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
152
153
154
155
156
157
158
159
160
161
162
163
164

import_stdlib!();

use ops::{Add, Sub};

use chrono::{DateTime, Utc, TimeZone, SecondsFormat, NaiveDate, NaiveDateTime, Timelike};

use anyhow::bail;

use crate::{CBORCodable, CBOREncodable, CBORTaggedEncodable, Tag, CBOR, CBORDecodable, CBORTaggedDecodable, CBORTaggedCodable, CBORTagged};

/// A CBOR-friendly representation of a date and time.
#[derive(Debug, Clone, PartialEq, Eq, Hash, PartialOrd, Ord)]
pub struct Date(DateTime<Utc>);

impl Date {
    /// Creates a new `Date` from the given chrono `DateTime`.
    pub fn from_datetime(date_time: DateTime<Utc>) -> Self {
        Date(date_time)
    }

    /// Creates a new `Date` from seconds since (or before) the Unix epoch.
    pub fn from_timestamp(seconds_since_unix_epoch: f64) -> Self {
        let whole_seconds_since_unix_epoch = seconds_since_unix_epoch.trunc() as i64;
        let nsecs = (seconds_since_unix_epoch.fract() * 1_000_000_000.0) as u32;
        Self::from_datetime(Utc.timestamp_opt(whole_seconds_since_unix_epoch, nsecs).unwrap())
    }

    /// Creates a new `Date` from a string containing an ISO-8601 (RFC-3339) date (with or without time).
    pub fn new_from_string(value: &str) -> anyhow::Result<Self> {
        // try parsing as DateTime
        if let Ok(dt) = DateTime::parse_from_rfc3339(value) {
            return Ok(Self::from_datetime(dt.with_timezone(&Utc)));
        }

        // try parsing as just a date (with assumed zero time)
        if let Ok(d) = NaiveDate::parse_from_str(value, "%Y-%m-%d") {
            let dt = NaiveDateTime::new(d, chrono::NaiveTime::from_hms_opt(0, 0, 0).unwrap());
            return Ok(Self::from_datetime(DateTime::from_naive_utc_and_offset(dt, Utc)));
        }

        bail!("Invalid date string")
    }

    /// Creates a new `Date` containing the current date and time.
    pub fn now() -> Self {
        Self::from_datetime(Utc::now())
    }

    /// Returns the underlying chrono `DateTime` struct.
    pub fn datetime(&self) -> DateTime<Utc> {
        self.0
    }

    /// Returns the `Date` as the number of seconds since the Unix epoch.
    pub fn timestamp(&self) -> f64 {
        let d = self.datetime();
        let whole_seconds_since_unix_epoch = d.timestamp();
        let nsecs = d.nanosecond();
        (whole_seconds_since_unix_epoch as f64) + ((nsecs as f64) / 1_000_000_000.0)
    }
}

// Support adding seconds as f64
impl Add<f64> for Date {
    type Output = Self;

    fn add(self, rhs: f64) -> Self::Output {
        Self::from_timestamp(self.timestamp() + rhs)
    }
}

// Support subtracting another date and returning the number of seconds as f64
impl Sub for Date {
    type Output = f64;

    fn sub(self, rhs: Self) -> Self::Output {
        self.timestamp() - rhs.timestamp()
    }
}

impl Default for Date {
    fn default() -> Self {
        Self::now()
    }
}

impl TryFrom<&str> for Date {
    type Error = anyhow::Error;

    fn try_from(value: &str) -> Result<Self, Self::Error> {
        Self::new_from_string(value)
    }
}

impl From<DateTime<Utc>> for Date {
    fn from(value: DateTime<Utc>) -> Self {
        Self::from_datetime(value)
    }
}

impl From<Date> for CBOR {
    fn from(value: Date) -> Self {
        value.cbor()
    }
}

impl AsRef<Date> for Date {
    fn as_ref(&self) -> &Self {
        self
    }
}

impl CBOREncodable for Date {
    fn cbor(&self) -> CBOR {
        self.tagged_cbor()
    }

    fn cbor_data(&self) -> Vec<u8> {
        self.tagged_cbor().cbor_data()
    }
}

impl CBORDecodable for Date {
    fn from_cbor(cbor: &CBOR) -> anyhow::Result<Self> {
        Self::from_tagged_cbor(cbor)
    }
}

impl TryFrom<CBOR> for Date {
    type Error = anyhow::Error;

    fn try_from(cbor: CBOR) -> Result<Self, Self::Error> {
        Self::from_cbor(&cbor)
    }
}

impl CBORCodable for Date { }

impl CBORTagged for Date {
    fn cbor_tags() -> Vec<Tag> {
        vec![Tag::new(1)]
    }
}

impl CBORTaggedEncodable for Date {
    fn untagged_cbor(&self) -> CBOR {
        self.timestamp().cbor()
    }
}

impl CBORTaggedDecodable for Date {
    fn from_untagged_cbor(cbor: &CBOR) -> anyhow::Result<Self> {
        let n = f64::from_cbor(cbor)?;
        Ok(Date::from_timestamp(n))
    }
}

impl CBORTaggedCodable for Date { }

impl fmt::Display for Date {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        f.write_str(self.datetime().to_rfc3339_opts(SecondsFormat::Secs, true).as_str())
    }
}