use serde::{Deserialize, Serialize};
use serde_with::serde_as;
use validator::Validate;

/// 分页响应结构
#[derive(Serialize)]
pub struct PaginatedResponse<T> {
    pub data: Vec<T>,
    pub total: i64,
    pub page: u32,
    pub page_size: i32,
    pub total_pages: u32,
}

impl<T> PaginatedResponse<T> {
    /// 创建分页响应
    pub fn new(data: Vec<T>, total: i64, page: u32, page_size: i32) -> Self {
        let total_pages = if page_size > 0 {
            ((total as f64) / (page_size as f64)).ceil() as u32
        } else {
            0
        };

        Self {
            data,
            total,
            page,
            page_size,
            total_pages,
        }
    }
}

/// 分页查询参数
#[serde_as]
#[derive(Debug, Deserialize, Validate)]
pub struct PaginationParams {
    #[validate(range(min = 1))]
    #[serde_as(as = "serde_with::DisplayFromStr")]
    #[serde(default = "default_page")]
    pub page: u32,
    #[validate(range(min = -1, max = 100))]
    #[serde_as(as = "serde_with::DisplayFromStr")]
    #[serde(default = "default_page_size")]
    pub page_size: i32,
}

fn default_page() -> u32 {
    1
}

fn default_page_size() -> i32 {
    20
}

impl PaginationParams {
    /// 计算偏移量
    pub fn offset(&self) -> u32 {
        (self.page - 1) * self.page_size.max(0) as u32
    }
}