main.go

package main

import (
	"context"
	"encoding/json"
	"fmt"
	"log"
	"net/http"
	"os"
	"time"

	"github.com/bwmarrin/discordgo"
	"github.com/joho/godotenv"
	"golang.org/x/oauth2"
	"golang.org/x/oauth2/google"
	"google.golang.org/api/drive/v3"
	"google.golang.org/api/option"
)

const (
	googleCredentials = "./google-drive-credentials.json"
)

func main() {
	godotenv.Load(".env")
	discordToken := os.Getenv("DISCORD_TOKEN")
	discordChannelID := os.Getenv("DISCORD_CHANNEL_ID")
	fileID := os.Getenv("GOOGLE_DRIVE_FILE_ID")

	// Start Discord bot
	dg, err := discordgo.New("Bot " + discordToken)
	if err != nil {
		log.Fatalf("Error creating Discord session: %v", err)
	}

	err = dg.Open()
	if err != nil {
		log.Fatalf("Error opening Discord session: %v", err)
	}
	defer dg.Close()

	// Setup Google Drive API client
	b, err := os.ReadFile(googleCredentials)
	if err != nil {
		log.Fatalf("Unable to read client secret file: %v", err)
	}

	config, err := google.ConfigFromJSON(b, drive.DriveMetadataReadonlyScope)
	if err != nil {
		log.Fatalf("Unable to parse client secret file to config: %v", err)
	}

	client := getClient(config)
	// srv, err := drive.New(client)
	ctx := context.Background()
	srv, err := drive.NewService(ctx, option.WithHTTPClient(client))
	if err != nil {
		log.Fatalf("Unable to retrieve Drive client: %v", err)
	}

	// Monitor file updates
	lastModifiedTime := time.Now()
	for {

		// Get file metadata with specific fields
		file, err := srv.Files.Get(fileID).Fields("modifiedTime").Do()
		if err != nil {
			log.Printf("Unable to retrieve file metadata: %v", err)
			continue
		}

		modifiedTime, err := time.Parse(time.RFC3339, file.ModifiedTime)
		if err != nil {
			log.Printf("Unable to parse modified time: %v", err)
			continue
		}

		if modifiedTime.After(lastModifiedTime) {
			lastModifiedTime = modifiedTime

			message := fmt.Sprintf("Novo APK disponivel!\n[Link Acesso](https://drive.google.com/file/d/1-C8KRfua1gqy-wj81e9oTyeWmzYO6oS3/view?usp=sharing)")
			_, err := dg.ChannelMessageSend(discordChannelID, message)
			if err != nil {
				log.Printf("Unable to send message to Discord: %v", err)
			}
		}
		time.Sleep(5 * time.Second)
	}
}

// Retrieve a token, saves the token, then returns the generated client.
func getClient(config *oauth2.Config) *http.Client {
	tokenFile := "token.json"
	tok, err := tokenFromFile(tokenFile)
	if err != nil {
		tok = getTokenFromWeb(config)
		saveToken(tokenFile, tok)
	}
	return config.Client(context.Background(), tok)
}

// Request a token from the web, then returns the retrieved token.
func getTokenFromWeb(config *oauth2.Config) *oauth2.Token {
	authURL := config.AuthCodeURL("state-token", oauth2.AccessTypeOffline)
	fmt.Printf("Go to the following link in your browser then type the authorization code: \n%v\n", authURL)

	var authCode string
	if _, err := fmt.Scan(&authCode); err != nil {
		log.Fatalf("Unable to read authorization code: %v", err)
	}

	tok, err := config.Exchange(context.Background(), authCode)
	if err != nil {
		log.Fatalf("Unable to retrieve token from web: %v", err)
	}
	return tok
}

// Retrieves a token from a local file.
func tokenFromFile(file string) (*oauth2.Token, error) {
	f, err := os.Open(file)
	if err != nil {
		return nil, err
	}
	defer f.Close()
	tok := &oauth2.Token{}
	err = json.NewDecoder(f).Decode(tok)
	return tok, err
}

// Saves a token to a file path.
func saveToken(path string, token *oauth2.Token) {
	fmt.Printf("Saving credential file to: %s\n", path)
	f, err := os.Create(path)
	if err != nil {
		log.Fatalf("Unable to cache oauth token: %v", err)
	}
	defer f.Close()
	json.NewEncoder(f).Encode(token)
}