label.go

/*
Copyright 2016 The Kubernetes 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 label

import (
	"fmt"
	"regexp"
	"strings"

	"github.com/sirupsen/logrus"

	"k8s.io/apimachinery/pkg/util/sets"
	"k8s.io/test-infra/prow/config"
	"k8s.io/test-infra/prow/github"
	prowlabels "k8s.io/test-infra/prow/labels"
	"k8s.io/test-infra/prow/pluginhelp"
	"k8s.io/test-infra/prow/plugins"
)

const (
	PluginName = "label"
)

var (
	defaultLabels          = []string{"kind", "priority", "area"}
	commentRegex           = regexp.MustCompile(`(?s)<!--(.*?)-->`)
	labelRegex             = regexp.MustCompile(`(?m)^/(area|committee|kind|language|priority|sig|triage|wg)\s*(.*?)\s*$`)
	removeLabelRegex       = regexp.MustCompile(`(?m)^/remove-(area|committee|kind|language|priority|sig|triage|wg)\s*(.*?)\s*$`)
	customLabelRegex       = regexp.MustCompile(`(?m)^/label\s*(.*?)\s*$`)
	customRemoveLabelRegex = regexp.MustCompile(`(?m)^/remove-label\s*(.*?)\s*$`)
)

func init() {
	plugins.RegisterGenericCommentHandler(PluginName, handleGenericComment, helpProvider)
	plugins.RegisterPullRequestHandler(PluginName, handlePullRequest, helpProvider)
}

func configString(labels []string) string {
	var formattedLabels []string
	for _, label := range labels {
		formattedLabels = append(formattedLabels, fmt.Sprintf(`"%s/*"`, label))
	}
	return fmt.Sprintf("The label plugin will work on %s and %s labels.", strings.Join(formattedLabels[:len(formattedLabels)-1], ", "), formattedLabels[len(formattedLabels)-1])
}

func helpProvider(config *plugins.Configuration, _ []config.OrgRepo) (*pluginhelp.PluginHelp, error) {
	labels := []string{}
	labels = append(labels, defaultLabels...)
	labels = append(labels, config.Label.AdditionalLabels...)
	yamlSnippet, err := plugins.CommentMap.GenYaml(&plugins.Configuration{
		Label: plugins.Label{
			AdditionalLabels: []string{"api-review", "community/discussion"},
			RestrictedLabels: map[string][]plugins.RestrictedLabel{
				"*": {{
					Label:        "restricted-label",
					AllowedTeams: []string{"authorized-team"},
					AllowedUsers: []string{"alice", "bob"},
					AssignOn:     []plugins.AssignOnLabel{{Label: "other-label"}},
				}},
			},
		},
	})
	if err != nil {
		logrus.WithError(err).Warnf("cannot generate comments for %s plugin", PluginName)
	}
	pluginHelp := &pluginhelp.PluginHelp{
		Description: "The label plugin provides commands that add or remove certain types of labels. Labels of the following types can be manipulated: 'area/*', 'committee/*', 'kind/*', 'language/*', 'priority/*', 'sig/*', 'triage/*', and 'wg/*'. More labels can be configured to be used via the /label command. Restricted labels are only able to be added by the teams and users present in their configuration, and those users can be automatically assigned when another label is added using the assign_on config.",
		Config: map[string]string{
			"": configString(labels),
		},
		Snippet: yamlSnippet,
	}
	pluginHelp.AddCommand(pluginhelp.Command{
		Usage:       "/[remove-](area|committee|kind|language|priority|sig|triage|wg|label) <target>",
		Description: "Applies or removes a label from one of the recognized types of labels.",
		Featured:    false,
		WhoCanUse:   "Anyone can trigger this command on issues and PRs. `triage/accepted` can only be added by org members. Restricted labels are only able to be added by teams and users in their configuration.",
		Examples:    []string{"/kind bug", "/remove-area prow", "/sig testing", "/language zh", "/label foo-bar-baz"},
	})
	return pluginHelp, nil
}

func handleGenericComment(pc plugins.Agent, e github.GenericCommentEvent) error {
	return handleComment(pc.GitHubClient, pc.Logger, pc.PluginConfig.Label, &e)
}

func handlePullRequest(pc plugins.Agent, e github.PullRequestEvent) error {
	return handleLabelAdd(pc.GitHubClient, pc.Logger, pc.PluginConfig.Label, &e)
}

type githubClient interface {
	CreateComment(owner, repo string, number int, comment string) error
	AddLabel(owner, repo string, number int, label string) error
	IsMember(org, user string) (bool, error)
	RemoveLabel(owner, repo string, number int, label string) error
	GetRepoLabels(owner, repo string) ([]github.Label, error)
	GetIssueLabels(org, repo string, number int) ([]github.Label, error)
	TeamBySlugHasMember(org string, teamSlug string, memberLogin string) (bool, error)
	AssignIssue(owner, repo string, number int, assignees []string) error
}

// Get Labels from Regexp matches
func getLabelsFromREMatches(matches [][]string) (labels []string) {
	for _, match := range matches {
		for _, label := range strings.Split(strings.TrimSpace(match[0]), " ")[1:] {
			label = strings.ToLower(match[1] + "/" + strings.TrimSpace(label))
			labels = append(labels, label)
		}
	}
	return
}

// getLabelsFromGenericMatches returns label matches with extra labels if those
// have been configured in the plugin config.
func getLabelsFromGenericMatches(matches [][]string, labelFilter func(string) bool, invalidLabels *[]string) []string {
	var labels []string
	for _, match := range matches {
		parts := strings.Split(strings.TrimSpace(match[0]), " ")
		if ((parts[0] != "/label") && (parts[0] != "/remove-label")) || len(parts) != 2 {
			continue
		}
		if labelFilter(strings.ToLower(parts[1])) {
			labels = append(labels, strings.ToLower(parts[1]))
		} else {
			*invalidLabels = append(*invalidLabels, match[0])
		}
	}
	return labels
}

func handleComment(gc githubClient, log *logrus.Entry, config plugins.Label, e *github.GenericCommentEvent) error {
	if e.Action != github.GenericCommentActionCreated {
		return nil
	}

	bodyWithoutComments := commentRegex.ReplaceAllString(e.Body, "")
	labelMatches := labelRegex.FindAllStringSubmatch(bodyWithoutComments, -1)
	removeLabelMatches := removeLabelRegex.FindAllStringSubmatch(bodyWithoutComments, -1)
	customLabelMatches := customLabelRegex.FindAllStringSubmatch(bodyWithoutComments, -1)
	customRemoveLabelMatches := customRemoveLabelRegex.FindAllStringSubmatch(bodyWithoutComments, -1)
	if len(labelMatches) == 0 && len(removeLabelMatches) == 0 && len(customLabelMatches) == 0 && len(customRemoveLabelMatches) == 0 {
		return nil
	}

	org := e.Repo.Owner.Login
	repo := e.Repo.Name
	user := e.User.Login

	repoLabels, err := gc.GetRepoLabels(org, repo)
	if err != nil {
		return err
	}
	labels, err := gc.GetIssueLabels(org, repo, e.Number)
	if err != nil {
		return err
	}

	RepoLabelsExisting := sets.String{}
	for _, l := range repoLabels {
		RepoLabelsExisting.Insert(strings.ToLower(l.Name))
	}
	var (
		nonexistent             []string
		noSuchLabelsInRepo      []string
		noSuchLabelsOnIssue     []string
		labelsToAdd             []string
		labelsToRemove          []string
		nonMemberTriageAccepted bool
	)

	additionalLabelSet := sets.String{}
	for _, label := range config.AdditionalLabels {
		additionalLabelSet.Insert(strings.ToLower(label))
	}
	restrictedLabels := config.RestrictedLabelsFor(e.Repo.Owner.Login, e.Repo.Name)
	labelFilter := func(label string) bool {
		label = strings.ToLower(label)
		_, restrictedLabel := restrictedLabels[label]
		return restrictedLabel || additionalLabelSet.Has(label)
	}

	// Get labels to add and labels to remove from regexp matches
	labelsToAdd = append(getLabelsFromREMatches(labelMatches), getLabelsFromGenericMatches(customLabelMatches, labelFilter, &nonexistent)...)
	labelsToRemove = append(getLabelsFromREMatches(removeLabelMatches), getLabelsFromGenericMatches(customRemoveLabelMatches, labelFilter, &nonexistent)...)
	// Add labels
	for _, labelToAdd := range labelsToAdd {
		if github.HasLabel(labelToAdd, labels) {
			continue
		}

		if !RepoLabelsExisting.Has(labelToAdd) {
			noSuchLabelsInRepo = append(noSuchLabelsInRepo, labelToAdd)
			continue
		}

		// only org members can add triage/accepted
		if labelToAdd == prowlabels.TriageAccepted {
			if member, err := gc.IsMember(org, user); err != nil {
				log.WithError(err).Errorf("error in IsMember(%s): %v", org, err)
				continue
			} else if !member {
				nonMemberTriageAccepted = true
				continue
			}
		}

		canSetLabel, canNotSetLabelReason, err := canUserSetLabel(gc, org, e.User.Login, labelToAdd, restrictedLabels)
		if err != nil {
			log.WithError(err).WithField("label", labelToAdd).Error("failed to check if user can set label")
			continue
		}

		if !canSetLabel {
			gc.CreateComment(org, repo, e.Number, plugins.FormatResponseRaw(bodyWithoutComments, e.HTMLURL, e.User.Login, canNotSetLabelReason))
			continue
		}

		if err := gc.AddLabel(org, repo, e.Number, labelToAdd); err != nil {
			log.WithError(err).WithField("label", labelToAdd).Error("GitHub failed to add the label")
		}
	}

	// Remove labels
	for _, labelToRemove := range labelsToRemove {
		if !github.HasLabel(labelToRemove, labels) {
			noSuchLabelsOnIssue = append(noSuchLabelsOnIssue, labelToRemove)
			continue
		}

		if !RepoLabelsExisting.Has(labelToRemove) {
			continue
		}

		canSetLabel, canNotSetLabelReason, err := canUserSetLabel(gc, org, e.User.Login, labelToRemove, restrictedLabels)
		if err != nil {
			log.WithError(err).WithField("label", labelToRemove).Error("failed to check if user can set label")
			continue
		}

		if !canSetLabel {
			gc.CreateComment(org, repo, e.Number, plugins.FormatResponseRaw(bodyWithoutComments, e.HTMLURL, e.User.Login, canNotSetLabelReason))
			continue
		}

		if err := gc.RemoveLabel(org, repo, e.Number, labelToRemove); err != nil {
			log.WithError(err).WithField("label", labelToRemove).Error("GitHub failed to remove the label")
		}
	}

	if len(nonexistent) > 0 {
		log.Infof("Nonexistent labels: %v", nonexistent)
		msg := fmt.Sprintf("The label(s) `%s` cannot be applied. These labels are supported: `%s`. Is this label configured under `labels -> additional_labels` or `labels -> restricted_labels` in `plugin.yaml`?", strings.Join(nonexistent, ", "), strings.Join(append(config.AdditionalLabels, sets.StringKeySet(restrictedLabels).List()...), ", "))
		return gc.CreateComment(org, repo, e.Number, plugins.FormatResponseRaw(bodyWithoutComments, e.HTMLURL, e.User.Login, msg))
	}

	if len(noSuchLabelsInRepo) > 0 {
		log.Infof("Labels missing in repo: %v", noSuchLabelsInRepo)
		msg := fmt.Sprintf("The label(s) `%s` cannot be applied, because the repository doesn't have them.", strings.Join(noSuchLabelsInRepo, ", "))
		return gc.CreateComment(org, repo, e.Number, plugins.FormatResponseRaw(bodyWithoutComments, e.HTMLURL, e.User.Login, msg))
	}

	// Tried to remove Labels that were not present on the Issue
	if len(noSuchLabelsOnIssue) > 0 {
		msg := fmt.Sprintf("Those labels are not set on the issue: `%v`", strings.Join(noSuchLabelsOnIssue, ", "))
		return gc.CreateComment(org, repo, e.Number, plugins.FormatResponseRaw(bodyWithoutComments, e.HTMLURL, e.User.Login, msg))
	}

	if nonMemberTriageAccepted {
		msg := fmt.Sprintf("The label `%s` cannot be applied. Only GitHub organization members can add the label.", prowlabels.TriageAccepted)
		return gc.CreateComment(org, repo, e.Number, plugins.FormatResponseRaw(bodyWithoutComments, e.HTMLURL, e.User.Login, msg))
	}

	return nil
}

func canUserSetLabel(ghc githubClient, org string, user string, label string, restrictedLabels map[string]plugins.RestrictedLabel) (canSet bool, canNotSetReason string, err error) {
	config, isRestricted := restrictedLabels[label]
	if !isRestricted {
		return true, "", nil
	}

	for _, allowedUser := range config.AllowedUsers {
		if strings.EqualFold(allowedUser, user) {
			return true, "", nil
		}
	}

	for _, team := range config.AllowedTeams {
		isMember, err := ghc.TeamBySlugHasMember(org, team, user)
		if err != nil {
			return false, "", err
		}
		if isMember {
			return true, "", nil
		}
	}

	return false, fmt.Sprintf("Can not set label %s: Must be member in one of these teams: %v", label, config.AllowedTeams), nil
}

func handleLabelAdd(gc githubClient, log *logrus.Entry, config plugins.Label, e *github.PullRequestEvent) error {
	if e.Action != github.PullRequestActionLabeled {
		return nil
	}

	org := e.Repo.Owner.Login
	repo := e.Repo.Name
	number := e.PullRequest.Number
	restrictedLabels := config.RestrictedLabelsFor(e.Repo.Owner.Login, e.Repo.Name)

	for _, restrictedLabel := range restrictedLabels {
		for _, assignOn := range restrictedLabel.AssignOn {
			if strings.EqualFold(e.Label.Name, assignOn.Label) {
				log.WithField("label", restrictedLabel.Label).Info("Assigning users for restricted label")
				// It's okay to re-assign users so no need to check if they are assigned
				if err := gc.AssignIssue(org, repo, number, restrictedLabel.AllowedUsers); err != nil {
					log.WithError(err).WithField("label", restrictedLabel.Label).Error("GitHub failed to assign reviewers for the label")
				}
			}
		}
	}
	return nil
}