// Copyright 2018 The Prometheus Authors
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

//go:build linux
// +build linux

package sysfs

import (
	"fmt"
	"os"
	"path/filepath"

	"github.com/prometheus/procfs/internal/util"
)

const netclassPath = "class/net"

// NetClassIface contains info from files in /sys/class/net/<iface>
// for single interface (iface).
type NetClassIface struct {
	Name             string // Interface name
	AddrAssignType   *int64 // /sys/class/net/<iface>/addr_assign_type
	AddrLen          *int64 // /sys/class/net/<iface>/addr_len
	Address          string // /sys/class/net/<iface>/address
	Broadcast        string // /sys/class/net/<iface>/broadcast
	Carrier          *int64 // /sys/class/net/<iface>/carrier
	CarrierChanges   *int64 // /sys/class/net/<iface>/carrier_changes
	CarrierUpCount   *int64 // /sys/class/net/<iface>/carrier_up_count
	CarrierDownCount *int64 // /sys/class/net/<iface>/carrier_down_count
	DevID            *int64 // /sys/class/net/<iface>/dev_id
	Dormant          *int64 // /sys/class/net/<iface>/dormant
	Duplex           string // /sys/class/net/<iface>/duplex
	Flags            *int64 // /sys/class/net/<iface>/flags
	IfAlias          string // /sys/class/net/<iface>/ifalias
	IfIndex          *int64 // /sys/class/net/<iface>/ifindex
	IfLink           *int64 // /sys/class/net/<iface>/iflink
	LinkMode         *int64 // /sys/class/net/<iface>/link_mode
	MTU              *int64 // /sys/class/net/<iface>/mtu
	NameAssignType   *int64 // /sys/class/net/<iface>/name_assign_type
	NetDevGroup      *int64 // /sys/class/net/<iface>/netdev_group
	OperState        string // /sys/class/net/<iface>/operstate
	PhysPortID       string // /sys/class/net/<iface>/phys_port_id
	PhysPortName     string // /sys/class/net/<iface>/phys_port_name
	PhysSwitchID     string // /sys/class/net/<iface>/phys_switch_id
	Speed            *int64 // /sys/class/net/<iface>/speed
	TxQueueLen       *int64 // /sys/class/net/<iface>/tx_queue_len
	Type             *int64 // /sys/class/net/<iface>/type
}

// NetClass is collection of info for every interface (iface) in /sys/class/net. The map keys
// are interface (iface) names.
type NetClass map[string]NetClassIface

// NetClassDevices scans /sys/class/net for devices and returns them as a list of names.
func (fs FS) NetClassDevices() ([]string, error) {
	var res []string
	path := fs.sys.Path(netclassPath)

	devices, err := os.ReadDir(path)
	if err != nil {
		return res, fmt.Errorf("cannot access dir %q: %w", path, err)
	}

	for _, deviceDir := range devices {
		if deviceDir.Type().IsRegular() {
			continue
		}
		res = append(res, deviceDir.Name())
	}

	return res, nil
}

// NetClassByIface returns info for a single net interfaces (iface).
func (fs FS) NetClassByIface(devicePath string) (*NetClassIface, error) {
	path := fs.sys.Path(netclassPath)

	interfaceClass, err := parseNetClassIface(filepath.Join(path, devicePath))
	if err != nil {
		return nil, err
	}
	interfaceClass.Name = devicePath

	return interfaceClass, nil
}

// NetClass returns info for all net interfaces (iface) read from /sys/class/net/<iface>.
func (fs FS) NetClass() (NetClass, error) {
	devices, err := fs.NetClassDevices()
	if err != nil {
		return nil, err
	}

	path := fs.sys.Path(netclassPath)
	netClass := NetClass{}
	for _, devicePath := range devices {
		interfaceClass, err := parseNetClassIface(filepath.Join(path, devicePath))
		if err != nil {
			return nil, err
		}
		interfaceClass.Name = devicePath
		netClass[devicePath] = *interfaceClass
	}

	return netClass, nil
}

// parseNetClassIface scans predefined files in /sys/class/net/<iface>
// directory and gets their contents.
func parseNetClassIface(devicePath string) (*NetClassIface, error) {
	interfaceClass := NetClassIface{}

	files, err := os.ReadDir(devicePath)
	if err != nil {
		return nil, err
	}

	for _, f := range files {
		if !f.Type().IsRegular() {
			continue
		}
		name := filepath.Join(devicePath, f.Name())
		value, err := util.SysReadFile(name)
		if err != nil {
			if os.IsNotExist(err) || os.IsPermission(err) || err.Error() == "operation not supported" || err.Error() == "invalid argument" {
				continue
			}
			return nil, fmt.Errorf("failed to read file %q: %w", name, err)
		}
		vp := util.NewValueParser(value)
		switch f.Name() {
		case "addr_assign_type":
			interfaceClass.AddrAssignType = vp.PInt64()
		case "addr_len":
			interfaceClass.AddrLen = vp.PInt64()
		case "address":
			interfaceClass.Address = value
		case "broadcast":
			interfaceClass.Broadcast = value
		case "carrier":
			interfaceClass.Carrier = vp.PInt64()
		case "carrier_changes":
			interfaceClass.CarrierChanges = vp.PInt64()
		case "carrier_up_count":
			interfaceClass.CarrierUpCount = vp.PInt64()
		case "carrier_down_count":
			interfaceClass.CarrierDownCount = vp.PInt64()
		case "dev_id":
			interfaceClass.DevID = vp.PInt64()
		case "dormant":
			interfaceClass.Dormant = vp.PInt64()
		case "duplex":
			interfaceClass.Duplex = value
		case "flags":
			interfaceClass.Flags = vp.PInt64()
		case "ifalias":
			interfaceClass.IfAlias = value
		case "ifindex":
			interfaceClass.IfIndex = vp.PInt64()
		case "iflink":
			interfaceClass.IfLink = vp.PInt64()
		case "link_mode":
			interfaceClass.LinkMode = vp.PInt64()
		case "mtu":
			interfaceClass.MTU = vp.PInt64()
		case "name_assign_type":
			interfaceClass.NameAssignType = vp.PInt64()
		case "netdev_group":
			interfaceClass.NetDevGroup = vp.PInt64()
		case "operstate":
			interfaceClass.OperState = value
		case "phys_port_id":
			interfaceClass.PhysPortID = value
		case "phys_port_name":
			interfaceClass.PhysPortName = value
		case "phys_switch_id":
			interfaceClass.PhysSwitchID = value
		case "speed":
			interfaceClass.Speed = vp.PInt64()
		case "tx_queue_len":
			interfaceClass.TxQueueLen = vp.PInt64()
		case "type":
			interfaceClass.Type = vp.PInt64()
		}
	}

	return &interfaceClass, nil
}
