Decouple core Yaak logic from Tauri (#354)

crates/yaak-models/src/connection_or_tx.rs

@@ -0,0 +1,25 @@
+use r2d2::PooledConnection;
+use r2d2_sqlite::SqliteConnectionManager;
+use rusqlite::{Connection, Statement, ToSql, Transaction};
+
+pub enum ConnectionOrTx<'a> {
+    Connection(PooledConnection<SqliteConnectionManager>),
+    Transaction(&'a Transaction<'a>),
+}
+
+impl<'a> ConnectionOrTx<'a> {
+    pub(crate) fn resolve(&self) -> &Connection {
+        match self {
+            ConnectionOrTx::Connection(c) => c,
+            ConnectionOrTx::Transaction(c) => c,
+        }
+    }
+
+    pub(crate) fn prepare(&self, sql: &str) -> rusqlite::Result<Statement<'_>> {
+        self.resolve().prepare(sql)
+    }
+
+    pub(crate) fn execute(&self, sql: &str, params: &[&dyn ToSql]) -> rusqlite::Result<usize> {
+        self.resolve().execute(sql, params)
+    }
+}