Split core and TUI crates

crates/tele-core/src/utils.rs

@@ -0,0 +1,9 @@
+use chrono::{DateTime, Local, NaiveDate, Utc};
+
+pub fn get_day(timestamp: i32) -> i64 {
+    let epoch = NaiveDate::from_ymd_opt(1970, 1, 1).expect("valid epoch date");
+    let msg_day = DateTime::<Utc>::from_timestamp(timestamp as i64, 0)
+        .map(|dt| dt.with_timezone(&Local).date_naive())
+        .unwrap_or(epoch);
+    msg_day.signed_duration_since(epoch).num_days()
+}