Gmail delete by query

cmd_internal_auth.go

package internal

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

	"golang.org/x/oauth2"
)

// GetClient retrieve a token, saves the token, then returns the generated client.
func GetClient(ctx context.Context, config *oauth2.Config) (*http.Client, error) {
	// 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.
	// Don't leave in plain text for all to read...
	tokFile := "token.json"
	tok, err := tokenFromFile(tokFile)
	if err != nil {
		tok, err = getTokenFromWeb(ctx, config)
		if err != nil {
			return nil, err
		}
		if err = saveToken(tokFile, tok); err != nil {
			return nil, err
		}
	}
	return config.Client(ctx, tok), nil
}

// Request a token from the web, then returns the retrieved token.
func getTokenFromWeb(ctx context.Context, config *oauth2.Config) (*oauth2.Token, error) {
	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 {
		return nil, err
	}

	tok, err := config.Exchange(ctx, authCode)
	if err != nil {
		return nil, err
	}

	return tok, nil
}

// 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) error {
	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 {
		return err
	}
	defer f.Close()
	return json.NewEncoder(f).Encode(token)
}

cmd_main.go

package main

import (
	"fmt"
	"io/ioutil"
	"os"

	"github.com/ingcr3at1on/scrubox/cmd/internal"
	"github.com/ingcr3at1on/x/sigctx"
	"golang.org/x/net/context"
	"golang.org/x/oauth2/google"
	"google.golang.org/api/gmail/v1"
)

func deleteMessagesByQuery(srv *gmail.Service, query string) error {
	user := "me"
	call := srv.Users.Messages.List(user).Q(query)

	for {
		r, err := call.Do()
		if err != nil {
			return err
		}

		var ids []string
		for _, m := range r.Messages {
			ids = append(ids, m.Id)
		}

		if err = srv.Users.Messages.BatchDelete(user, &gmail.BatchDeleteMessagesRequest{
			Ids: ids,
		}).Do(); err != nil {
			return err
		}

		if r.NextPageToken == `` {
			break
		}

		call.PageToken(r.NextPageToken)
	}

	return nil
}

func main() {
	if len(os.Args) != 2 {
		fmt.Printf("usage: %s <gmail query string>", os.Args[0])
		os.Exit(1)
	}

	if err := sigctx.StartWith(func(ctx context.Context) error {
		// FIXME: don't hardcode.
		byt, err := ioutil.ReadFile("credentials.json")
		if err != nil {
			return err
		}

		// If modifying these scopes, delete your previously saved token.json.
		config, err := google.ConfigFromJSON(byt, gmail.MailGoogleComScope)
		if err != nil {
			return err
		}

		client, err := internal.GetClient(ctx, config)
		if err != nil {
			return err
		}

		srv, err := gmail.New(client)
		if err != nil {
			return err
		}

		if err := deleteMessagesByQuery(srv, os.Args[1]); err != nil {
			return err
		}

		return nil
	}); err != nil {
		fmt.Println(err)
		os.Exit(1)
	}
}