reverse

gpx-rs/engine/src/core/algorithm/mod.rs

@@ -1,8 +1,10 @@
 mod anchors;
+mod reverse;
 mod simplify;
 mod smooth;
 mod timestamps;
 
 pub use anchors::*;
+pub use reverse::*;
 pub use simplify::*;
 pub use timestamps::*;

gpx-rs/engine/src/core/algorithm/reverse.rs

@@ -0,0 +1,194 @@
+//! Reversing a path: the order of its trackpoints, and of the segments and tracks that hold them.
+//!
+//! The timestamps are mirrored, so that the reversed path goes through the same period of time:
+//! a trackpoint at time `t` of a part that spans `start..end` ends up at `start + end - t`. When
+//! the part is made of several ones (the segments of a track, the tracks of a file), the gaps
+//! between them are kept: every part comes after the previous one in the new order, as late as the
+//! original one came after the part that followed it.
+
+use crate::{Track, TrackSegment, Trackpoint};
+
+/// The time of the first trackpoint of a segment.
+pub fn start_time(segment: &TrackSegment) -> Option<i64> {
+    segment.iter().next().and_then(|trkpt| trkpt.time)
+}
+
+/// The time of the last trackpoint of a segment.
+pub fn end_time(segment: &TrackSegment) -> Option<i64> {
+    segment.last_index().and_then(|idx| segment[idx].time)
+}
+
+/// The time of the first trackpoint of a track.
+pub fn track_start_time(track: &Track) -> Option<i64> {
+    track.trkseg.first().and_then(start_time)
+}
+
+/// The time of the last trackpoint of a track.
+pub fn track_end_time(track: &Track) -> Option<i64> {
+    track.trkseg.last().and_then(end_time)
+}
+
+/// Reverses the trackpoints of a segment.
+///
+/// `original_next` is the time at which what came after the segment started, and `new_previous`
+/// the time at which what comes before it now ends: the segment is mirrored to start there. Both
+/// are those of the segment itself if the segment is reversed on its own, which are the ones
+/// used when they are missing (`new_previous` is the start of the segment, and `original_next`
+/// follows from the duration of the segment). Without timestamps, the trackpoints are only put
+/// in the opposite order.
+pub fn reverse_segment(
+    segment: &mut TrackSegment,
+    original_next: Option<i64>,
+    new_previous: Option<i64>,
+) {
+    let (original_start, original_end) = (start_time(segment), end_time(segment));
+    let new_previous = new_previous.or(original_start);
+    let original_next = original_next.or_else(|| {
+        // the segment lasts as long as before
+        Some(new_previous? + original_end? - original_start?)
+    });
+
+    let len = segment.len();
+    let mut points: Vec<Trackpoint> = segment.iter().cloned().collect();
+    if let (Some(next), Some(previous), Some(end)) = (original_next, new_previous, original_end) {
+        let new_start = previous + next - end;
+        for point in points.iter_mut() {
+            point.time = point.time.map(|time| new_start + (end - time));
+        }
+    }
+    points.reverse();
+    segment.splice(0, len, points);
+    segment.rev_id = Default::default();
+}
+
+/// Reverses the segments of a track, and their trackpoints: see [`reverse_segment`] for the
+/// meaning of the times, which are the ones of the track as a whole.
+pub fn reverse_segments(
+    segments: &mut [TrackSegment],
+    original_next: Option<i64>,
+    new_previous: Option<i64>,
+) {
+    segments.reverse();
+    let (mut next, mut previous) = (original_next, new_previous);
+    for segment in segments.iter_mut() {
+        // the next one is the one that was before, which started here
+        let original_start = start_time(segment);
+        reverse_segment(segment, next, previous);
+        next = original_start;
+        previous = end_time(segment);
+    }
+}
+
+/// Reverses the tracks of a file, and their segments and trackpoints.
+pub fn reverse_tracks(tracks: &mut [Track], original_next: Option<i64>, new_previous: Option<i64>) {
+    tracks.reverse();
+    let (mut next, mut previous) = (original_next, new_previous);
+    for track in tracks.iter_mut() {
+        let original_start = track_start_time(track);
+        reverse_segments(&mut track.trkseg, next, previous);
+        next = original_start;
+        previous = track_end_time(track);
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::LngLat;
+
+    use super::*;
+
+    fn segment(points: &[(f64, Option<i64>)]) -> TrackSegment {
+        let mut segment = TrackSegment::default();
+        let points = points
+            .iter()
+            .map(|(lng, time)| Trackpoint {
+                coordinates: LngLat {
+                    lng: *lng,
+                    lat: 0.0,
+                },
+                time: *time,
+                ..Default::default()
+            })
+            .collect();
+        segment.splice(0, 0, points);
+        segment
+    }
+
+    fn lngs(segment: &TrackSegment) -> Vec<f64> {
+        segment.iter().map(|p| p.coordinates.lng).collect()
+    }
+
+    fn times(segment: &TrackSegment) -> Vec<Option<i64>> {
+        segment.iter().map(|p| p.time).collect()
+    }
+
+    #[test]
+    fn test_a_segment_is_mirrored_in_its_own_time_span() {
+        let mut s = segment(&[(0.0, Some(0)), (1.0, Some(10)), (2.0, Some(40))]);
+        let (start, end) = (start_time(&s), end_time(&s));
+        reverse_segment(&mut s, end, start);
+        assert_eq!(lngs(&s), [2.0, 1.0, 0.0]);
+        // same span, the durations between points follow the points
+        assert_eq!(times(&s), [Some(0), Some(30), Some(40)]);
+    }
+
+    #[test]
+    fn test_reverse_segment_defaults() {
+        // without the times around, the segment is mirrored where it is
+        let mut s = segment(&[(0.0, Some(100)), (1.0, Some(130))]);
+        reverse_segment(&mut s, None, None);
+        assert_eq!(times(&s), [Some(100), Some(130)]);
+        assert_eq!(lngs(&s), [1.0, 0.0]);
+    }
+
+    #[test]
+    fn test_a_segment_without_times_is_only_reversed() {
+        let mut s = segment(&[(0.0, None), (1.0, None), (2.0, None)]);
+        reverse_segment(&mut s, None, None);
+        assert_eq!(lngs(&s), [2.0, 1.0, 0.0]);
+        assert_eq!(times(&s), [None, None, None]);
+    }
+
+    #[test]
+    fn test_segments_keep_the_gaps_between_them() {
+        // 0..20, then 100..120: a gap of 80
+        let mut segments = vec![
+            segment(&[(0.0, Some(0)), (1.0, Some(10)), (2.0, Some(20))]),
+            segment(&[(3.0, Some(100)), (4.0, Some(110)), (5.0, Some(120))]),
+        ];
+        let (end, start) = (end_time(&segments[1]), start_time(&segments[0]));
+        reverse_segments(&mut segments, end, start);
+        assert_eq!(lngs(&segments[0]), [5.0, 4.0, 3.0]);
+        assert_eq!(lngs(&segments[1]), [2.0, 1.0, 0.0]);
+        assert_eq!(times(&segments[0]), [Some(0), Some(10), Some(20)]);
+        // the gap is still 80
+        assert_eq!(times(&segments[1]), [Some(100), Some(110), Some(120)]);
+    }
+
+    #[test]
+    fn test_tracks_are_reversed_like_segments() {
+        let track = |segments: Vec<TrackSegment>| Track {
+            trkseg: segments,
+            ..Default::default()
+        };
+        let mut tracks = vec![
+            track(vec![
+                segment(&[(0.0, Some(0)), (1.0, Some(10))]),
+                segment(&[(2.0, Some(50)), (3.0, Some(60))]),
+            ]),
+            track(vec![segment(&[(4.0, Some(200)), (5.0, Some(230))])]),
+        ];
+        let (end, start) = (track_end_time(&tracks[1]), track_start_time(&tracks[0]));
+        reverse_tracks(&mut tracks, end, start);
+        let all: Vec<f64> = tracks
+            .iter()
+            .flat_map(|t| t.trkseg.iter().flat_map(lngs))
+            .collect();
+        assert_eq!(all, [5.0, 4.0, 3.0, 2.0, 1.0, 0.0]);
+        // 3 segments: durations 10, 10, 30 and gaps 40 and 140 are reversed to 30, 10, 10 and
+        // gaps 140 and 40 (the first part of the time is the longest)
+        assert_eq!(times(&tracks[0].trkseg[0]), [Some(0), Some(30)]);
+        assert_eq!(times(&tracks[1].trkseg[0]), [Some(170), Some(180)]);
+        assert_eq!(times(&tracks[1].trkseg[1]), [Some(220), Some(230)]);
+    }
+}

gpx-rs/engine/src/engine/command/tools/reverse.rs

@@ -1,11 +1,294 @@
-use crate::{Apply, CommandError, State};
+use std::rc::Rc;
 
+use crate::{
+    Apply, CommandError, File, FileId, Selection, State, TrackId, TrackSegmentId, end_time,
+    reverse_segment, reverse_segments, reverse_tracks, start_time, track_end_time,
+    track_start_time,
+};
+
+/// Reverses the direction of the selected elements: the whole of each selected file (its tracks,
+/// the segments of its tracks and their trackpoints are in the opposite order), of each selected
+/// track (its segments and their trackpoints), or each selected segment on its own (its
+/// trackpoints). The timestamps are mirrored, see [`reverse_segment`].
 #[derive(Debug)]
 pub struct Reverse;
 
 impl Apply for Reverse {
-    fn apply(self, _state: &mut State) -> Result<(), CommandError> {
-        // TODO
-        Err(CommandError::NotImplemented("reverse"))
+    fn apply(self, state: &mut State) -> Result<(), CommandError> {
+        let locations = state
+            .selection
+            .segment_locations(state.files, &state.order.0);
+        let points: usize = locations
+            .iter()
+            .map(|location| {
+                state.files[&location.file_id].trk[location.trk].trkseg[location.seg].len()
+            })
+            .sum();
+        if points <= 1 {
+            return Err(CommandError::NothingToDo);
+        }
+
+        let mut files: Vec<(FileId, File)> = vec![];
+        let mut edit = |file_id: &FileId, f: &dyn Fn(&mut File)| {
+            if let Some(file) = state.files.get(file_id) {
+                let mut file = (**file).clone();
+                f(&mut file);
+                files.push((*file_id, file));
+            }
+        };
+        match &*state.selection {
+            Selection::File { file_ids } => {
+                for file_id in file_ids {
+                    edit(file_id, &|file| {
+                        let end = file.trk.last().and_then(track_end_time);
+                        let start = file.trk.first().and_then(track_start_time);
+                        reverse_tracks(&mut file.trk, end, start);
+                    });
+                }
+            }
+            Selection::Track { file_id, trk_ids } => edit(file_id, &|file| {
+                reverse_selected_tracks(file, trk_ids);
+            }),
+            Selection::TrackSegment {
+                file_id,
+                trk_id,
+                trkseg_ids,
+            } => edit(file_id, &|file| {
+                reverse_selected_segments(file, *trk_id, trkseg_ids);
+            }),
+            Selection::Empty | Selection::Waypoints { .. } | Selection::Waypoint { .. } => {}
+        }
+
+        for (file_id, file) in files {
+            state.files.insert(file_id, Rc::new(file));
+        }
+        Ok(())
+    }
+}
+
+fn reverse_selected_tracks(file: &mut File, ids: &std::collections::HashSet<TrackId>) {
+    for track in file.trk.iter_mut().filter(|track| ids.contains(&track.id)) {
+        let end = track.trkseg.last().and_then(end_time);
+        let start = track.trkseg.first().and_then(start_time);
+        reverse_segments(&mut track.trkseg, end, start);
+    }
+}
+
+fn reverse_selected_segments(
+    file: &mut File,
+    track_id: TrackId,
+    ids: &std::collections::HashSet<TrackSegmentId>,
+) {
+    for track in file.trk.iter_mut().filter(|track| track.id == track_id) {
+        for segment in track
+            .trkseg
+            .iter_mut()
+            .filter(|segment| ids.contains(&segment.id))
+        {
+            let (end, start) = (end_time(segment), start_time(segment));
+            reverse_segment(segment, end, start);
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use std::collections::HashSet;
+
+    use crate::{Load, TrackSegment, engine::command::fixture::Fixture};
+
+    use super::*;
+
+    fn loaded(path: &str) -> (Fixture, FileId) {
+        let mut fx = Fixture::default();
+        let data = std::fs::read(path).unwrap();
+        Load {
+            data: &data,
+            name: "file",
+        }
+        .apply(&mut fx.state())
+        .unwrap();
+        let id = fx.order.0[0];
+        fx.selection = Selection::File {
+            file_ids: HashSet::from([id]),
+        };
+        (fx, id)
+    }
+
+    fn all_segments(fx: &Fixture, id: FileId) -> Vec<TrackSegment> {
+        fx.files[&id]
+            .trk
+            .iter()
+            .flat_map(|track| track.trkseg.iter().cloned())
+            .collect()
+    }
+
+    fn lngs(segment: &TrackSegment) -> Vec<f64> {
+        segment.iter().map(|p| p.coordinates.lng).collect()
+    }
+
+    #[test]
+    fn test_reversing_a_file_reverses_tracks_segments_and_points() {
+        let (mut fx, id) = loaded("data/with_tracks_and_segments.gpx");
+        let before = all_segments(&fx, id);
+        assert!(before.len() >= 3);
+        let (tracks_before, ids_before): (Vec<usize>, Vec<_>) = (
+            fx.files[&id].trk.iter().map(|t| t.trkseg.len()).collect(),
+            fx.files[&id].trk.iter().map(|t| t.id).collect(),
+        );
+
+        Reverse.apply(&mut fx.state()).unwrap();
+
+        let after = all_segments(&fx, id);
+        assert_eq!(after.len(), before.len());
+        // the whole path is the opposite one
+        let path =
+            |segments: &[TrackSegment]| -> Vec<f64> { segments.iter().flat_map(lngs).collect() };
+        let mut expected = path(&before);
+        expected.reverse();
+        assert_eq!(path(&after), expected);
+        // the tracks are in the opposite order, each with the same number of segments
+        let tracks_after: Vec<usize> = fx.files[&id].trk.iter().map(|t| t.trkseg.len()).collect();
+        let mut reversed = tracks_before.clone();
+        reversed.reverse();
+        assert_eq!(tracks_after, reversed);
+        let ids_after: Vec<_> = fx.files[&id].trk.iter().map(|t| t.id).collect();
+        let mut reversed_ids = ids_before;
+        reversed_ids.reverse();
+        assert_eq!(ids_after, reversed_ids);
+        // the segments changed, and they still end where they should
+        assert!(after.iter().all(|s| s.rev_id != before[0].rev_id));
+        for segment in &after {
+            assert_eq!(segment[0].anchor, Some(0));
+            assert_eq!(segment[segment.len() - 1].anchor, Some(0));
+        }
+    }
+
+    #[test]
+    fn test_reversing_a_file_twice_gives_the_same_path_and_times() {
+        let (mut fx, id) = loaded("data/with_tracks_and_segments.gpx");
+        let before = all_segments(&fx, id);
+        let times = |segments: &[TrackSegment]| -> Vec<Option<i64>> {
+            segments
+                .iter()
+                .flat_map(|s| s.iter().map(|p| p.time))
+                .collect()
+        };
+        Reverse.apply(&mut fx.state()).unwrap();
+        Reverse.apply(&mut fx.state()).unwrap();
+        let after = all_segments(&fx, id);
+        for (a, b) in before.iter().zip(&after) {
+            assert_eq!(lngs(a), lngs(b));
+            assert_eq!(a.id, b.id);
+        }
+        assert_eq!(times(&before), times(&after));
+    }
+
+    #[test]
+    fn test_reversing_segments_keeps_the_others() {
+        let (mut fx, id) = loaded("data/with_tracks_and_segments.gpx");
+        let file = fx.files[&id].clone();
+        let trk = &file.trk[0];
+        assert!(trk.trkseg.len() >= 2);
+        let target = &trk.trkseg[1];
+        fx.selection = Selection::TrackSegment {
+            file_id: id,
+            trk_id: trk.id,
+            trkseg_ids: HashSet::from([target.id]),
+        };
+        Reverse.apply(&mut fx.state()).unwrap();
+
+        let after = &fx.files[&id].trk[0];
+        // the segment is reversed in place
+        let mut expected = lngs(target);
+        expected.reverse();
+        assert_eq!(lngs(&after.trkseg[1]), expected);
+        assert_eq!(after.trkseg[1].id, target.id);
+        assert_ne!(after.trkseg[1].rev_id, target.rev_id);
+        // the other ones are the same
+        for (i, segment) in trk.trkseg.iter().enumerate().filter(|(i, _)| *i != 1) {
+            assert_eq!(after.trkseg[i].rev_id, segment.rev_id, "{i}");
+        }
+        assert_eq!(fx.files[&id].trk.len(), file.trk.len());
+    }
+
+    #[test]
+    fn test_reversing_tracks_reverses_their_segments_in_place() {
+        let (mut fx, id) = loaded("data/with_tracks_and_segments.gpx");
+        let file = fx.files[&id].clone();
+        let (index, trk) = file
+            .trk
+            .iter()
+            .enumerate()
+            .find(|(_, t)| t.trkseg.len() >= 2)
+            .unwrap();
+        fx.selection = Selection::Track {
+            file_id: id,
+            trk_ids: HashSet::from([trk.id]),
+        };
+        Reverse.apply(&mut fx.state()).unwrap();
+
+        let after = &fx.files[&id];
+        // the track stays where it is, its segments are the opposite way
+        assert_eq!(after.trk[index].id, trk.id);
+        let path = |t: &crate::Track| -> Vec<f64> { t.trkseg.iter().flat_map(lngs).collect() };
+        let mut expected = path(trk);
+        expected.reverse();
+        assert_eq!(path(&after.trk[index]), expected);
+        // and the other tracks do not change
+        for (i, other) in file.trk.iter().enumerate().filter(|(i, _)| *i != index) {
+            assert_eq!(path(&after.trk[i]), path(other));
+        }
+    }
+
+    #[test]
+    fn test_times_are_mirrored() {
+        let (mut fx, id) = loaded("data/with_time.gpx");
+        let before = all_segments(&fx, id).remove(0);
+        Reverse.apply(&mut fx.state()).unwrap();
+        let after = all_segments(&fx, id).remove(0);
+        let (start, end) = (start_time(&before).unwrap(), end_time(&before).unwrap());
+        // the same period of time, the first point of the new path is the last one
+        assert_eq!(start_time(&after), Some(start));
+        assert_eq!(end_time(&after), Some(end));
+        let n = before.len();
+        for i in 0..n {
+            assert_eq!(
+                after[i].time.unwrap(),
+                start + end - before[n - 1 - i].time.unwrap()
+            );
+            assert_eq!(after[i].coordinates.lng, before[n - 1 - i].coordinates.lng);
+        }
+    }
+
+    #[test]
+    fn test_nothing_to_reverse() {
+        let (mut fx, id) = loaded("data/simple.gpx");
+        let before = fx.files[&id].clone();
+        fx.selection = Selection::Empty;
+        assert_eq!(
+            Reverse.apply(&mut fx.state()),
+            Err(CommandError::NothingToDo)
+        );
+        fx.selection = Selection::Waypoints { file_id: id };
+        assert_eq!(
+            Reverse.apply(&mut fx.state()),
+            Err(CommandError::NothingToDo)
+        );
+        assert!(Rc::ptr_eq(&fx.files[&id], &before));
+
+        // a single trackpoint has no direction
+        let mut file = (*fx.files[&id]).clone();
+        let segment = &mut file.trk[0].trkseg[0];
+        let len = segment.len();
+        segment.splice(1, len, vec![]);
+        fx.files.insert(id, Rc::new(file));
+        fx.selection = Selection::File {
+            file_ids: HashSet::from([id]),
+        };
+        assert_eq!(
+            Reverse.apply(&mut fx.state()),
+            Err(CommandError::NothingToDo)
+        );
     }
 }