package cni

import (
	"fmt"

	"github.com/vishvananda/netlink"

	"github.com/guildhouse-co/kedge/internal/topology"
)

// attachUnderlayRoutes connects the host-side veth to VLAN bridge interfaces
// for underlay mode routing.
func attachUnderlayRoutes(hostVeth string, routes []SubnetRoute, topo *topology.MeshTopology) error {
	if len(routes) == 0 {
		return nil
	}

	hostLink, err := netlink.LinkByName(hostVeth)
	if err != nil {
		return fmt.Errorf("host veth %s not found: %w", hostVeth, err)
	}

	for _, route := range routes {
		bridgeName := route.Via // e.g., "vlan100"
		bridge, err := netlink.LinkByName(bridgeName)
		if err != nil {
			return fmt.Errorf("bridge %s not found for route %s: %w", bridgeName, route.Dst, err)
		}

		// Attach host veth to the VLAN bridge.
		if err := netlink.LinkSetMaster(hostLink, bridge); err != nil {
			return fmt.Errorf("failed to attach %s to bridge %s: %w", hostVeth, bridgeName, err)
		}
	}

	return nil
}