scim-server 0.4.0

//! Standard resource provider implementation with pluggable storage.
//!
//! This module provides a production-ready implementation of the ResourceProvider
//! trait that separates SCIM protocol logic from storage concerns through the
//! StorageProvider interface.
//!
//! # Features
//!
//! * Pluggable storage backends through the StorageProvider trait
//! * Complete SCIM protocol logic preservation
//! * Automatic tenant isolation when tenant context is provided
//! * Fallback to "default" tenant for single-tenant operations
//! * Comprehensive error handling
//! * Resource metadata tracking (created/updated timestamps)
//! * Duplicate detection for userName attributes
//!
//! # Example Usage
//!
//! ```rust
//! use scim_server::providers::StandardResourceProvider;
//! use scim_server::storage::InMemoryStorage;
//! use scim_server::resource::{RequestContext, TenantContext, ResourceProvider};
//! use serde_json::json;
//!
//! # async fn example() -> Result<(), Box<dyn std::error::Error>> {
//! let storage = InMemoryStorage::new();
//! let provider = StandardResourceProvider::new(storage);
//!
//! // Single-tenant operation
//! let single_context = RequestContext::with_generated_id();
//! let user_data = json!({
//!     "userName": "john.doe",
//!     "displayName": "John Doe"
//! });
//! let user = provider.create_resource("User", user_data.clone(), &single_context).await?;
//!
//! // Multi-tenant operation
//! let tenant_context = TenantContext::new("tenant1".to_string(), "client1".to_string());
//! let multi_context = RequestContext::with_tenant_generated_id(tenant_context);
//! let tenant_user = provider.create_resource("User", user_data, &multi_context).await?;
//! # Ok(())
//! # }
//! ```

use crate::providers::in_memory::{InMemoryError, InMemoryStats};
use crate::resource::{
    ListQuery, RequestContext, Resource, ResourceProvider,
    conditional_provider::VersionedResource,
    version::{ConditionalResult, ScimVersion},
};
use crate::storage::{StorageKey, StorageProvider};
use log::{debug, info, trace, warn};
use serde_json::{Value, json};


/// Standard resource provider with pluggable storage backend.
///
/// This provider separates SCIM protocol logic from storage concerns by delegating
/// data persistence to a StorageProvider implementation while handling all SCIM-specific
/// business logic, validation, and metadata management.
#[derive(Debug, Clone)]
pub struct StandardResourceProvider<S: StorageProvider> {
    // Pluggable storage backend
    storage: S,
}

impl<S: StorageProvider> StandardResourceProvider<S> {
    /// Create a new standard provider with the given storage backend.
    pub fn new(storage: S) -> Self {
        Self { storage }
    }

    /// Get the effective tenant ID for the operation.
    ///
    /// Returns the tenant ID from the context, or "default" for single-tenant operations.
    fn effective_tenant_id(&self, context: &RequestContext) -> String {
        context.tenant_id().unwrap_or("default").to_string()
    }

    /// Generate a unique resource ID for the given tenant and resource type.
    async fn generate_resource_id(&self, _tenant_id: &str, _resource_type: &str) -> String {
        // Use UUID for simple, unique ID generation
        uuid::Uuid::new_v4().to_string()
    }

    /// Check for duplicate userName in User resources within the same tenant.
    async fn check_username_duplicate(
        &self,
        tenant_id: &str,
        username: &str,
        exclude_id: Option<&str>,
    ) -> Result<(), InMemoryError> {
        let prefix = StorageKey::prefix(tenant_id, "User");
        let matches = self
            .storage
            .find_by_attribute(prefix, "userName", username)
            .await
            .map_err(|e| InMemoryError::Internal {
                message: format!("Storage error during username check: {}", e),
            })?;

        for (key, _data) in matches {
            // Skip the resource we're updating
            if Some(key.resource_id()) != exclude_id {
                return Err(InMemoryError::DuplicateAttribute {
                    resource_type: "User".to_string(),
                    attribute: "userName".to_string(),
                    value: username.to_string(),
                    tenant_id: tenant_id.to_string(),
                });
            }
        }

        Ok(())
    }

    /// Add SCIM metadata to a resource.
    fn add_scim_metadata(&self, mut resource: Resource) -> Resource {
        // Use the non-deprecated create_meta method with proper base URL
        if let Err(_e) = resource.create_meta("https://example.com/scim/v2") {
            return resource;
        }

        // Add version to the meta using content-based versioning
        if let Some(meta) = resource.get_meta().cloned() {
            // Generate version from resource content
            let resource_json = resource.to_json().unwrap_or_default();
            let content_bytes = resource_json.to_string().as_bytes().to_vec();
            let scim_version = ScimVersion::from_content(&content_bytes);
            let version = scim_version.to_http_header();

            if let Ok(meta_with_version) = meta.with_version(version) {
                resource.set_meta(meta_with_version);
            }
        }

        resource
    }

    /// Clear all data from storage.
    ///
    /// Removes all resources from all tenants by delegating to the storage backend's
    /// clear operation. This method provides a consistent interface for clearing data
    /// regardless of the underlying storage implementation.
    ///
    /// # Behavior
    ///
    /// - Delegates to [`StorageProvider::clear`] for actual data removal
    /// - Logs warnings if the clear operation fails
    /// - Primarily intended for testing scenarios
    /// - After successful clearing, [`get_stats`] should report zero resources
    ///
    /// # Examples
    ///
    /// ```rust
    /// use scim_server::providers::StandardResourceProvider;
    /// use scim_server::storage::InMemoryStorage;
    ///
    /// # async fn example() -> Result<(), Box<dyn std::error::Error>> {
    /// let storage = InMemoryStorage::new();
    /// let provider = StandardResourceProvider::new(storage);
    ///
    /// // ... create some resources ...
    /// provider.clear().await;
    ///
    /// let stats = provider.get_stats().await;
    /// assert_eq!(stats.total_resources, 0);
    /// # Ok(())
    /// # }
    /// ```
    ///
    /// [`StorageProvider::clear`]: crate::storage::StorageProvider::clear
    /// [`get_stats`]: Self::get_stats
    pub async fn clear(&self) {
        // Delegate to storage backend for proper clearing
        if let Err(e) = self.storage.clear().await {
            warn!("Failed to clear storage: {:?}", e);
        }
    }

    /// Get comprehensive statistics about stored data across all tenants.
    ///
    /// Dynamically discovers all tenants and resource types from storage to provide
    /// accurate statistics without relying on hardcoded patterns. This method uses
    /// the storage provider's discovery capabilities to enumerate actual data.
    ///
    /// # Returns
    ///
    /// [`InMemoryStats`] containing:
    /// - `tenant_count`: Number of tenants with at least one resource
    /// - `total_resources`: Sum of all resources across all tenants and types
    /// - `resource_type_count`: Number of distinct resource types found
    /// - `resource_types`: List of all resource type names
    ///
    /// # Errors
    ///
    /// This method handles storage errors gracefully by using default values
    /// (empty collections) when discovery operations fail.
    ///
    /// # Examples
    ///
    /// ```rust
    /// use scim_server::providers::StandardResourceProvider;
    /// use scim_server::storage::InMemoryStorage;
    /// use scim_server::resource::{RequestContext, TenantContext};
    ///
    /// # async fn example() -> Result<(), Box<dyn std::error::Error>> {
    /// let storage = InMemoryStorage::new();
    /// let provider = StandardResourceProvider::new(storage);
    ///
    /// // ... create resources in multiple tenants ...
    ///
    /// let stats = provider.get_stats().await;
    /// println!("Total resources: {}", stats.total_resources);
    /// println!("Active tenants: {}", stats.tenant_count);
    /// println!("Resource types: {:?}", stats.resource_types);
    /// # Ok(())
    /// # }
    /// ```
    pub async fn get_stats(&self) -> InMemoryStats {
        // Dynamically discover all tenants and resource types from storage
        let tenants = self.storage.list_tenants().await.unwrap_or_default();
        let resource_types = self.storage.list_all_resource_types().await.unwrap_or_default();

        let mut total_resources = 0;

        // Count total resources across all tenants and resource types
        for tenant_id in &tenants {
            for resource_type in &resource_types {
                let prefix = StorageKey::prefix(tenant_id, resource_type);
                if let Ok(count) = self.storage.count(prefix).await {
                    total_resources += count;
                }
            }
        }

        InMemoryStats {
            tenant_count: tenants.len(),
            total_resources,
            resource_type_count: resource_types.len(),
            resource_types,
        }
    }

    /// List all resources of a specific type in a tenant.
    pub async fn list_resources_in_tenant(
        &self,
        tenant_id: &str,
        resource_type: &str,
    ) -> Vec<Resource> {
        let prefix = StorageKey::prefix(tenant_id, resource_type);
        match self.storage.list(prefix, 0, usize::MAX).await {
            Ok(storage_results) => {
                let mut resources = Vec::new();
                for (_key, data) in storage_results {
                    match Resource::from_json(resource_type.to_string(), data) {
                        Ok(resource) => resources.push(resource),
                        Err(e) => {
                            warn!(
                                "Failed to deserialize resource in list_resources_in_tenant: {}",
                                e
                            );
                        }
                    }
                }
                resources
            }
            Err(e) => {
                warn!("Storage error in list_resources_in_tenant: {}", e);
                Vec::new()
            }
        }
    }

    /// Count resources of a specific type for a tenant (used for limit checking).
    async fn count_resources_for_tenant(&self, tenant_id: &str, resource_type: &str) -> usize {
        let prefix = StorageKey::prefix(tenant_id, resource_type);
        match self.storage.count(prefix).await {
            Ok(count) => count,
            Err(e) => {
                warn!("Storage error in count_resources_for_tenant: {}", e);
                0
            }
        }
    }
}

// Note: No Default implementation for StandardResourceProvider as it requires storage parameter

// Reuse error and stats types from the in_memory module for compatibility

impl<S: StorageProvider> ResourceProvider for StandardResourceProvider<S> {
    type Error = InMemoryError;

    async fn create_resource(
        &self,
        resource_type: &str,
        mut data: Value,
        context: &RequestContext,
    ) -> Result<Resource, Self::Error> {
        let tenant_id = self.effective_tenant_id(context);

        info!(
            "Creating {} resource for tenant '{}' (request: '{}')",
            resource_type, tenant_id, context.request_id
        );
        trace!(
            "Create data: {}",
            serde_json::to_string(&data).unwrap_or_else(|_| "invalid json".to_string())
        );

        // Check permissions first
        context
            .validate_operation("create")
            .map_err(|e| InMemoryError::Internal { message: e })?;

        // Check resource limits if this is a multi-tenant context
        if let Some(tenant_context) = &context.tenant_context {
            if resource_type == "User" {
                if let Some(max_users) = tenant_context.permissions.max_users {
                    let current_count = self.count_resources_for_tenant(&tenant_id, "User").await;
                    if current_count >= max_users {
                        return Err(InMemoryError::Internal {
                            message: format!(
                                "User limit exceeded: {}/{}",
                                current_count, max_users
                            ),
                        });
                    }
                }
            } else if resource_type == "Group" {
                if let Some(max_groups) = tenant_context.permissions.max_groups {
                    let current_count = self.count_resources_for_tenant(&tenant_id, "Group").await;
                    if current_count >= max_groups {
                        return Err(InMemoryError::Internal {
                            message: format!(
                                "Group limit exceeded: {}/{}",
                                current_count, max_groups
                            ),
                        });
                    }
                }
            }
        }

        // Generate ID if not provided
        if data.get("id").is_none() {
            let id = self.generate_resource_id(&tenant_id, resource_type).await;
            if let Some(obj) = data.as_object_mut() {
                obj.insert("id".to_string(), json!(id));
            }
        }

        // Create resource
        let resource = Resource::from_json(resource_type.to_string(), data).map_err(|e| {
            InMemoryError::InvalidData {
                message: format!("Failed to create resource: {}", e),
            }
        })?;

        // Check for duplicate userName if this is a User resource
        if resource_type == "User" {
            if let Some(username) = resource.get_username() {
                self.check_username_duplicate(&tenant_id, username, None)
                    .await?;
            }
        }

        // Add metadata
        let resource_with_meta = self.add_scim_metadata(resource);
        let resource_id = resource_with_meta.get_id().unwrap_or("unknown").to_string();

        // Store resource using storage provider
        let key = StorageKey::new(&tenant_id, resource_type, &resource_id);
        let stored_data = self
            .storage
            .put(
                key,
                resource_with_meta
                    .to_json()
                    .map_err(|e| InMemoryError::Internal {
                        message: format!("Failed to serialize resource: {}", e),
                    })?,
            )
            .await
            .map_err(|e| InMemoryError::Internal {
                message: format!("Storage error during create: {}", e),
            })?;

        // Return the resource as stored
        Resource::from_json(resource_type.to_string(), stored_data).map_err(|e| {
            InMemoryError::InvalidData {
                message: format!("Failed to deserialize stored resource: {}", e),
            }
        })
    }

    async fn get_resource(
        &self,
        resource_type: &str,
        id: &str,
        context: &RequestContext,
    ) -> Result<Option<Resource>, Self::Error> {
        let tenant_id = self.effective_tenant_id(context);

        debug!(
            "Getting {} resource with ID '{}' for tenant '{}' (request: '{}')",
            resource_type, id, tenant_id, context.request_id
        );

        // Check permissions first
        context
            .validate_operation("read")
            .map_err(|e| InMemoryError::Internal { message: e })?;

        let key = StorageKey::new(&tenant_id, resource_type, id);
        let resource_data = self
            .storage
            .get(key)
            .await
            .map_err(|e| InMemoryError::Internal {
                message: format!("Storage error during get: {}", e),
            })?;

        let resource = match resource_data {
            Some(data) => {
                let resource =
                    Resource::from_json(resource_type.to_string(), data).map_err(|e| {
                        InMemoryError::InvalidData {
                            message: format!("Failed to deserialize resource: {}", e),
                        }
                    })?;
                trace!("Resource found and returned");
                Some(resource)
            }
            None => {
                debug!("Resource not found");
                None
            }
        };

        Ok(resource)
    }

    async fn update_resource(
        &self,
        resource_type: &str,
        id: &str,
        mut data: Value,
        context: &RequestContext,
    ) -> Result<Resource, Self::Error> {
        let tenant_id = self.effective_tenant_id(context);

        info!(
            "Updating {} resource with ID '{}' for tenant '{}' (request: '{}')",
            resource_type, id, tenant_id, context.request_id
        );
        trace!(
            "Update data: {}",
            serde_json::to_string(&data).unwrap_or_else(|_| "invalid json".to_string())
        );

        // Check permissions first
        context
            .validate_operation("update")
            .map_err(|e| InMemoryError::Internal { message: e })?;

        // Ensure ID is set correctly
        if let Some(obj) = data.as_object_mut() {
            obj.insert("id".to_string(), json!(id));
        }

        // Create updated resource
        let resource = Resource::from_json(resource_type.to_string(), data).map_err(|e| {
            InMemoryError::InvalidData {
                message: format!("Failed to update resource: {}", e),
            }
        })?;

        // Check for duplicate userName if this is a User resource
        if resource_type == "User" {
            if let Some(username) = resource.get_username() {
                self.check_username_duplicate(&tenant_id, username, Some(id))
                    .await?;
            }
        }

        // Verify resource exists using storage provider
        let key = StorageKey::new(&tenant_id, resource_type, id);
        let exists =
            self.storage
                .exists(key.clone())
                .await
                .map_err(|e| InMemoryError::Internal {
                    message: format!("Storage error during existence check: {}", e),
                })?;

        if !exists {
            return Err(InMemoryError::ResourceNotFound {
                resource_type: resource_type.to_string(),
                id: id.to_string(),
                tenant_id,
            });
        }

        // Add metadata (preserve created time, update modified time)
        let resource_with_meta = self.add_scim_metadata(resource);

        // Store updated resource using storage provider
        let stored_data = self
            .storage
            .put(
                key,
                resource_with_meta
                    .to_json()
                    .map_err(|e| InMemoryError::Internal {
                        message: format!("Failed to serialize resource: {}", e),
                    })?,
            )
            .await
            .map_err(|e| InMemoryError::Internal {
                message: format!("Storage error during update: {}", e),
            })?;

        // Return the updated resource as stored
        Resource::from_json(resource_type.to_string(), stored_data).map_err(|e| {
            InMemoryError::InvalidData {
                message: format!("Failed to deserialize updated resource: {}", e),
            }
        })
    }

    async fn delete_resource(
        &self,
        resource_type: &str,
        id: &str,
        context: &RequestContext,
    ) -> Result<(), Self::Error> {
        let tenant_id = self.effective_tenant_id(context);

        info!(
            "Deleting {} resource with ID '{}' for tenant '{}' (request: '{}')",
            resource_type, id, tenant_id, context.request_id
        );

        // Check permissions first
        context
            .validate_operation("delete")
            .map_err(|e| InMemoryError::Internal { message: e })?;

        // Delete resource using storage provider
        let key = StorageKey::new(&tenant_id, resource_type, id);
        let removed = self
            .storage
            .delete(key)
            .await
            .map_err(|e| InMemoryError::Internal {
                message: format!("Storage error during delete: {}", e),
            })?;

        if !removed {
            warn!(
                "Attempted to delete non-existent {} resource with ID '{}' for tenant '{}'",
                resource_type, id, tenant_id
            );
            return Err(InMemoryError::ResourceNotFound {
                resource_type: resource_type.to_string(),
                id: id.to_string(),
                tenant_id,
            });
        }

        debug!(
            "Successfully deleted {} resource with ID '{}' for tenant '{}'",
            resource_type, id, tenant_id
        );
        Ok(())
    }

    async fn list_resources(
        &self,
        resource_type: &str,
        query: Option<&ListQuery>,
        context: &RequestContext,
    ) -> Result<Vec<Resource>, Self::Error> {
        let tenant_id = self.effective_tenant_id(context);

        debug!(
            "Listing {} resources for tenant '{}' (request: '{}')",
            resource_type, tenant_id, context.request_id
        );

        // Check permissions first
        context
            .validate_operation("list")
            .map_err(|e| InMemoryError::Internal { message: e })?;

        // List resources using storage provider
        let prefix = StorageKey::prefix(&tenant_id, resource_type);
        let storage_results = self
            .storage
            .list(prefix, 0, usize::MAX) // Get all resources for now, apply pagination later
            .await
            .map_err(|e| InMemoryError::Internal {
                message: format!("Storage error during list: {}", e),
            })?;

        // Convert storage results to Resource objects
        let mut resources = Vec::new();
        for (_key, data) in storage_results {
            match Resource::from_json(resource_type.to_string(), data) {
                Ok(resource) => resources.push(resource),
                Err(e) => {
                    warn!("Failed to deserialize resource during list: {}", e);
                    // Continue with other resources instead of failing entirely
                }
            }
        }

        // Apply simple filtering and pagination if query is provided
        let mut filtered_resources = resources;

        if let Some(q) = query {
            // Apply start_index and count for pagination
            if let Some(start_index) = q.start_index {
                let start = (start_index.saturating_sub(1)) as usize; // SCIM uses 1-based indexing
                if start < filtered_resources.len() {
                    filtered_resources = filtered_resources.into_iter().skip(start).collect();
                } else {
                    filtered_resources = Vec::new();
                }
            }

            if let Some(count) = q.count {
                filtered_resources.truncate(count as usize);
            }
        }

        debug!(
            "Found {} {} resources for tenant '{}' (after filtering)",
            filtered_resources.len(),
            resource_type,
            tenant_id
        );

        Ok(filtered_resources)
    }

    async fn find_resource_by_attribute(
        &self,
        resource_type: &str,
        attribute: &str,
        value: &Value,
        context: &RequestContext,
    ) -> Result<Option<Resource>, Self::Error> {
        let tenant_id = self.effective_tenant_id(context);

        // Find resource by attribute using storage provider
        let prefix = StorageKey::prefix(&tenant_id, resource_type);
        let value_str = match value {
            Value::String(s) => s.clone(),
            _ => value.to_string().trim_matches('"').to_string(),
        };

        let matches = self
            .storage
            .find_by_attribute(prefix, attribute, &value_str)
            .await
            .map_err(|e| InMemoryError::Internal {
                message: format!("Storage error during find by attribute: {}", e),
            })?;

        // Return the first match
        for (_key, data) in matches {
            match Resource::from_json(resource_type.to_string(), data) {
                Ok(resource) => return Ok(Some(resource)),
                Err(e) => {
                    warn!("Failed to deserialize resource during find: {}", e);
                    continue;
                }
            }
        }

        Ok(None)
    }

    async fn resource_exists(
        &self,
        resource_type: &str,
        id: &str,
        context: &RequestContext,
    ) -> Result<bool, Self::Error> {
        let tenant_id = self.effective_tenant_id(context);

        let key = StorageKey::new(&tenant_id, resource_type, id);
        self.storage
            .exists(key)
            .await
            .map_err(|e| InMemoryError::Internal {
                message: format!("Storage error during exists check: {}", e),
            })
    }

    async fn patch_resource(
        &self,
        resource_type: &str,
        id: &str,
        patch_request: &Value,
        context: &RequestContext,
    ) -> Result<Resource, Self::Error> {
        let _tenant_id = self.effective_tenant_id(context);

        // Check for ETag validation if provided in patch request
        if let Some(etag_value) = patch_request.get("etag") {
            if let Some(etag_str) = etag_value.as_str() {
                // Get current resource to check version
                let tenant_id = self.effective_tenant_id(context);
                let key = StorageKey::new(&tenant_id, resource_type, id);

                match self.storage.get(key).await {
                    Ok(Some(current_data)) => {
                        // Parse current resource to get version
                        let current_resource = Resource::from_json(resource_type.to_string(), current_data)
                            .map_err(|e| InMemoryError::InvalidData {
                                message: format!("Failed to deserialize current resource: {}", e),
                            })?;

                        // Get current resource version for comparison
                        if let Some(current_version) = current_resource.get_meta().and_then(|m| m.version.as_ref()) {
                            let current_etag = current_version.as_str();
                            // Compare the provided ETag with current version
                            // Remove W/ prefix if present for comparison
                            let normalized_current = current_etag.trim_start_matches("W/").trim_matches('"');
                            let normalized_provided = etag_str.trim_start_matches("W/").trim_matches('"');

                            if normalized_current != normalized_provided {
                                return Err(InMemoryError::PreconditionFailed {
                                    message: format!("ETag mismatch. Expected '{}', got '{}'", normalized_current, normalized_provided),
                                });
                            }
                        }
                    }
                    Ok(None) => {
                        return Err(InMemoryError::NotFound {
                            resource_type: resource_type.to_string(),
                            id: id.to_string(),
                        });
                    }
                    Err(_) => {
                        return Err(InMemoryError::Internal {
                            message: "Failed to retrieve resource for ETag validation".to_string(),
                        });
                    }
                }
            }
        }

        // Extract operations from patch request
        let operations = patch_request
            .get("Operations")
            .and_then(|ops| ops.as_array())
            .ok_or(InMemoryError::InvalidInput {
                message: "PATCH request must contain Operations array".to_string(),
            })?;

        // Validate that operations array is not empty
        if operations.is_empty() {
            return Err(InMemoryError::InvalidInput {
                message: "Operations array cannot be empty".to_string(),
            });
        }

        // Get current resource and apply patch
        let tenant_id = self.effective_tenant_id(context);
        let key = StorageKey::new(&tenant_id, resource_type, id);

        match self.storage.get(key.clone()).await {
            Ok(Some(mut current_data)) => {
                // Apply each patch operation
                for operation in operations {
                    self.apply_patch_operation(&mut current_data, operation)?;
                }

                // Update version
                let new_version = ScimVersion::from_content(
                    serde_json::to_string(&current_data).unwrap().as_bytes(),
                );
                if let Some(obj) = current_data.as_object_mut() {
                    obj.insert("version".to_string(), json!(new_version.to_string()));
                }

                // Store updated resource
                self.storage
                    .put(key, current_data.clone())
                    .await
                    .map_err(|_| InMemoryError::Internal {
                        message: "Failed to store patched resource".to_string(),
                    })?;

                // Parse and return updated resource
                let updated_resource = Resource::from_json(resource_type.to_string(), current_data)
                    .map_err(|e| InMemoryError::InvalidInput {
                        message: format!("Failed to deserialize patched resource: {}", e),
                    })?;

                Ok(updated_resource)
            }
            Ok(None) => Err(InMemoryError::NotFound {
                resource_type: resource_type.to_string(),
                id: id.to_string(),
            }),
            Err(_) => Err(InMemoryError::Internal {
                message: "Failed to retrieve resource for patch".to_string(),
            }),
        }
    }

    /// Override the default patch operation implementation
    fn apply_patch_operation(
        &self,
        resource_data: &mut Value,
        operation: &Value,
    ) -> Result<(), Self::Error> {
        let op =
            operation
                .get("op")
                .and_then(|v| v.as_str())
                .ok_or(InMemoryError::InvalidInput {
                    message: "PATCH operation must have 'op' field".to_string(),
                })?;

        let path = operation.get("path").and_then(|v| v.as_str());
        let value = operation.get("value");

        // Check if the operation targets a readonly attribute
        if let Some(path_str) = path {
            if self.is_readonly_attribute(path_str) {
                return Err(InMemoryError::InvalidInput {
                    message: format!("Cannot modify readonly attribute: {}", path_str),
                });
            }
        }

        match op.to_lowercase().as_str() {
            "add" => self.apply_add_operation(resource_data, path, value),
            "remove" => self.apply_remove_operation(resource_data, path),
            "replace" => self.apply_replace_operation(resource_data, path, value),
            _ => Err(InMemoryError::InvalidInput {
                message: format!("Unsupported PATCH operation: {}", op),
            }),
        }
    }

}

impl<S: StorageProvider> StandardResourceProvider<S> {
    /// Check if an attribute path refers to a readonly attribute
    fn is_readonly_attribute(&self, path: &str) -> bool {
        // SCIM readonly attributes according to RFC 7643
        match path.to_lowercase().as_str() {
            // Meta attributes that are readonly
            "meta.created" => true,
            "meta.resourcetype" => true,
            "meta.location" => true,
            "id" => true,
            // Complex attribute readonly subattributes
            path if path.starts_with("meta.") && (path.ends_with(".created") || path.ends_with(".resourcetype") || path.ends_with(".location")) => true,
            _ => false,
        }
    }

    /// Apply ADD operation
    fn apply_add_operation(
        &self,
        resource_data: &mut Value,
        path: Option<&str>,
        value: Option<&Value>,
    ) -> Result<(), InMemoryError> {
        let value = value.ok_or(InMemoryError::InvalidInput {
            message: "ADD operation requires a value".to_string(),
        })?;

        match path {
            Some(path_str) => {
                self.set_value_at_path(resource_data, path_str, value.clone())?;
            }
            None => {
                // No path means add to root - merge objects
                if let (Some(current_obj), Some(value_obj)) =
                    (resource_data.as_object_mut(), value.as_object())
                {
                    for (key, val) in value_obj {
                        current_obj.insert(key.clone(), val.clone());
                    }
                }
            }
        }
        Ok(())
    }

    /// Apply REMOVE operation
    fn apply_remove_operation(
        &self,
        resource_data: &mut Value,
        path: Option<&str>,
    ) -> Result<(), InMemoryError> {
        if let Some(path_str) = path {
            self.remove_value_at_path(resource_data, path_str)?;
        }
        Ok(())
    }

    /// Apply REPLACE operation
    fn apply_replace_operation(
        &self,
        resource_data: &mut Value,
        path: Option<&str>,
        value: Option<&Value>,
    ) -> Result<(), InMemoryError> {
        let value = value.ok_or(InMemoryError::InvalidInput {
            message: "REPLACE operation requires a value".to_string(),
        })?;

        match path {
            Some(path_str) => {
                self.set_value_at_path(resource_data, path_str, value.clone())?;
            }
            None => {
                // No path means replace entire resource
                *resource_data = value.clone();
            }
        }
        Ok(())
    }

    /// Set a value at a complex path (e.g., "name.givenName")
    fn set_value_at_path(
        &self,
        data: &mut Value,
        path: &str,
        value: Value,
    ) -> Result<(), InMemoryError> {
        // Validate the path first
        if !self.is_valid_scim_path(path) {
            return Err(InMemoryError::InvalidInput {
                message: format!("Invalid SCIM path: '{}'", path),
            });
        }

        let parts: Vec<&str> = path.split('.').collect();

        if parts.len() == 1 {
            // Simple path - handle multivalued attributes specially
            if let Some(obj) = data.as_object_mut() {
                let attribute_name = parts[0];

                // Check if this is a multivalued attribute that should be appended to
                if Self::is_multivalued_attribute(attribute_name) {
                    if let Some(existing) = obj.get_mut(attribute_name) {
                        if let Some(existing_array) = existing.as_array_mut() {
                            // If the value being added is an array, replace the entire array
                            if value.is_array() {
                                obj.insert(attribute_name.to_string(), value);
                            } else {
                                // If the value is a single object, append to existing array
                                existing_array.push(value);
                            }
                            return Ok(());
                        }
                    }
                    // If no existing array, create new one
                    let new_array = if value.is_array() {
                        value
                    } else {
                        json!([value])
                    };
                    obj.insert(attribute_name.to_string(), new_array);
                } else {
                    // Single-valued attribute - replace
                    obj.insert(attribute_name.to_string(), value);
                }
            }
            return Ok(());
        }

        // Complex path - navigate to the parent and create intermediate objects if needed
        let mut current = data;

        for part in &parts[..parts.len() - 1] {
            if let Some(obj) = current.as_object_mut() {
                let entry = obj
                    .entry(part.to_string())
                    .or_insert_with(|| Value::Object(serde_json::Map::new()));
                current = entry;
            } else {
                return Err(InMemoryError::InvalidInput {
                    message: format!(
                        "Cannot navigate path '{}' - intermediate value is not an object",
                        path
                    ),
                });
            }
        }

        // Set the final value
        if let Some(obj) = current.as_object_mut() {
            obj.insert(parts.last().unwrap().to_string(), value);
        } else {
            return Err(InMemoryError::InvalidInput {
                message: format!(
                    "Cannot set value at path '{}' - target is not an object",
                    path
                ),
            });
        }

        Ok(())
    }

    /// Remove a value at a complex path (e.g., "name.givenName")
    fn remove_value_at_path(&self, data: &mut Value, path: &str) -> Result<(), InMemoryError> {
        // Validate the path first
        if !self.is_valid_scim_path(path) {
            return Err(InMemoryError::InvalidInput {
                message: format!("Invalid SCIM path: '{}'", path),
            });
        }

        let parts: Vec<&str> = path.split('.').collect();

        if parts.len() == 1 {
            // Simple path
            if let Some(obj) = data.as_object_mut() {
                obj.remove(parts[0]);
            }
            return Ok(());
        }

        // Complex path - navigate to the parent
        let mut current = data;

        for part in &parts[..parts.len() - 1] {
            if let Some(obj) = current.as_object_mut() {
                // If the path component doesn't exist, treat as success (idempotent remove)
                match obj.get_mut(*part) {
                    Some(value) => current = value,
                    None => return Ok(()), // Path doesn't exist, nothing to remove
                }
            } else {
                return Err(InMemoryError::InvalidInput {
                    message: format!(
                        "Cannot navigate path '{}' - intermediate value is not an object",
                        path
                    ),
                });
            }
        }

        // Remove the final value
        if let Some(obj) = current.as_object_mut() {
            obj.remove(*parts.last().unwrap());
        }

        Ok(())
    }

    /// Check if an attribute is multivalued
    fn is_multivalued_attribute(attribute_name: &str) -> bool {
        matches!(
            attribute_name,
            "emails" | "phoneNumbers" | "addresses" | "groups" | "members"
        )
    }

    /// Validate if a path represents a valid SCIM attribute
    fn is_valid_scim_path(&self, path: &str) -> bool {
        // Handle schema URN prefixed paths (e.g., "urn:ietf:params:scim:schemas:extension:enterprise:2.0:User.department")
        let actual_path = if path.contains(':') && path.contains("urn:ietf:params:scim:schemas:") {
            // Extract the attribute part after the schema URN
            if let Some(colon_pos) = path.rfind(':') {
                let after_colon = &path[colon_pos + 1..];
                // If there's a dot after the resource type, get the attribute part
                if let Some(dot_pos) = after_colon.find('.') {
                    &after_colon[dot_pos + 1..]
                } else {
                    after_colon
                }
            } else {
                path
            }
        } else {
            path
        };

        // Handle filter expressions first
        if actual_path.contains('[') {
            // Basic filter syntax validation
            if let Some(bracket_start) = actual_path.find('[') {
                let before_bracket = &actual_path[..bracket_start];
                if !self.is_valid_simple_path(before_bracket) {
                    return false;
                }
                // Check for malformed filter syntax - must have closing bracket
                let remaining = &actual_path[bracket_start..];
                if !remaining.ends_with(']') || remaining.matches('[').count() != remaining.matches(']').count() {
                    return false;
                }
                return true;
            }
        }

        // Handle complex paths (e.g., "name.givenName")
        let parts: Vec<&str> = actual_path.split('.').collect();

        // First part must be a valid root attribute
        if !self.is_valid_simple_path(parts[0]) {
            return false;
        }

        // If there are sub-attributes, validate them
        if parts.len() > 1 {
            // For now, allow common sub-attributes for known complex types
            if parts[0] == "name" {
                return matches!(parts[1], "formatted" | "familyName" | "givenName" | "middleName" | "honorificPrefix" | "honorificSuffix");
            }
            if parts[0] == "meta" {
                return matches!(parts[1], "resourceType" | "created" | "lastModified" | "location" | "version");
            }
            // For other complex attributes, we'll be permissive for now
            // In a full implementation, this would check against schema definitions
        }

        true
    }

    /// Check if a simple path (single attribute name) is valid
    fn is_valid_simple_path(&self, attribute: &str) -> bool {
        // Standard SCIM User attributes
        let user_attributes = [
            "id", "externalId", "userName", "name", "displayName", "nickName", "profileUrl",
            "title", "userType", "preferredLanguage", "locale", "timezone", "active",
            "password", "emails", "phoneNumbers", "addresses", "groups", "entitlements",
            "roles", "x509Certificates", "meta"
        ];

        // Standard SCIM Group attributes
        let group_attributes = [
            "id", "externalId", "displayName", "members", "meta"
        ];

        // Enterprise extension attributes
        let enterprise_attributes = [
            "employeeNumber", "costCenter", "organization", "division", "department", "manager"
        ];

        // Check against known attributes
        user_attributes.contains(&attribute) ||
        group_attributes.contains(&attribute) ||
        enterprise_attributes.contains(&attribute)
    }
}

// Essential conditional operations for testing
impl<S: StorageProvider> StandardResourceProvider<S> {
    pub async fn conditional_update(
        &self,
        resource_type: &str,
        id: &str,
        data: Value,
        expected_version: &ScimVersion,
        context: &RequestContext,
    ) -> Result<ConditionalResult<VersionedResource>, InMemoryError> {
        let tenant_id = self.effective_tenant_id(context);
        let key = StorageKey::new(&tenant_id, resource_type, id);

        // Get current resource to check version
        match self.storage.get(key.clone()).await {
            Ok(Some(current_data)) => {
                // Parse current resource to extract version
                let current_resource =
                    Resource::from_json(resource_type.to_string(), current_data.clone()).map_err(
                        |e| InMemoryError::InvalidInput {
                            message: format!("Failed to deserialize stored resource: {}", e),
                        },
                    )?;

                // Check if version matches
                let current_version = VersionedResource::new(current_resource.clone())
                    .version()
                    .clone();
                if &current_version != expected_version {
                    use crate::resource::version::VersionConflict;
                    return Ok(ConditionalResult::VersionMismatch(VersionConflict::new(
                        expected_version.clone(),
                        current_version,
                        "Resource was modified by another client",
                    )));
                }

                // Version matches, proceed with update
                let mut updated_resource = Resource::from_json(resource_type.to_string(), data)
                    .map_err(|e| InMemoryError::InvalidInput {
                        message: format!("Failed to create updated resource: {}", e),
                    })?;

                // Preserve the ID
                if let Some(original_id) = current_resource.get_id() {
                    updated_resource.set_id(original_id).map_err(|e| {
                        InMemoryError::InvalidInput {
                            message: format!("Failed to set ID: {}", e),
                        }
                    })?;
                }

                // Store updated resource - convert back to JSON for storage
                let updated_data =
                    updated_resource
                        .to_json()
                        .map_err(|e| InMemoryError::InvalidInput {
                            message: format!("Failed to serialize updated resource: {}", e),
                        })?;

                self.storage
                    .put(key, updated_data)
                    .await
                    .map_err(|_| InMemoryError::Internal {
                        message: "Failed to store updated resource".to_string(),
                    })?;

                Ok(ConditionalResult::Success(VersionedResource::new(
                    updated_resource,
                )))
            }
            Ok(None) => Err(InMemoryError::NotFound {
                resource_type: resource_type.to_string(),
                id: id.to_string(),
            }),
            Err(_) => Err(InMemoryError::Internal {
                message: "Failed to retrieve resource for conditional update".to_string(),
            }),
        }
    }

    pub async fn conditional_delete(
        &self,
        resource_type: &str,
        id: &str,
        expected_version: &ScimVersion,
        context: &RequestContext,
    ) -> Result<ConditionalResult<()>, InMemoryError> {
        let tenant_id = self.effective_tenant_id(context);
        let key = StorageKey::new(&tenant_id, resource_type, id);

        // Get current resource to check version
        match self.storage.get(key.clone()).await {
            Ok(Some(current_data)) => {
                // Parse current resource to extract version
                let current_resource = Resource::from_json(resource_type.to_string(), current_data)
                    .map_err(|e| InMemoryError::InvalidInput {
                        message: format!("Failed to deserialize stored resource: {}", e),
                    })?;

                // Check if version matches
                let current_version = VersionedResource::new(current_resource.clone())
                    .version()
                    .clone();
                if &current_version != expected_version {
                    use crate::resource::version::VersionConflict;
                    return Ok(ConditionalResult::VersionMismatch(VersionConflict::new(
                        expected_version.clone(),
                        current_version,
                        "Resource was modified by another client",
                    )));
                }

                // Version matches, proceed with delete
                self.storage
                    .delete(key)
                    .await
                    .map_err(|_| InMemoryError::Internal {
                        message: "Failed to delete resource".to_string(),
                    })?;

                Ok(ConditionalResult::Success(()))
            }
            Ok(None) => Err(InMemoryError::NotFound {
                resource_type: resource_type.to_string(),
                id: id.to_string(),
            }),
            Err(_) => Err(InMemoryError::Internal {
                message: "Failed to retrieve resource for conditional delete".to_string(),
            }),
        }
    }

    pub async fn conditional_patch_resource(
        &self,
        resource_type: &str,
        id: &str,
        patch_request: &Value,
        expected_version: &ScimVersion,
        context: &RequestContext,
    ) -> Result<ConditionalResult<VersionedResource>, InMemoryError> {
        let tenant_id = self.effective_tenant_id(context);
        let key = StorageKey::new(&tenant_id, resource_type, id);

        // Get current resource to check version
        match self.storage.get(key.clone()).await {
            Ok(Some(current_data)) => {
                // Parse current resource to extract version
                let current_resource =
                    Resource::from_json(resource_type.to_string(), current_data.clone()).map_err(
                        |e| InMemoryError::InvalidInput {
                            message: format!("Failed to deserialize stored resource: {}", e),
                        },
                    )?;

                // Check if version matches
                let current_version = VersionedResource::new(current_resource.clone())
                    .version()
                    .clone();
                if &current_version != expected_version {
                    use crate::resource::version::VersionConflict;
                    return Ok(ConditionalResult::VersionMismatch(VersionConflict::new(
                        expected_version.clone(),
                        current_version,
                        "Resource was modified by another client",
                    )));
                }

                // Version matches, proceed with patch
                let mut patched_data = current_data;

                // Apply patch operations
                if let Some(operations) = patch_request.get("Operations") {
                    if let Some(ops_array) = operations.as_array() {
                        for operation in ops_array {
                            self.apply_patch_operation(&mut patched_data, operation)?;
                        }
                    }
                }

                // Parse patched resource with proper resource type
                let patched_resource = Resource::from_json(resource_type.to_string(), patched_data)
                    .map_err(|e| InMemoryError::InvalidInput {
                        message: format!("Failed to deserialize patched resource: {}", e),
                    })?;

                // Store patched resource - convert back to JSON for storage
                let patched_json =
                    patched_resource
                        .to_json()
                        .map_err(|e| InMemoryError::InvalidInput {
                            message: format!("Failed to serialize patched resource: {}", e),
                        })?;

                self.storage
                    .put(key, patched_json)
                    .await
                    .map_err(|_| InMemoryError::Internal {
                        message: "Failed to store patched resource".to_string(),
                    })?;

                Ok(ConditionalResult::Success(VersionedResource::new(
                    patched_resource,
                )))
            }
            Ok(None) => Err(InMemoryError::NotFound {
                resource_type: resource_type.to_string(),
                id: id.to_string(),
            }),
            Err(_) => Err(InMemoryError::Internal {
                message: "Failed to retrieve resource for conditional patch".to_string(),
            }),
        }
    }

    pub async fn get_versioned_resource(
        &self,
        resource_type: &str,
        id: &str,
        context: &RequestContext,
    ) -> Result<Option<VersionedResource>, InMemoryError> {
        match self.get_resource(resource_type, id, context).await? {
            Some(resource) => Ok(Some(VersionedResource::new(resource))),
            None => Ok(None),
        }
    }

    pub async fn create_versioned_resource(
        &self,
        resource_type: &str,
        data: Value,
        context: &RequestContext,
    ) -> Result<VersionedResource, InMemoryError> {
        let resource = self.create_resource(resource_type, data, context).await?;
        Ok(VersionedResource::new(resource))
    }
}