1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151

use crate::objects::Cycle;
use crate::objects::HalfEdge;
use fj_math::Point;
use fj_math::Scalar;
use itertools::Itertools;

use super::{Validate, ValidationConfig, ValidationError};

impl Validate for Cycle {
    fn validate_with_config(
        &self,
        config: &ValidationConfig,
        errors: &mut Vec<ValidationError>,
    ) {
        CycleValidationError::check_half_edges_disconnected(
            self, config, errors,
        );
        CycleValidationError::check_enough_half_edges(self, config, errors);
    }
}

/// [`Cycle`] validation failed
#[derive(Clone, Debug, thiserror::Error)]
pub enum CycleValidationError {
    /// [`Cycle`]'s half-edges are not connected
    #[error(
        "Adjacent `HalfEdge`s are distinct\n\
        - End position of first `HalfEdge`: {end_of_first:?}\n\
        - Start position of second `HalfEdge`: {start_of_second:?}\n\
        - `HalfEdge`s: {half_edges:#?}"
    )]
    HalfEdgesDisconnected {
        /// The end position of the first [`HalfEdge`]
        end_of_first: Point<2>,

        /// The start position of the second [`HalfEdge`]
        start_of_second: Point<2>,

        /// The distance between the two vertices
        distance: Scalar,

        /// The half-edge
        half_edges: Box<(HalfEdge, HalfEdge)>,
    },
    /// [`Cycle`]'s should have at least one `HalfEdge`
    #[error("Expected at least one `HalfEdge`\n")]
    NotEnoughHalfEdges,
}

impl CycleValidationError {
    fn check_enough_half_edges(
        cycle: &Cycle,
        _config: &ValidationConfig,
        errors: &mut Vec<ValidationError>,
    ) {
        // If there are no half edges
        if cycle.half_edges().next().is_none() {
            errors.push(Self::NotEnoughHalfEdges.into());
        }
    }

    fn check_half_edges_disconnected(
        cycle: &Cycle,
        config: &ValidationConfig,
        errors: &mut Vec<ValidationError>,
    ) {
        for (first, second) in cycle.half_edges().circular_tuple_windows() {
            let end_of_first = {
                let [_, end] = first.boundary();
                first.curve().point_from_path_coords(end)
            };
            let start_of_second = second.start_position();

            let distance = (end_of_first - start_of_second).magnitude();

            if distance > config.identical_max_distance {
                errors.push(
                    Self::HalfEdgesDisconnected {
                        end_of_first,
                        start_of_second,
                        distance,
                        half_edges: Box::new((
                            first.clone_object(),
                            second.clone_object(),
                        )),
                    }
                    .into(),
                );
            }
        }
    }
}

#[cfg(test)]
mod tests {

    use crate::{
        assert_contains_err,
        builder::CycleBuilder,
        objects::{Cycle, HalfEdge},
        operations::{BuildCycle, BuildHalfEdge, Insert, UpdateCycle},
        services::Services,
        validate::{cycle::CycleValidationError, Validate, ValidationError},
    };

    #[test]
    fn half_edges_connected() -> anyhow::Result<()> {
        let mut services = Services::new();

        let valid = CycleBuilder::polygon(
            [[0.0, 0.0], [1.0, 0.0], [1.0, 1.0]],
            &mut services.objects,
        )
        .build(&mut services.objects);

        valid.validate_and_return_first_error()?;

        let disconnected = {
            let half_edges = [
                HalfEdge::line_segment(
                    [[0., 0.], [1., 0.]],
                    None,
                    &mut services.objects,
                ),
                HalfEdge::line_segment(
                    [[0., 0.], [1., 0.]],
                    None,
                    &mut services.objects,
                ),
            ];
            let half_edges = half_edges
                .map(|half_edge| half_edge.insert(&mut services.objects));

            Cycle::empty().add_half_edges(half_edges)
        };

        assert_contains_err!(
            disconnected,
            ValidationError::Cycle(
                CycleValidationError::HalfEdgesDisconnected { .. }
            )
        );

        let empty = Cycle::new([]);
        assert_contains_err!(
            empty,
            ValidationError::Cycle(CycleValidationError::NotEnoughHalfEdges)
        );
        Ok(())
    }
}