main.go

package main

import (
	"flag"
	"fmt"
	"math/rand"
	"sync"
	"time"

	"os"

	log "github.com/sirupsen/logrus"
	"gorm.io/gorm"
)

// initialize logging
func init() {
	log.SetFormatter(&log.TextFormatter{
		DisableColors: true,
	})
	log.SetOutput(os.Stdout)
}

// AppName to store application name
var AppName string = "restockbot"

// AppVersion to set version at compilation time
var AppVersion string = "9999"

// GitCommit to set git commit at compilation time (can be empty)
var GitCommit string

// GoVersion to set Go version at compilation time
var GoVersion string

func main() {

	rand.Seed(time.Now().UnixNano())

	var err error
	config := NewConfig()

	version := flag.Bool("version", false, "Print version and exit")
	quiet := flag.Bool("quiet", false, "Log errors only")
	verbose := flag.Bool("verbose", false, "Print more logs")
	debug := flag.Bool("debug", false, "Print even more logs")
	databaseFileName := flag.String("database", AppName+".db", "Database file name")
	configFileName := flag.String("config", AppName+".json", "Configuration file name")
	logFileName := flag.String("log-file", "", "Log file name")
	disableNotifications := flag.Bool("disable-notifications", false, "Do not send notifications")
	workers := flag.Int("workers", 1, "Number of workers for parsing shops")
	pidFile := flag.String("pid-file", "", "Write process ID to this file to disable concurrent executions")
	pidWaitTimeout := flag.Int("pid-wait-timeout", 0, "Seconds to wait before giving up when another instance is running")
	retention := flag.Int("retention", 0, "Automatically remove products from the database with this number of days old (disabled by default)")
	api := flag.Bool("api", false, "Start the HTTP API")
	monitor := flag.Bool("monitor", false, "Perform health check with Nagios output")
	warningTimeout := flag.Int("monitor-warning-timeout", 300, "Raise a warning alert when the last execution time has reached this number of seconds (see -monitor)")
	criticalTimeout := flag.Int("monitor-critical-timeout", 600, "Raise a critical alert when the last execution time has reached this number of seconds (see -monitor)")

	flag.Parse()

	if *version {
		showVersion()
		return
	}

	log.SetLevel(log.WarnLevel)
	if *debug {
		log.SetLevel(log.DebugLevel)
	}
	if *verbose {
		log.SetLevel(log.InfoLevel)
	}
	if *quiet {
		log.SetLevel(log.ErrorLevel)
	}

	if *logFileName != "" {
		fd, err := os.OpenFile(*logFileName, os.O_WRONLY|os.O_CREATE|os.O_APPEND, 0644)
		if err != nil {
			fmt.Printf("cannot open file for logging: %s\n", err)
		}
		log.SetOutput(fd)
	}

	if *configFileName != "" {
		err = config.Read(*configFileName)
		if err != nil {
			log.Fatalf("cannot parse configuration file: %s", err)
		}
	}
	log.Debugf("configuration file %s parsed", *configFileName)

	// handle PID file
	if *pidFile != "" {
		if err := waitPid(*pidFile, *pidWaitTimeout); err != nil {
			log.Warnf("%s", err)
			return
		}
		if err := writePid(*pidFile); err != nil {
			log.Fatalf("cannot write PID file: %s", err)
		}
		defer removePid(*pidFile)
	}

	// connect to the database
	var db *gorm.DB
	if config.HasDatabase() {
		db, err = NewDatabaseFromConfig(config.DatabaseConfig)
	} else {
		db, err = NewDatabaseFromFile(*databaseFileName)
	}
	if err != nil {
		log.Fatalf("cannot connect to database: %s", err)
	}
	log.Debugf("connected to database")

	// create tables
	if err := db.AutoMigrate(&Product{}); err != nil {
		log.Fatalf("cannot create products table")
	}
	if err := db.AutoMigrate(&Shop{}); err != nil {
		log.Fatalf("cannot create shops table")
	}

	// delete products not updated since retention
	if *retention != 0 {
		var oldProducts []Product
		retentionDate := time.Now().Local().Add(-time.Hour * 24 * time.Duration(*retention))
		trx := db.Where("updated_at < ?", retentionDate).Find(&oldProducts)
		if trx.Error != nil {
			log.Warnf("cannot find stale products: %s", trx.Error)
		}
		for _, p := range oldProducts {
			log.Debugf("found old product: %s", p.Name)
			if trx = db.Unscoped().Delete(&p); trx.Error != nil {
				log.Warnf("cannot remove stale product %s (%s): %s", p.Name, p.URL, trx.Error)
			} else {
				log.Printf("stale product %s (%s) removed from database", p.Name, p.URL)
			}
		}
	}

	// start monitoring
	if *monitor {
		os.Exit(Monitor(db, *warningTimeout, *criticalTimeout))
	}

	// start the api
	if *api {
		log.Fatal(StartAPI(db, config.APIConfig))
	}

	// register notifiers
	notifiers := []Notifier{}

	if !*disableNotifications {
		if config.HasTwitter() {
			twitterNotifier, err := NewTwitterNotifier(&config.TwitterConfig, db)
			if err != nil {
				log.Fatalf("cannot create twitter client: %s", err)
			}
			notifiers = append(notifiers, twitterNotifier)
		}
		if config.HasTelegram() {
			telegramNotifier, err := NewTelegramNotifier(&config.TelegramConfig, db)
			if err != nil {
				log.Fatalf("cannot create telegram client: %s", err)
			}
			notifiers = append(notifiers, telegramNotifier)
		}
	}

	// register filters
	filters := []Filter{}
	if config.IncludeRegex != "" {
		includeFilter, err := NewIncludeFilter(config.IncludeRegex)
		if err != nil {
			log.Fatalf("cannot create include filter: %s", err)
		}
		filters = append(filters, includeFilter)
	}
	if config.ExcludeRegex != "" {
		excludeFilter, err := NewExcludeFilter(config.ExcludeRegex)
		if err != nil {
			log.Fatalf("cannot create exclude filter: %s", err)
		}
		filters = append(filters, excludeFilter)
	}
	if len(config.PriceRanges) > 0 {
		converter := NewCurrencyConverter()
		for _, pr := range config.PriceRanges {
			rangeFilter, err := NewRangeFilter(pr.Model, pr.Min, pr.Max, pr.Currency, converter)
			if err != nil {
				log.Fatalf("cannot create price range filter: %s", err)
			}
			filters = append(filters, rangeFilter)
		}
	}

	// create parsers
	parsers := []Parser{}

	if config.HasURLs() {
		// create a parser for all web pages
		for _, url := range config.URLs {
			parser := NewURLParser(url, config.BrowserAddress)
			parsers = append(parsers, parser)
			log.Debugf("parser %s registered", parser)
		}
	}

	if config.HasAmazon() {
		// create a parser for all marketplaces
		for _, marketplace := range config.AmazonConfig.Marketplaces {
			parser := NewAmazonParser(marketplace.Name, marketplace.PartnerTag, config.AmazonConfig.AccessKey, config.AmazonConfig.SecretKey, config.AmazonConfig.Searches, config.AmazonConfig.AmazonFulfilled, config.AmazonConfig.AmazonMerchant, config.AmazonConfig.AffiliateLinks)
			if err != nil {
				log.Warnf("could not create Amazon parser for marketplace %s: %s", marketplace, err)
				continue
			}

			parsers = append(parsers, parser)
			log.Debugf("parser %s registered", parser)
		}
	}

	if config.HasNvidiaFE() {
		// create a parser for all locations
		for _, location := range config.NvidiaFEConfig.Locations {
			parser, err := NewNvidiaFRParser(location, config.NvidiaFEConfig.GPUs, config.NvidiaFEConfig.UserAgent, config.NvidiaFEConfig.Timeout)
			if err != nil {
				log.Warnf("could not create NVIDIA FE parser for location %s: %s", location, err)
				continue
			}

			parsers = append(parsers, parser)
			log.Debugf("parser %s registered", parser)
		}
	}

	// parse asynchronously
	var wg sync.WaitGroup
	jobsCount := 0

	for _, parser := range parsers {
		for {
			if jobsCount < *workers {
				wg.Add(1)
				jobsCount++
				go handleProducts(parser, notifiers, filters, db, &wg)
				break
			} else {
				log.Debugf("waiting for intermediate jobs to end")
				wg.Wait()
				jobsCount = 0
			}
		}
	}

	log.Debugf("waiting for all jobs to end")
	wg.Wait()
}

// For parser to return a list of products, then eventually send notifications
func handleProducts(parser Parser, notifiers []Notifier, filters []Filter, db *gorm.DB, wg *sync.WaitGroup) {
	defer wg.Done()

	log.Debugf("parsing with %s", parser)

	// read shop from database or create it
	var shop Shop
	shopName, err := parser.ShopName()
	if err != nil {
		log.Warnf("cannot extract shop name from parser: %s", err)
		return
	}
	trx := db.Where(Shop{Name: shopName}).FirstOrCreate(&shop)
	if trx.Error != nil {
		log.Warnf("cannot create or select shop %s to/from database: %s", shopName, trx.Error)
		return
	}

	// parse products
	products, err := parser.Parse()
	if err != nil {
		log.Warnf("cannot parse: %s", err)
		return
	}

	for _, product := range products {

		// skip products not matching all filters
		included := true
		for _, filter := range filters {
			if included && !filter.Include(product) {
				included = false
				continue
			}
		}
		if !included {
			continue
		}

		log.Debugf("detected product %+v", product)

		if !product.IsValid() {
			log.Warnf("parsed malformatted product: %+v", product)
			continue
		}

		// check if product is already in the database
		// sometimes new products are detected on the website, directly available, without reference in the database
		// the bot has to send a notification instead of blindly creating it in the database and check availability afterwards
		var count int64
		trx := db.Model(&Product{}).Where(Product{URL: product.URL}).Count(&count)
		if trx.Error != nil {
			log.Warnf("cannot see if product %s already exists in the database: %s", product.Name, trx.Error)
			continue
		}

		// fetch product from database or create it if it doesn't exist
		var dbProduct Product
		trx = db.Where(Product{URL: product.URL}).Attrs(Product{Name: product.Name, Shop: shop, Price: product.Price, PriceCurrency: product.PriceCurrency, Available: product.Available}).FirstOrCreate(&dbProduct)
		if trx.Error != nil {
			log.Warnf("cannot fetch product %s from database: %s", product.Name, trx.Error)
			continue
		}
		log.Debugf("product %s found in database", dbProduct.Name)

		// detect availability change
		duration := time.Now().Sub(dbProduct.UpdatedAt).Truncate(time.Second)
		createThread := false
		closeThread := false

		// non-existing product directly available
		if count == 0 && product.Available {
			log.Infof("product %s on %s is now available", product.Name, shop.Name)
			createThread = true
		}

		// existing product with availability change
		if count > 0 && (dbProduct.Available != product.Available) {
			if product.Available {
				log.Infof("product %s on %s is now available", product.Name, shop.Name)
				createThread = true
			} else {
				log.Infof("product %s on %s is not available anymore", product.Name, shop.Name)
				closeThread = true
			}
		}

		// update product in database before sending notification
		// if there is a database failure, we don't want the bot to send a notification at each run
		if dbProduct.ToMerge(product) {
			dbProduct.Merge(product)
			trx = db.Save(&dbProduct)
			if trx.Error != nil {
				log.Warnf("cannot save product %s to database: %s", dbProduct.Name, trx.Error)
				continue
			}
			log.Debugf("product %s updated in database", dbProduct.Name)
		}

		// send notifications
		if duration > 0 {
			if createThread {
				for _, notifier := range notifiers {
					if err := notifier.NotifyWhenAvailable(shop.Name, dbProduct.Name, dbProduct.Price, dbProduct.PriceCurrency, dbProduct.URL); err != nil {
						log.Errorf("%s", err)
					}
				}
			} else if closeThread {
				for _, notifier := range notifiers {
					if err := notifier.NotifyWhenNotAvailable(dbProduct.URL, duration); err != nil {
						log.Errorf("%s", err)
					}
				}
			}
		}

		// keep track of active products
		dbProduct.UpdatedAt = time.Now().Local()
		if trx := db.Save(&dbProduct); trx.Error != nil {
			log.Warnf("cannot update product %s to database: %s", dbProduct.Name, trx.Error)
		}

	}
}

func showVersion() {
	if GitCommit != "" {
		AppVersion = fmt.Sprintf("%s-%s", AppVersion, GitCommit)
	}
	fmt.Printf("%s version %s (compiled with %s)\n", AppName, AppVersion, GoVersion)
}