box-o-sand/wherewhen/quickstart.go
2017-12-17 18:25:45 -05:00

138 lines
3.7 KiB
Go

package main
import (
"encoding/json"
"fmt"
"io/ioutil"
"log"
"net/http"
"net/url"
"os"
"os/user"
"path/filepath"
"time"
"golang.org/x/net/context"
"golang.org/x/oauth2"
"golang.org/x/oauth2/google"
"google.golang.org/api/calendar/v3"
)
// getClient uses a Context and Config to retrieve a Token
// then generate a Client. It returns the generated Client.
func getClient(ctx context.Context, config *oauth2.Config) *http.Client {
cacheFile, err := tokenCacheFile()
if err != nil {
log.Fatalf("Unable to get path to cached credential file. %v", err)
}
tok, err := tokenFromFile(cacheFile)
if err != nil {
tok = getTokenFromWeb(config)
saveToken(cacheFile, tok)
}
return config.Client(ctx, tok)
}
// getTokenFromWeb uses Config to request a Token.
// It 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 code string
if _, err := fmt.Scan(&code); err != nil {
log.Fatalf("Unable to read authorization code %v", err)
}
tok, err := config.Exchange(oauth2.NoContext, code)
if err != nil {
log.Fatalf("Unable to retrieve token from web %v", err)
}
return tok
}
// tokenCacheFile generates credential file path/filename.
// It returns the generated credential path/filename.
func tokenCacheFile() (string, error) {
usr, err := user.Current()
if err != nil {
return "", err
}
tokenCacheDir := filepath.Join(usr.HomeDir, ".credentials")
os.MkdirAll(tokenCacheDir, 0700)
return filepath.Join(tokenCacheDir,
url.QueryEscape("calendar-go-quickstart.json")), err
}
// tokenFromFile retrieves a Token from a given file path.
// It returns the retrieved Token and any read error encountered.
func tokenFromFile(file string) (*oauth2.Token, error) {
f, err := os.Open(file)
if err != nil {
return nil, err
}
t := &oauth2.Token{}
err = json.NewDecoder(f).Decode(t)
defer f.Close()
return t, err
}
// saveToken uses a file path to create a file and store the
// token in it.
func saveToken(file string, token *oauth2.Token) {
fmt.Printf("Saving credential file to: %s\n", file)
f, err := os.OpenFile(file, 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() {
ctx := context.Background()
b, err := ioutil.ReadFile("client_secret.json")
if err != nil {
log.Fatalf("Unable to read client secret file: %v", err)
}
// If modifying these scopes, delete your previously saved credentials
// at ~/.credentials/calendar-go-quickstart.json
config, err := google.ConfigFromJSON(b, calendar.CalendarReadonlyScope)
if err != nil {
log.Fatalf("Unable to parse client secret file to config: %v", err)
}
client := getClient(ctx, config)
srv, err := calendar.New(client)
if err != nil {
log.Fatalf("Unable to retrieve calendar Client %v", err)
}
t := time.Now().Format(time.RFC3339)
events, err := srv.Events.List("primary").ShowDeleted(false).
SingleEvents(true).TimeMin(t).MaxResults(10).OrderBy("startTime").Do()
if err != nil {
log.Fatalf("Unable to retrieve next ten of the user's events. %v", err)
}
fmt.Println("Upcoming events:")
if len(events.Items) > 0 {
for _, i := range events.Items {
var when string
// If the DateTime is an empty string the Event is an all-day Event.
// So only Date is available.
if i.Start.DateTime != "" {
when = i.Start.DateTime
} else {
when = i.Start.Date
}
fmt.Printf("%s (%s)\n", i.Summary, when)
}
} else {
fmt.Printf("No upcoming events found.\n")
}
}