cachelito-core 0.16.0

//! # Cache Invalidation
//!
//! Smart cache invalidation mechanisms beyond simple TTL expiration.
//!
//! This module provides fine-grained control over cache invalidation through:
//! - **Tag-based invalidation**: Group related entries and invalidate them together
//! - **Event-driven invalidation**: Trigger invalidation based on events
//! - **Dependency-based invalidation**: Cascade invalidation to dependent caches
//! - **Conditional invalidation**: Custom check functions for invalidation logic (v0.13.0)
//!
//! # Examples
//!
//! ```rust
//! use cachelito_core::invalidation::{InvalidationRegistry, InvalidationMetadata};
//!
//! // Register a cache with tags
//! let registry = InvalidationRegistry::global();
//! let metadata = InvalidationMetadata::new(
//!     vec!["user_data".to_string(), "profile".to_string()],
//!     vec![],
//!     vec![]
//! );
//! registry.register("user_profile", metadata);
//!
//! // Invalidate all caches tagged with "user_data"
//! registry.invalidate_by_tag("user_data");
//! ```

use parking_lot::RwLock;
use std::collections::{HashMap, HashSet};
use std::sync::Arc;

/// Strategy for cache invalidation
#[derive(Debug, Clone, PartialEq, Eq)]
pub enum InvalidationStrategy {
    /// Invalidate by tag
    Tag(String),
    /// Invalidate by event
    Event(String),
    /// Invalidate by dependency
    Dependency(String),
}

/// Metadata about cache invalidation configuration
#[derive(Debug, Clone)]
pub struct InvalidationMetadata {
    /// Tags associated with this cache
    pub tags: Vec<String>,
    /// Events that trigger invalidation
    pub events: Vec<String>,
    /// Dependencies that trigger cascade invalidation
    pub dependencies: Vec<String>,
}

impl InvalidationMetadata {
    /// Create new invalidation metadata
    pub fn new(tags: Vec<String>, events: Vec<String>, dependencies: Vec<String>) -> Self {
        Self {
            tags,
            events,
            dependencies,
        }
    }

    /// Check if metadata has any invalidation rules
    pub fn is_empty(&self) -> bool {
        self.tags.is_empty() && self.events.is_empty() && self.dependencies.is_empty()
    }
}

/// Registry for managing cache invalidation
///
/// This struct maintains mappings between tags/events/dependencies and cache names,
/// allowing efficient invalidation of related caches.
pub struct InvalidationRegistry {
    /// Map from tag to set of cache names
    tag_to_caches: RwLock<HashMap<String, HashSet<String>>>,
    /// Map from event to set of cache names
    event_to_caches: RwLock<HashMap<String, HashSet<String>>>,
    /// Map from dependency to set of dependent cache names
    dependency_to_caches: RwLock<HashMap<String, HashSet<String>>>,
    /// Map from cache name to its metadata
    cache_metadata: RwLock<HashMap<String, InvalidationMetadata>>,
    /// Callbacks for full invalidation actions (cache_name -> clear function)
    clear_callbacks: RwLock<HashMap<String, Arc<dyn Fn() + Send + Sync>>>,
    /// Callbacks for selective invalidation checks (cache_name -> check function)
    /// These callbacks receive a check function and invalidate entries that match it
    invalidation_check_callbacks:
        RwLock<HashMap<String, Arc<dyn Fn(&dyn Fn(&str) -> bool) + Send + Sync>>>,
}

impl InvalidationRegistry {
    /// Create a new empty invalidation registry
    fn new() -> Self {
        Self {
            tag_to_caches: RwLock::new(HashMap::new()),
            event_to_caches: RwLock::new(HashMap::new()),
            dependency_to_caches: RwLock::new(HashMap::new()),
            cache_metadata: RwLock::new(HashMap::new()),
            clear_callbacks: RwLock::new(HashMap::new()),
            invalidation_check_callbacks: RwLock::new(HashMap::new()),
        }
    }

    /// Get the global invalidation registry
    pub fn global() -> &'static InvalidationRegistry {
        static INSTANCE: std::sync::OnceLock<InvalidationRegistry> = std::sync::OnceLock::new();
        INSTANCE.get_or_init(InvalidationRegistry::new)
    }

    /// Register a cache with its invalidation metadata
    ///
    /// # Arguments
    ///
    /// * `cache_name` - Unique name of the cache
    /// * `metadata` - Invalidation metadata (tags, events, dependencies)
    pub fn register(&self, cache_name: &str, metadata: InvalidationMetadata) {
        // Register tags
        {
            let mut tag_map = self.tag_to_caches.write();
            for tag in &metadata.tags {
                tag_map
                    .entry(tag.clone())
                    .or_insert_with(HashSet::new)
                    .insert(cache_name.to_string());
            }
        }

        // Register events
        {
            let mut event_map = self.event_to_caches.write();
            for event in &metadata.events {
                event_map
                    .entry(event.clone())
                    .or_insert_with(HashSet::new)
                    .insert(cache_name.to_string());
            }
        }

        // Register dependencies
        {
            let mut dep_map = self.dependency_to_caches.write();
            for dep in &metadata.dependencies {
                dep_map
                    .entry(dep.clone())
                    .or_insert_with(HashSet::new)
                    .insert(cache_name.to_string());
            }
        }

        // Store metadata
        self.cache_metadata
            .write()
            .insert(cache_name.to_string(), metadata);
    }

    /// Register an invalidation callback for a cache
    ///
    /// This callback will be invoked when the cache needs to be invalidated.
    ///
    /// # Arguments
    ///
    /// * `cache_name` - Name of the cache
    /// * `callback` - Function to call when invalidating
    pub fn register_callback<F>(&self, cache_name: &str, callback: F)
    where
        F: Fn() + Send + Sync + 'static,
    {
        self.clear_callbacks
            .write()
            .insert(cache_name.to_string(), Arc::new(callback));
    }

    /// Register an invalidation callback for a cache
    ///
    /// This callback will be invoked when invalidating entries based on a check function.
    /// The check function receives the cache key and returns true if the entry
    /// should be invalidated.
    ///
    /// # Arguments
    ///
    /// * `cache_name` - Name of the cache
    /// * `callback` - Function that takes a check function and invalidates matching entries
    pub fn register_invalidation_callback<F>(&self, cache_name: &str, callback: F)
    where
        F: Fn(&dyn Fn(&str) -> bool) + Send + Sync + 'static,
    {
        self.invalidation_check_callbacks
            .write()
            .insert(cache_name.to_string(), Arc::new(callback));
    }

    /// Invalidate all caches associated with a tag
    ///
    /// # Arguments
    ///
    /// * `tag` - The tag to invalidate
    ///
    /// # Returns
    ///
    /// Number of caches invalidated
    pub fn invalidate_by_tag(&self, tag: &str) -> usize {
        let cache_names = self
            .tag_to_caches
            .read()
            .get(tag)
            .cloned()
            .unwrap_or_default();

        self.invalidate_caches(&cache_names)
    }

    /// Invalidate all caches associated with an event
    ///
    /// # Arguments
    ///
    /// * `event` - The event that occurred
    ///
    /// # Returns
    ///
    /// Number of caches invalidated
    pub fn invalidate_by_event(&self, event: &str) -> usize {
        let cache_names = self
            .event_to_caches
            .read()
            .get(event)
            .cloned()
            .unwrap_or_default();

        self.invalidate_caches(&cache_names)
    }

    /// Invalidate all dependent caches when a dependency changes
    ///
    /// # Arguments
    ///
    /// * `dependency` - The dependency that changed
    ///
    /// # Returns
    ///
    /// Number of caches invalidated
    pub fn invalidate_by_dependency(&self, dependency: &str) -> usize {
        let cache_names = self
            .dependency_to_caches
            .read()
            .get(dependency)
            .cloned()
            .unwrap_or_default();

        self.invalidate_caches(&cache_names)
    }

    /// Invalidate a specific cache by name
    ///
    /// # Arguments
    ///
    /// * `cache_name` - Name of the cache to invalidate
    ///
    /// # Returns
    ///
    /// `true` if the cache was found and invalidated
    pub fn invalidate_cache(&self, cache_name: &str) -> bool {
        if let Some(callback) = self.clear_callbacks.read().get(cache_name) {
            callback();
            true
        } else {
            false
        }
    }

    /// Invalidate multiple caches
    ///
    /// # Arguments
    ///
    /// * `cache_names` - Set of cache names to invalidate
    ///
    /// # Returns
    ///
    /// Number of caches successfully invalidated
    fn invalidate_caches(&self, cache_names: &HashSet<String>) -> usize {
        let callbacks = self.clear_callbacks.read();
        let mut count = 0;

        for name in cache_names {
            if let Some(callback) = callbacks.get(name) {
                callback();
                count += 1;
            }
        }

        count
    }

    /// Get all caches associated with a tag
    pub fn get_caches_by_tag(&self, tag: &str) -> Vec<String> {
        self.tag_to_caches
            .read()
            .get(tag)
            .map(|set| set.iter().cloned().collect())
            .unwrap_or_default()
    }

    /// Get all caches associated with an event
    pub fn get_caches_by_event(&self, event: &str) -> Vec<String> {
        self.event_to_caches
            .read()
            .get(event)
            .map(|set| set.iter().cloned().collect())
            .unwrap_or_default()
    }

    /// Get all dependent caches
    pub fn get_dependent_caches(&self, dependency: &str) -> Vec<String> {
        self.dependency_to_caches
            .read()
            .get(dependency)
            .map(|set| set.iter().cloned().collect())
            .unwrap_or_default()
    }

    /// Invalidate entries in a specific cache based on a check function
    ///
    /// # Arguments
    ///
    /// * `cache_name` - Name of the cache to invalidate
    /// * `predicate` - Check function that returns true for keys that should be invalidated
    ///
    /// # Returns
    ///
    /// `true` if the cache was found and the check function was applied
    ///
    /// # Examples
    ///
    /// ```ignore
    /// use cachelito_core::InvalidationRegistry;
    ///
    /// let registry = InvalidationRegistry::global();
    ///
    /// // Invalidate all entries where user_id > 1000
    /// registry.invalidate_with("get_user", |key| {
    ///     key.parse::<u64>().unwrap_or(0) > 1000
    /// });
    /// ```
    pub fn invalidate_with<F>(&self, cache_name: &str, predicate: F) -> bool
    where
        F: Fn(&str) -> bool,
    {
        if let Some(callback) = self.invalidation_check_callbacks.read().get(cache_name) {
            callback(&predicate);
            true
        } else {
            false
        }
    }

    /// Invalidate entries across all caches based on a check function
    ///
    /// # Arguments
    ///
    /// * `predicate` - Check function that returns true for keys that should be invalidated
    ///
    /// # Returns
    ///
    /// Number of caches that had the check function applied
    ///
    /// # Examples
    ///
    /// ```ignore
    /// use cachelito_core::InvalidationRegistry;
    ///
    /// let registry = InvalidationRegistry::global();
    ///
    /// // Invalidate all entries with numeric keys > 1000 across all caches
    /// registry.invalidate_all_with(|_cache_name, key| {
    ///     key.parse::<u64>().unwrap_or(0) > 1000
    /// });
    /// ```
    pub fn invalidate_all_with<F>(&self, predicate: F) -> usize
    where
        F: Fn(&str, &str) -> bool,
    {
        let callbacks = self.invalidation_check_callbacks.read();
        let mut count = 0;

        for (cache_name, callback) in callbacks.iter() {
            let cache_name_clone = cache_name.clone();
            callback(&|key: &str| predicate(&cache_name_clone, key));
            count += 1;
        }

        count
    }

    /// Clear all registrations
    pub fn clear(&self) {
        self.tag_to_caches.write().clear();
        self.event_to_caches.write().clear();
        self.dependency_to_caches.write().clear();
        self.cache_metadata.write().clear();
        self.clear_callbacks.write().clear();
        self.invalidation_check_callbacks.write().clear();
    }
}

impl Default for InvalidationRegistry {
    fn default() -> Self {
        Self::new()
    }
}

/// Global convenience function to invalidate all caches with a given tag
///
/// # Arguments
///
/// * `tag` - The tag to match
///
/// # Returns
///
/// Number of caches invalidated
///
/// # Example
///
/// ```ignore
/// use cachelito_core::invalidate_by_tag;
///
/// let count = invalidate_by_tag("user_data");
/// println!("Invalidated {} caches", count);
/// ```
pub fn invalidate_by_tag(tag: &str) -> usize {
    InvalidationRegistry::global().invalidate_by_tag(tag)
}

/// Global convenience function to invalidate all caches listening to an event
///
/// # Arguments
///
/// * `event` - The event that occurred
///
/// # Returns
///
/// Number of caches invalidated
///
/// # Example
///
/// ```ignore
/// use cachelito_core::invalidate_by_event;
///
/// let count = invalidate_by_event("user_updated");
/// println!("Invalidated {} caches", count);
/// ```
pub fn invalidate_by_event(event: &str) -> usize {
    InvalidationRegistry::global().invalidate_by_event(event)
}

/// Global convenience function to invalidate all dependent caches
///
/// # Arguments
///
/// * `dependency` - The dependency that changed
///
/// # Returns
///
/// Number of caches invalidated
///
/// # Example
///
/// ```ignore
/// use cachelito_core::invalidate_by_dependency;
///
/// let count = invalidate_by_dependency("get_user");
/// println!("Invalidated {} caches", count);
/// ```
pub fn invalidate_by_dependency(dependency: &str) -> usize {
    InvalidationRegistry::global().invalidate_by_dependency(dependency)
}

/// Invalidate a specific cache by its name
///
/// This function invalidates a single cache identified by its name.
///
/// # Arguments
///
/// * `cache_name` - The name of the cache to invalidate
///
/// # Returns
///
/// `true` if the cache was found and invalidated, `false` otherwise
///
/// # Examples
///
/// ```ignore
/// use cachelito_core::invalidate_cache;
///
/// // Invalidate a specific cache:
/// invalidate_cache("get_user_profile");
/// ```
pub fn invalidate_cache(cache_name: &str) -> bool {
    InvalidationRegistry::global().invalidate_cache(cache_name)
}

/// Invalidate entries in a specific cache based on a check function
///
/// This function allows conditional invalidation of cache entries based on their keys.
///
/// # Arguments
///
/// * `cache_name` - Name of the cache to invalidate
/// * `predicate` - Check function that returns true for keys that should be invalidated
///
/// # Returns
///
/// `true` if the cache was found and the check function was applied
///
/// # Examples
///
/// ```ignore
/// use cachelito_core::invalidate_with;
///
/// // Invalidate all entries where user_id > 1000
/// invalidate_with("get_user", |key| {
///     key.parse::<u64>().unwrap_or(0) > 1000
/// });
/// ```
pub fn invalidate_with<F>(cache_name: &str, predicate: F) -> bool
where
    F: Fn(&str) -> bool,
{
    InvalidationRegistry::global().invalidate_with(cache_name, predicate)
}

/// Invalidate entries across all caches based on a check function
///
/// This function applies a check function to all registered caches.
///
/// # Arguments
///
/// * `predicate` - Check function that receives cache name and key, returns true for entries to invalidate
///
/// # Returns
///
/// Number of caches that had the check function applied
///
/// # Examples
///
/// ```ignore
/// use cachelito_core::invalidate_all_with;
///
/// // Invalidate all entries with numeric keys > 1000 across all caches
/// invalidate_all_with(|_cache_name, key| {
///     key.parse::<u64>().unwrap_or(0) > 1000
/// });
/// ```
pub fn invalidate_all_with<F>(predicate: F) -> usize
where
    F: Fn(&str, &str) -> bool,
{
    InvalidationRegistry::global().invalidate_all_with(predicate)
}

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

    #[test]
    fn test_tag_based_invalidation() {
        let registry = InvalidationRegistry::new();
        let counter1 = Arc::new(AtomicUsize::new(0));
        let counter2 = Arc::new(AtomicUsize::new(0));

        let c1 = counter1.clone();
        let c2 = counter2.clone();

        // Register two caches with same tag
        registry.register(
            "cache1",
            InvalidationMetadata::new(vec!["user_data".to_string()], vec![], vec![]),
        );
        registry.register(
            "cache2",
            InvalidationMetadata::new(vec!["user_data".to_string()], vec![], vec![]),
        );

        registry.register_callback("cache1", move || {
            c1.fetch_add(1, Ordering::SeqCst);
        });
        registry.register_callback("cache2", move || {
            c2.fetch_add(1, Ordering::SeqCst);
        });

        // Invalidate by tag
        let count = registry.invalidate_by_tag("user_data");
        assert_eq!(count, 2);
        assert_eq!(counter1.load(Ordering::SeqCst), 1);
        assert_eq!(counter2.load(Ordering::SeqCst), 1);
    }

    #[test]
    fn test_event_based_invalidation() {
        let registry = InvalidationRegistry::new();
        let counter = Arc::new(AtomicUsize::new(0));
        let c = counter.clone();

        registry.register(
            "cache1",
            InvalidationMetadata::new(vec![], vec!["user_updated".to_string()], vec![]),
        );
        registry.register_callback("cache1", move || {
            c.fetch_add(1, Ordering::SeqCst);
        });

        let count = registry.invalidate_by_event("user_updated");
        assert_eq!(count, 1);
        assert_eq!(counter.load(Ordering::SeqCst), 1);
    }

    #[test]
    fn test_dependency_based_invalidation() {
        let registry = InvalidationRegistry::new();
        let counter = Arc::new(AtomicUsize::new(0));
        let c = counter.clone();

        registry.register(
            "cache1",
            InvalidationMetadata::new(vec![], vec![], vec!["get_user".to_string()]),
        );
        registry.register_callback("cache1", move || {
            c.fetch_add(1, Ordering::SeqCst);
        });

        let count = registry.invalidate_by_dependency("get_user");
        assert_eq!(count, 1);
        assert_eq!(counter.load(Ordering::SeqCst), 1);
    }

    #[test]
    fn test_get_caches_by_tag() {
        let registry = InvalidationRegistry::new();

        registry.register(
            "cache1",
            InvalidationMetadata::new(vec!["tag1".to_string()], vec![], vec![]),
        );
        registry.register(
            "cache2",
            InvalidationMetadata::new(vec!["tag1".to_string()], vec![], vec![]),
        );

        let caches = registry.get_caches_by_tag("tag1");
        assert_eq!(caches.len(), 2);
        assert!(caches.contains(&"cache1".to_string()));
        assert!(caches.contains(&"cache2".to_string()));
    }

    #[test]
    fn test_invalidate_specific_cache() {
        let registry = InvalidationRegistry::new();
        let counter = Arc::new(AtomicUsize::new(0));
        let c = counter.clone();

        registry.register_callback("cache1", move || {
            c.fetch_add(1, Ordering::SeqCst);
        });

        assert!(registry.invalidate_cache("cache1"));
        assert_eq!(counter.load(Ordering::SeqCst), 1);

        // Non-existent cache
        assert!(!registry.invalidate_cache("cache2"));
    }

    #[test]
    fn test_clear_registry() {
        let registry = InvalidationRegistry::new();
        registry.register("cache1", InvalidationMetadata::new(vec![], vec![], vec![]));
        registry.clear();
        assert!(registry.cache_metadata.read().is_empty());
    }

    #[test]
    fn test_conditional_invalidation() {
        use std::sync::Mutex;

        let registry = InvalidationRegistry::new();
        let removed_keys = Arc::new(Mutex::new(Vec::new()));
        let removed_keys_clone = removed_keys.clone();

        // Register a check function callback that tracks removed keys
        registry.register_invalidation_callback(
            "cache1",
            move |check_fn: &dyn Fn(&str) -> bool| {
                let test_keys = vec!["key1", "key2", "key100", "key500", "key1001"];
                let mut removed = removed_keys_clone.lock().unwrap();
                removed.clear();

                for key in test_keys {
                    if check_fn(key) {
                        removed.push(key.to_string());
                    }
                }
            },
        );

        // Invalidate keys that parse to numbers > 100
        registry.invalidate_with("cache1", |key: &str| {
            key.strip_prefix("key")
                .and_then(|s| s.parse::<u64>().ok())
                .map(|n| n > 100)
                .unwrap_or(false)
        });

        let removed = removed_keys.lock().unwrap();
        assert_eq!(removed.len(), 2);
        assert!(removed.contains(&"key500".to_string()));
        assert!(removed.contains(&"key1001".to_string()));
        assert!(!removed.contains(&"key1".to_string()));
        assert!(!removed.contains(&"key2".to_string()));
        assert!(!removed.contains(&"key100".to_string()));
    }

    #[test]
    fn test_conditional_invalidation_nonexistent_cache() {
        let registry = InvalidationRegistry::new();

        // Should return false for non-registered cache
        let result = registry.invalidate_with("nonexistent", |_key: &str| true);
        assert!(!result);
    }

    #[test]
    fn test_invalidate_all_with_check_function() {
        use std::sync::Mutex;

        let registry = InvalidationRegistry::new();

        // Track invalidations for multiple caches
        let cache1_removed = Arc::new(Mutex::new(Vec::new()));
        let cache2_removed = Arc::new(Mutex::new(Vec::new()));

        let cache1_removed_clone = cache1_removed.clone();
        let cache2_removed_clone = cache2_removed.clone();

        // Register check function callbacks for two caches
        registry.register_invalidation_callback(
            "cache1",
            move |check_fn: &dyn Fn(&str) -> bool| {
                let test_keys = vec!["1", "2", "3", "4", "5"];
                let mut removed = cache1_removed_clone.lock().unwrap();
                removed.clear();

                for key in test_keys {
                    if check_fn(key) {
                        removed.push(key.to_string());
                    }
                }
            },
        );

        registry.register_invalidation_callback(
            "cache2",
            move |check_fn: &dyn Fn(&str) -> bool| {
                let test_keys = vec!["10", "20", "30"];
                let mut removed = cache2_removed_clone.lock().unwrap();
                removed.clear();

                for key in test_keys {
                    if check_fn(key) {
                        removed.push(key.to_string());
                    }
                }
            },
        );

        // Invalidate all entries with numeric keys >= 3 across all caches
        let count = registry.invalidate_all_with(|_cache_name: &str, key: &str| {
            key.parse::<u64>().unwrap_or(0) >= 3
        });

        assert_eq!(count, 2); // Two caches processed

        let cache1_removed = cache1_removed.lock().unwrap();
        assert_eq!(cache1_removed.len(), 3); // 3, 4, 5
        assert!(cache1_removed.contains(&"3".to_string()));
        assert!(cache1_removed.contains(&"4".to_string()));
        assert!(cache1_removed.contains(&"5".to_string()));

        let cache2_removed = cache2_removed.lock().unwrap();
        assert_eq!(cache2_removed.len(), 3); // 10, 20, 30
        assert!(cache2_removed.contains(&"10".to_string()));
        assert!(cache2_removed.contains(&"20".to_string()));
        assert!(cache2_removed.contains(&"30".to_string()));
    }

    #[test]
    fn test_complex_conditional_checks() {
        use std::sync::Mutex;

        let registry = InvalidationRegistry::new();
        let removed_keys = Arc::new(Mutex::new(Vec::new()));
        let removed_keys_clone = removed_keys.clone();

        registry.register_invalidation_callback(
            "cache1",
            move |check_fn: &dyn Fn(&str) -> bool| {
                let test_keys = vec!["user_10", "user_20", "user_30", "user_40", "user_50"];
                let mut removed = removed_keys_clone.lock().unwrap();
                removed.clear();

                for key in test_keys {
                    if check_fn(key) {
                        removed.push(key.to_string());
                    }
                }
            },
        );

        // Invalidate keys where ID is divisible by 20
        registry.invalidate_with("cache1", |key: &str| {
            key.strip_prefix("user_")
                .and_then(|s| s.parse::<u64>().ok())
                .map(|n| n % 20 == 0)
                .unwrap_or(false)
        });

        let removed = removed_keys.lock().unwrap();
        assert_eq!(removed.len(), 2);
        assert!(removed.contains(&"user_20".to_string()));
        assert!(removed.contains(&"user_40".to_string()));
        assert!(!removed.contains(&"user_10".to_string()));
        assert!(!removed.contains(&"user_30".to_string()));
    }
}