chore: refactor into a RecordingDataManager, lay the ground work for a RenderManager

src/recording_data/month.rs

@@ -0,0 +1,55 @@
+use futures::{TryStream, TryStreamExt as _};
+use snafu::{OptionExt as _, ResultExt as _, Snafu};
+
+use super::{CreateListerSnafu, ListError, RecordingDataManager, Year};
+
+pub use time::Month;
+
+#[derive(Debug, Snafu)]
+pub enum TakeError {
+    /// months are supposed to be directories, but this wasn't (because it didn't end with `/`)
+    NotADirectory,
+
+    /// could not parse the month as its name
+    ParseMonthNameError { source: time::error::InvalidVariant },
+}
+
+pub fn take(s: &str) -> Result<(Month, &str), TakeError> {
+    let (month, rest) = s.split_once('/').context(NotADirectorySnafu)?;
+
+    let month = month.parse().context(ParseMonthNameSnafu)?;
+
+    Ok((month, rest))
+}
+
+#[derive(Debug, Snafu)]
+pub enum MonthEntryError {
+    /// failed to get an entry from the storage operator's lister
+    ReceiveEntryError { source: opendal::Error },
+
+    /// failed to parse the entry as a month
+    ParseError { source: TakeError },
+}
+
+impl RecordingDataManager {
+    pub async fn months(
+        &self,
+        year: Year,
+    ) -> Result<impl TryStream<Ok = Month, Error = MonthEntryError> + Unpin, ListError> {
+        let lister = self
+            .operator
+            .lister(&format!("{year}/"))
+            .await
+            .context(CreateListerSnafu)?;
+
+        Ok(lister
+            .map_err(|error| MonthEntryError::ReceiveEntryError { source: error })
+            .and_then(|entry| {
+                std::future::ready(
+                    take(entry.name())
+                        .map(|(month, rest)| month)
+                        .context(ParseSnafu),
+                )
+            }))
+    }
+}