//! Tool system for agent capabilities

use std::collections::HashMap;
use std::sync::Arc;
use async_trait::async_trait;
use serde_json::Value;
use tokio::sync::mpsc;
use zclaw_types::{AgentId, Result};

use crate::driver::ToolDefinition;
use crate::loop_runner::LoopEvent;
use crate::tool::builtin::PathValidator;

/// Tool trait for implementing agent tools
#[async_trait]
pub trait Tool: Send + Sync {
    /// Get the tool name
    fn name(&self) -> &str;

    /// Get the tool description
    fn description(&self) -> &str;

    /// Get the JSON schema for input parameters
    fn input_schema(&self) -> Value;

    /// Execute the tool
    async fn execute(&self, input: Value, context: &ToolContext) -> Result<Value>;
}

/// Skill executor trait for runtime skill execution
/// This allows tools to execute skills without direct dependency on zclaw-skills
#[async_trait]
pub trait SkillExecutor: Send + Sync {
    /// Execute a skill by ID
    async fn execute_skill(
        &self,
        skill_id: &str,
        agent_id: &str,
        session_id: &str,
        input: Value,
    ) -> Result<Value>;

    /// Return metadata for on-demand skill loading.
    /// Default returns `None` (skill detail not available).
    fn get_skill_detail(&self, skill_id: &str) -> Option<SkillDetail> {
        let _ = skill_id;
        None
    }

    /// Return lightweight index of all available skills.
    /// Default returns empty (no index available).
    fn list_skill_index(&self) -> Vec<SkillIndexEntry> {
        Vec::new()
    }
}

/// Lightweight skill index entry for system prompt injection.
#[derive(Debug, Clone, serde::Serialize)]
pub struct SkillIndexEntry {
    pub id: String,
    pub description: String,
    pub triggers: Vec<String>,
}

/// Full skill detail returned by `skill_load` tool.
#[derive(Debug, Clone, serde::Serialize)]
pub struct SkillDetail {
    pub id: String,
    pub name: String,
    pub description: String,
    pub category: Option<String>,
    pub input_schema: Option<Value>,
    pub triggers: Vec<String>,
    pub capabilities: Vec<String>,
}

/// Context provided to tool execution
pub struct ToolContext {
    pub agent_id: AgentId,
    pub working_directory: Option<String>,
    pub session_id: Option<String>,
    pub skill_executor: Option<Arc<dyn SkillExecutor>>,
    /// Path validator for file system operations
    pub path_validator: Option<PathValidator>,
    /// Optional event sender for streaming tool progress to the frontend.
    /// Tools like TaskTool use this to emit sub-agent status events.
    pub event_sender: Option<mpsc::Sender<LoopEvent>>,
}

impl std::fmt::Debug for ToolContext {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        f.debug_struct("ToolContext")
            .field("agent_id", &self.agent_id)
            .field("working_directory", &self.working_directory)
            .field("session_id", &self.session_id)
            .field("skill_executor", &self.skill_executor.as_ref().map(|_| "SkillExecutor"))
            .field("path_validator", &self.path_validator.as_ref().map(|_| "PathValidator"))
            .field("event_sender", &self.event_sender.as_ref().map(|_| "Sender<LoopEvent>"))
            .finish()
    }
}

impl Clone for ToolContext {
    fn clone(&self) -> Self {
        Self {
            agent_id: self.agent_id.clone(),
            working_directory: self.working_directory.clone(),
            session_id: self.session_id.clone(),
            skill_executor: self.skill_executor.clone(),
            path_validator: self.path_validator.clone(),
            event_sender: self.event_sender.clone(),
        }
    }
}

/// Tool registry for managing available tools
/// Uses HashMap for O(1) lookup performance
#[derive(Clone)]
pub struct ToolRegistry {
    /// Tool lookup by name (O(1))
    tools: HashMap<String, Arc<dyn Tool>>,
    /// Registration order for consistent iteration
    tool_order: Vec<String>,
}

impl ToolRegistry {
    pub fn new() -> Self {
        Self {
            tools: HashMap::new(),
            tool_order: Vec::new(),
        }
    }

    pub fn register(&mut self, tool: Box<dyn Tool>) {
        let tool: Arc<dyn Tool> = Arc::from(tool);
        let name = tool.name().to_string();

        // Track order for new tools
        if !self.tools.contains_key(&name) {
            self.tool_order.push(name.clone());
        }

        self.tools.insert(name, tool);
    }

    /// Get tool by name - O(1) lookup
    pub fn get(&self, name: &str) -> Option<Arc<dyn Tool>> {
        self.tools.get(name).cloned()
    }

    /// List all tools in registration order
    pub fn list(&self) -> Vec<&dyn Tool> {
        self.tool_order
            .iter()
            .filter_map(|name| self.tools.get(name).map(|t| t.as_ref()))
            .collect()
    }

    /// Get tool definitions in registration order
    pub fn definitions(&self) -> Vec<ToolDefinition> {
        self.tool_order
            .iter()
            .filter_map(|name| {
                self.tools.get(name).map(|t| {
                    ToolDefinition::new(
                        t.name(),
                        t.description(),
                        t.input_schema(),
                    )
                })
            })
            .collect()
    }

    /// Get number of registered tools
    pub fn len(&self) -> usize {
        self.tools.len()
    }

    /// Check if registry is empty
    pub fn is_empty(&self) -> bool {
        self.tools.is_empty()
    }
}

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

// Built-in tools module
pub mod builtin;