use std::collections::HashMap;
use std::sync::{Arc, Mutex};
use crate::error::{DocTreeError, Result};

/// Storage backend for doctree
pub struct RedisStorage {
    // Using a simple in-memory storage for demonstration
    // In a real implementation, this would be a Redis client
    collections: Arc<Mutex<HashMap<String, HashMap<String, String>>>>,
}

impl RedisStorage {
    /// Create a new RedisStorage instance
    ///
    /// # Arguments
    ///
    /// * `url` - Redis connection URL (e.g., "redis://localhost:6379")
    ///   This is ignored in the in-memory implementation
    ///
    /// # Returns
    ///
    /// A new RedisStorage instance or an error
    pub fn new(_url: &str) -> Result<Self> {
        Ok(Self {
            collections: Arc::new(Mutex::new(HashMap::new())),
        })
    }
    
    /// Store a collection entry
    ///
    /// # Arguments
    ///
    /// * `collection` - Collection name
    /// * `key` - Entry key
    /// * `value` - Entry value
    ///
    /// # Returns
    ///
    /// Ok(()) on success or an error
    pub fn store_collection_entry(&self, collection: &str, key: &str, value: &str) -> Result<()> {
        let mut collections = self.collections.lock().unwrap();
        
        // Get or create the collection
        let collection_entries = collections
            .entry(format!("collections:{}", collection))
            .or_insert_with(HashMap::new);
        
        // Store the entry
        collection_entries.insert(key.to_string(), value.to_string());
        
        Ok(())
    }
    
    /// Get a collection entry
    ///
    /// # Arguments
    ///
    /// * `collection` - Collection name
    /// * `key` - Entry key
    ///
    /// # Returns
    ///
    /// The entry value or an error
    pub fn get_collection_entry(&self, collection: &str, key: &str) -> Result<String> {
        let collections = self.collections.lock().unwrap();
        
        // Get the collection
        let collection_key = format!("collections:{}", collection);
        let collection_entries = collections.get(&collection_key)
            .ok_or_else(|| DocTreeError::CollectionNotFound(collection.to_string()))?;
        
        // Get the entry
        collection_entries.get(key)
            .cloned()
            .ok_or_else(|| DocTreeError::FileNotFound(key.to_string()))
    }
    
    /// Delete a collection entry
    ///
    /// # Arguments
    ///
    /// * `collection` - Collection name
    /// * `key` - Entry key
    ///
    /// # Returns
    ///
    /// Ok(()) on success or an error
    pub fn delete_collection_entry(&self, collection: &str, key: &str) -> Result<()> {
        let mut collections = self.collections.lock().unwrap();
        
        // Get the collection
        let collection_key = format!("collections:{}", collection);
        let collection_entries = collections.get_mut(&collection_key)
            .ok_or_else(|| DocTreeError::CollectionNotFound(collection.to_string()))?;
        
        // Remove the entry
        collection_entries.remove(key);
        
        Ok(())
    }
    
    /// List all entries in a collection
    ///
    /// # Arguments
    ///
    /// * `collection` - Collection name
    ///
    /// # Returns
    ///
    /// A vector of entry keys or an error
    pub fn list_collection_entries(&self, collection: &str) -> Result<Vec<String>> {
        let collections = self.collections.lock().unwrap();
        
        // Get the collection
        let collection_key = format!("collections:{}", collection);
        let collection_entries = collections.get(&collection_key)
            .ok_or_else(|| DocTreeError::CollectionNotFound(collection.to_string()))?;
        
        // Get the keys
        let keys = collection_entries.keys().cloned().collect();
        
        Ok(keys)
    }
    
    /// Delete a collection
    ///
    /// # Arguments
    ///
    /// * `collection` - Collection name
    ///
    /// # Returns
    ///
    /// Ok(()) on success or an error
    pub fn delete_collection(&self, collection: &str) -> Result<()> {
        let mut collections = self.collections.lock().unwrap();
        
        // Remove the collection
        collections.remove(&format!("collections:{}", collection));
        
        Ok(())
    }
    
    /// Check if a collection exists
    ///
    /// # Arguments
    ///
    /// * `collection` - Collection name
    ///
    /// # Returns
    ///
    /// true if the collection exists, false otherwise
    pub fn collection_exists(&self, collection: &str) -> Result<bool> {
        let collections = self.collections.lock().unwrap();
        
        // Check if the collection exists
        let exists = collections.contains_key(&format!("collections:{}", collection));
        
        Ok(exists)
    }
}

// Implement Clone for RedisStorage
impl Clone for RedisStorage {
    fn clone(&self) -> Self {
        Self {
            collections: Arc::clone(&self.collections),
        }
    }
}