2 files changed, 47 insertions, 0 deletions
diff --git a/src/event/repo/mod.rs b/src/event/repo/mod.rs
index e216a50..cee840c 100644
--- a/src/event/repo/mod.rs
+++ b/src/event/repo/mod.rs
@@ -1 +1,4 @@
 pub mod message;
+mod sequence;
+
+pub use self::sequence::Provider;
diff --git a/src/event/repo/sequence.rs b/src/event/repo/sequence.rs
new file mode 100644
index 0000000..c985869
--- /dev/null
+++ b/src/event/repo/sequence.rs
@@ -0,0 +1,44 @@
+use sqlx::{sqlite::Sqlite, SqliteConnection, Transaction};
+
+use crate::event::Sequence;
+
+pub trait Provider {
+    fn sequence(&mut self) -> Sequences;
+}
+
+impl<'c> Provider for Transaction<'c, Sqlite> {
+    fn sequence(&mut self) -> Sequences {
+        Sequences(self)
+    }
+}
+
+pub struct Sequences<'t>(&'t mut SqliteConnection);
+
+impl<'c> Sequences<'c> {
+    pub async fn next(&mut self) -> Result<Sequence, sqlx::Error> {
+        let next = sqlx::query_scalar!(
+            r#"
+                update event_sequence
+                set last_value = last_value + 1
+                returning last_value as "next_value: Sequence"
+            "#,
+        )
+        .fetch_one(&mut *self.0)
+        .await?;
+
+        Ok(next)
+    }
+
+    pub async fn current(&mut self) -> Result<Sequence, sqlx::Error> {
+        let next = sqlx::query_scalar!(
+            r#"
+                select last_value as "last_value: Sequence"
+                from event_sequence
+            "#,
+        )
+        .fetch_one(&mut *self.0)
+        .await?;
+
+        Ok(next)
+    }
+}