(hole, coord);
        min_distance = match (min_distance, hole_distance) {
            (Some(a), Some(b)) => Some(a.min(b)),
            (Some(a), None) => Some(a),
            (None, Some(b)) => Some(b),
            (None, None) => None,
        };
    }
    min_distance.filter(|distance| *distance <= tolerance_meters)
}

fn line_distance(coords: &[GeoCoord], coord: &GeoCoord) -> Option<f64> {
    if coords.len() < 2 {
        return None;
    }
    let p = world_xy(coord);
    coords
        .windows(2)
        .map(|segment| point_to_segment_distance(p, world_xy(&segment[0]), world_xy(&segment[1])))
        .min_by(f64::total_cmp)
}

fn point_in_ring(ring: &[GeoCoord], coord: &GeoCoord) -> bool {
    if ring.len() < 3 {
        return false;
    }
    let p = world_xy(coord);
    let mut inside = false;
    let mut prev = world_xy(ring.last().expect("ring last"));
    for current_coord in ring {
        let current = world_xy(current_coord);
        let intersects = ((current[1] > p[1]) != (prev[1] > p[1]))
            && (p[0]
                < (prev[0] - current[0]) * (p[1] - current[1])
                    / (prev[1] - current[1]).max(f64::EPSILON)
                    + current[0]);
        if intersects {
            inside = !inside;
        }
        prev = current;
    }
    inside
}

fn point_to_segment_distance(point: [f64; 2], a: [f64; 2], b: [f64; 2]) -> f64 {
    let ab = [b[0] - a[0], b[1] - a[1]];
    let ap = [point[0] - a[0], point[1] - a[1]];
    let len2 = ab[0] * ab[0] + ab[1] * ab[1];
    if len2 <= f64::EPSILON {
        return ((point[0] - a[0]).powi(2) + (point[1] - a[1]).powi(2)).sqrt();
    }
    let t = ((ap[0] * ab[0] + ap[1] * ab[1]) / len2).clamp(0.0, 1.0);
    let closest = [a[0] + ab[0] * t, a[1] + ab[1] * t];
    ((point[0] - closest[0]).powi(2) + (point[1] - closest[1]).powi(2)).sqrt()
}

fn world_distance(a: &GeoCoord, b: &GeoCoord) -> f64 {
    let a = world_xy(a);
    let b = world_xy(b);
    ((a[0] - b[0]).powi(2) + (a[1] - b[1]).powi(2)).sqrt()
}

fn world_xy(coord: &GeoCoord) -> [f64; 2] {
    let projected = WebMercator::project(coord);
    [projected.position.x, projected.position.y]
}

// ---------------------------------------------------------------------------
// Bounding-box intersection for box queries
// ---------------------------------------------------------------------------

/// Axis-aligned bounding box in Web Mercator world-space, used by box/rectangle
/// rendered-feature queries.
///
/// Coordinates are in the same projected space as [`world_xy`], i.e. Web
/// Mercator metres. `min` is the south-west corner, `max` is the north-east
/// corner.
#[derive(Debug, Clone, Copy)]
pub struct GeoBBox {
    /// Minimum (south-west) corner in projected world space.
    pub min: [f64; 2],
    /// Maximum (north-east) corner in projected world space.
    pub max: [f64; 2],
}

impl GeoBBox {
    /// Build a bounding box from two geographic coordinates.
    ///
    /// The coordinates need not be ordered; the constructor normalises them so
    /// `min <= max` on both axes.
    pub fn from_geo_coords(a: &GeoCoord, b: &GeoCoord) -> Self {
        let pa = world_xy(a);
        let pb = world_xy(b);
        Self {
            min: [pa[0].min(pb[0]), pa[1].min(pb[1])],
            max: [pa[0].max(pb[0]), pa[1].max(pb[1])],
        }
    }

    /// Whether a projected point lies inside this bounding box.
    fn contains_point(&self, p: [f64; 2]) -> bool {
        p[0] >= self.min[0] && p[0] <= self.max[0] && p[1] >= self.min[1] && p[1] <= self.max[1]
    }

    /// Whether another bounding box overlaps this one.
    fn overlaps(&self, other: &GeoBBox) -> bool {
        self.min[0] <= other.max[0]
            && self.max[0] >= other.min[0]
            && self.min[1] <= other.max[1]
            && self.max[1] >= other.min[1]
    }
}

/// Test whether a feature geometry intersects a geographic bounding box.
///
/// Returns `true` when any part of the geometry touches or overlaps the box.
/// The test is performed in Web Mercator projected world space.
///
/// This is the geometric predicate underlying
/// [`MapState::query_rendered_features_in_box`](crate::MapState::query_rendered_features_in_box).
pub fn geometry_intersects_bbox(geometry: &Geometry, bbox: &GeoBBox) -> bool {
    match geometry {
        Geometry::Point(point) => bbox.contains_point(world_xy(&point.coord)),
        Geometry::LineString(line) => linestring_intersects_bbox(&line.coords, bbox),
        Geometry::Polygon(polygon) => polygon_intersects_bbox(polygon, bbox),
        Geometry::MultiPoint(points) => points
            .points
            .iter()
            .any(|p| bbox.contains_point(world_xy(&p.coord))),
        Geometry::MultiLineString(lines) => lines
            .lines
            .iter()
            .any(|line| linestring_intersects_bbox(&line.coords, bbox)),
        Geometry::MultiPolygon(polygons) => polygons
            .polygons
            .iter()
            .any(|poly| polygon_intersects_bbox(poly, bbox)),
        Geometry::GeometryCollection(geometries) => {
            geometries.iter().any(|g| geometry_intersects_bbox(g, bbox))
        }
    }
}

/// Test whether a line string intersects a bounding box.
///
/// A line intersects the box if any vertex lies inside or any segment crosses
/// one of the four box edges.
fn linestring_intersects_bbox(coords: &[GeoCoord], bbox: &GeoBBox) -> bool {
    // Fast check: any vertex inside the box?
    for coord in coords {
        if bbox.contains_point(world_xy(coord)) {
            return true;
        }
    }
    // Segment-edge crossing check.
    for pair in coords.windows(2) {
        let a = world_xy(&pair[0]);
        let b = world_xy(&pair[1]);
        if segment_intersects_bbox(a, b, bbox) {
            return true;
        }
    }
    false
}

/// Test whether a polygon intersects a bounding box.
///
/// A polygon intersects the box if:
/// 1. any vertex of the exterior ring lies inside the box, or
/// 2. any exterior-ring segment crosses a box edge, or
/// 3. the centre of the box lies inside the polygon (polygon fully contains box).
fn polygon_intersects_bbox(polygon: &crate::geometry::Polygon, bbox: &GeoBBox) -> bool {
    // Quick AABB overlap check for the polygon exterior.
    let poly_bbox = ring_bbox(&polygon.exterior);
    if !bbox.overlaps(&poly_bbox) {
        return false;
    }
    // Any exterior vertex inside the box?
    for coord in &polygon.exterior {
        if bbox.contains_point(world_xy(coord)) {
            return true;
        }
    }
    // Any exterior segment crossing a box edge?
    for pair in polygon.exterior.windows(2) {
        let a = world_xy(&pair[0]);
        let b = world_xy(&pair[1]);
        if segment_intersects_bbox(a, b, bbox) {
            return true;
        }
    }
    // Polygon fully encloses the box? Test the box centre.
    let centre_world = rustial_math::WorldCoord::new(
        (bbox.min[0] + bbox.max[0]) * 0.5,
        (bbox.min[1] + bbox.max[1]) * 0.5,
        0.0,
    );
    let centre_geo = WebMercator::unproject(&centre_world);
    if point_in_ring(&polygon.exterior, &centre_geo)
        && !polygon
            .interiors
            .iter()
            .any(|hole| point_in_ring(hole, &centre_geo))
    {
        return true;
    }
    false
}

/// Compute an axis-aligned bounding box for a coordinate ring.
fn ring_bbox(ring: &[GeoCoord]) -> GeoBBox {
    let mut min = [f64::MAX, f64::MAX];
    let mut max = [f64::MIN, f64::MIN];
    for coord in ring {
        let p = world_xy(coord);
        min[0] = min[0].min(p[0]);
        min[1] = min[1].min(p[1]);
        max[0] = max[0].max(p[0]);
        max[1] = max[1].max(p[1]);
    }
    GeoBBox { min, max }
}

/// Test whether a segment (a->b) intersects an axis-aligned bounding box.
///
/// Uses the Liang-Barsky segment-AABB intersection algorithm.
fn segment_intersects_bbox(a: [f64; 2], b: [f64; 2], bbox: &GeoBBox) -> bool {
    let dx = b[0] - a[0];
    let dy = b[1] - a[1];
    let mut t_min = 0.0_f64;
    let mut t_max = 1.0_f64;

    let clips = [
        (-dx, a[0] - bbox.min[0]),
        (dx, bbox.max[0] - a[0]),
        (-dy, a[1] - bbox.min[1]),
        (dy, bbox.max[1] - a[1]),
    ];

    for &(p, q) in &clips {
        if p.abs() < f64::EPSILON {
            // Segment is parallel to this slab.
            if q < 0.0 {
                return false;
            }
        } else {
            let t = q / p;
            if p < 0.0 {
                t_min = t_min.max(t);
            } else {
                t_max = t_max.min(t);
            }
            if t_min > t_max {
                return false;
            }
        }
    }
    true
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::geometry::{Feature, LineString, Point, Polygon};
    use std::collections::HashMap;

    #[test]
    fn feature_id_prefers_id_property() {
        let mut properties = HashMap::new();
        properties.insert("id".into(), PropertyValue::String("abc".into()));
        let feature = Feature {
            geometry: Geometry::Point(Point {
                coord: GeoCoord::from_lat_lon(0.0, 0.0),
            }),
            properties,
        };
        assert_eq!(feature_id_for_feature(&feature, 3), "abc");
    }

    #[test]
    fn point_query_uses_tolerance() {
        let geometry = Geometry::Point(Point {
            coord: GeoCoord::from_lat_lon(0.0, 0.0),
        });
        assert!(geometry_hit_distance(&geometry, &GeoCoord::from_lat_lon(0.0, 0.0), 1.0).is_some());
    }

    #[test]
    fn line_query_measures_distance() {
        let geometry = Geometry::LineString(LineString {
            coords: vec![
                GeoCoord::from_lat_lon(0.0, 0.0),
                GeoCoord::from_lat_lon(0.0, 0.001),
            ],
        });
        assert!(
            geometry_hit_distance(&geometry, &GeoCoord::from_lat_lon(0.00001, 0.0005), 32.0)
                .is_some()
        );
    }

    #[test]
    fn polygon_query_hits_inside() {
        let geometry = Geometry::Polygon(Polygon {
            exterior: vec![
                GeoCoord::from_lat_lon(0.0, 0.0),
                GeoCoord::from_lat_lon(0.0, 0.01),
                GeoCoord::from_lat_lon(0.01, 0.01),
                GeoCoord::from_lat_lon(0.01, 0.0),
                GeoCoord::from_lat_lon(0.0, 0.0),
            ],
            interiors: vec![],
        });
        assert_eq!(
            geometry_hit_distance(&geometry, &GeoCoord::from_lat_lon(0.005, 0.005), 1.0),
            Some(0.0)
        );
    }

    // -----------------------------------------------------------------------
    // Bounding-box intersection tests
    // -----------------------------------------------------------------------

    /// Helper: build a bbox from two lat/lon corners.
    fn bbox(lat1: f64, lon1: f64, lat2: f64, lon2: f64) -> GeoBBox {
        GeoBBox::from_geo_coords(
            &GeoCoord::from_lat_lon(lat1, lon1),
            &GeoCoord::from_lat_lon(lat2, lon2),
        )
    }

    #[test]
    fn point_inside_bbox() {
        let geom = Geometry::Point(Point {
            coord: GeoCoord::from_lat_lon(0.005, 0.005),
        });
        let b = bbox(0.0, 0.0, 0.01, 0.01);
        assert!(geometry_intersects_bbox(&geom, &b));
    }

    #[test]
    fn point_outside_bbox() {
        let geom = Geometry::Point(Point {
            coord: GeoCoord::from_lat_lon(1.0, 1.0),
        });
        let b = bbox(0.0, 0.0, 0.01, 0.01);
        assert!(!geometry_intersects_bbox(&geom, &b));
    }

    #[test]
    fn line_crossing_bbox() {
        // A line that starts outside the box on one side and ends outside
        // on the other side, passing through the box.
        let geom = Geometry::LineString(LineString {
            coords: vec![
                GeoCoord::from_lat_lon(-0.01, 0.005),
                GeoCoord::from_lat_lon(0.02, 0.005),
            ],
        });
        let b = bbox(0.0, 0.0, 0.01, 0.01);
        assert!(geometry_intersects_bbox(&geom, &b));
    }

    #[test]
    fn line_fully_outside_bbox() {
        let geom = Geometry::LineString(LineString {
            coords: vec![
                GeoCoord::from_lat_lon(1.0, 1.0),
                GeoCoord::from_lat_lon(1.0, 1.01),
            ],
        });
        let b = bbox(0.0, 0.0, 0.01, 0.01);
        assert!(!geometry_intersects_bbox(&geom, &b));
    }

    #[test]
    fn polygon_overlapping_bbox() {
        let geom = Geometry::Polygon(Polygon {
            exterior: vec![
                GeoCoord::from_lat_lon(0.0, 0.0),
                GeoCoord::from_lat_lon(0.0, 0.01),
                GeoCoord::from_lat_lon(0.01, 0.01),
                GeoCoord::from_lat_lon(0.01, 0.0),
                GeoCoord::from_lat_lon(0.0, 0.0),
            ],
            interiors: vec![],
        });
        let b = bbox(0.003, 0.003, 0.007, 0.007);
        assert!(geometry_intersects_bbox(&geom, &b));
    }

    #[test]
    fn polygon_enclosing_bbox() {
        // Large polygon fully enclosing a small box -- should still intersect.
        let geom = Geometry::Polygon(Polygon {
            exterior: vec![
                GeoCoord::from_lat_lon(-1.0, -1.0),
                GeoCoord::from_lat_lon(-1.0, 1.0),
                GeoCoord::from_lat_lon(1.0, 1.0),
                GeoCoord::from_lat_lon(1.0, -1.0),
                GeoCoord::from_lat_lon(-1.0, -1.0),
            ],
            interiors: vec![],
        });
        let b = bbox(0.0, 0.0, 0.01, 0.01);
        assert!(geometry_intersects_bbox(&geom, &b));
    }

    #[test]
    fn polygon_disjoint_from_bbox() {
        let geom = Geometry::Polygon(Polygon {
            exterior: vec![
                GeoCoord::from_lat_lon(10.0, 10.0),
                GeoCoord::from_lat_lon(10.0, 10.01),
                GeoCoord::from_lat_lon(10.01, 10.01),
                GeoCoord::from_lat_lon(10.01, 10.0),
                GeoCoord::from_lat_lon(10.0, 10.0),
            ],
            interiors: vec![],
        });
        let b = bbox(0.0, 0.0, 0.01, 0.01);
        assert!(!geometry_intersects_bbox(&geom, &b));
    }
}