model: add lockfile migration system (v1 -> v2)

Signed-off-by: NotAShelf <raf@notashelf.dev>
Change-Id: I335406fc4ee4a04071f6dcb6782e1a076a6a6964

src/model/lockfile.rs

@@ -384,7 +384,8 @@ mod tests {
     assert_eq!(loaded.mc_versions, mc_versions);
     assert_eq!(loaded.loaders, loaders);
     assert_eq!(loaded.projects.len(), 2);
-    assert_eq!(loaded.lockfile_version, 1);
+    // Lockfile should be migrated from v1 to v2 on load
+    assert_eq!(loaded.lockfile_version, 2);
   }
 
   #[test]
@@ -423,6 +424,95 @@ mod tests {
     assert!(lockfile.validate().is_ok());
   }
 
+  #[test]
+  fn test_lockfile_migration_v1_to_v2() {
+    // Test that v1 lockfiles are migrated to v2
+    let temp_dir = TempDir::new().unwrap();
+
+    let mut loaders = HashMap::new();
+    loaders.insert("fabric".to_string(), "0.15.0".to_string());
+
+    // Create a v1 lockfile manually
+    let v1_content = r#"{
+      "target": "modrinth",
+      "mc_versions": ["1.20.1"],
+      "loaders": {"fabric": "0.15.0"},
+      "projects": [],
+      "lockfile_version": 1
+    }"#;
+
+    let lockfile_path = temp_dir.path().join("pakku-lock.json");
+    std::fs::write(&lockfile_path, v1_content).unwrap();
+
+    // Load should trigger migration
+    let loaded = LockFile::load(temp_dir.path()).unwrap();
+    assert_eq!(loaded.lockfile_version, 2);
+
+    // Verify the migrated file was saved
+    let reloaded = LockFile::load(temp_dir.path()).unwrap();
+    assert_eq!(reloaded.lockfile_version, 2);
+  }
+
+  #[test]
+  fn test_lockfile_migration_preserves_projects() {
+    // Test that migration preserves all project data
+    let temp_dir = TempDir::new().unwrap();
+
+    // Create a v1 lockfile with projects (using correct enum case)
+    let v1_content = r#"{
+      "target": "modrinth",
+      "mc_versions": ["1.20.1"],
+      "loaders": {"fabric": "0.15.0"},
+      "projects": [
+        {
+          "pakku_id": "test-id-1",
+          "type": "MOD",
+          "side": "BOTH",
+          "name": {"modrinth": "Test Mod"},
+          "slug": {"modrinth": "test-mod"},
+          "id": {"modrinth": "abc123"},
+          "files": [],
+          "pakku_links": [],
+          "aliases": [],
+          "update_strategy": "LATEST",
+          "redistributable": true,
+          "export": true
+        }
+      ],
+      "lockfile_version": 1
+    }"#;
+
+    let lockfile_path = temp_dir.path().join("pakku-lock.json");
+    std::fs::write(&lockfile_path, v1_content).unwrap();
+
+    let loaded = LockFile::load(temp_dir.path()).unwrap();
+    assert_eq!(loaded.lockfile_version, 2);
+    assert_eq!(loaded.projects.len(), 1);
+    assert_eq!(loaded.projects[0].pakku_id, Some("test-id-1".to_string()));
+  }
+
+  #[test]
+  fn test_lockfile_rejects_future_version() {
+    // Test that lockfiles with version > current are rejected
+    let temp_dir = TempDir::new().unwrap();
+
+    let future_content = r#"{
+      "target": "modrinth",
+      "mc_versions": ["1.20.1"],
+      "loaders": {"fabric": "0.15.0"},
+      "projects": [],
+      "lockfile_version": 999
+    }"#;
+
+    let lockfile_path = temp_dir.path().join("pakku-lock.json");
+    std::fs::write(&lockfile_path, future_content).unwrap();
+
+    let result = LockFile::load(temp_dir.path());
+    assert!(result.is_err());
+    let err = result.unwrap_err().to_string();
+    assert!(err.contains("newer than supported"));
+  }
+
   #[test]
   fn test_lockfile_pretty_json_format() {
     // Test that saved JSON is pretty-printed
@@ -472,7 +562,10 @@ mod tests {
   }
 }
 
-const LOCKFILE_VERSION: u32 = 1;
+/// Current lockfile version - bump this when making breaking changes
+const LOCKFILE_VERSION: u32 = 2;
+/// Minimum supported lockfile version for migration
+const MIN_SUPPORTED_VERSION: u32 = 1;
 const LOCKFILE_NAME: &str = "pakku-lock.json";
 
 #[derive(Debug, Clone, Serialize, Deserialize)]
@@ -494,13 +587,26 @@ impl LockFile {
     path: P,
     validate: bool,
   ) -> Result<Self> {
-    let path = path.as_ref().join(LOCKFILE_NAME);
+    let path_ref = path.as_ref();
+    let lockfile_path = path_ref.join(LOCKFILE_NAME);
     let content =
-      std::fs::read_to_string(&path).map_err(PakkerError::IoError)?;
+      std::fs::read_to_string(&lockfile_path).map_err(PakkerError::IoError)?;
 
     let mut lockfile: Self = serde_json::from_str(&content)
       .map_err(|e| PakkerError::InvalidLockFile(e.to_string()))?;
 
+    // Check if migration is needed
+    if lockfile.lockfile_version < LOCKFILE_VERSION {
+      lockfile = lockfile.migrate()?;
+      // Save migrated lockfile
+      lockfile.save_without_validation(path_ref)?;
+      log::info!(
+        "Migrated lockfile from version {} to {}",
+        lockfile.lockfile_version,
+        LOCKFILE_VERSION
+      );
+    }
+
     if validate {
       lockfile.validate()?;
     }
@@ -509,6 +615,42 @@ impl LockFile {
     Ok(lockfile)
   }
 
+  /// Migrate lockfile from older version to current version
+  fn migrate(mut self) -> Result<Self> {
+    if self.lockfile_version < MIN_SUPPORTED_VERSION {
+      return Err(PakkerError::InvalidLockFile(format!(
+        "Lockfile version {} is too old to migrate. Minimum supported: {}",
+        self.lockfile_version, MIN_SUPPORTED_VERSION
+      )));
+    }
+
+    // Migration from v1 to v2
+    if self.lockfile_version == 1 {
+      log::info!("Migrating lockfile from v1 to v2...");
+
+      // v2 changes:
+      // - Projects now have explicit export field (defaults to true)
+      // - Side detection is more granular
+      for project in &mut self.projects {
+        // Ensure export field is set (v1 didn't always have it)
+        // Already has a default in Project, but be explicit
+        if !project.export {
+          project.export = true;
+        }
+      }
+
+      self.lockfile_version = 2;
+    }
+
+    // Future migrations would go here:
+    // if self.lockfile_version == 2 {
+    //   // migrate v2 -> v3
+    //   self.lockfile_version = 3;
+    // }
+
+    Ok(self)
+  }
+
   pub fn save<P: AsRef<Path>>(&self, path: P) -> Result<()> {
     self.validate()?;
     let path = path.as_ref().join(LOCKFILE_NAME);
@@ -525,10 +667,17 @@ impl LockFile {
   }
 
   pub fn validate(&self) -> Result<()> {
-    if self.lockfile_version != LOCKFILE_VERSION {
+    if self.lockfile_version > LOCKFILE_VERSION {
       return Err(PakkerError::InvalidLockFile(format!(
-        "Unsupported lockfile version: {}",
-        self.lockfile_version
+        "Lockfile version {} is newer than supported version {}. Please \
+         upgrade Pakker.",
+        self.lockfile_version, LOCKFILE_VERSION
+      )));
+    }
+    if self.lockfile_version < MIN_SUPPORTED_VERSION {
+      return Err(PakkerError::InvalidLockFile(format!(
+        "Lockfile version {} is too old. Minimum supported: {}",
+        self.lockfile_version, MIN_SUPPORTED_VERSION
       )));
     }