//go:build linux

package tc

import (
	"github.com/vishvananda/netlink"
)

var (
	defaultQuantum uint32 = 1514
)

type Class struct {
	attrs    netlink.ClassAttrs
	rate     uint64
	quantum  uint32
	priority uint32
}

func NewClass() *Class {
	return &Class{}
}

func (c *Class) WithAttrs(attrs netlink.ClassAttrs) *Class {
	c.attrs = attrs
	return c
}

func (c *Class) WithRateLimit(rate uint64) *Class {
	c.rate = rate
	return c
}

func (c *Class) WithQuantum(quantum uint32) *Class {
	c.quantum = quantum
	return c
}

func (c *Class) WithPriority(priority uint32) *Class {
	c.priority = priority
	return c
}

func (c *Class) Add() error {
	class := c.Build()
	if err := netlink.ClassAdd(class); err != nil {
		return formatTcError("error creating class", class.Attrs().LinkIndex, class.Attrs().Parent, class.Attrs().Handle, err)
	}
	return nil
}

// atomic del/add on class
func (c *Class) Replace() error {
	class := c.Build()
	if err := netlink.ClassReplace(class); err != nil {
		return formatTcError("error replacing class", class.Attrs().LinkIndex, class.Attrs().Parent, class.Attrs().Handle, err)
	}
	return nil
}

func (c *Class) Delete() error {
	class := c.Build()
	if err := netlink.ClassDel(class); err != nil && !errorIsNotFound(err) {
		return err
	}
	return nil
}

func (c *Class) Build() netlink.Class {
	htbClassAttrs := netlink.HtbClassAttrs{}
	htbClassAttrs.Rate = c.rate
	htbClassAttrs.Ceil = c.rate
	htbClassAttrs.Prio = c.priority
	if c.quantum == 0 {
		htbClassAttrs.Quantum = defaultQuantum
	}
	return netlink.NewHtbClass(c.attrs, htbClassAttrs)
}