Drover's back, baby!

go/src/infra/tools/drover/main.go

Index: go/src/infra/tools/drover/main.go
diff --git a/go/src/infra/tools/drover/main.go b/go/src/infra/tools/drover/main.go
new file mode 100644
index 0000000000000000000000000000000000000000..d4da4553eafda133f2ad930cfa05738ccb3e05ca
--- /dev/null
+++ b/go/src/infra/tools/drover/main.go
@@ -0,0 +1,215 @@
+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+package main
+
+import (
+	"bufio"
+	"flag"
+	"fmt"
+	"io/ioutil"
+	"os"
+	"strings"
+
+	"github.com/daviddengcn/go-colortext"
+
+	"infra/libs/git"
+	"infra/libs/git/repo"
+	"infra/libs/gitiles"
+)
+
+var commitish = flag.String("commit", "", "The commit to process (or commit position number).")
+var action = flag.String("action", "", "The action to take. Must specify `cherry-pick|revert`.")
+var ref = flag.String("ref", "", "The target ref to change.")
+var workdir string
+
+func getCodereviewSettings(g *gitiles.Gitiles, ref string) (ret map[string]string) {
+	crSettings, err := g.Text("+", ref, "codereview.settings")
+	if err == nil {
+		lines := strings.Split(string(crSettings), "\n")
+		ret = make(map[string]string, len(lines))
+		for _, line := range lines {
+			if len(line) == 0 || line[0] == '#' {
+				continue
+			}
+			keyVal := strings.Split(line, ":")
+			if len(keyVal) == 2 {
+				ret[keyVal[0]] = strings.TrimSpace(keyVal[1])
+			}
+		}
+	}
+	return ret
+}
+
+func getLandingCommit(g *gitiles.Gitiles, ref string, settings map[string]string) (*git.Commit, string) {
+	prefix, ok := settings["PENDING_REF_PREFIX"]
+	if ok {
+		ref = strings.Replace(ref, "refs/", prefix, 1)
+	}
+	result, err := g.GetObjectFromPath(ref)
+	failIf(err)
+	if result.Type() != git.CommitType {
+		panic(fmt.Errorf("ref points at non-commit? %#v", result))
+	}
+	return result.(*git.Commit), ref
+}
+
+func confirmAction(URL, action, ref string, commit *git.Commit, diff string) {
+	verbPart := "to"
+	if action == "revert" {
+		verbPart = "from"
+	}
+
+	fmt.Printf("Planning to %s commit %s %s %s in %s:\n\n",
+		action, commit.ID(), verbPart, ref, URL)
+
+	ct.ChangeColor(ct.Yellow, false, ct.None, false)
+	fmt.Println("commit", commit.ID())
+	ct.ResetColor()
+	fmt.Printf("Author: %s <%s>\n", commit.Author().Name, commit.Author().Email)
+	fmt.Printf("Date: %s\n", commit.Author().Time)
+	fmt.Println()
+	for _, l := range commit.MessageLines() {
+		fmt.Printf("    %s\n", l)
+	}
+	fmt.Println()
+	for _, pair := range commit.FooterPairs() {
+		ct.ChangeColor(ct.White, true, ct.None, false)
+		fmt.Printf("    %s: ", pair.Key)
+		ct.ResetColor()
+		fmt.Println(pair.Value)
+	}
+	fmt.Println()
+	for _, line := range strings.Split(diff, "\n") {
+		if len(line) > 0 {
+			switch {
+			case strings.HasPrefix(line, "+++") || strings.HasPrefix(line, "---"):
+				ct.ChangeColor(ct.White, true, ct.None, false)
+			case line[0] == '@':
+				ct.ChangeColor(ct.Cyan, false, ct.None, false)
+				bits := strings.SplitN(line, "@@", 3)
+				fmt.Print("@@", bits[1], "@@")
+				ct.ResetColor()
+				fmt.Println(bits[2])
+				continue
+			case line[0] == '+':
+				ct.ChangeColor(ct.Green, false, ct.None, false)
+			case line[0] == '-':
+				ct.ChangeColor(ct.Red, false, ct.None, false)
+			case line[0] == ' ':
+				ct.ResetColor()
+			default:
+				ct.ChangeColor(ct.White, true, ct.None, false)
+			}
+		}
+		fmt.Println(line)
+	}
+	ct.ResetColor()
+
+	fmt.Println()
+	fmt.Printf("Continue? [y/N] ")
+	answerRaw, err := bufio.NewReader(os.Stdin).ReadBytes('\n')
+	failIf(err)
+
+	answer := strings.TrimSpace(string(answerRaw))
+
+	if len(answer) != 0 && strings.HasPrefix("yes", strings.ToLower(answer)) {
+		return
+	}
+
+	fmt.Println("Action aborted")
+	os.Exit(1)
+}
+
+func getCommitData(g *gitiles.Gitiles, gitSha string) (*git.Commit, git.TreeDiff) {
+	commitRslt, err := g.GetObjectFromPath(gitSha)
+	failIf(err)
+
+	commit, ok := commitRslt.(*git.Commit)
+	if !ok {
+		failIf(fmt.Errorf("%s is not a commit?", gitSha))
+	}
+
+	commitDiffRslt, err := g.GetCommitDiff(gitSha)
+	failIf(err)
+
+	return commit, commitDiffRslt
+}
+
+func main() {
+	cwd, err := os.Getwd()
+	if err != nil {
+		panic(err)
+	}
+	flag.StringVar(&workdir, "workdir", cwd, "The work directory to use.")
+
+	flag.Usage = func() {
+		fmt.Println("Usage: git drover -commit deadbeef -action cherry-pick -ref 2125")
+		flag.PrintDefaults()
+	}
+	flag.Parse()
+	if *commitish == "" || *action == "" || *ref == "" {
+		flag.PrintDefaults()
+		fmt.Println("must specify commitish, action and ref")
+		os.Exit(1)
+	}
+	if *action != "cherry-pick" && *action != "revert" {
+		flag.PrintDefaults()
+		fmt.Printf(
+			"must action must be 'cherry-pick' or 'revert'. Got '%s'.\n", *action)
+		os.Exit(1)
+	}
+
+	repo := repo.NewRepo(workdir)
+	if repo.RunOk("rev-parse", "--git-dir") {
+		if repo.RunOutputS("config", "drover.repo") != "true" {
+			fmt.Println("must be run from an empty directory or a drover git repo")
+			os.Exit(1)
+		}
+	} else {
+		files, err := ioutil.ReadDir(workdir)
+		failIf(err)
+		if len(files) == 0 {
+			fmt.Println("Initializing current directory as a drover git repo")
+			repo.MustRunOk("init")
+			repo.MustRunOk("config", "drover.repo", "true")
+		} else {
+			flag.PrintDefaults()
+			fmt.Println("must be run from an empty directory or a drover git repo")
+			os.Exit(1)
+		}
+	}
+
+	gitSha, gitilesURL, err := disambiguateCommit(*commitish)
+	failIf(err)
+
+	g := gitiles.NewGitiles(gitilesURL, 8)
+
+	*ref, err = disambiguateRef(g, gitSha, *ref)
+	failIf(err)
+
+	commit, treeDiff := getCommitData(g, gitSha)
+	textDiff, err := g.GetTextCommitDiff(commit.ID())
+	failIf(err)
+
+	settings := getCodereviewSettings(g, *ref)
+	landCommit, real_ref := getLandingCommit(g, *ref, settings)
+
+	confirmAction(g.URL(), *action, *ref, commit, textDiff)
+
+	acquireObjects(repo, g, commit, landCommit, treeDiff)
+
+	var left, right *git.ObjectID
+	if *action == "cherry-pick" {
+		left, right = commit.Parents()[0], commit.ID()
+	} else if *action == "revert" {
+		right, left = commit.Parents()[0], commit.ID()
+	}
+	toPush := createCommit(*action, repo, left, right, landCommit.ID())
+	id := toPush.ID().String()
+
+	diff, err := repo.GetTextDiff(id+"~", id)
+	failIf(err)
+
+	confirmAction(g.URL(), "push", real_ref, toPush, diff)
+}