cmd/releasebot: add modes for making a release tweet programmatically

This allows exercising (and benefiting from improvements offered by)
the programmatic tweet creation tasks as soon as the next minor release.
The same task will be added and used by relui when possible.

For golang/go#40279.
Updates golang/go#47403.

Change-Id: I8b47f86489e753bea6a767990ff98dd525e668df
Reviewed-on: https://go-review.googlesource.com/c/build/+/358899
Run-TryBot: Dmitri Shuralyov <dmitshur@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Trust: Dmitri Shuralyov <dmitshur@golang.org>
Trust: Alexander Rakoczy <alex@golang.org>
Reviewed-by: Alexander Rakoczy <alex@golang.org>

cmd/releasebot/main.go

@@ -11,6 +11,7 @@ import (
 	"context"
 	"crypto/sha1"
 	"crypto/sha256"
+	"encoding/json"
 	"errors"
 	"flag"
 	"fmt"
@@ -30,6 +31,7 @@ import (
 	"golang.org/x/build/buildenv"
 	"golang.org/x/build/internal/envutil"
 	"golang.org/x/build/internal/task"
+	"golang.org/x/build/internal/workflow"
 	"golang.org/x/build/maintner"
 )
 
@@ -69,13 +71,19 @@ var releaseTargets = []Target{
 }
 
 var releaseModes = map[string]bool{
-	"prepare":    true,
-	"release":    true,
+	"prepare": true,
+	"release": true,
+
 	"mail-dl-cl": true,
+
+	"tweet-minor": true,
+	"tweet-beta":  true,
+	"tweet-rc":    true,
+	"tweet-major": true,
 }
 
 func usage() {
-	fmt.Fprintln(os.Stderr, "usage: releasebot -mode {prepare|release|mail-dl-cl} [-security] [-dry-run] {go1.8.5|go1.10beta2|go1.11rc1}")
+	fmt.Fprintln(os.Stderr, "usage: releasebot -mode {prepare|release|mail-dl-cl|tweet-{minor,beta,rc,major}} [-security] [-dry-run] {go1.8.5|go1.10beta2|go1.11rc1}")
 	flag.PrintDefaults()
 	os.Exit(2)
 }
@@ -101,6 +109,10 @@ func main() {
 	} else if *modeFlag == "mail-dl-cl" {
 		mailDLCL()
 		return
+	} else if strings.HasPrefix(*modeFlag, "tweet-") {
+		kind := (*modeFlag)[len("tweet-"):]
+		postTweet(kind)
+		return
 	} else if flag.NArg() != 1 {
 		fmt.Fprintln(os.Stderr, "need to provide a release name")
 		usage()
@@ -200,9 +212,11 @@ func mailDLCL() {
 	}
 	changeURL, err := task.MailDLCL(context.Background(), versions)
 	if err != nil {
-		log.Fatalf(`task.MailDLCL(ctx, %#v) failed: %v
+		log.Fatalf(`task.MailDLCL(ctx, %#v) failed:
+
+	%v
 
-If it's neccessary to perform it manually as a workaround,
+If it's necessary to perform it manually as a workaround,
 consider the following steps:
 
 	git clone https://go.googlesource.com/dl && cd dl
@@ -216,6 +230,71 @@ Discuss with the secondary release coordinator as needed.`, versions, err)
 	fmt.Printf("\nPlease review and submit %s\nand then refer to the playbook for the next steps.\n\n", changeURL)
 }
 
+// postTweet parses command-line arguments for the tweet-* modes,
+// and runs it.
+// kind must be one of "minor", "beta", "rc", or "major".
+func postTweet(kind string) {
+	if flag.NArg() != 1 {
+		fmt.Fprintln(os.Stderr, "need to provide 1 release tweet JSON object")
+		usage()
+	}
+	var tweet task.ReleaseTweet
+	err := json.Unmarshal([]byte(flag.Arg(0)), &tweet)
+	if err != nil {
+		log.Fatalln("error parsing release tweet JSON object:", err)
+	}
+
+	versions := []string{tweet.Version}
+	if tweet.SecondaryVersion != "" {
+		versions = append(versions, tweet.SecondaryVersion+" (secondary)")
+	}
+	fmt.Printf("About to tweet about the release of the following Go versions:\n\n\t• %s\n\n", strings.Join(versions, "\n\t• "))
+	if tweet.Security != "" {
+		fmt.Printf("with the following security sentence (%d characters long):\n\n\t%s\n\n", len([]rune(tweet.Security)), tweet.Security)
+	} else {
+		fmt.Print("with no security fixes being mentioned,\n\n")
+	}
+	if tweet.Announcement != "" {
+		fmt.Printf("and with the following announcement URL:\n\n\t%s\n\n", tweet.Announcement)
+	}
+	fmt.Print("Ok? (Y/n) ")
+	var response string
+	_, err = fmt.Scanln(&response)
+	if err != nil {
+		log.Fatalln(err)
+	}
+	if response != "Y" && response != "y" {
+		log.Fatalln("stopped as requested")
+	}
+	tweetRelease := map[string]func(workflow.TaskContext, task.ReleaseTweet, bool) (string, error){
+		"minor": task.TweetMinorRelease,
+		"beta":  task.TweetBetaRelease,
+		"rc":    task.TweetRCRelease,
+		"major": task.TweetMajorRelease,
+	}[kind]
+	tweetURL, err := tweetRelease(workflow.TaskContext{Context: context.Background(), Logger: log.Default()}, tweet, dryRun)
+	if errors.Is(err, task.ErrTweetTooLong) && len([]rune(tweet.Security)) > 120 {
+		log.Fatalf(`A tweet was not created because it's too long.
+
+The provided security sentence is somewhat long (%d characters),
+so try making it shorter to avoid exceeding Twitter's limits.`, len([]rune(tweet.Security)))
+	} else if err != nil {
+		log.Fatalf(`tweetRelease(ctx, %#v) failed:
+
+	%v
+
+If it's necessary to perform it manually as a workaround,
+consider the following options:
+
+	• use the template displayed in the log above (if any)
+	• use the same format as the last tweet for the release
+	  of the same kind
+
+Discuss with the secondary release coordinator as needed.`, tweet, err)
+	}
+	fmt.Printf("\nPlease check that %s looks okay\nand then refer to the playbook for the next steps.\n\n", tweetURL)
+}
+
 // checkForGitCodereview exits the program if git-codereview is not installed
 // in the user's path.
 func checkForGitCodereview() {