use graphql for repo milestones on issue list

Since we can obtain the necessary ID for the query on
node ID from the GraphQL API, it makes sense to remove
the REST version.

api/queries_issue.go

@@ -2,8 +2,9 @@ package api
 
 import (
 	"context"
+	"encoding/base64"
 	"fmt"
-	"strconv"
+	"strings"
 	"time"
 
 	"github.com/cli/cli/internal/ghrepo"
@@ -249,13 +250,19 @@ func IssueList(client *Client, repo ghrepo.Interface, state string, labels []str
 	}
 
 	if milestoneString != "" {
-		milestones, err := RepoMilestonesREST(client, repo)
+		milestones, err := RepoMilestones(client, repo)
 		if err != nil {
 			return nil, err
 		}
+
 		for i := range milestones {
-			if milestones[i].Title == milestoneString {
-				variables["milestone"] = strconv.Itoa(milestones[i].ID)
+			if strings.EqualFold(milestones[i].Title, milestoneString) {
+				// The query for milestones requires the use of the milestone's database ID (see #1441)
+				id, err := milestoneNodeIdToDatabaseId(milestones[i].ID)
+				if err != nil {
+					return nil, err
+				}
+				variables["milestone"] = id
 				break
 			}
 		}
@@ -430,3 +437,20 @@ func IssueReopen(client *Client, repo ghrepo.Interface, issue Issue) error {
 
 	return err
 }
+
+// milestoneNodeIdToDatabaseId extracts the REST Database ID from the GraphQL Node ID
+func milestoneNodeIdToDatabaseId(id string) (string, error) {
+	// The node id is base64 obfuscated
+	decoded, err := base64.StdEncoding.DecodeString(id)
+	if err != nil {
+		return "", err
+	}
+
+	// The decoded node ID has a pattern like '09:Milestone12345'
+	splitted := strings.Split(string(decoded), "Milestone")
+	if len(splitted) != 2 {
+		return "", fmt.Errorf("couldn't get database id from node id")
+	}
+
+	return splitted[1], nil
+}

api/queries_repo.go

@@ -7,7 +7,6 @@ import (
 	"errors"
 	"fmt"
 	"sort"
-	"strconv"
 	"strings"
 	"time"
 
@@ -802,30 +801,3 @@ func RepoMilestones(client *Client, repo ghrepo.Interface) ([]RepoMilestone, err
 
 	return milestones, nil
 }
-
-type RepoMilestoneREST struct {
-	ID    int
-	Title string
-}
-
-func RepoMilestonesREST(client *Client, repo ghrepo.Interface) ([]RepoMilestoneREST, error) {
-	var allMilestones []RepoMilestoneREST
-
-	path := fmt.Sprintf("repos/%s/%s/milestones", repo.RepoOwner(), repo.RepoName())
-
-	for page := 1; ; page++ {
-		var milestonesFromPage []RepoMilestoneREST
-
-		err := client.REST("GET", path+"?page="+strconv.Itoa(page), nil, &milestonesFromPage)
-		if err != nil {
-			return nil, err
-		}
-
-		if len(milestonesFromPage) == 0 {
-			break
-		}
-		allMilestones = append(allMilestones, milestonesFromPage...)
-	}
-
-	return allMilestones, nil
-}

api/queries_repo_test.go

@@ -54,14 +54,6 @@ func Test_RepoMetadata(t *testing.T) {
 			"pageInfo": { "hasNextPage": false }
 		} } } }
 		`))
-	http.Register(
-		httpmock.REST("GET", "repos/OWNER/REPO/milestones"),
-		httpmock.StringResponse(`
-		[
-			{ "title": "GA", "id": 1 },
-			{ "title": "Big One.oh", "id": 2 }
-		]	
-		`))
 	http.Register(
 		httpmock.GraphQL(`query RepositoryProjectList\b`),
 		httpmock.StringResponse(`