//! 公共类型和工具函数

use serde::Serialize;

/// 分页响应通用包装
#[derive(Debug, Serialize)]
pub struct PaginatedResponse<T: Serialize> {
    pub items: Vec<T>,
    pub total: i64,
    pub page: u32,
    pub page_size: u32,
}

/// 分页上限
pub const MAX_PAGE_SIZE: u32 = 100;

/// 默认分页大小
pub const DEFAULT_PAGE_SIZE: u32 = 20;

/// 规范化分页参数，返回 (page, page_size, offset)
pub fn normalize_pagination(page: Option<u32>, page_size: Option<u32>) -> (u32, u32, i64) {
    let p = page.unwrap_or(1).max(1);
    let ps = page_size.unwrap_or(DEFAULT_PAGE_SIZE).min(MAX_PAGE_SIZE).max(1);
    let offset = ((p - 1) * ps) as i64;
    (p, ps, offset)
}

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

    #[test]
    fn test_normalize_pagination_defaults() {
        let (page, size, offset) = normalize_pagination(None, None);
        assert_eq!(page, 1);
        assert_eq!(size, DEFAULT_PAGE_SIZE);
        assert_eq!(offset, 0);
    }

    #[test]
    fn test_normalize_pagination_clamp() {
        let (page, size, offset) = normalize_pagination(None, Some(999));
        assert_eq!(size, MAX_PAGE_SIZE);
    }

    #[test]
    fn test_normalize_pagination_offset() {
        let (page, size, offset) = normalize_pagination(Some(3), Some(10));
        assert_eq!(offset, 20);
    }
}