foundation_db 0.0.2

//! JSON file storage backend implementation.
//!
//! Provides simple JSON-on-disk persistence for key-value data.
//! Uses atomic writes (temp file + rename) for crash safety and
//! Zeroizing for secure memory handling of sensitive data.

use serde::{de::DeserializeOwned, Serialize};
use std::collections::HashMap;
use std::fs::{self, File};
use std::io::{BufReader, Write};
use std::path::{Path, PathBuf};
use std::sync::{Arc, Mutex};
use zeroize::Zeroizing;

use crate::core::errors::{StorageError, StorageResult};
use crate::core::storage_provider::{
    AsyncBlobStore, AsyncKeyValueStore, AsyncListStream,
    BlobStore, DataValue, KeyValueStore, QueryStore, RateLimiterStore, SqlRow, StorageItemStream,
};
use foundation_core::valtron::Stream;

/// JSON file storage backend.
///
/// Stores data as JSON on disk with atomic writes for crash safety.
/// Uses a Mutex for thread-safe access and Zeroizing for sensitive data.
pub struct JsonFileStorage {
    /// Path to the JSON file
    file_path: PathBuf,
    /// In-memory cache of data (protected by Mutex)
    data: Arc<Mutex<HashMap<String, Zeroizing<Vec<u8>>>>>,
}

impl JsonFileStorage {
    /// Create a new JSON file storage instance.
    ///
    /// # Arguments
    ///
    /// * `file_path` - Path to the JSON file for persistence
    ///
    /// # Errors
    ///
    /// Returns a `StorageError` if the file cannot be read or parsed.
    pub fn new<P: AsRef<Path>>(file_path: P) -> StorageResult<Self> {
        let file_path = file_path.as_ref().to_path_buf();

        // Load existing data if file exists
        let data = if file_path.exists() {
            Self::load_from_file(&file_path)?
        } else {
            HashMap::new()
        };

        Ok(Self {
            file_path,
            data: Arc::new(Mutex::new(data)),
        })
    }

    /// Load data from JSON file.
    ///
    /// # Errors
    ///
    /// Returns a `StorageError` if file I/O or parsing fails.
    fn load_from_file(file_path: &Path) -> StorageResult<HashMap<String, Zeroizing<Vec<u8>>>> {
        let file = File::open(file_path).map_err(StorageError::Io)?;

        let reader = BufReader::new(file);
        let raw_data: HashMap<String, Vec<u8>> =
            serde_json::from_reader(reader).map_err(StorageError::Json)?;

        // Convert to Zeroizing wrappers
        Ok(raw_data
            .into_iter()
            .map(|(k, v)| (k, Zeroizing::new(v)))
            .collect())
    }

    /// Flush data to disk atomically.
    ///
    /// Writes to a temp file first, then renames for atomicity.
    ///
    /// # Errors
    ///
    /// Returns a `StorageError` if file I/O or serialization fails.
    fn flush_to_disk(&self) -> StorageResult<()> {
        let data = self
            .data
            .lock()
            .map_err(|e| StorageError::Backend(format!("Mutex poisoned: {e}")))?;

        // Serialize to Vec<u8> first (without Zeroizing for disk storage)
        let raw_data: HashMap<String, Vec<u8>> = data
            .iter()
            .map(|(k, v)| (k.clone(), (**v).clone()))
            .collect();

        let json_bytes = serde_json::to_vec(&raw_data).map_err(StorageError::Json)?;

        // Write to temp file first
        let temp_path = self.file_path.with_extension("json.tmp");

        let mut temp_file = File::create(&temp_path).map_err(StorageError::Io)?;

        temp_file.write_all(&json_bytes).map_err(StorageError::Io)?;

        // Ensure data is flushed to disk
        temp_file.sync_all().map_err(StorageError::Io)?;

        // Atomic rename
        fs::rename(&temp_path, &self.file_path).map_err(StorageError::Io)?;

        Ok(())
    }
}

impl KeyValueStore for JsonFileStorage {
    fn get<V: DeserializeOwned + Send + 'static>(&self, key: &str) -> StorageResult<Option<V>> {
        let data = self
            .data
            .lock()
            .map_err(|e| StorageError::Backend(format!("Mutex poisoned: {e}")))?;

        match data.get(key) {
            Some(bytes) => {
                let value: V = serde_json::from_slice(bytes)
                    .map_err(|e| StorageError::Serialization(e.to_string()))?;
                Ok(Some(value))
            }
            None => Ok(None),
        }
    }

    fn set<V: Serialize>(&self, key: &str, value: V) -> StorageResult<()> {
        let bytes =
            serde_json::to_vec(&value).map_err(|e| StorageError::Serialization(e.to_string()))?;

        let mut data = self
            .data
            .lock()
            .map_err(|e| StorageError::Backend(format!("Mutex poisoned: {e}")))?;

        data.insert(key.to_string(), Zeroizing::new(bytes));
        drop(data); // Release lock before flushing

        self.flush_to_disk()
    }

    fn delete(&self, key: &str) -> StorageResult<()> {
        let mut data = self
            .data
            .lock()
            .map_err(|e| StorageError::Backend(format!("Mutex poisoned: {e}")))?;

        data.remove(key);
        drop(data); // Release lock before flushing

        self.flush_to_disk()
    }

    fn exists(&self, key: &str) -> StorageResult<bool> {
        let data = self
            .data
            .lock()
            .map_err(|e| StorageError::Backend(format!("Mutex poisoned: {e}")))?;
        Ok(data.contains_key(key))
    }

    fn list_keys(&self, prefix: Option<&str>) -> StorageResult<StorageItemStream<'_, String>> {
        let data = self
            .data
            .lock()
            .map_err(|e| StorageError::Backend(format!("Mutex poisoned: {e}")))?;

        let keys: Vec<String> = data
            .keys()
            .filter(|k| prefix.is_none_or(|p| k.starts_with(p)))
            .cloned()
            .collect();

        Ok(Box::new(keys.into_iter().map(|k| Stream::Next(Ok(k)))))
    }
}

/// `QueryStore` not supported for `JsonFileStorage`.
impl QueryStore for JsonFileStorage {
    fn query(
        &self,
        _sql: &str,
        _params: &[DataValue],
    ) -> StorageResult<StorageItemStream<'_, SqlRow>> {
        Err(StorageError::Generic(
            "QueryStore not supported for JsonFileStorage".to_string(),
        ))
    }

    fn execute(
        &self,
        _sql: &str,
        _params: &[DataValue],
    ) -> StorageResult<u64> {
        Err(StorageError::Generic(
            "QueryStore not supported for JsonFileStorage".to_string(),
        ))
    }

    fn execute_batch(&self, _sql: &str) -> StorageResult<()> {
        Err(StorageError::Generic(
            "QueryStore not supported for JsonFileStorage".to_string(),
        ))
    }
}

/// `RateLimiterStore` not supported for `JsonFileStorage`.
impl RateLimiterStore for JsonFileStorage {
    fn check_rate_limit(
        &self,
        _key: &str,
        _max_count: u32,
        _window_seconds: u64,
    ) -> StorageResult<bool> {
        Err(StorageError::Generic(
            "RateLimiterStore not supported for JsonFileStorage".to_string(),
        ))
    }

    fn record_rate_limit(&self, _key: &str) -> StorageResult<u32> {
        Err(StorageError::Generic(
            "RateLimiterStore not supported for JsonFileStorage".to_string(),
        ))
    }

    fn reset_rate_limit(&self, _key: &str) -> StorageResult<()> {
        Err(StorageError::Generic(
            "RateLimiterStore not supported for JsonFileStorage".to_string(),
        ))
    }
}

impl BlobStore for JsonFileStorage {
    fn put_blob(&self, key: &str, data: &[u8]) -> StorageResult<()> {
        let mut storage = self
            .data
            .lock()
            .map_err(|e| StorageError::Backend(format!("Mutex poisoned: {e}")))?;
        storage.insert(key.to_string(), Zeroizing::new(data.to_vec()));
        drop(storage); // Release lock before flushing
        self.flush_to_disk()
    }

    fn get_blob(&self, key: &str) -> StorageResult<Option<Vec<u8>>> {
        let data = self
            .data
            .lock()
            .map_err(|e| StorageError::Backend(format!("Mutex poisoned: {e}")))?;
        Ok(data.get(key).cloned().map(|z| z.to_vec()))
    }

    fn delete_blob(&self, key: &str) -> StorageResult<()> {
        let mut data = self
            .data
            .lock()
            .map_err(|e| StorageError::Backend(format!("Mutex poisoned: {e}")))?;
        data.remove(key);
        drop(data); // Release lock before flushing
        self.flush_to_disk()
    }

    fn blob_exists(&self, key: &str) -> StorageResult<bool> {
        let data = self
            .data
            .lock()
            .map_err(|e| StorageError::Backend(format!("Mutex poisoned: {e}")))?;
        Ok(data.contains_key(key))
    }
}

// ===========================================================================
// Async trait implementations — disk-backed, but async since I/O is involved.
// ===========================================================================

#[async_trait::async_trait]
impl AsyncKeyValueStore for JsonFileStorage {
    async fn get_async<V: DeserializeOwned + Send + 'static>(&self, key: &str) -> StorageResult<Option<V>> {
        let data = self.data.lock()
            .map_err(|e| StorageError::Backend(format!("Mutex poisoned: {e}")))?;
        let result = match data.get(key) {
            Some(bytes) => {
                let value: V = serde_json::from_slice(bytes)
                    .map_err(|e| StorageError::Serialization(e.to_string()))?;
                Some(value)
            }
            None => None,
        };
        Ok(result)
    }

    async fn set_async<V: Serialize + Send + 'static>(&self, key: &str, value: V) -> StorageResult<()> {
        let bytes =
            serde_json::to_vec(&value).map_err(|e| StorageError::Serialization(e.to_string()))?;
        let mut data = self.data.lock()
            .map_err(|e| StorageError::Backend(format!("Mutex poisoned: {e}")))?;
        data.insert(key.to_string(), Zeroizing::new(bytes));
        drop(data);
        self.flush_to_disk()
    }

    async fn delete_async(&self, key: &str) -> StorageResult<()> {
        let mut data = self.data.lock()
            .map_err(|e| StorageError::Backend(format!("Mutex poisoned: {e}")))?;
        data.remove(key);
        drop(data);
        self.flush_to_disk()
    }

    async fn exists_async(&self, key: &str) -> StorageResult<bool> {
        let data = self.data.lock()
            .map_err(|e| StorageError::Backend(format!("Mutex poisoned: {e}")))?;
        Ok(data.contains_key(key))
    }

    async fn list_keys_async(&self, prefix: Option<&str>) -> StorageResult<AsyncListStream> {
        let data = self.data.lock()
            .map_err(|e| StorageError::Backend(format!("Mutex poisoned: {e}")))?;
        let keys: Vec<String> = data.keys()
            .filter(|k| prefix.is_none_or(|p| k.starts_with(p)))
            .cloned()
            .collect();
        Ok(AsyncListStream::new(futures_lite::stream::iter(
            keys.into_iter().map(Ok)
        )))
    }
}

#[async_trait::async_trait]
impl AsyncBlobStore for JsonFileStorage {
    async fn put_blob_async(&self, key: &str, data: &[u8]) -> StorageResult<()> {
        let mut storage = self.data.lock()
            .map_err(|e| StorageError::Backend(format!("Mutex poisoned: {e}")))?;
        storage.insert(key.to_string(), Zeroizing::new(data.to_vec()));
        drop(storage);
        self.flush_to_disk()
    }

    async fn get_blob_async(&self, key: &str) -> StorageResult<Option<Vec<u8>>> {
        let data = self.data.lock()
            .map_err(|e| StorageError::Backend(format!("Mutex poisoned: {e}")))?;
        Ok(data.get(key).cloned().map(|z| z.to_vec()))
    }

    async fn delete_blob_async(&self, key: &str) -> StorageResult<()> {
        let mut data = self.data.lock()
            .map_err(|e| StorageError::Backend(format!("Mutex poisoned: {e}")))?;
        data.remove(key);
        drop(data);
        self.flush_to_disk()
    }

    async fn blob_exists_async(&self, key: &str) -> StorageResult<bool> {
        let data = self.data.lock()
            .map_err(|e| StorageError::Backend(format!("Mutex poisoned: {e}")))?;
        Ok(data.contains_key(key))
    }
}