Add storage behind a trait

Reviewed-on: https://git.deuxfleurs.fr/Deuxfleurs/aerogramme/pulls/32

1 files changed, 65 insertions, 0 deletions

diff --git a/src/timestamp.rs b/src/timestamp.rs
new file mode 100644
index 0000000..76cb74b
--- /dev/null
+++ b/src/timestamp.rs
@@ -0,0 +1,65 @@
+use rand::prelude::*;
+use std::str::FromStr;
+use std::time::{SystemTime, UNIX_EPOCH};
+
+/// Returns milliseconds since UNIX Epoch
+pub fn now_msec() -> u64 {
+    SystemTime::now()
+        .duration_since(UNIX_EPOCH)
+        .expect("Fix your clock :o")
+        .as_millis() as u64
+}
+
+#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Debug)]
+pub struct Timestamp {
+    pub msec: u64,
+    pub rand: u64,
+}
+
+impl Timestamp {
+    #[allow(dead_code)]
+    // 2023-05-15 try to make clippy happy and not sure if this fn will be used in the future.
+    pub fn now() -> Self {
+        let mut rng = thread_rng();
+        Self {
+            msec: now_msec(),
+            rand: rng.gen::<u64>(),
+        }
+    }
+
+    pub fn after(other: &Self) -> Self {
+        let mut rng = thread_rng();
+        Self {
+            msec: std::cmp::max(now_msec(), other.msec + 1),
+            rand: rng.gen::<u64>(),
+        }
+    }
+
+    pub fn zero() -> Self {
+        Self { msec: 0, rand: 0 }
+    }
+}
+
+impl ToString for Timestamp {
+    fn to_string(&self) -> String {
+        let mut bytes = [0u8; 16];
+        bytes[0..8].copy_from_slice(&u64::to_be_bytes(self.msec));
+        bytes[8..16].copy_from_slice(&u64::to_be_bytes(self.rand));
+        hex::encode(bytes)
+    }
+}
+
+impl FromStr for Timestamp {
+    type Err = &'static str;
+
+    fn from_str(s: &str) -> Result<Timestamp, &'static str> {
+        let bytes = hex::decode(s).map_err(|_| "invalid hex")?;
+        if bytes.len() != 16 {
+            return Err("bad length");
+        }
+        Ok(Self {
+            msec: u64::from_be_bytes(bytes[0..8].try_into().unwrap()),
+            rand: u64::from_be_bytes(bytes[8..16].try_into().unwrap()),
+        })
+    }
+}