remdb 0.3.2

// 角色管理器实现

use crate::ha::HARole;
use crate::ha::Result;
use crate::pubsub;
use core::sync::atomic::{AtomicU8, Ordering};

#[cfg(feature = "log")]
use crate::log::{debug, error};

// 角色变更主题ID
const ROLE_CHANGE_TOPIC: u16 = 4;

// 全局角色变更回调函数
// 注意：由于pubsub::subscribe只接受函数指针，我们使用全局回调
static mut ROLE_CHANGE_CALLBACK: Option<fn(HARole) -> bool> = None;

/// 角色变更处理回调函数
fn handle_role_change(topic_id: u16, data: &[u8]) -> bool {
    if topic_id != ROLE_CHANGE_TOPIC {
        return false;
    }

    if data.is_empty() {
        return false;
    }

    // 解析角色变更数据
    let role = match data[0] {
        0 => HARole::Master,
        1 => HARole::Slave,
        2 => HARole::Auto,
        _ => HARole::Auto,
    };

    #[cfg(feature = "log")]
    debug!("Role change notification received: {:?}", role);
    // 调用全局回调函数
    unsafe {
        if let Some(callback) = ROLE_CHANGE_CALLBACK {
            callback(role)
        } else {
            true
        }
    }
}

/// 角色管理器
pub struct RoleManager {
    /// 当前角色（原子操作，确保线程安全）
    current_role: AtomicU8,
    /// 自旋锁
    lock: u32,
    /// 是否初始化
    is_initialized: bool,
}

impl RoleManager {
    /// 创建新的角色管理器
    pub fn new(initial_role: HARole) -> Result<Self> {
        Ok(Self {
            current_role: AtomicU8::new(initial_role as u8),
            lock: 0,
            is_initialized: false,
        })
    }

    /// 初始化角色管理器
    pub fn init(&self) -> Result<()> {
        // 初始化pubsub系统（如果尚未初始化）
        self.init_pubsub()?;
        // 订阅角色变更通知
        self.subscribe_to_role_changes()?;

        Ok(())
    }

    /// 初始化pubsub系统
    fn init_pubsub(&self) -> Result<()> {
        // pubsub系统已经由HA管理器统一初始化，无需再次初始化
        // 这里只做日志记录
        #[cfg(feature = "log")]
        debug!("Role manager using existing pubsub system");
        Ok(())
    }

    /// 订阅角色变更通知
    fn subscribe_to_role_changes(&self) -> Result<()> {
        // 订阅角色变更主题
        match pubsub::subscribe(ROLE_CHANGE_TOPIC, handle_role_change) {
            Ok(_) => {
                #[cfg(feature = "log")]
                debug!("Successfully subscribed to role change notifications");
                Ok(())
            }
            Err(e) => {
                #[cfg(feature = "log")]
                error!("Failed to subscribe to role change notifications: {:?}", e);
                // 订阅失败不影响角色管理器的初始化
                Ok(())
            }
        }
    }

    /// 获取当前角色
    pub fn get_role(&self) -> HARole {
        match self.current_role.load(Ordering::Relaxed) {
            0 => HARole::Master,
            1 => HARole::Slave,
            2 => HARole::Auto,
            _ => HARole::Auto, // 默认值
        }
    }

    /// 设置角色
    pub fn set_role(&self, role: HARole) -> Result<()> {
        // 检查角色是否变化
        let current_role = self.get_role();
        if current_role == role {
            return Ok(());
        }

        #[cfg(feature = "log")]
        debug!("Role changing from {:?} to {:?}", current_role, role);
        // 更新角色
        self.current_role.store(role as u8, Ordering::Relaxed);
        // 发布角色变更通知
        self.publish_role_change(role)?;

        Ok(())
    }

    /// 发布角色变更通知
    fn publish_role_change(&self, role: HARole) -> Result<()> {
        // 构建角色变更数据
        let role_data = [role as u8; 1];
        // 发布角色变更消息
        // 注意：在测试环境中，pubsub可能未正确初始化，此时忽略发布失败
        match pubsub::publish(ROLE_CHANGE_TOPIC, &role_data) {
            Ok(_) => {
                #[cfg(feature = "log")]
                debug!("Role change notification published: {:?}", role);
                Ok(())
            }
            Err(e) => {
                #[cfg(feature = "log")]
                error!("Failed to publish role change notification: {:?}", e);
                // 忽略发布失败，角色已经更新
                Ok(())
            }
        }
    }

    /// 订阅角色变更通知
    pub fn subscribe_role_change(&self, callback: fn(HARole) -> bool) -> Result<()> {
        unsafe {
            ROLE_CHANGE_CALLBACK = Some(callback);
        }
        Ok(())
    }

    /// 关闭角色管理器
    pub fn shutdown(&self) -> Result<()> {
        #[cfg(feature = "log")]
        debug!("Role manager shutdown");
        Ok(())
    }
}