//! Actor service layer providing business logic for actor management operations.
//!
//! Implements the service layer of the actor management system, handling business logic,
//! validation, and orchestration.
//!
//! For full documentation, architecture, and examples, see the [crate README](../README.md).

use forge_models::Actor;
use forge_repositories::ActorRepository;

/// Service layer implementation for actor business logic and operations.
///
/// Orchestrates actor management operations, handling business logic, validation,
/// and data transformation. See [crate README](../README.md) for details.
///
/// # Thread Safety
/// Thread-safe when used with a thread-safe repository.
pub struct ActorService<R: ActorRepository> {
    /// The repository instance used for all data persistence operations.
    ///
    /// This repository handles the actual storage and retrieval of actor data,
    /// abstracting away the specific database implementation details.
    repository: R,
}

impl<R: ActorRepository> ActorService<R> {
    /// Creates a new actor service with the provided repository.
    ///
    /// The repository must be initialized and ready for use.
    pub fn new(repository: R) -> Self {
        Self { repository }
    }

    /// Creates a new actor with the provided ID and JSON data.
    ///
    /// Handles validation, duplicate checking, and persistence.
    /// See [crate README](../README.md) for JSON format and business rules.
    pub fn create_actor(&self, actor_id: String, json_data: String) -> Result<Actor, String> {
        // Create base actor with the provided UID
        let new_actor = Actor::new(actor_id.clone()).map_err(|e| e.to_string())?;

        // Check if actor already exists to prevent duplicates
        if self.repository.exists(&actor_id)? {
            return Err(format!("Actor with UID '{}' already exists", actor_id));
        }

        // Parse and validate JSON input
        let json_obj: serde_json::Value =
            serde_json::from_str(&json_data).map_err(|e| format!("Invalid Actor JSON: {}", e))?;

        // Ensure JSON is an object (not array, string, etc.)
        if let serde_json::Value::Object(mut map) = json_obj {
            // Remove UID field to prevent conflicts (UID is immutable)
            map.remove("uid");
            let update_data = serde_json::Value::Object(map);

            // Apply JSON data to the base actor
            let mut final_actor = new_actor;
            final_actor.update_from_json(update_data)?;

            // Store the actor in the repository
            self.repository.create(&final_actor)?;
            Ok(final_actor)
        } else {
            Err("JSON data must be an object".to_string())
        }
    }

    /// Retrieves an actor by their unique identifier with automatic fallback creation.
    ///
    /// Implements a "get-or-create" pattern: if the actor doesn't exist, a new one
    /// with default values is returned (but not persisted).
    pub fn get_actor(&self, actor_id: String) -> Result<Actor, String> {
        // Attempt to retrieve actor from repository
        match self.repository.get_by_id(&actor_id)? {
            // Actor found - return it
            Some(actor) => Ok(actor),
            // Actor not found - create fallback actor with default values
            None => Actor::new(actor_id).map_err(|e| e.to_string()),
        }
    }

    /// Updates an existing actor with new data from JSON.
    ///
    /// Handles partial updates, validation, and persistence.
    /// See [crate README](../README.md) for JSON format and concurrency details.
    pub fn update_actor(&self, actor_id: String, json_update: String) -> Result<Actor, String> {
        // Retrieve existing actor from repository
        let mut actor = match self.repository.get_by_id(&actor_id)? {
            Some(actor) => actor,
            None => return Err(format!("Actor with UID '{}' not found", actor_id)),
        };

        // Parse and validate JSON update data
        let update_data: serde_json::Value =
            serde_json::from_str(&json_update).map_err(|e| format!("Invalid JSON: {}", e))?;

        // Ensure update data is a JSON object
        if !update_data.is_object() {
            return Err("Update data must be a JSON object".to_string());
        }

        // Apply updates to the actor (this validates the changes)
        actor.update_from_json(update_data)?;

        // Persist the updated actor to repository
        self.repository.update(&actor)?;

        Ok(actor)
    }

    /// Permanently deletes an actor from the system.
    ///
    /// Irreversible operation. Delegates to repository.
    pub fn delete_actor(&self, actor_id: String) -> Result<(), String> {
        // Delegate deletion to repository layer
        // Future enhancements could add business logic here:
        // - Authorization checks
        // - Audit logging
        // - Cascade deletion
        // - Soft deletion
        self.repository.delete(&actor_id)
    }

    /// Checks if an actor exists in the system.
    ///
    /// Lightweight check without data retrieval.
    pub fn actor_exists(&self, actor_id: String) -> Result<bool, String> {
        // Delegate existence check to repository layer
        // This is a lightweight operation that doesn't retrieve data
        self.repository.exists(&actor_id)
    }
}