main.go

package main

import (
	"context"
	"drive-sync/types"
	"drive-sync/utils"
	"errors"
	"path/filepath"
	"sync"
	"time"

	"encoding/json"
	"fmt"
	"log"
	"net/http"
	"os"

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

// Retrieve a token, saves the token, then returns the generated client.
func getClient(config *oauth2.Config) *http.Client {
	// The file token.json stores the user's access and refresh tokens, and is
	// created automatically when the authorization flow completes for the first
	// time.
	tokFile := "token.json"
	tok, err := tokenFromFile(tokFile)

	if err != nil {
		tok = getTokenFromWeb(config)
		saveToken(tokFile, 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: "+
		"\n%v\n\nEnter the authorization code below. If the last page errors you can find the auth code as the query param 'code' of the final oAuth page URL", authURL)

	fmt.Println("\n\nAuthorization Code:")

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

	tok, err := config.Exchange(context.TODO(), 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)

	if tok.Expiry.Unix() < time.Now().Unix() {
		return nil, errors.New("Could not reresh token")
	}

	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.OpenFile(path, os.O_RDWR|os.O_CREATE|os.O_TRUNC, 0600)
	if err != nil {
		log.Fatalf("Unable to cache oauth token: %v", err)
	}
	defer f.Close()
	json.NewEncoder(f).Encode(token)
}

func main() {
	godotenv.Load(".env")
	rootDriveId := os.Getenv("ROOT_DRIVE_ID")
	ctx := context.Background()
	b, err := os.ReadFile("credentials.json")

	_, fileFoundErr := os.Stat("./db.json")

	if os.IsNotExist(fileFoundErr) {
		emptyBrackets := []byte("{}")

		os.WriteFile("./db.json", emptyBrackets, 0644)
	}

	absFilePath, _ := filepath.Abs("./db.json")

	file, err := os.ReadFile(absFilePath)

	DB := types.DBContainer{
		Items: map[string]types.DBItem{},
	}

	if err != nil {
		log.Printf("Could not open DB: %v", err.Error())
	}

	json.Unmarshal(file, &DB)

	waitGroup := &sync.WaitGroup{}

	if err != nil {
		log.Fatalf("Unable to read client secret file: %v", err)
	}

	scopes := []string{"https://www.googleapis.com/auth/drive"}

	// If modifying these scopes, delete your previously saved token.json.
	config, err := google.ConfigFromJSON(b, scopes...)

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

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

	rootFolder, rootDirErr := srv.Files.Get(rootDriveId).Do()

	if rootDirErr != nil {
		log.Fatalf("Could not get root dir, error: %v", rootDirErr.Error())
	}

	utils.GetFoldersFolders(rootFolder, srv, "./backup", waitGroup, &DB)
	waitGroup.Wait()

	dataBytes, _ := json.Marshal(&DB)

	os.WriteFile(absFilePath, dataBytes, 0644)

	uploadWaitGroup := &sync.WaitGroup{}

	utils.CheckForUploadableFiles(srv, &DB, "./backup", uploadWaitGroup)
}