From c5b8b360ed7c001d6a45d604fad1e39fe19bbbd8 Mon Sep 17 00:00:00 2001
From: Austen Adler <agadler@austenadler.com>
Date: Sat, 22 Apr 2023 13:23:20 -0400
Subject: [PATCH] Normalize dms and dmm to always have positive degrees

---
 spatial-coordinate-systems/src/common.rs    |  9 ++++++++
 spatial-coordinate-systems/src/dmm.rs       | 23 ++++++++++---------
 spatial-coordinate-systems/src/dms.rs       | 25 +++++++++++----------
 spatial-coordinate-systems/src/lib.rs       | 10 +++++++++
 spatial-coordinate-systems/src/skyvector.rs | 10 +++++++++
 5 files changed, 54 insertions(+), 23 deletions(-)

diff --git a/spatial-coordinate-systems/src/common.rs b/spatial-coordinate-systems/src/common.rs
index 20b4946..8948d0c 100644
--- a/spatial-coordinate-systems/src/common.rs
+++ b/spatial-coordinate-systems/src/common.rs
@@ -36,6 +36,15 @@ pub fn parse_direction(i: &str) -> IResult<&str, Direction> {
     ))(i)
 }
 
+/// Changes degrees to a positive number and flips the direction if required
+pub fn normalize_degrees_direction(degrees: i16, direction: Direction) -> (i16, Direction) {
+    if degrees < 0 {
+        (-degrees, direction.inverse())
+    } else {
+        (degrees, direction)
+    }
+}
+
 pub fn parse_f64(i: &str) -> IResult<&str, f64> {
     map_opt(
         tuple((
diff --git a/spatial-coordinate-systems/src/dmm.rs b/spatial-coordinate-systems/src/dmm.rs
index 3d5576b..5774c50 100644
--- a/spatial-coordinate-systems/src/dmm.rs
+++ b/spatial-coordinate-systems/src/dmm.rs
@@ -1,5 +1,5 @@
 use crate::{
-    common::{optional_separator, parse_direction, parse_f64},
+    common::{normalize_degrees_direction, optional_separator, parse_direction, parse_f64},
     Direction, Error, LatLon,
 };
 use nom::{
@@ -95,16 +95,12 @@ impl DMM {
                 ),
             )),
             |((degrees, minutes), _, direction)| {
-                let negate = direction == Direction::West || direction == Direction::South;
+                let (degrees, direction) = normalize_degrees_direction(degrees, direction);
 
                 Self {
-                    degrees: degrees * if negate { -1 } else { 1 },
+                    degrees,
                     minutes,
-                    direction: if direction.is_lat() {
-                        Direction::North
-                    } else {
-                        Direction::East
-                    },
+                    direction,
                 }
             },
         )(i)
@@ -114,14 +110,19 @@ impl DMM {
         let degrees = d as i16;
         let minutes = d.fract() * 60_f64;
 
-        Self {
+        let (degrees, direction) = normalize_degrees_direction(
             degrees,
-            minutes,
-            direction: if is_latitude {
+            if is_latitude {
                 Direction::North
             } else {
                 Direction::East
             },
+        );
+
+        Self {
+            degrees,
+            minutes,
+            direction,
         }
     }
 
diff --git a/spatial-coordinate-systems/src/dms.rs b/spatial-coordinate-systems/src/dms.rs
index 1f7c060..6eb94fd 100644
--- a/spatial-coordinate-systems/src/dms.rs
+++ b/spatial-coordinate-systems/src/dms.rs
@@ -1,5 +1,5 @@
 use crate::{
-    common::{optional_separator, parse_direction, parse_f64},
+    common::{normalize_degrees_direction, optional_separator, parse_direction, parse_f64},
     Direction, Error, LatLon,
 };
 use nom::{
@@ -94,17 +94,13 @@ impl DMS {
                 ),
             )),
             |((degrees, minutes, seconds), _, direction)| {
-                let negate = direction == Direction::West || direction == Direction::South;
+                let (degrees, direction) = normalize_degrees_direction(degrees, direction);
 
                 Self {
-                    degrees: degrees * if negate { -1 } else { 1 },
+                    degrees,
                     minutes,
                     seconds,
-                    direction: if direction.is_lat() {
-                        Direction::North
-                    } else {
-                        Direction::East
-                    },
+                    direction,
                 }
             },
         )(i)
@@ -116,15 +112,20 @@ impl DMS {
         let seconds = minutes.fract() * 60_f64;
         let minutes = minutes as i16;
 
-        Self {
+        let (degrees, direction) = normalize_degrees_direction(
             degrees,
-            minutes,
-            seconds,
-            direction: if is_latitude {
+            if is_latitude {
                 Direction::North
             } else {
                 Direction::East
             },
+        );
+
+        Self {
+            degrees,
+            minutes,
+            seconds,
+            direction,
         }
     }
 
diff --git a/spatial-coordinate-systems/src/lib.rs b/spatial-coordinate-systems/src/lib.rs
index 478c2d0..747823b 100644
--- a/spatial-coordinate-systems/src/lib.rs
+++ b/spatial-coordinate-systems/src/lib.rs
@@ -61,6 +61,16 @@ impl Direction {
     pub fn is_positive(&self) -> bool {
         self == &Self::North || self == &Self::East
     }
+
+    /// Flips the direction
+    pub fn inverse(&self) -> Self {
+        match self {
+            Direction::North => Direction::South,
+            Direction::South => Direction::North,
+            Direction::East => Direction::West,
+            Direction::West => Direction::East,
+        }
+    }
 }
 
 #[derive(Debug, PartialEq, Clone, EnumDiscriminants)]
diff --git a/spatial-coordinate-systems/src/skyvector.rs b/spatial-coordinate-systems/src/skyvector.rs
index 6aa7c59..05c1b3f 100644
--- a/spatial-coordinate-systems/src/skyvector.rs
+++ b/spatial-coordinate-systems/src/skyvector.rs
@@ -149,6 +149,16 @@ mod tests {
             "120000N1000000E"
         );
 
+        assert_eq!(
+            Coordinate::from(LatLon::new(90.0_f64, 100.0_f64).unwrap()).0,
+            "900000N1000000E"
+        );
+
+        assert_eq!(
+            Coordinate::from(LatLon::new(-90.0_f64, 100.0_f64).unwrap()).0,
+            "900000S1000000E"
+        );
+
         // p!("0° 0' N", DMS);
         // p!("0° 0'N", DMS);
         // p!("N 0° 0'", DMS);