rskit-storage 0.2.0-alpha.3

//! Explicit storage backend registry.

use std::collections::BTreeMap;
use std::sync::Arc;

use rskit_errors::{AppError, AppResult, ErrorCode};
use serde::{Deserialize, Serialize};

use super::{FileStore, LocalStore, LocalStoreConfig};

/// Config-driven storage backend selection.
#[derive(Debug, Clone, Deserialize, Serialize)]
pub struct StorageConfig {
    /// Backend name looked up in an injected [`StorageRegistry`].
    #[serde(default = "default_backend")]
    pub backend: String,
    /// Local filesystem backend options.
    #[serde(default)]
    pub local: LocalStoreConfig,
}

impl Default for StorageConfig {
    fn default() -> Self {
        Self {
            backend: default_backend(),
            local: LocalStoreConfig::default(),
        }
    }
}

fn default_backend() -> String {
    "local".to_owned()
}

/// Async factory for storage backends.
#[async_trait::async_trait]
pub trait StorageFactory: Send + Sync {
    /// Build a storage backend from config.
    async fn create(&self, config: &StorageConfig) -> AppResult<Arc<dyn FileStore>>;
}

/// Explicit storage backend registry.
#[derive(Default)]
pub struct StorageRegistry {
    factories: BTreeMap<String, Arc<dyn StorageFactory>>,
}

impl StorageRegistry {
    /// Create an empty registry. No backend is registered implicitly.
    #[must_use]
    pub fn new() -> Self {
        Self::default()
    }

    /// Register a backend factory under `name`.
    pub fn register(
        &mut self,
        name: impl Into<String>,
        factory: Arc<dyn StorageFactory>,
    ) -> AppResult<()> {
        let name = name.into().trim().to_owned();
        if name.is_empty() {
            return Err(AppError::new(
                ErrorCode::InvalidInput,
                "storage backend name is required",
            ));
        }
        if self.factories.contains_key(&name) {
            return Err(AppError::new(
                ErrorCode::AlreadyExists,
                format!("storage backend '{name}' is already registered"),
            ));
        }
        self.factories.insert(name, factory);
        Ok(())
    }

    /// Return true when a backend exists in the registry.
    #[must_use]
    pub fn contains(&self, name: &str) -> bool {
        self.factories.contains_key(name)
    }

    /// Number of registered backend factories.
    #[must_use]
    pub fn len(&self) -> usize {
        self.factories.len()
    }

    /// Return true when no backends are registered.
    #[must_use]
    pub fn is_empty(&self) -> bool {
        self.factories.is_empty()
    }

    /// Build the backend selected by [`StorageConfig::backend`].
    pub async fn build(&self, config: &StorageConfig) -> AppResult<Arc<dyn FileStore>> {
        let backend = config.backend.trim();
        if backend.is_empty() {
            return Err(AppError::new(
                ErrorCode::InvalidInput,
                "storage backend name is required",
            ));
        }
        self.factories
            .get(backend)
            .ok_or_else(|| {
                AppError::new(
                    ErrorCode::NotFound,
                    format!("storage backend '{backend}' is not registered"),
                )
            })?
            .create(config)
            .await
    }
}

struct LocalFactory;

#[async_trait::async_trait]
impl StorageFactory for LocalFactory {
    async fn create(&self, config: &StorageConfig) -> AppResult<Arc<dyn FileStore>> {
        Ok(Arc::new(LocalStore::new(config.local.clone())?))
    }
}

/// Explicitly register the local filesystem backend.
pub fn register_local(registry: &mut StorageRegistry) -> AppResult<()> {
    registry.register("local", Arc::new(LocalFactory))
}

#[cfg(test)]
mod tests {
    use std::sync::atomic::{AtomicUsize, Ordering};

    use bytes::Bytes;

    use super::*;
    use crate::FileSource;
    use crate::store::UploadOptions;

    struct CountingFactory {
        calls: Arc<AtomicUsize>,
    }

    #[async_trait::async_trait]
    impl StorageFactory for CountingFactory {
        async fn create(&self, _config: &StorageConfig) -> AppResult<Arc<dyn FileStore>> {
            self.calls.fetch_add(1, Ordering::SeqCst);
            Ok(Arc::new(LocalStore::new(LocalStoreConfig::default())?))
        }
    }

    #[tokio::test]
    async fn registry_registers_and_builds_explicit_factories() {
        let calls = Arc::new(AtomicUsize::new(0));
        let mut registry = StorageRegistry::new();
        assert!(registry.is_empty());
        assert_eq!(registry.len(), 0);

        registry
            .register(
                " memory ",
                Arc::new(CountingFactory {
                    calls: Arc::clone(&calls),
                }),
            )
            .unwrap();

        assert!(registry.contains("memory"));
        assert_eq!(registry.len(), 1);
        let store = registry
            .build(&StorageConfig {
                backend: "memory".to_string(),
                local: LocalStoreConfig::default(),
            })
            .await
            .unwrap();
        store
            .upload(
                &FileSource::from_bytes(Bytes::from_static(b"data")),
                "item.bin",
                UploadOptions::new(),
            )
            .await
            .unwrap();
        assert_eq!(calls.load(Ordering::SeqCst), 1);
    }

    #[tokio::test]
    async fn registry_rejects_empty_duplicate_and_missing_backends() {
        let mut registry = StorageRegistry::new();
        let factory = Arc::new(CountingFactory {
            calls: Arc::new(AtomicUsize::new(0)),
        });

        assert_eq!(
            registry.register(" ", factory.clone()).unwrap_err().code(),
            ErrorCode::InvalidInput
        );
        registry.register("local", factory.clone()).unwrap();
        assert_eq!(
            registry.register("local", factory).unwrap_err().code(),
            ErrorCode::AlreadyExists
        );
        assert_eq!(
            registry
                .build(&StorageConfig {
                    backend: " ".to_string(),
                    local: LocalStoreConfig::default(),
                })
                .await
                .err()
                .unwrap()
                .code(),
            ErrorCode::InvalidInput
        );
        assert_eq!(
            registry
                .build(&StorageConfig {
                    backend: "missing".to_string(),
                    local: LocalStoreConfig::default(),
                })
                .await
                .err()
                .unwrap()
                .code(),
            ErrorCode::NotFound
        );
    }

    #[tokio::test]
    async fn local_registration_builds_local_store_from_config() {
        let dir = tempfile::tempdir().unwrap();
        let mut registry = StorageRegistry::new();
        register_local(&mut registry).unwrap();

        let store = registry
            .build(&StorageConfig {
                backend: "local".to_string(),
                local: LocalStoreConfig {
                    root_dir: dir.path().to_path_buf(),
                    auto_create: false,
                },
            })
            .await
            .unwrap();

        store
            .upload(
                &FileSource::from_bytes(Bytes::from_static(b"local")),
                "local.bin",
                UploadOptions::new(),
            )
            .await
            .unwrap();
        assert!(dir.path().join("local.bin").exists());
    }
}