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

use std::{convert::Infallible, str::FromStr};

use serde::{Deserialize, Serialize};

/// Fields by which to sort results.
#[derive(Debug, Deserialize, Serialize, PartialEq)]
pub struct Sortby {
    /// The field to sort by.
    pub field: String,

    /// The direction to sort by.
    pub direction: Direction,
}

#[derive(Debug, Deserialize, Serialize, PartialEq)]
pub enum Direction {
    #[serde(rename = "asc")]
    Ascending,
    #[serde(rename = "desc")]
    Descending,
}

impl Sortby {
    /// Creates a new ascending sortby for the field.
    ///
    /// # Examples
    ///
    /// ```
    /// # use stac_api::Sortby;
    /// let sortby = Sortby::asc("id");
    /// ```
    pub fn asc(field: impl ToString) -> Sortby {
        Sortby {
            field: field.to_string(),
            direction: Direction::Ascending,
        }
    }

    /// Creates a new descending sortby for the field.
    ///
    /// # Examples
    ///
    /// ```
    /// # use stac_api::Sortby;
    /// let sortby = Sortby::desc("id");
    /// ```
    pub fn desc(field: impl ToString) -> Sortby {
        Sortby {
            field: field.to_string(),
            direction: Direction::Descending,
        }
    }

    /// Creates a vector of [Sortbys](Sortby) from a comma-delimited list.
    ///
    /// # Examples
    ///
    /// ```
    /// # use stac_api::Sortby;
    /// let sortbys = Sortby::from_query_param("+id,-datetime");
    /// ```
    pub fn from_query_param(s: &str) -> Vec<Sortby> {
        s.split(',')
            .filter_map(|s| {
                if s.is_empty() {
                    None
                } else {
                    Some(s.parse().unwrap()) // infallible
                }
            })
            .collect()
    }
}

impl FromStr for Sortby {
    type Err = Infallible;

    fn from_str(s: &str) -> Result<Self, Self::Err> {
        if s.starts_with('+') {
            Ok(Sortby::asc(&s[1..]))
        } else if s.starts_with('-') {
            Ok(Sortby::desc(&s[1..]))
        } else {
            Ok(Sortby::asc(s))
        }
    }
}

#[cfg(test)]
mod tests {
    use super::Sortby;
    use serde_json::json;

    #[test]
    fn optional_plus() {
        assert_eq!(
            "properties.created".parse::<Sortby>().unwrap(),
            "+properties.created".parse().unwrap()
        );
    }

    #[test]
    fn descending() {
        assert_eq!(Sortby::desc("id"), "-id".parse().unwrap());
    }

    #[test]
    fn ordering() {
        assert_eq!(
            vec![
                Sortby::asc("properties.created"),
                Sortby::desc("properties.eo:cloud_cover"),
                Sortby::desc("id"),
                Sortby::asc("collection")
            ],
            Sortby::from_query_param(
                "+properties.created,-properties.eo:cloud_cover,-id,collection"
            )
        )
    }

    #[test]
    fn names() {
        assert_eq!(
            json!({"field": "foo", "direction": "asc"}),
            serde_json::to_value(Sortby::asc("foo")).unwrap()
        );
        assert_eq!(
            json!({"field": "foo", "direction": "desc"}),
            serde_json::to_value(Sortby::desc("foo")).unwrap()
        );
    }
}