// Copyright 2019 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

package main

// Program to map Fuchsia devices to their associated serial connection on a
// controller machine.  Connects to all available serial connections on the
// controller machine, invokes `dlog` (kernel debug log) and attempts to
// extract nodename=(.*?) from netsvc start up.

import (
	"bufio"
	"context"
	"fmt"
	"io"
	"io/ioutil"
	"os/exec"
	"path"
	"regexp"
	"strings"
	"sync"
	"time"

	"go.fuchsia.dev/tools/logger"
	"go.fuchsia.dev/tools/serial"
)

const (
	// The default path under which /lib/udev/rules.d/60-serial.rules
	// will create serial device files with full identifiers.
	serialDir = "/dev/serial/by-id"
)

type DeviceInfo struct {
	mac      string
	nodename string
	serial   string
}

func getDeviceInfo(fPath string) (*DeviceInfo, error) {
	device, err := serial.Open(fPath)
	defer device.Close()
	if err != nil {
		return nil, err
	}

	if _, err = io.WriteString(device, "\ndlog\n"); err != nil {
		return nil, err
	}

	nodenameRe := regexp.MustCompile("nodename='(.*?)'")
	macRe := regexp.MustCompile("macaddr: ([0-9a-f]{2}[:]){5}([0-9a-f]{2})")

	scanner := bufio.NewScanner(device)
	info := &DeviceInfo{
		nodename: "",
		mac:      "",
		serial:   "",
	}
	for scanner.Scan() {
		line := scanner.Text()
		nodenameMatch := nodenameRe.FindStringSubmatch(line)
		macMatch := macRe.FindStringSubmatch(line)

		if nodenameMatch != nil {
			info.nodename = nodenameMatch[1]
		} else if macMatch != nil {
			info.mac = strings.Split(macMatch[0], " ")[1]
		}

		if info.nodename != "" && info.mac != "" {
			break
		}
	}

	if err := scanner.Err(); err != nil {
		return nil, err
	} else if info.nodename == "" && info.mac == "" {
		return nil, fmt.Errorf("info not found")
	}

	return info, nil
}

func runFastbootDevices() string {
	cmd := exec.Command("fastboot", "devices")
	output, err := cmd.Output()
	if err != nil {
		return ""
	}
	return strings.Split(string(output), "\t")[0]
}

func runFastbootReboot() error {
	cmd := exec.Command("fastboot", "reboot")
	return cmd.Run()
}

func getSerialNumber(fPath string) (string, error) {
	device, err := serial.Open(fPath)
	defer device.Close()
	if err != nil {
		return "", err
	}
	if _, err := io.WriteString(device, "\ndm reboot-bootloader\n"); err != nil {
		return "", err
	}
	time.Sleep(15 * time.Second)
	if serial := runFastbootDevices(); serial != "" {
		if err := runFastbootReboot(); err != nil {
			return "", err
		}
		return serial, nil
	}
	return "", fmt.Errorf("could not get device into fastboot")
}

func main() {
	ctx := context.Background()

	files, err := ioutil.ReadDir(serialDir)
	if err != nil {
		logger.Fatalf(ctx, "failed to readdir() %s: %s", serialDir, err)
	}

	mapping := make(map[string]*DeviceInfo)
	var mapLock sync.Mutex

	var wg sync.WaitGroup
	wg.Add(len(files))
	for _, f := range files {
		fPath := path.Join(serialDir, f.Name())
		go func() {
			defer wg.Done()
			info, err := getDeviceInfo(fPath)
			if err != nil {
				logger.Errorf(ctx, "could not get device info from %s: %v", fPath, err)
			} else {
				mapLock.Lock()
				mapping[fPath] = info
				mapLock.Unlock()
			}
		}()
	}
	wg.Wait()
	fmt.Printf("\n\nserial\tnodename\tmac\tfastbootSernum\n")
	for k, v := range mapping {
		serial, err := getSerialNumber(k)
		time.Sleep(30 * time.Second)
		if err != nil {
			fmt.Printf("err: %v\n", err)
			continue
		}
		v.serial = serial
		fmt.Printf("%s\t%s\t%s\t%s\n", k, v.nodename, v.mac, v.serial)
	}
}