use serde::Deserialize;

/// 聊天连接的心跳周期。存活的在线占位与 presence 状态都按它的两倍续期，
/// 由 `online_ttl_secs()` 派生。
#[derive(Clone, Debug, Deserialize)]
#[serde(default)]
pub struct ChatWsConfig {
    pub heartbeat_secs: u64,
}

impl Default for ChatWsConfig {
    fn default() -> Self {
        Self { heartbeat_secs: 30 }
    }
}

#[derive(Clone, Debug, Deserialize)]
#[serde(default)]
pub struct ChatUploadConfig {
    pub max_size: i64,
    pub presign_ttl_secs: u64,
}

impl Default for ChatUploadConfig {
    fn default() -> Self {
        Self {
            max_size: 104_857_600,
            presign_ttl_secs: 3600,
        }
    }
}

#[derive(Clone, Debug, Deserialize)]
#[serde(default)]
pub struct ChatConfig {
    pub max_pagination: u64,
    pub default_pagination: u64,
    pub max_message_len: usize,
    pub max_topic_len: usize,
    pub max_thread_name_len: usize,
    pub max_reaction_emoji_len: usize,
    pub max_emoji_name_len: usize,
    pub max_bookmark_title_len: usize,
    pub max_webhook_name_len: usize,
    pub max_mentions_per_message: usize,
    pub max_attachments_per_message: usize,
    pub max_members_per_add: usize,
    pub max_pending_attachments_per_user: i64,
    pub typing_ttl_secs: u64,
    pub presence_ttl_secs: u64,
    pub ws: ChatWsConfig,
    pub upload: ChatUploadConfig,
}

impl Default for ChatConfig {
    fn default() -> Self {
        Self {
            max_pagination: 200,
            default_pagination: 50,
            max_message_len: 4000,
            max_topic_len: 1024,
            max_thread_name_len: 255,
            max_reaction_emoji_len: 64,
            max_emoji_name_len: 64,
            max_bookmark_title_len: 255,
            max_webhook_name_len: 100,
            max_mentions_per_message: 20,
            max_attachments_per_message: 10,
            max_members_per_add: 50,
            max_pending_attachments_per_user: 200,
            typing_ttl_secs: 5,
            presence_ttl_secs: 300,
            ws: ChatWsConfig::default(),
            upload: ChatUploadConfig::default(),
        }
    }
}

impl ChatConfig {
    /// 聊天 WS 在线占位与可见在线状态的 TTL：两倍心跳——丢一个 tick 不掉线，
    /// 进程崩溃后最多两个心跳周期就会由 TTL 兜底回到离线。
    ///
    /// 与 `presence_ttl_secs` 的区别：那个是"手动设置一次状态"的存活时间，
    /// 这个只用于跟随 WS 生命周期的自动续期。
    pub fn online_ttl_secs(&self) -> u64 {
        self.ws.heartbeat_secs.max(5).saturating_mul(2)
    }
}

impl ChatConfig {
    pub fn is_valid(&self) -> Result<(), String> {
        if self.max_pagination == 0 || self.default_pagination == 0 {
            return Err("chat pagination must be positive".to_string());
        }
        if self.max_message_len == 0 {
            return Err("chat max_message_len must be positive".to_string());
        }
        if self.ws.heartbeat_secs == 0 {
            return Err("chat ws heartbeat_secs must be positive".to_string());
        }
        Ok(())
    }
}