// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// `go mod` ignores file names for the purpose of resolving
// dependencies, and fdio doesn't build on not-Fuchsia.
// +build fuchsia

package net

import (
	"context"
	"sync"
	"syscall/zx"
	"syscall/zx/fdio"
	"syscall/zx/net/stack"
)

var stackHandle struct {
	mu struct {
		sync.Mutex
		h zx.Handle
	}
}

func stackClient() (stack.StackWithCtxInterface, error) {
	stackHandle.mu.Lock()
	defer stackHandle.mu.Unlock()

	if stackHandle.mu.h == zx.HandleInvalid {
		local, remote, err := zx.NewChannel(0)
		if err != nil {
			return stack.StackWithCtxInterface{}, err
		}
		if err := fdio.ServiceConnect("/svc/"+stack.StackName, zx.Handle(remote)); err != nil {
			return stack.StackWithCtxInterface{}, err
		}
		stackHandle.mu.h = zx.Handle(local)
	}
	return stack.StackWithCtxInterface{Channel: zx.Channel(stackHandle.mu.h)}, nil
}

// If the ifindex is zero, interfaceTable returns mappings of all
// network interfaces. Otherwise it returns a mapping of a specific interface.
func interfaceTable(ifindex int) ([]Interface, error) {
	c, err := stackClient()
	if err != nil {
		return nil, err
	}
	ifInfos, err := c.ListInterfaces(context.Background())
	if err != nil {
		return nil, err
	}
	ifs := make([]Interface, 0, len(ifInfos))
	for _, info := range ifInfos {
		ifs = append(ifs, Interface{
			// TODO(jayzhuang): fill `Flags` when they are all available in stack.InterfaceInfo.
			Index:        int(info.Id),
			MTU:          int(info.Properties.Mtu),
			Name:         info.Properties.Name,
			HardwareAddr: info.Properties.Mac.Octets[:],
		})
	}
	return ifs, nil
}

// If the ifi is nil, interfaceAddrTable returns addresses for all
// network interfaces. Otherwise it returns addresses for a specific interface.
func interfaceAddrTable(ifi *Interface) ([]Addr, error) {
	// TODO(44532): implement
	return nil, nil
}

// interfaceMulticastAddrTable returns addresses for a specific interface.
func interfaceMulticastAddrTable(ifi *Interface) ([]Addr, error) {
	// TODO(44532): implement
	return nil, nil
}