wip: limited schema migration capability

offline-web-storage/src/integration_tests.rs

@@ -172,4 +172,22 @@ async fn test_reference_without_content_address() {
     assert!(matches!(result, Err(StoreError::NoSuchContentAddress)));
 }
 
+#[tokio::test]
+async fn test_schema_version_management() {
+    let store = create_test_store().await;
+    
+    // Verify the schema version is correctly set
+    let version = store.get_current_schema_version().await.unwrap();
+    assert_eq!(version, 1, "Schema version should be 1");
+    
+    // Verify we can still perform basic operations
+    let reference = Reference::new(
+        Some("test_content".to_string()),
+        "test_schema_version".to_string(),
+    );
+    
+    store.store_reference(&reference).await.unwrap();
+    let retrieved = store.get_reference(&reference.id).await.unwrap();
+    assert_eq!(retrieved.name, reference.name);
+}
 

offline-web-storage/src/lib.rs

@@ -1,9 +1,14 @@
 use std::sync::Arc;
+use std::collections::{BTreeMap, HashMap};
 
 use thiserror::Error;
 use offline_web_model::Reference;
 use sqlx::{Pool, Row, Sqlite, SqlitePool};
 
+// Schema version constants
+const CURRENT_SCHEMA_VERSION: i32 = 1;
+const INITIAL_SCHEMA_VERSION: i32 = 0;
+
 pub struct SqliteReferenceStore {
     pool: Pool<Sqlite>,
 }
@@ -33,7 +38,95 @@ impl SqliteReferenceStore {
             .await
             .map_err(|e| StoreError::StorageError(Box::new(e)))?;
         
-        // Create tables if they don't exist
+        let store = Self { pool };
+        
+        // Check current schema version and migrate if necessary
+        let current_version = store.get_current_schema_version().await?;
+        if current_version != CURRENT_SCHEMA_VERSION {
+            store.migrate_schema(current_version, CURRENT_SCHEMA_VERSION).await?;
+        }
+
+        Ok(store)
+    }
+
+    async fn get_current_schema_version(&self) -> Result<i32, StoreError> {
+        // First, ensure the schema_version table exists
+        sqlx::query(
+            r#"
+            CREATE TABLE IF NOT EXISTS schema_version (
+                version INTEGER PRIMARY KEY,
+                applied_at DATETIME DEFAULT CURRENT_TIMESTAMP,
+                description TEXT
+            )
+            "#,
+        )
+        .execute(&self.pool)
+        .await
+        .map_err(|e| StoreError::StorageError(Box::new(e)))?;
+
+        // Get the current version
+        let row = sqlx::query(
+            r#"
+            SELECT version FROM schema_version ORDER BY version DESC LIMIT 1
+            "#,
+        )
+        .fetch_optional(&self.pool)
+        .await
+        .map_err(|e| StoreError::StorageError(Box::new(e)))?;
+
+        match row {
+            Some(row) => {
+                let version: i32 = row.get("version");
+                Ok(version)
+            }
+            None => {
+                // No version found, this is a fresh database
+                Ok(INITIAL_SCHEMA_VERSION)
+            }
+        }
+    }
+
+    async fn migrate_schema(&self, from_version: i32, to_version: i32) -> Result<(), StoreError> {
+        if from_version == to_version {
+            return Ok(());
+        }
+
+        if from_version > to_version {
+            return Err(StoreError::StorageError(
+                "Downward migrations not currently supported".into()
+            ));
+        }
+
+        // Use a transaction for the entire migration process
+        let mut tx = self.pool.begin().await
+            .map_err(|e| StoreError::StorageError(Box::new(e)))?;
+
+        // Apply migrations step by step
+        let mut current_version = from_version;
+        while current_version < to_version {
+            match current_version {
+                0 => {
+                    // Migration from version 0 to 1: Initial schema setup
+                    self.migrate_to_v1(&mut tx).await?;
+                    current_version = 1;
+                }
+                _ => {
+                    return Err(StoreError::StorageError(
+                        format!("Unknown migration path from version {}", current_version).into()
+                    ));
+                }
+            }
+        }
+
+        // Commit all migrations
+        tx.commit().await
+            .map_err(|e| StoreError::StorageError(Box::new(e)))?;
+
+        Ok(())
+    }
+
+    async fn migrate_to_v1(&self, tx: &mut sqlx::Transaction<'_, Sqlite>) -> Result<(), StoreError> {
+        // Create the main application tables
         sqlx::query(
             r#"
             CREATE TABLE IF NOT EXISTS ref_entries (
@@ -43,7 +136,7 @@ impl SqliteReferenceStore {
             )
             "#,
         )
-        .execute(&pool)
+        .execute(&mut **tx)
         .await
         .map_err(|e| StoreError::StorageError(Box::new(e)))?;
 
@@ -58,7 +151,7 @@ impl SqliteReferenceStore {
             )
             "#,
         )
-        .execute(&pool)
+        .execute(&mut **tx)
         .await
         .map_err(|e| StoreError::StorageError(Box::new(e)))?;
 
@@ -70,11 +163,24 @@ impl SqliteReferenceStore {
             )
             "#,
         )
-        .execute(&pool)
+        .execute(&mut **tx)
         .await
         .map_err(|e| StoreError::StorageError(Box::new(e)))?;
 
-        Ok(Self { pool })
+        // Record the schema version
+        sqlx::query(
+            r#"
+            INSERT OR REPLACE INTO schema_version (version, description)
+            VALUES (?, ?)
+            "#,
+        )
+        .bind(1)
+        .bind("Initial schema with ref_entries, ref_dependencies, and content_store tables")
+        .execute(&mut **tx)
+        .await
+        .map_err(|e| StoreError::StorageError(Box::new(e)))?;
+
+        Ok(())
     }
 
     pub async fn store_reference(&self, reference: &Reference) -> Result<(), StoreError> {
@@ -299,8 +405,8 @@ impl SqliteReferenceStore {
         .map_err(|e| StoreError::StorageError(Box::new(e)))?;
 
         // Build the dependency tree iteratively
-        let mut reference_map: std::collections::HashMap<String, Reference> = std::collections::HashMap::new();
+        let mut reference_map: HashMap<String, Reference> = HashMap::new();
-        let mut children_map: std::collections::HashMap<String, Vec<String>> = std::collections::HashMap::new();
+        let mut children_map: HashMap<String, Vec<String>> = HashMap::new();
 
         // First pass: create all references and build the children map
         for row in &rows {
@@ -321,7 +427,7 @@ impl SqliteReferenceStore {
         }
 
         // Second pass: build the dependency tree from bottom up (highest depth first)
-        let mut depth_groups: std::collections::BTreeMap<i32, Vec<String>> = std::collections::BTreeMap::new();
+        let mut depth_groups: BTreeMap<i32, Vec<String>> = BTreeMap::new();
         for row in &rows {
             let id: String = row.get("id");
             let depth: i32 = row.get("depth");