//! 进化引擎中间件
//! 在管家对话中检测并呈现"技能进化确认"提示
//! 优先级 78（在 ButlerRouter@80 之前运行）

use async_trait::async_trait;
use std::sync::Arc;
use tokio::sync::RwLock;
use crate::middleware::{
    AgentMiddleware, MiddlewareContext, MiddlewareDecision,
};
use zclaw_types::Result;

/// 待确认的进化事件
#[derive(Debug, Clone)]
pub struct PendingEvolution {
    pub pattern_name: String,
    pub trigger_suggestion: String,
    pub description: String,
}

/// 进化引擎中间件
/// 检查是否有待确认的进化事件，根据模式：
/// - suggest 模式（默认）: 注入确认提示到 system prompt
/// - auto 模式: 不注入，仅排队等待 kernel 自动处理
pub struct EvolutionMiddleware {
    pending: Arc<RwLock<Vec<PendingEvolution>>>,
    auto_mode: bool,
}

impl EvolutionMiddleware {
    pub fn new() -> Self {
        Self {
            pending: Arc::new(RwLock::new(Vec::new())),
            auto_mode: false,
        }
    }

    /// Create with auto mode enabled
    pub fn new_auto() -> Self {
        Self {
            pending: Arc::new(RwLock::new(Vec::new())),
            auto_mode: true,
        }
    }

    /// Check if auto mode is enabled
    pub fn is_auto_mode(&self) -> bool {
        self.auto_mode
    }

    /// 添加一个待确认的进化事件
    pub async fn add_pending(&self, evolution: PendingEvolution) {
        let mut pending = self.pending.write().await;
        if pending.len() >= 100 {
            tracing::warn!(
                "[EvolutionMiddleware] Pending queue full (100), dropping oldest event"
            );
            pending.remove(0);
        }
        pending.push(evolution);
    }

    /// 获取并清除所有待确认事件
    pub async fn drain_pending(&self) -> Vec<PendingEvolution> {
        let mut pending = self.pending.write().await;
        std::mem::take(&mut *pending)
    }

    /// 当前待确认事件数量
    pub async fn pending_count(&self) -> usize {
        self.pending.read().await.len()
    }
}

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

#[async_trait]
impl AgentMiddleware for EvolutionMiddleware {
    fn name(&self) -> &str {
        "evolution"
    }

    fn priority(&self) -> i32 {
        78 // 在 ButlerRouter(80) 之前
    }

    fn parallel_safe(&self) -> bool { true }

    async fn before_completion(
        &self,
        ctx: &mut MiddlewareContext,
    ) -> Result<MiddlewareDecision> {
        // 先用 read lock 快速判空，避免每次对话都获取写锁
        if self.pending.read().await.is_empty() {
            return Ok(MiddlewareDecision::Continue);
        }

        // Auto mode: don't inject into prompt, leave for kernel to process
        if self.auto_mode {
            return Ok(MiddlewareDecision::Continue);
        }

        // Suggest mode: 只移除第一个事件，保留后续事件留待下次注入
        let to_inject = {
            let mut pending = self.pending.write().await;
            if pending.is_empty() {
                return Ok(MiddlewareDecision::Continue);
            }
            pending.remove(0)
        };

        let injection = format!(
            "\n\n<evolution-suggestion>\n\
我注意到你经常做「{pattern}」相关的事情。\n\
我可以帮你整理成一个技能，以后直接说「{trigger}」就能用了。\n\
技能描述：{desc}\n\
如果你同意，请回复 '确认保存技能'。如果你想调整，可以告诉我怎么改。\n\
</evolution-suggestion>",
            pattern = to_inject.pattern_name,
            trigger = to_inject.trigger_suggestion,
            desc = to_inject.description,
        );
        ctx.system_prompt.push_str(&injection);

        tracing::info!(
            "[EvolutionMiddleware] Injected evolution suggestion for: {}",
            to_inject.pattern_name
        );

        Ok(MiddlewareDecision::Continue)
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[tokio::test]
    async fn test_no_pending_continues() {
        let mw = EvolutionMiddleware::new();
        assert_eq!(mw.pending_count().await, 0);
    }

    #[tokio::test]
    async fn test_add_and_drain() {
        let mw = EvolutionMiddleware::new();
        mw.add_pending(PendingEvolution {
            pattern_name: "报表生成".to_string(),
            trigger_suggestion: "生成报表".to_string(),
            description: "自动生成每日报表".to_string(),
        })
        .await;
        assert_eq!(mw.pending_count().await, 1);

        let drained = mw.drain_pending().await;
        assert_eq!(drained.len(), 1);
        assert_eq!(drained[0].pattern_name, "报表生成");
        assert_eq!(mw.pending_count().await, 0);
    }

    #[tokio::test]
    async fn test_name_and_priority() {
        let mw = EvolutionMiddleware::new();
        assert_eq!(mw.name(), "evolution");
        assert_eq!(mw.priority(), 78);
    }

    #[tokio::test]
    async fn test_only_first_event_injected() {
        let mw = EvolutionMiddleware::new();
        mw.add_pending(PendingEvolution {
            pattern_name: "事件A".to_string(),
            trigger_suggestion: "触发A".to_string(),
            description: "描述A".to_string(),
        })
        .await;
        mw.add_pending(PendingEvolution {
            pattern_name: "事件B".to_string(),
            trigger_suggestion: "触发B".to_string(),
            description: "描述B".to_string(),
        })
        .await;

        // 模拟注入：用 read 判空 + write 取第一个
        let first = {
            let mut pending = mw.pending.write().await;
            pending.remove(0)
        };
        assert_eq!(first.pattern_name, "事件A");
        assert_eq!(mw.pending_count().await, 1); // 事件B 仍保留
    }
}