tools: Flesh out the gerrit package

Add more helpers for interfacing with Gerrit.

Move dawn-specific constants out to a new 'dawn' package. Keeps the
packages dawn-specific-free.

Bug: dawn:1342
Change-Id: Iaebe0b68d877340fc848d711c848d01705ddae57
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/86524
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Commit-Queue: Ben Clayton <bclayton@chromium.org>
Kokoro: Kokoro <noreply+kokoro@google.com>

tools/src/cmd/gerrit-stats/main.go

@@ -24,6 +24,7 @@ import (
 	"regexp"
 	"time"
 
+	"dawn.googlesource.com/dawn/tools/src/dawn"
 	"dawn.googlesource.com/dawn/tools/src/gerrit"
 	"dawn.googlesource.com/dawn/tools/src/git"
 )
@@ -90,7 +91,9 @@ func run() error {
 		after = before.Add(-time.Hour * time.Duration(24**daysFlag))
 	}
 
-	g, err := gerrit.New(gerrit.Config{Username: *gerritUser, Password: *gerritPass})
+	g, err := gerrit.New(dawn.GerritURL, gerrit.Credentials{
+		Username: *gerritUser, Password: *gerritPass,
+	})
 	if err != nil {
 		return err
 	}
@@ -154,8 +157,8 @@ func run() error {
 	}
 
 	fmt.Printf("\n")
-	fmt.Printf("Submitted query: %vq/%v\n", gerrit.URL, url.QueryEscape(submittedQuery))
+	fmt.Printf("Submitted query: %vq/%v\n", dawn.GerritURL, url.QueryEscape(submittedQuery))
-	fmt.Printf("Review query: %vq/%v\n", gerrit.URL, url.QueryEscape(reviewQuery))
+	fmt.Printf("Review query: %vq/%v\n", dawn.GerritURL, url.QueryEscape(reviewQuery))
 
 	return nil
 }

tools/src/cmd/snippets/main.go

@@ -23,6 +23,7 @@ import (
 	"strings"
 	"time"
 
+	"dawn.googlesource.com/dawn/tools/src/dawn"
 	"dawn.googlesource.com/dawn/tools/src/gerrit"
 	"dawn.googlesource.com/dawn/tools/src/git"
 )
@@ -87,7 +88,9 @@ func run() error {
 		after = before.Add(-time.Hour * time.Duration(24**daysFlag))
 	}
 
-	g, err := gerrit.New(gerrit.Config{Username: *gerritUser, Password: *gerritPass})
+	g, err := gerrit.New(dawn.GerritURL, gerrit.Credentials{
+		Username: *gerritUser, Password: *gerritPass,
+	})
 	if err != nil {
 		return err
 	}
@@ -103,7 +106,7 @@ func run() error {
 
 	changesByProject := map[string][]string{}
 	for _, change := range submitted {
-		str := fmt.Sprintf(`* [%s](%sc/%s/+/%d)`, change.Subject, gerrit.URL, change.Project, change.Number)
+		str := fmt.Sprintf(`* [%s](%sc/%s/+/%d)`, change.Subject, dawn.GerritURL, change.Project, change.Number)
 		changesByProject[change.Project] = append(changesByProject[change.Project], str)
 	}
 

tools/src/dawn/dawn.go

@@ -0,0 +1,19 @@
+// Copyright 2022 The Dawn Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Package dawn holds constants specific to the Dawn project
+package dawn
+
+// The Dawn gerrit URL
+const GerritURL = "https://dawn-review.googlesource.com/"

tools/src/gerrit/gerrit.go

@@ -12,78 +12,115 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-// gerrit provides helpers for obtaining information from Tint's gerrit instance
+// Package gerrit provides helpers for obtaining information from Tint's gerrit instance
 package gerrit
 
 import (
+	"flag"
 	"fmt"
 	"io/ioutil"
+	"net/url"
 	"os"
 	"regexp"
+	"strconv"
 	"strings"
 
 	"github.com/andygrunwald/go-gerrit"
 )
 
-const URL = "https://dawn-review.googlesource.com/"
+// Gerrit is the interface to gerrit
-
+type Gerrit struct {
-// G is the interface to gerrit
-type G struct {
 	client        *gerrit.Client
 	authenticated bool
 }
 
-type Config struct {
+// Credentials holds the user name and password used to access Gerrit.
+type Credentials struct {
 	Username string
 	Password string
 }
 
-func LoadCredentials() (user, pass string) {
+// Patchset refers to a single gerrit patchset
-	cookiesFile := os.Getenv("HOME") + "/.gitcookies"
+type Patchset struct {
-	if cookies, err := ioutil.ReadFile(cookiesFile); err == nil {
+	// Gerrit host
-		re := regexp.MustCompile(`dawn-review.googlesource.com\s+(?:FALSE|TRUE)[\s/]+(?:FALSE|TRUE)\s+[0-9]+\s+.\s+(.*)=(.*)`)
+	Host string
-		match := re.FindStringSubmatch(string(cookies))
+	// Gerrit project
-		if len(match) == 3 {
+	Project string
-			return match[1], match[2]
+	// Change ID
-		}
+	Change int
-	}
+	// Patchset ID
-	return "", ""
+	Patchset int
 }
 
-func New(cfg Config) (*G, error) {
+// ChangeInfo is an alias to gerrit.ChangeInfo
-	client, err := gerrit.NewClient(URL, nil)
+type ChangeInfo = gerrit.ChangeInfo
+
+// LatestPatchest returns the latest Patchset from the ChangeInfo
+func LatestPatchest(change *ChangeInfo) Patchset {
+	u, _ := url.Parse(change.URL)
+	ps := Patchset{
+		Host:     u.Host,
+		Project:  change.Project,
+		Change:   change.Number,
+		Patchset: change.Revisions[change.CurrentRevision].Number,
+	}
+	return ps
+}
+
+// RegisterFlags registers the command line flags to populate p
+func (p *Patchset) RegisterFlags(defaultHost, defaultProject string) {
+	flag.StringVar(&p.Host, "host", defaultHost, "gerrit host")
+	flag.StringVar(&p.Project, "project", defaultProject, "gerrit project")
+	flag.IntVar(&p.Change, "cl", 0, "gerrit change id")
+	flag.IntVar(&p.Patchset, "ps", 0, "gerrit patchset id")
+}
+
+// LoadCredentials attempts to load the gerrit credentials for the given gerrit
+// URL from the git cookies file. Returns an empty Credentials on failure.
+func LoadCredentials(url string) Credentials {
+	cookiesFile := os.Getenv("HOME") + "/.gitcookies"
+	if cookies, err := ioutil.ReadFile(cookiesFile); err == nil {
+		url := strings.TrimPrefix(url, "https://")
+		re := regexp.MustCompile(url + `\s+(?:FALSE|TRUE)[\s/]+(?:FALSE|TRUE)\s+[0-9]+\s+.\s+(.*)=(.*)`)
+		match := re.FindStringSubmatch(string(cookies))
+		if len(match) == 3 {
+			return Credentials{match[1], match[2]}
+		}
+	}
+	return Credentials{}
+}
+
+// New returns a new Gerrit instance. If credentials are not provided, then
+// New() will automatically attempt to load them from the gitcookies file.
+func New(url string, cred Credentials) (*Gerrit, error) {
+	client, err := gerrit.NewClient(url, nil)
 	if err != nil {
 		return nil, fmt.Errorf("couldn't create gerrit client: %w", err)
 	}
 
-	user, pass := cfg.Username, cfg.Password
+	if cred.Username == "" {
-	if user == "" {
+		cred = LoadCredentials(url)
-		user, pass = LoadCredentials()
 	}
 
-	if user != "" {
+	if cred.Username != "" {
-		client.Authentication.SetBasicAuth(user, pass)
+		client.Authentication.SetBasicAuth(cred.Username, cred.Password)
 	}
 
-	return &G{client, user != ""}, nil
+	return &Gerrit{client, cred.Username != ""}, nil
 }
 
-func (g *G) QueryChanges(queryParts ...string) (changes []gerrit.ChangeInfo, query string, err error) {
+// QueryChanges returns the changes that match the given query strings.
+// See: https://gerrit-review.googlesource.com/Documentation/user-search.html#search-operators
+func (g *Gerrit) QueryChanges(querys ...string) (changes []gerrit.ChangeInfo, query string, err error) {
 	changes = []gerrit.ChangeInfo{}
-	query = strings.Join(queryParts, "+")
+	query = strings.Join(querys, "+")
 	for {
 		batch, _, err := g.client.Changes.QueryChanges(&gerrit.QueryChangeOptions{
 			QueryOptions: gerrit.QueryOptions{Query: []string{query}},
 			Skip:         len(changes),
 		})
 		if err != nil {
-			if !g.authenticated {
+			return nil, "", g.maybeWrapError(err)
-				err = fmt.Errorf(`query failed, possibly because of authentication.
-	See https://dawn-review.googlesource.com/new-password for obtaining a username
-	and password which can be provided with --gerrit-user and --gerrit-pass.
-	%w`, err)
-			}
-			return nil, "", err
 		}
 
 		changes = append(changes, *batch...)
@@ -93,3 +130,96 @@ func (g *G) QueryChanges(queryParts ...string) (changes []gerrit.ChangeInfo, que
 	}
 	return changes, query, nil
 }
+
+// Abandon abandons the change with the given changeID.
+func (g *Gerrit) Abandon(changeID string) error {
+	_, _, err := g.client.Changes.AbandonChange(changeID, &gerrit.AbandonInput{})
+	if err != nil {
+		return g.maybeWrapError(err)
+	}
+	return nil
+}
+
+// CreateChange creates a new change in the given project and branch, with the
+// given subject. If wip is true, then the change is constructed as
+// Work-In-Progress.
+func (g *Gerrit) CreateChange(project, branch, subject string, wip bool) (*ChangeInfo, error) {
+	change, _, err := g.client.Changes.CreateChange(&gerrit.ChangeInput{
+		Project:        project,
+		Branch:         branch,
+		Subject:        subject,
+		WorkInProgress: wip,
+	})
+	if err != nil {
+		return nil, g.maybeWrapError(err)
+	}
+	return change, nil
+}
+
+// EditFiles replaces the content of the files in the given change.
+// If newCommitMsg is not an empty string, then the commit message is replaced
+// with the string value.
+func (g *Gerrit) EditFiles(changeID, newCommitMsg string, files map[string]string) (Patchset, error) {
+	if newCommitMsg != "" {
+		resp, err := g.client.Changes.ChangeCommitMessageInChangeEdit(changeID, &gerrit.ChangeEditMessageInput{
+			Message: newCommitMsg,
+		})
+		if err != nil && resp.StatusCode != 409 { // 409 no changes were made
+			return Patchset{}, g.maybeWrapError(err)
+		}
+	}
+	for path, content := range files {
+		resp, err := g.client.Changes.ChangeFileContentInChangeEdit(changeID, path, content)
+		if err != nil && resp.StatusCode != 409 { // 409 no changes were made
+			return Patchset{}, g.maybeWrapError(err)
+		}
+	}
+
+	resp, err := g.client.Changes.PublishChangeEdit(changeID, "NONE")
+	if err != nil && resp.StatusCode != 409 { // 409 no changes were made
+		return Patchset{}, g.maybeWrapError(err)
+	}
+
+	return g.LatestPatchest(changeID)
+}
+
+// LatestPatchest returns the latest patchset for the change.
+func (g *Gerrit) LatestPatchest(changeID string) (Patchset, error) {
+	change, _, err := g.client.Changes.GetChange(changeID, &gerrit.ChangeOptions{
+		AdditionalFields: []string{"CURRENT_REVISION"},
+	})
+	if err != nil {
+		return Patchset{}, g.maybeWrapError(err)
+	}
+	ps := Patchset{
+		Host:     g.client.BaseURL().Host,
+		Project:  change.Project,
+		Change:   change.Number,
+		Patchset: change.Revisions[change.CurrentRevision].Number,
+	}
+	return ps, nil
+}
+
+// Comment posts a review comment on the given patchset.
+func (g *Gerrit) Comment(ps Patchset, msg string) error {
+	_, _, err := g.client.Changes.SetReview(
+		strconv.Itoa(ps.Change),
+		strconv.Itoa(ps.Patchset),
+		&gerrit.ReviewInput{
+			Message: msg,
+		})
+	if err != nil {
+		return g.maybeWrapError(err)
+	}
+	return nil
+}
+func (g *Gerrit) maybeWrapError(err error) error {
+	if err != nil && !g.authenticated {
+		return fmt.Errorf(`query failed, possibly because of authentication.
+See https://dawn-review.googlesource.com/new-password for obtaining a username
+and password which can be provided with --gerrit-user and --gerrit-pass.
+Note: This tool will scan ~/.gitcookies for credentials.
+%w`, err)
+	}
+	return err
+}