mlt-core 0.18.0

//! `GeoJSON` -like data to represent decoded MLT data with i32 coordinates

use std::collections::BTreeMap;
use std::str::FromStr;

use geo_types::Geometry;
use serde::ser::SerializeMap as _;
use serde::{Deserialize, Serialize};
use serde_json::{Number, Value};

use crate::decoder::PropValueRef;
use crate::{LendingIterator, MltResult, ParsedLayer};
#[cfg(feature = "unstable-v2")]
use crate::{
    ParsedLayer02, ZStep,
    tile::{MValue, NestedValue},
};

/// `GeoJSON` [`FeatureCollection`]
#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
pub struct FeatureCollection {
    #[serde(rename = "type")]
    pub ty: String,
    pub features: Vec<Feature>,
}

impl FeatureCollection {
    /// Convert already-decoded layers to a `GeoJSON` [`FeatureCollection`], consuming them.
    /// Make sure to call `decode_all` on Layer before calling this (won't compile otherwise)
    pub fn from_layers<'a>(layers: impl IntoIterator<Item = ParsedLayer<'a>>) -> MltResult<Self> {
        let mut features = Vec::new();
        for layer in layers {
            // Read the v2-only columns first: the rest of the loop needs only the
            // shared ones, which is all `parsed` keeps.
            #[cfg(feature = "unstable-v2")]
            let mut m_values = match &layer {
                ParsedLayer::Tag01(_) | ParsedLayer::Unknown(_) => Vec::new().into_iter(),
                ParsedLayer::Tag02(l) => m_value_properties(l)?.into_iter(),
            };
            #[cfg(feature = "unstable-v2")]
            let mut nested = match &layer {
                ParsedLayer::Tag01(_) | ParsedLayer::Unknown(_) => Vec::new().into_iter(),
                ParsedLayer::Tag02(l) => nested_properties(l)?.into_iter(),
            };
            #[cfg(feature = "unstable-v2")]
            let (z_step, mut z) = match &layer {
                ParsedLayer::Tag01(_) | ParsedLayer::Unknown(_) => (None, Vec::new().into_iter()),
                ParsedLayer::Tag02(l) => z_values(l)?,
            };
            let parsed = match layer {
                ParsedLayer::Tag01(l) => l,
                #[cfg(feature = "unstable-v2")]
                ParsedLayer::Tag02(l) => l.into_layer(),
                ParsedLayer::Unknown(_) => continue,
            };
            let layer_name = parsed.name();
            let extent = parsed.extent().get();
            let mut feat_iter = parsed.iter_features();
            while let Some(feat) = feat_iter.next() {
                let feat = feat?;
                let mut properties = BTreeMap::new();
                for p in feat.iter_properties() {
                    properties.insert(p.name().to_string(), p.value().into());
                }
                #[cfg(feature = "unstable-v2")]
                properties.extend(m_values.next().unwrap_or_default());
                #[cfg(feature = "unstable-v2")]
                properties.extend(nested.next().unwrap_or_default());
                #[cfg(feature = "unstable-v2")]
                if let Some(step) = z_step {
                    properties.insert("_z_step".into(), step.exponent().into());
                }
                #[cfg(feature = "unstable-v2")]
                let feature_z = z.next();
                #[cfg(not(feature = "unstable-v2"))]
                let feature_z = None;
                properties.insert("_layer".into(), Value::String(layer_name.to_string()));
                properties.insert("_extent".into(), Value::Number(extent.into()));
                features.push(Feature {
                    geometry: feat.geometry().clone(),
                    z: feature_z,
                    id: feat.id(),
                    properties,
                    ty: "Feature".into(),
                });
            }
        }
        Ok(Self {
            features,
            ty: "FeatureCollection".into(),
        })
    }

    pub fn equals(&self, other: &Self) -> Result<bool, serde_json::Error> {
        let self_val = normalize_tiny_floats(serde_json::to_value(self)?);
        let other_val = normalize_tiny_floats(serde_json::to_value(other)?);
        Ok(json_values_equal(&self_val, &other_val))
    }
}

impl FromStr for FeatureCollection {
    type Err = serde_json::Error;

    fn from_str(s: &str) -> Result<Self, Self::Err> {
        serde_json::from_str(s)
    }
}

/// `GeoJSON` [`Feature`]
#[derive(Debug, Clone, PartialEq, Deserialize)]
#[serde(from = "FeatureWire")]
pub struct Feature {
    pub geometry: Geometry<i32>,
    /// The z of each stored vertex in vertex order, written as the third value of each position.
    pub z: Option<Vec<i32>>,
    pub id: Option<u64>,
    pub properties: BTreeMap<String, Value>,
    pub ty: String,
}

#[derive(Deserialize)]
struct FeatureWire {
    #[serde(deserialize_with = "geom_serde::deserialize")]
    geometry: geom_serde::GeometryWithZ,
    #[serde(default)]
    id: Option<u64>,
    #[serde(default)]
    properties: BTreeMap<String, Value>,
    #[serde(rename = "type")]
    ty: String,
}

impl From<FeatureWire> for Feature {
    fn from(wire: FeatureWire) -> Self {
        let (geometry, z) = wire.geometry;
        Self {
            geometry,
            z,
            id: wire.id,
            properties: wire.properties,
            ty: wire.ty,
        }
    }
}

struct Geom32Wire<'a>(&'a Geometry<i32>, Option<&'a [i32]>);
impl Serialize for Geom32Wire<'_> {
    fn serialize<S: serde::Serializer>(&self, s: S) -> Result<S::Ok, S::Error> {
        geom_serde::serialize(self.0, self.1, s)
    }
}

/// Serialize with the preferred order of the keys
impl Serialize for Feature {
    fn serialize<S: serde::Serializer>(&self, serializer: S) -> Result<S::Ok, S::Error> {
        let len = 3 + usize::from(self.id.is_some());
        let mut map = serializer.serialize_map(Some(len))?;
        map.serialize_entry("type", &self.ty)?;
        if let Some(id) = self.id {
            map.serialize_entry("id", &id)?;
        }
        map.serialize_entry("properties", &self.properties)?;
        map.serialize_entry("geometry", &Geom32Wire(&self.geometry, self.z.as_deref()))?;
        map.end()
    }
}

/// Serialize/deserialize [`Geometry<i32>`](geo_types::Geometry) in `GeoJSON` wire format:
/// `{"type":"…","coordinates":…}` with `[x, y]` integer arrays, or `[x, y, z]` when the feature has z.
mod geom_serde {
    use geo_types::{
        Coord, Geometry, LineString, MultiLineString, MultiPoint, MultiPolygon, Point, Polygon,
    };
    use serde::de::Error as _;
    use serde::ser::{Error, SerializeMap as _};
    use serde::{Deserialize, Deserializer, Serializer};
    use serde_json::Value;

    use crate::tile::stored_ring_len;

    /// A geometry and the z of each stored vertex, when it has any.
    pub type GeometryWithZ = (Geometry<i32>, Option<Vec<i32>>);

    /// Writes positions, taking the next z for each stored vertex.
    struct Writer<'a>(Option<std::slice::Iter<'a, i32>>);

    impl Writer<'_> {
        fn pos(&mut self, c: Coord<i32>) -> Result<Value, &'static str> {
            let mut pos = vec![Value::from(c.x), Value::from(c.y)];
            if let Some(z) = &mut self.0 {
                pos.push(Value::from(*z.next().ok_or("fewer z than vertices")?));
            }
            Ok(Value::Array(pos))
        }

        fn line(&mut self, ls: &LineString<i32>) -> Result<Value, &'static str> {
            ls.0.iter().map(|&c| self.pos(c)).collect()
        }

        /// A ring's closing position repeats its first, z included, because MLT does not store it.
        fn ring(&mut self, ring: &LineString<i32>) -> Result<Value, &'static str> {
            let stored = stored_ring_len(ring);
            let mut positions = ring.0[..stored]
                .iter()
                .map(|&c| self.pos(c))
                .collect::<Result<Vec<_>, _>>()?;
            if stored < ring.0.len() {
                positions.push(positions[0].clone());
            }
            Ok(Value::Array(positions))
        }

        fn poly(&mut self, poly: &Polygon<i32>) -> Result<Value, &'static str> {
            std::iter::once(poly.exterior())
                .chain(poly.interiors())
                .map(|ring| self.ring(ring))
                .collect()
        }

        fn coordinates(
            &mut self,
            g: &Geometry<i32>,
        ) -> Result<(&'static str, Value), &'static str> {
            Ok(match g {
                Geometry::Point(p) => ("Point", self.pos(p.0)?),
                Geometry::LineString(ls) => ("LineString", self.line(ls)?),
                Geometry::Polygon(poly) => ("Polygon", self.poly(poly)?),
                Geometry::MultiPoint(mp) => (
                    "MultiPoint",
                    mp.0.iter()
                        .map(|p| self.pos(p.0))
                        .collect::<Result<_, _>>()?,
                ),
                Geometry::MultiLineString(mls) => (
                    "MultiLineString",
                    mls.iter()
                        .map(|ls| self.line(ls))
                        .collect::<Result<_, _>>()?,
                ),
                Geometry::MultiPolygon(mpoly) => (
                    "MultiPolygon",
                    mpoly
                        .iter()
                        .map(|p| self.poly(p))
                        .collect::<Result<_, _>>()?,
                ),
                Geometry::Line(_)
                | Geometry::Rect(_)
                | Geometry::Triangle(_)
                | Geometry::GeometryCollection(_) => return Err("unsupported geometry variant"),
            })
        }
    }

    pub fn serialize<S: Serializer>(
        g: &Geometry<i32>,
        z: Option<&[i32]>,
        s: S,
    ) -> Result<S::Ok, S::Error> {
        let mut writer = Writer(z.map(<[i32]>::iter));
        let (ty, coords) = writer.coordinates(g).map_err(S::Error::custom)?;
        if writer.0.is_some_and(|mut z| z.next().is_some()) {
            return Err(S::Error::custom("more z than vertices"));
        }
        let mut m = s.serialize_map(Some(2))?;
        m.serialize_entry("type", ty)?;
        m.serialize_entry("coordinates", &coords)?;
        m.end()
    }

    /// Reads positions, collecting the z of each stored vertex.
    #[derive(Default)]
    struct Reader {
        z: Vec<i32>,
        has_z: Option<bool>,
    }

    impl Reader {
        fn pos(&mut self, pos: &[i32]) -> Result<Coord<i32>, &'static str> {
            let (coord, z) = match *pos {
                [x, y] => (Coord { x, y }, None),
                [x, y, z] => (Coord { x, y }, Some(z)),
                _ => return Err("a position needs two or three coordinates"),
            };
            if *self.has_z.get_or_insert(z.is_some()) != z.is_some() {
                return Err("either every position has z or none does");
            }
            self.z.extend(z);
            Ok(coord)
        }

        fn line(&mut self, positions: &[Vec<i32>]) -> Result<LineString<i32>, &'static str> {
            positions.iter().map(|p| self.pos(p)).collect()
        }

        fn ring(&mut self, positions: &[Vec<i32>]) -> Result<LineString<i32>, &'static str> {
            let ring = self.line(positions)?;
            if self.has_z == Some(true) && stored_ring_len(&ring) < ring.0.len() {
                self.z.pop();
            }
            Ok(ring)
        }

        fn poly(&mut self, rings: &[Vec<Vec<i32>>]) -> Result<Polygon<i32>, &'static str> {
            let Some((ext, interiors)) = rings.split_first() else {
                return Ok(Polygon::new(LineString(vec![]), vec![]));
            };
            let ext = self.ring(ext)?;
            let interiors = interiors
                .iter()
                .map(|ring| self.ring(ring))
                .collect::<Result<_, _>>()?;
            Ok(Polygon::new(ext, interiors))
        }

        fn finish(self) -> Option<Vec<i32>> {
            self.has_z.unwrap_or(false).then_some(self.z)
        }
    }

    pub fn deserialize<'de, D: Deserializer<'de>>(d: D) -> Result<GeometryWithZ, D::Error> {
        fn parse<T: serde::de::DeserializeOwned, E: serde::de::Error>(v: Value) -> Result<T, E> {
            serde_json::from_value(v).map_err(E::custom)
        }

        #[derive(Deserialize)]
        struct Wire {
            #[serde(rename = "type")]
            ty: String,
            coordinates: Value,
        }

        let Wire { ty, coordinates: c } = Wire::deserialize(d)?;
        let mut r = Reader::default();
        let geometry = match ty.as_str() {
            "Point" => r
                .pos(&parse::<Vec<i32>, _>(c)?)
                .map(|c| Geometry::Point(Point(c))),
            "LineString" => r.line(&parse::<Vec<_>, _>(c)?).map(Geometry::LineString),
            "Polygon" => r.poly(&parse::<Vec<_>, _>(c)?).map(Geometry::Polygon),
            "MultiPoint" => parse::<Vec<Vec<i32>>, _>(c)?
                .into_iter()
                .map(|p| r.pos(&p).map(Point))
                .collect::<Result<_, _>>()
                .map(|points| Geometry::MultiPoint(MultiPoint(points))),
            "MultiLineString" => parse::<Vec<Vec<Vec<i32>>>, _>(c)?
                .iter()
                .map(|ls| r.line(ls))
                .collect::<Result<_, _>>()
                .map(|lines| Geometry::MultiLineString(MultiLineString(lines))),
            "MultiPolygon" => parse::<Vec<Vec<Vec<Vec<i32>>>>, _>(c)?
                .iter()
                .map(|p| r.poly(p))
                .collect::<Result<_, _>>()
                .map(|polys| Geometry::MultiPolygon(MultiPolygon(polys))),
            _ => {
                return Err(D::Error::unknown_variant(
                    &ty,
                    &[
                        "Point",
                        "LineString",
                        "Polygon",
                        "MultiPoint",
                        "MultiLineString",
                        "MultiPolygon",
                    ],
                ));
            }
        }
        .map_err(D::Error::custom)?;
        Ok((geometry, r.finish()))
    }
}

/// Convert f32 to `GeoJSON` value: finite as number, non-finite as string per issue #978.
#[must_use]
pub fn f32_to_json(f: f32) -> Value {
    if f.is_nan() {
        Value::String("f32::NAN".to_owned())
    } else if f == f32::INFINITY {
        Value::String("f32::INFINITY".to_owned())
    } else if f == f32::NEG_INFINITY {
        Value::String("f32::NEG_INFINITY".to_owned())
    } else {
        Number::from_f64(f64::from(f)).expect("finite f32").into()
    }
}

/// Convert f64 to `GeoJSON` value: finite as number, non-finite as string per issue #978.
#[must_use]
pub fn f64_to_json(f: f64) -> Value {
    if f.is_nan() {
        Value::String("f64::NAN".to_owned())
    } else if f == f64::INFINITY {
        Value::String("f64::INFINITY".to_owned())
    } else if f == f64::NEG_INFINITY {
        Value::String("f64::NEG_INFINITY".to_owned())
    } else {
        Number::from_f64(f).expect("finite f64").into()
    }
}

/// Every feature's m-values as `m:<name>` properties, in feature order.
///
/// A feature with no values for a column has no property for it, the way a null
/// property is left out.
#[cfg(feature = "unstable-v2")]
fn m_value_properties(layer: &ParsedLayer02<'_>) -> MltResult<Vec<Vec<(String, Value)>>> {
    let geometry = layer.layer().geometry_values();
    let mut features = vec![Vec::new(); geometry.feature_count()];
    for column in layer.m_values() {
        let key = format!("m:{}", column.name());
        for (index, span) in column.spans(geometry).enumerate() {
            let values = column.values().row(column.name(), span?)?;
            if let Some(value) = m_value_to_json(&values) {
                features[index].push((key.clone(), value));
            }
        }
    }
    Ok(features)
}

/// The layer's z grid and every feature's z coordinates in vertex order.
#[cfg(feature = "unstable-v2")]
fn z_values(layer: &ParsedLayer02<'_>) -> MltResult<(Option<ZStep>, std::vec::IntoIter<Vec<i32>>)> {
    let geometry = layer.layer().geometry_values();
    let Some(step) = geometry.z_step() else {
        return Ok((None, Vec::new().into_iter()));
    };
    let z = (0..geometry.feature_count())
        .map(|index| geometry.z(index))
        .collect::<MltResult<Vec<_>>>()?;
    Ok((Some(step), z.into_iter()))
}

/// Every feature's nested columns as JSON, one entry per column under its own name.
#[cfg(feature = "unstable-v2")]
fn nested_properties(layer: &ParsedLayer02<'_>) -> MltResult<Vec<Vec<(String, Value)>>> {
    let mut features = vec![Vec::new(); layer.layer().geometry_values().feature_count()];
    for column in layer.nested() {
        for (index, feature) in features.iter_mut().enumerate() {
            feature.push((
                column.name().to_string(),
                nested_to_json(&column.row(index)?),
            ));
        }
    }
    Ok(features)
}

/// One nested value as the JSON it stands for: an object, an array, a scalar or null.
#[cfg(feature = "unstable-v2")]
fn nested_to_json(value: &NestedValue) -> Value {
    match value {
        NestedValue::Leaf(leaf) => prop_to_json(leaf),
        NestedValue::List(None) | NestedValue::Map(None) => Value::Null,
        NestedValue::List(Some(items)) => Value::Array(items.iter().map(nested_to_json).collect()),
        NestedValue::Map(Some(entries)) => Value::Object(
            entries
                .iter()
                .map(|(key, value)| (key.clone(), nested_to_json(value)))
                .collect(),
        ),
    }
}

/// One scalar as JSON, a null value included.
#[cfg(feature = "unstable-v2")]
fn prop_to_json(value: &crate::PropValue) -> Value {
    use crate::PropValue as P;
    match value {
        P::Bool(v) => v.map_or(Value::Null, Value::Bool),
        P::I8(v) => v.map_or(Value::Null, Value::from),
        P::U8(v) => v.map_or(Value::Null, Value::from),
        P::I32(v) => v.map_or(Value::Null, Value::from),
        P::U32(v) => v.map_or(Value::Null, Value::from),
        P::I64(v) => v.map_or(Value::Null, Value::from),
        P::U64(v) => v.map_or(Value::Null, Value::from),
        P::F32(v) => v.map_or(Value::Null, f32_to_json),
        P::F64(v) => v.map_or(Value::Null, f64_to_json),
        P::Str(v) => v.clone().map_or(Value::Null, Value::String),
    }
}

/// One feature's m-values as a JSON array, or [`None`] when it carries none.
#[cfg(feature = "unstable-v2")]
fn m_value_to_json(values: &MValue) -> Option<Value> {
    /// A present run, mapped value by value.
    macro_rules! array {
        ($values:expr, $to_json:expr) => {
            Value::Array($values.iter().copied().map($to_json).collect())
        };
    }
    Some(match values {
        MValue::Bool(v) => array!(v.as_ref()?, Value::Bool),
        MValue::I8(v) => array!(v.as_ref()?, Value::from),
        MValue::U8(v) => array!(v.as_ref()?, Value::from),
        MValue::I32(v) => array!(v.as_ref()?, Value::from),
        MValue::U32(v) => array!(v.as_ref()?, Value::from),
        MValue::I64(v) => array!(v.as_ref()?, Value::from),
        MValue::U64(v) => array!(v.as_ref()?, Value::from),
        MValue::F32(v) => array!(v.as_ref()?, f32_to_json),
        MValue::F64(v) => array!(v.as_ref()?, f64_to_json),
        MValue::Str(v) => Value::Array(
            v.as_ref()?
                .iter()
                .map(|s| Value::String(s.clone()))
                .collect(),
        ),
    })
}

impl From<PropValueRef<'_>> for Value {
    fn from(v: PropValueRef<'_>) -> Self {
        match v {
            PropValueRef::Bool(v) => Self::Bool(v),
            PropValueRef::I8(v) => Self::from(v),
            PropValueRef::U8(v) => Self::from(v),
            PropValueRef::I32(v) => Self::from(v),
            PropValueRef::U32(v) => Self::from(v),
            PropValueRef::I64(v) => Self::from(v),
            PropValueRef::U64(v) => Self::from(v),
            PropValueRef::F32(v) => f32_to_json(v),
            PropValueRef::F64(v) => f64_to_json(v),
            PropValueRef::Str(s) => Self::String(s.to_string()),
        }
    }
}

/// Replace tiny float values (e.g. `1e-40`) with `0.0` to handle codec precision issues.
fn normalize_tiny_floats(value: Value) -> Value {
    match value {
        Value::Number(ref n) => {
            let eps = f64::from(f32::EPSILON);
            if let Some(f) = n.as_f64()
                && f.is_finite()
                && f.abs() < eps
            {
                Value::from(0.0)
            } else {
                value
            }
        }
        Value::Array(arr) => Value::Array(arr.into_iter().map(normalize_tiny_floats).collect()),
        Value::Object(obj) => Value::Object(
            obj.into_iter()
                .map(|(k, v)| (k, normalize_tiny_floats(v)))
                .collect(),
        ),
        Value::Null | Value::Bool(_) | Value::String(_) => value,
    }
}

/// Compare two JSON values for equality. Numbers are compared with float tolerance so that
/// f32 round-trip (e.g. 3.14 vs 3.140000104904175) and Java minimal decimal (e.g. 3.4028235e+38)
/// match the Rust decoder output.
fn json_values_equal(a: &Value, b: &Value) -> bool {
    match (a, b) {
        (Value::Number(na), Value::Number(nb)) if na.is_f64() && nb.is_f64() => {
            let na = na.as_f64().expect("f64");
            let nb = nb.as_f64().expect("f64");
            assert!(
                !na.is_nan() && !nb.is_nan(),
                "unexpected non-finite numbers"
            );
            let abs_diff = (na - nb).abs();
            let max_abs = na.abs().max(nb.abs()).max(1.0);
            abs_diff <= f64::from(f32::EPSILON) * max_abs * 2.0
        }
        (Value::Array(aa), Value::Array(ab)) => {
            aa.len() == ab.len()
                && aa
                    .iter()
                    .zip(ab.iter())
                    .all(|(x, y)| json_values_equal(x, y))
        }
        (Value::Object(ao), Value::Object(bo)) => {
            ao.len() == bo.len()
                && ao
                    .iter()
                    .all(|(k, v)| bo.get(k).is_some_and(|w| json_values_equal(v, w)))
        }
        _ => a == b,
    }
}

#[cfg(test)]
mod tests {
    use geo_types::{
        Coord, GeometryCollection, Line, LineString, MultiLineString, MultiPoint, MultiPolygon,
        Point, Polygon, Rect, Triangle,
    };
    use insta::assert_snapshot;
    use rstest::rstest;

    use super::*;

    fn ring(pts: &[(i32, i32)]) -> LineString<i32> {
        LineString::from(pts.iter().map(|&(x, y)| Coord { x, y }).collect::<Vec<_>>())
    }

    fn square_with_hole() -> Polygon<i32> {
        Polygon::new(
            ring(&[(0, 0), (8, 0), (8, 8), (0, 8), (0, 0)]),
            vec![ring(&[(2, 2), (4, 2), (4, 4), (2, 2)])],
        )
    }

    fn feature(geometry: Geometry<i32>) -> Feature {
        Feature {
            geometry,
            z: None,
            id: None,
            properties: BTreeMap::new(),
            ty: "Feature".into(),
        }
    }

    fn supported_geometries() -> Vec<Geometry<i32>> {
        vec![
            Geometry::Point(Point::new(1, -2)),
            Geometry::LineString(ring(&[(0, 0), (1, 1)])),
            Geometry::LineString(LineString(vec![])),
            Geometry::Polygon(square_with_hole()),
            Geometry::Polygon(Polygon::new(LineString(vec![]), vec![])),
            Geometry::MultiPoint(MultiPoint(vec![Point::new(1, 2), Point::new(3, 4)])),
            Geometry::MultiPoint(MultiPoint(vec![])),
            Geometry::MultiLineString(MultiLineString(vec![ring(&[(0, 0), (1, 1)])])),
            Geometry::MultiPolygon(MultiPolygon(vec![square_with_hole()])),
        ]
    }

    #[test]
    fn supported_geometries_round_trip_through_geojson() {
        let mut rendered = Vec::new();
        for geometry in supported_geometries() {
            let json = serde_json::to_string(&feature(geometry.clone())).expect("serialize");
            let back: Feature = serde_json::from_str(&json).expect("deserialize");
            assert_eq!(back.geometry, geometry);
            rendered.push(json);
        }

        assert_snapshot!(rendered.join("\n"), @r#"
        {"type":"Feature","properties":{},"geometry":{"type":"Point","coordinates":[1,-2]}}
        {"type":"Feature","properties":{},"geometry":{"type":"LineString","coordinates":[[0,0],[1,1]]}}
        {"type":"Feature","properties":{},"geometry":{"type":"LineString","coordinates":[]}}
        {"type":"Feature","properties":{},"geometry":{"type":"Polygon","coordinates":[[[0,0],[8,0],[8,8],[0,8],[0,0]],[[2,2],[4,2],[4,4],[2,2]]]}}
        {"type":"Feature","properties":{},"geometry":{"type":"Polygon","coordinates":[[]]}}
        {"type":"Feature","properties":{},"geometry":{"type":"MultiPoint","coordinates":[[1,2],[3,4]]}}
        {"type":"Feature","properties":{},"geometry":{"type":"MultiPoint","coordinates":[]}}
        {"type":"Feature","properties":{},"geometry":{"type":"MultiLineString","coordinates":[[[0,0],[1,1]]]}}
        {"type":"Feature","properties":{},"geometry":{"type":"MultiPolygon","coordinates":[[[[0,0],[8,0],[8,8],[0,8],[0,0]],[[2,2],[4,2],[4,4],[2,2]]]]}}
        "#);
    }

    #[rstest]
    #[case::line(Geometry::Line(Line::new(Coord { x: 0, y: 0 }, Coord { x: 1, y: 1 })))]
    #[case::rect(Geometry::Rect(Rect::new(Coord { x: 0, y: 0 }, Coord { x: 1, y: 1 })))]
    #[case::triangle(Geometry::Triangle(Triangle::new(
        Coord { x: 0, y: 0 },
        Coord { x: 1, y: 0 },
        Coord { x: 0, y: 1 },
    )))]
    #[case::collection(Geometry::GeometryCollection(GeometryCollection(vec![])))]
    fn geometries_outside_geojson_fail_to_serialize(#[case] geometry: Geometry<i32>) {
        let err = serde_json::to_string(&feature(geometry)).expect_err("must not serialize");
        assert_eq!(err.to_string(), "unsupported geometry variant");
    }

    #[rstest]
    #[case::point(Geometry::Point(Point::new(1, -2)), vec![7])]
    #[case::polygon_with_hole(Geometry::Polygon(square_with_hole()), (1..=7).collect())]
    #[case::multi_point(
        Geometry::MultiPoint(MultiPoint(vec![Point::new(1, 2), Point::new(3, 4)])),
        vec![-1, 1],
    )]
    fn z_round_trips_as_the_third_coordinate(#[case] geometry: Geometry<i32>, #[case] z: Vec<i32>) {
        let with_z = Feature {
            z: Some(z),
            ..feature(geometry)
        };
        let json = serde_json::to_string(&with_z).expect("serialize");
        let back: Feature = serde_json::from_str(&json).expect("deserialize");
        assert_eq!(back, with_z);
    }

    #[test]
    fn a_closing_position_repeats_the_first_z() {
        let with_z = Feature {
            z: Some((1..=7).collect()),
            ..feature(Geometry::Polygon(square_with_hole()))
        };
        insta::assert_snapshot!(
            serde_json::to_string(&with_z).expect("serialize"),
            @r#"{"type":"Feature","properties":{},"geometry":{"type":"Polygon","coordinates":[[[0,0,1],[8,0,2],[8,8,3],[0,8,4],[0,0,1]],[[2,2,5],[4,2,6],[4,4,7],[2,2,5]]]}}"#
        );
    }

    #[rstest]
    #[case::fewer_z(vec![1], "fewer z than vertices")]
    #[case::more_z(vec![1, 2, 3], "more z than vertices")]
    fn z_must_match_the_vertex_count(#[case] z: Vec<i32>, #[case] expected: &str) {
        let with_z = Feature {
            z: Some(z),
            ..feature(Geometry::LineString(ring(&[(0, 0), (1, 1)])))
        };
        let err = serde_json::to_string(&with_z).expect_err("must not serialize");
        assert_eq!(err.to_string(), expected);
    }

    #[rstest]
    #[case::mixed_z(
        "[[0,0,1],[1,1]]",
        "either every position has z or none does at line 1 column 81"
    )]
    #[case::four_coordinates(
        "[[0,0,1,2]]",
        "a position needs two or three coordinates at line 1 column 77"
    )]
    #[case::one_coordinate(
        "[[0]]",
        "a position needs two or three coordinates at line 1 column 71"
    )]
    fn malformed_positions_fail_to_deserialize(#[case] coordinates: &str, #[case] expected: &str) {
        let err = serde_json::from_str::<Feature>(&format!(
            r#"{{"type":"Feature","geometry":{{"type":"LineString","coordinates":{coordinates}}}}}"#
        ))
        .expect_err("must not deserialize");
        assert_eq!(err.to_string(), expected);
    }

    #[test]
    fn unknown_geometry_type_fails_to_deserialize() {
        let err = serde_json::from_str::<Feature>(
            r#"{"type":"Feature","properties":{},"geometry":{"type":"Circle","coordinates":[0,0]}}"#,
        )
        .expect_err("must not deserialize");
        assert_snapshot!(
            err,
            @"unknown variant `Circle`, expected one of `Point`, `LineString`, `Polygon`, `MultiPoint`, `MultiLineString`, `MultiPolygon` at line 1 column 83"
        );
    }

    #[test]
    fn a_feature_collection_round_trips_through_its_text_form() {
        let collection = FeatureCollection {
            ty: "FeatureCollection".into(),
            features: vec![Feature {
                geometry: Geometry::Point(Point::new(7, 9)),
                z: None,
                id: Some(42),
                properties: BTreeMap::from([
                    ("name".into(), Value::String("ß".into())),
                    ("rank".into(), Value::from(3)),
                ]),
                ty: "Feature".into(),
            }],
        };

        let text = serde_json::to_string(&collection).expect("serialize");
        assert_snapshot!(
            text,
            @r#"{"type":"FeatureCollection","features":[{"type":"Feature","id":42,"properties":{"name":"ß","rank":3},"geometry":{"type":"Point","coordinates":[7,9]}}]}"#
        );
        assert_eq!(
            FeatureCollection::from_str(&text).expect("parse"),
            collection
        );
    }

    #[test]
    fn floats_outside_the_json_number_range_become_names() {
        let values = [
            f32_to_json(1.5),
            f32_to_json(f32::NAN),
            f32_to_json(f32::INFINITY),
            f32_to_json(f32::NEG_INFINITY),
            f64_to_json(1.5),
            f64_to_json(f64::NAN),
            f64_to_json(f64::INFINITY),
            f64_to_json(f64::NEG_INFINITY),
        ];
        assert_snapshot!(
            Value::Array(values.to_vec()),
            @r#"[1.5,"f32::NAN","f32::INFINITY","f32::NEG_INFINITY",1.5,"f64::NAN","f64::INFINITY","f64::NEG_INFINITY"]"#
        );
    }

    #[test]
    fn every_property_kind_becomes_json() {
        let values = [
            PropValueRef::Bool(true),
            PropValueRef::I8(-8),
            PropValueRef::U8(8),
            PropValueRef::I32(i32::MIN),
            PropValueRef::U32(u32::MAX),
            PropValueRef::I64(i64::MIN),
            PropValueRef::U64(u64::MAX),
            PropValueRef::F32(0.5),
            PropValueRef::F64(f64::NAN),
            PropValueRef::Str("text"),
        ];
        let json = Value::Array(values.into_iter().map(Value::from).collect());
        assert_snapshot!(
            json,
            @r#"[true,-8,8,-2147483648,4294967295,-9223372036854775808,18446744073709551615,0.5,"f64::NAN","text"]"#
        );
    }

    fn collection_with(value: &str) -> FeatureCollection {
        FeatureCollection::from_str(&format!(
            r#"{{"type":"FeatureCollection","features":[{{"type":"Feature","properties":{{"a":{value}}},"geometry":{{"type":"Point","coordinates":[0,0]}}}}]}}"#
        ))
        .expect("parse")
    }

    #[rstest]
    #[case::identical("3.14", "3.14", true)]
    #[case::f32_round_trip("3.14", "3.140000104904175", true)]
    #[case::denormal_against_zero("1e-41", "0.0", true)]
    #[case::denormal_against_integer_zero("1e-41", "0", true)]
    #[case::largest_f32("3.4028235e38", "3.4028234663852886e38", true)]
    #[case::beyond_f32_tolerance("1.0", "1.001", false)]
    #[case::different_integers("1", "2", false)]
    #[case::nested_arrays("[1.0, [2.0]]", "[1.0, [2.0]]", true)]
    #[case::shorter_array("[1.0, 2.0]", "[1.0]", false)]
    #[case::nan_name(r#""f64::NAN""#, r#""f64::NAN""#, true)]
    #[case::number_against_string("1.0", r#""1.0""#, false)]
    fn equals_compares_with_float_tolerance(
        #[case] left: &str,
        #[case] right: &str,
        #[case] expected: bool,
    ) {
        let (left, right) = (collection_with(left), collection_with(right));
        assert_eq!(left.equals(&right).expect("compare"), expected);
        assert_eq!(right.equals(&left).expect("compare"), expected);
    }

    #[test]
    fn equals_is_false_for_a_missing_property() {
        let with_extra = FeatureCollection::from_str(
            r#"{"type":"FeatureCollection","features":[{"type":"Feature","properties":{"a":1.0,"b":2.0},"geometry":{"type":"Point","coordinates":[0,0]}}]}"#,
        )
        .expect("parse");
        assert!(!collection_with("1.0").equals(&with_extra).expect("compare"));
        assert!(!with_extra.equals(&collection_with("1.0")).expect("compare"));
    }
}