feat: implement payment order system (create-order, mock-confirm, get-quota)

src/db.rs

@@ -311,3 +311,96 @@ pub async fn update_user_profile(
         Err(e) => Err(format!("更新用户个人信息失败: {}", e)),
     }
 }
+
+// ===== 支付系统 DB 函数 =====
+
+/// 创建待支付订单
+pub async fn create_payment_order(
+    pool: &PgPool,
+    user_id: i32,
+    order_no: &str,
+    package_type: &str,
+    amount: i32,
+    expires_at: Option<chrono::DateTime<chrono::Utc>>,
+) -> Result<(), String> {
+    let query = r#"
+        INSERT INTO payment_orders (user_id, order_no, package_type, amount, expires_at)
+        VALUES ($1, $2, $3, $4, $5)
+    "#;
+
+    sqlx::query(query)
+        .bind(user_id)
+        .bind(order_no)
+        .bind(package_type)
+        .bind(amount)
+        .bind(expires_at)
+        .execute(pool)
+        .await
+        .map_err(|e| format!("创建订单失败: {}", e))?;
+
+    Ok(())
+}
+
+/// 确认订单支付（模拟）：更新订单状态 + 激活用户付费
+///
+/// 返回该订单的 expires_at（永久会员为 None）
+pub async fn confirm_payment_order(
+    pool: &PgPool,
+    order_no: &str,
+    user_id: i32,
+) -> Result<Option<chrono::DateTime<chrono::Utc>>, String> {
+    let row = sqlx::query_as::<_, (i32, String, Option<chrono::DateTime<chrono::Utc>>)>(
+        r#"SELECT user_id, status, expires_at FROM payment_orders WHERE order_no = $1"#,
+    )
+    .bind(order_no)
+    .fetch_optional(pool)
+    .await
+    .map_err(|e| format!("查询订单失败: {}", e))?;
+
+    let (order_user_id, status, expires_at) = match row {
+        Some(r) => r,
+        None => return Err("订单不存在".to_string()),
+    };
+
+    if order_user_id != user_id {
+        return Err("无权操作此订单".to_string());
+    }
+
+    if status != "pending" {
+        return Err("订单状态异常，无法确认支付".to_string());
+    }
+
+    sqlx::query(
+        r#"UPDATE payment_orders SET status = 'paid', paid_at = NOW() WHERE order_no = $1"#,
+    )
+    .bind(order_no)
+    .execute(pool)
+    .await
+    .map_err(|e| format!("更新订单状态失败: {}", e))?;
+
+    sqlx::query(
+        r#"UPDATE users SET is_paid = true, paid_expires_at = $1 WHERE id = $2"#,
+    )
+    .bind(expires_at)
+    .bind(user_id)
+    .execute(pool)
+    .await
+    .map_err(|e| format!("更新用户付费状态失败: {}", e))?;
+
+    Ok(expires_at)
+}
+
+/// 获取用户配额信息
+///
+/// 返回 (已用条数, 是否付费活跃, 到期时间)
+pub async fn get_user_quota(
+    pool: &PgPool,
+    user_id: i32,
+) -> Result<(i64, bool, Option<chrono::DateTime<chrono::Utc>>), String> {
+    let user = get_user_by_id(pool, user_id).await?;
+    let is_paid_active = user.is_paid
+        && (user.paid_expires_at.is_none()
+            || user.paid_expires_at.unwrap() > chrono::Utc::now());
+    let used = count_user_weather_data(pool, user_id).await?;
+    Ok((used, is_paid_active, user.paid_expires_at))
+}