Add github issue expansion for things that look like owner/repo#11

src/github.com/matrix-org/go-neb/services/github/github.go

@@ -1,13 +1,22 @@
 package services
 
 import (
+	"fmt"
+	log "github.com/Sirupsen/logrus"
+	"github.com/google/go-github/github"
 	"github.com/matrix-org/go-neb/database"
 	"github.com/matrix-org/go-neb/matrix"
 	"github.com/matrix-org/go-neb/plugin"
+	"golang.org/x/oauth2"
 	"regexp"
+	"strconv"
 	"strings"
 )
 
+// Matches alphanumeric then a /, then more alphanumeric then a #, then a number.
+// E.g. owner/repo#11 (issue/PR numbers) - Captured groups for owner/repo/number
+const ownerRepoIssueRegex = "([A-z0-9-_]+)/([A-z0-9-_]+)#([0-9]+)"
+
 type githubService struct {
 	id     string
 	UserID string
@@ -30,14 +39,29 @@ func (s *githubService) Plugin(roomID string) plugin.Plugin {
 		},
 		Expansions: []plugin.Expansion{
 			plugin.Expansion{
-				// E.g. owner/repo#11 (issue/PR numbers)
-				Regexp: regexp.MustCompile("[A-z0-9-_]+/[A-z0-9-_]+#[0-9]+"),
+				Regexp: regexp.MustCompile(ownerRepoIssueRegex),
 				Expand: func(roomID, matchingText string) interface{} {
-					// get the issue/PR number
-					repoAndNum := strings.Split(matchingText, "#")
+					cli := githubClient("")
+					owner, repo, num, err := ownerRepoNumberFromText(matchingText)
+					if err != nil {
+						log.WithError(err).WithField("text", matchingText).Print(
+							"Failed to extract owner,repo,number from matched string")
+						return nil
+					}
+
+					i, _, err := cli.Issues.Get(owner, repo, num)
+					if err != nil {
+						log.WithError(err).WithFields(log.Fields{
+							"owner":  owner,
+							"repo":   repo,
+							"number": num,
+						}).Print("Failed to fetch issue")
+						return nil
+					}
+
 					return &matrix.TextMessage{
 						"m.notice",
-						"Repo: " + repoAndNum[0] + " Num: " + repoAndNum[1],
+						fmt.Sprintf("%s : %s", *i.HTMLURL, *i.Title),
 					}
 				},
 			},
@@ -45,6 +69,34 @@ func (s *githubService) Plugin(roomID string) plugin.Plugin {
 	}
 }
 
+func githubClient(token string) *github.Client {
+	var tokenSource oauth2.TokenSource
+	if token != "" {
+		tokenSource = oauth2.StaticTokenSource(
+			&oauth2.Token{AccessToken: token},
+		)
+	}
+	httpCli := oauth2.NewClient(oauth2.NoContext, tokenSource)
+	return github.NewClient(httpCli)
+}
+
+// ownerRepoNumberFromText parses a GH issue string that looks like 'owner/repo#11'
+// into its constituient parts. Returns: owner, repo, issue#.
+func ownerRepoNumberFromText(ownerRepoNumberText string) (string, string, int, error) {
+	// TODO: cache this?
+	re := regexp.MustCompile(ownerRepoIssueRegex)
+	// [full_string, owner, repo, issue_number]
+	groups := re.FindStringSubmatch(ownerRepoNumberText)
+	if len(groups) != 4 {
+		return "", "", 0, fmt.Errorf("No match found for '%s'", ownerRepoNumberText)
+	}
+	num, err := strconv.Atoi(groups[3])
+	if err != nil {
+		return "", "", 0, err
+	}
+	return groups[1], groups[2], num, nil
+}
+
 func init() {
 	database.RegisterService(func(serviceID string) database.Service {
 		return &githubService{id: serviceID}