//! Title generation middleware — auto-generates conversation titles after the first turn.
//!
//! Inspired by DeerFlow's TitleMiddleware: after the first user-assistant exchange,
//! generates a short descriptive title using the LLM instead of defaulting to
//! "新对话" or truncating the user's first message.
//!
//! Priority 180 — runs after compaction (100) and memory (150), before skill index (200).
//!
//! NOTE: This is a structural placeholder. Full implementation requires an LLM driver
//! reference to generate titles asynchronously, which will be wired through the
//! middleware context in a future iteration. For now it simply passes through.

use async_trait::async_trait;
use crate::middleware::{AgentMiddleware, MiddlewareDecision};

/// Middleware that auto-generates conversation titles after the first exchange.
///
/// When fully implemented, this will:
/// 1. Detect the first user-assistant exchange (via message count)
/// 2. Call the LLM with a short prompt to generate a descriptive title
/// 3. Update the session title via the middleware context
///
/// For now, it serves as a registered placeholder in the middleware chain.
pub struct TitleMiddleware {
    _reserved: (),
}

impl TitleMiddleware {
    pub fn new() -> Self {
        Self { _reserved: () }
    }
}

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

#[async_trait]
impl AgentMiddleware for TitleMiddleware {
    fn name(&self) -> &str { "title" }
    fn priority(&self) -> i32 { 180 }

    // All hooks default to Continue — placeholder until LLM driver is wired in.
    async fn before_completion(&self, _ctx: &mut crate::middleware::MiddlewareContext) -> zclaw_types::Result<MiddlewareDecision> {
        Ok(MiddlewareDecision::Continue)
    }
}