1 files changed, 57 insertions, 0 deletions
diff --git a/src/genmeta.rs b/src/genmeta.rs
new file mode 100644
index 0000000..2ce4c4c
--- /dev/null
+++ b/src/genmeta.rs
@@ -0,0 +1,57 @@
+//! Backup generations metadata.
+
+use crate::schema::{SchemaVersion, VersionComponent};
+use serde::Serialize;
+use std::collections::HashMap;
+
+/// Metadata about the local generation.
+#[derive(Debug, Serialize)]
+pub struct GenerationMeta {
+    schema_version: SchemaVersion,
+    extras: HashMap<String, String>,
+}
+
+impl GenerationMeta {
+    /// Create from a hash map.
+    pub fn from(mut map: HashMap<String, String>) -> Result<Self, GenerationMetaError> {
+        let major: VersionComponent = metaint(&mut map, "schema_version_major")?;
+        let minor: VersionComponent = metaint(&mut map, "schema_version_minor")?;
+        Ok(Self {
+            schema_version: SchemaVersion::new(major, minor),
+            extras: map,
+        })
+    }
+
+    /// Return schema version of local generation.
+    pub fn schema_version(&self) -> SchemaVersion {
+        self.schema_version
+    }
+}
+
+fn metastr(map: &mut HashMap<String, String>, key: &str) -> Result<String, GenerationMetaError> {
+    if let Some(v) = map.remove(key) {
+        Ok(v)
+    } else {
+        Err(GenerationMetaError::NoMetaKey(key.to_string()))
+    }
+}
+
+fn metaint(map: &mut HashMap<String, String>, key: &str) -> Result<u32, GenerationMetaError> {
+    let v = metastr(map, key)?;
+    let v = v
+        .parse()
+        .map_err(|err| GenerationMetaError::BadMetaInteger(key.to_string(), err))?;
+    Ok(v)
+}
+
+/// Possible errors from getting generation metadata.
+#[derive(Debug, thiserror::Error)]
+pub enum GenerationMetaError {
+    /// Missing from from 'meta' table.
+    #[error("Generation 'meta' table does not have a row {0}")]
+    NoMetaKey(String),
+
+    /// Bad data in 'meta' table.
+    #[error("Generation 'meta' row {0} has badly formed integer: {1}")]
+    BadMetaInteger(String, std::num::ParseIntError),
+}