From 27b95c9186bd45edd4c982a7cc89cf69cf2c5d46 Mon Sep 17 00:00:00 2001
From: Joe Carstairs <me@joeac.net>
Date: Wed, 16 Oct 2024 12:51:21 +0100
Subject: All backend stuff lives in backend folder

---
 backend/app/src/models/date_time_utc.rs | 131 ++++++++++++++++++++++++++++++++
 1 file changed, 131 insertions(+)
 create mode 100644 backend/app/src/models/date_time_utc.rs

(limited to 'backend/app/src/models/date_time_utc.rs')

diff --git a/backend/app/src/models/date_time_utc.rs b/backend/app/src/models/date_time_utc.rs
new file mode 100644
index 0000000..03d5802
--- /dev/null
+++ b/backend/app/src/models/date_time_utc.rs
@@ -0,0 +1,131 @@
+use chrono::{DateTime, Datelike, Utc};
+use diesel::{
+    backend::Backend,
+    deserialize::{self, FromSql, FromSqlRow},
+    expression::AsExpression,
+    serialize::{self, ToSql},
+    sql_types::Text,
+    sqlite::Sqlite,
+};
+use serde::{Deserialize, Serialize};
+
+#[derive(
+    Eq,
+    PartialEq,
+    Ord,
+    PartialOrd,
+    Serialize,
+    Deserialize,
+    Copy,
+    Clone,
+    Debug,
+    AsExpression,
+    FromSqlRow,
+)]
+#[diesel(sql_type=Text)]
+pub struct DateTimeUtc(DateTime<Utc>);
+
+impl DateTimeUtc {
+    pub fn day_diff(&self, other: &DateTimeUtc) -> u32 {
+        self.0
+            .num_days_from_ce()
+            .abs_diff(other.0.num_days_from_ce())
+    }
+
+    pub fn to_day_str(&self) -> String {
+        self.0
+            .to_rfc3339()
+            .split_at_checked(10)
+            .map(|(day_str, _)| String::from(day_str))
+            .unwrap_or_else(|| String::from(""))
+    }
+
+    pub fn new(date_time_utc: DateTime<Utc>) -> Self {
+        Self(date_time_utc)
+    }
+
+    pub fn now() -> Self {
+        Self(Utc::now())
+    }
+}
+
+impl ToSql<Text, Sqlite> for DateTimeUtc {
+    fn to_sql<'b>(
+        &'b self,
+        out: &mut diesel::serialize::Output<'b, '_, Sqlite>,
+    ) -> serialize::Result {
+        out.set_value(self.to_day_str());
+        Ok(diesel::serialize::IsNull::No)
+    }
+}
+
+impl FromSql<Text, Sqlite> for DateTimeUtc {
+    fn from_sql(bytes: <Sqlite as Backend>::RawValue<'_>) -> deserialize::Result<DateTimeUtc> {
+        let str: String = FromSql::<Text, Sqlite>::from_sql(bytes)?;
+        let date_time = str.as_str().parse::<DateTime<Utc>>()?;
+        Ok(DateTimeUtc(date_time))
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use chrono::TimeZone;
+
+    use super::*;
+
+    #[test]
+    fn given_midnight_when_day_diff_next_midnight_less_1s_then_return_0() {
+        let start = DateTimeUtc::new(Utc.with_ymd_and_hms(2000, 1, 1, 0, 0, 0).unwrap().to_utc());
+        let end = DateTimeUtc::new(
+            Utc.with_ymd_and_hms(2000, 1, 1, 23, 59, 59)
+                .unwrap()
+                .to_utc(),
+        );
+
+        let day_diff = start.day_diff(&end);
+        let neg_day_diff = end.day_diff(&start);
+
+        assert_eq!(day_diff, 0);
+        assert_eq!(day_diff, neg_day_diff);
+    }
+
+    #[test]
+    fn given_midnight_when_day_diff_next_midnight_then_return_1() {
+        let start = DateTimeUtc::new(Utc.with_ymd_and_hms(2000, 1, 1, 0, 0, 0).unwrap().to_utc());
+        let end = DateTimeUtc::new(Utc.with_ymd_and_hms(2000, 1, 2, 0, 0, 0).unwrap().to_utc());
+
+        let day_diff = start.day_diff(&end);
+        let neg_day_diff = end.day_diff(&start);
+
+        assert_eq!(day_diff, 1);
+        assert_eq!(day_diff, neg_day_diff);
+    }
+
+    #[test]
+    fn given_midnight_less_1s_when_day_diff_midnight_then_return_1() {
+        let start = DateTimeUtc::new(
+            Utc.with_ymd_and_hms(2000, 1, 1, 23, 59, 59)
+                .unwrap()
+                .to_utc(),
+        );
+        let end = DateTimeUtc::new(Utc.with_ymd_and_hms(2000, 1, 2, 0, 0, 0).unwrap().to_utc());
+
+        let day_diff = start.day_diff(&end);
+        let neg_day_diff = end.day_diff(&start);
+
+        assert_eq!(day_diff, 1);
+        assert_eq!(day_diff, neg_day_diff);
+    }
+
+    #[test]
+    fn given_23_nov_1970_when_to_day_str_then_return_iso_day_str() {
+        let date_time_utc = DateTimeUtc::new(
+            Utc.with_ymd_and_hms(1970, 11, 23, 0, 0, 0)
+                .unwrap()
+                .to_utc(),
+        );
+        let day_str = date_time_utc.to_day_str();
+
+        assert_eq!(day_str, "1970-11-23");
+    }
+}
-- 
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