Refactor authors dropdown (send get request from frontend to avoid long wait time) (#23890)

Right now the authors search dropdown might take a long time to load if
amount of authors is huge.
Example: (In the video below, there are about 10000 authors, and it
takes about 10 seconds to open the author dropdown)

https://user-images.githubusercontent.com/17645053/229422229-98aa9656-3439-4f8c-9f4e-83bd8e2a2557.mov

Possible improvements can be made, which will take 2 steps (Thanks to
@wolfogre for advice):

Step 1：
Backend: Add a new api, which returns a limit of 30 posters with matched
prefix.
Frontend: Change the search behavior from frontend search(fomantic
search) to backend search(when input is changed, send a request to get
authors matching the current search prefix)

Step 2：
Backend: Optimize the api in step 1 using indexer to support fuzzy
search.

This PR is implements the first step. The main changes:
1. Added api: `GET /{type:issues|pulls}/posters` , which return a limit
of 30 users with matched prefix (prefix sent as query). If
`DEFAULT_SHOW_FULL_NAME` in `custom/conf/app.ini` is set to true, will
also include fullnames fuzzy search.
2. Added a tooltip saying "Shows a maximum of 30 users" to the author
search dropdown
3. Change the search behavior from frontend search to backend search

After:

https://user-images.githubusercontent.com/17645053/229430960-f88fafd8-fd5d-4f84-9df2-2677539d5d08.mov

Fixes: https://github.com/go-gitea/gitea/issues/22586

---------

Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>
Co-authored-by: silverwind <me@silverwind.io>

6 files changed, 114 insertions, 19 deletions

diff --git a/routers/web/repo/helper.go b/routers/web/repo/helper.go
new file mode 100644
index 0000000000..6f9ca4874b
--- /dev/null
+++ b/routers/web/repo/helper.go
@@ -0,0 +1,23 @@
+// Copyright 2023 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package repo
+
+import (
+	"sort"
+
+	"code.gitea.io/gitea/models/user"
+	"code.gitea.io/gitea/modules/context"
+)
+
+func makeSelfOnTop(ctx *context.Context, users []*user.User) []*user.User {
+	if ctx.Doer != nil {
+		sort.Slice(users, func(i, j int) bool {
+			if users[i].ID == users[j].ID {
+				return false
+			}
+			return users[i].ID == ctx.Doer.ID // if users[i] is self, put it before others, so less=true
+		})
+	}
+	return users
+}
diff --git a/routers/web/repo/helper_test.go b/routers/web/repo/helper_test.go
new file mode 100644
index 0000000000..e9ab44fe69
--- /dev/null
+++ b/routers/web/repo/helper_test.go
@@ -0,0 +1,27 @@
+// Copyright 2023 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package repo
+
+import (
+	"testing"
+
+	"code.gitea.io/gitea/models/user"
+	"code.gitea.io/gitea/modules/context"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestMakeSelfOnTop(t *testing.T) {
+	users := makeSelfOnTop(&context.Context{}, []*user.User{{ID: 2}, {ID: 1}})
+	assert.Len(t, users, 2)
+	assert.EqualValues(t, 2, users[0].ID)
+
+	users = makeSelfOnTop(&context.Context{Doer: &user.User{ID: 1}}, []*user.User{{ID: 2}, {ID: 1}})
+	assert.Len(t, users, 2)
+	assert.EqualValues(t, 1, users[0].ID)
+
+	users = makeSelfOnTop(&context.Context{Doer: &user.User{ID: 2}}, []*user.User{{ID: 2}, {ID: 1}})
+	assert.Len(t, users, 2)
+	assert.EqualValues(t, 2, users[0].ID)
+}
diff --git a/routers/web/repo/issue.go b/routers/web/repo/issue.go
index e4f1172dd9..5401d60b55 100644
--- a/routers/web/repo/issue.go
+++ b/routers/web/repo/issue.go
@@ -303,17 +303,12 @@ func issues(ctx *context.Context, milestoneID, projectID int64, isPullOption uti
 	ctx.Data["CommitStatuses"] = commitStatuses
 
 	// Get assignees.
-	ctx.Data["Assignees"], err = repo_model.GetRepoAssignees(ctx, repo)
+	assigneeUsers, err := repo_model.GetRepoAssignees(ctx, repo)
 	if err != nil {
-		ctx.ServerError("GetAssignees", err)
-		return
-	}
-
-	ctx.Data["Posters"], err = repo_model.GetIssuePosters(ctx, repo, isPullOption.IsTrue())
-	if err != nil {
-		ctx.ServerError("GetIssuePosters", err)
+		ctx.ServerError("GetRepoAssignees", err)
 		return
 	}
+	ctx.Data["Assignees"] = makeSelfOnTop(ctx, assigneeUsers)
 
 	handleTeamMentions(ctx)
 	if ctx.Written() {
@@ -479,11 +474,12 @@ func RetrieveRepoMilestonesAndAssignees(ctx *context.Context, repo *repo_model.R
 		return
 	}
 
-	ctx.Data["Assignees"], err = repo_model.GetRepoAssignees(ctx, repo)
+	assigneeUsers, err := repo_model.GetRepoAssignees(ctx, repo)
 	if err != nil {
-		ctx.ServerError("GetAssignees", err)
+		ctx.ServerError("GetRepoAssignees", err)
 		return
 	}
+	ctx.Data["Assignees"] = makeSelfOnTop(ctx, assigneeUsers)
 
 	handleTeamMentions(ctx)
 }
@@ -3354,3 +3350,46 @@ func handleTeamMentions(ctx *context.Context) {
 	ctx.Data["MentionableTeamsOrg"] = ctx.Repo.Owner.Name
 	ctx.Data["MentionableTeamsOrgAvatar"] = ctx.Repo.Owner.AvatarLink(ctx)
 }
+
+type userSearchInfo struct {
+	UserID     int64  `json:"user_id"`
+	UserName   string `json:"username"`
+	AvatarLink string `json:"avatar_link"`
+	FullName   string `json:"full_name"`
+}
+
+type userSearchResponse struct {
+	Results []*userSearchInfo `json:"results"`
+}
+
+// IssuePosters get posters for current repo's issues/pull requests
+func IssuePosters(ctx *context.Context) {
+	repo := ctx.Repo.Repository
+	isPullList := ctx.Params(":type") == "pulls"
+	search := strings.TrimSpace(ctx.FormString("q"))
+	posters, err := repo_model.GetIssuePostersWithSearch(ctx, repo, isPullList, search, setting.UI.DefaultShowFullName)
+	if err != nil {
+		ctx.JSON(http.StatusInternalServerError, err)
+		return
+	}
+
+	if search == "" && ctx.Doer != nil {
+		// the returned posters slice only contains limited number of users,
+		// to make the current user (doer) can quickly filter their own issues, always add doer to the posters slice
+		if !util.SliceContainsFunc(posters, func(user *user_model.User) bool { return user.ID == ctx.Doer.ID }) {
+			posters = append(posters, ctx.Doer)
+		}
+	}
+
+	posters = makeSelfOnTop(ctx, posters)
+
+	resp := &userSearchResponse{}
+	resp.Results = make([]*userSearchInfo, len(posters))
+	for i, user := range posters {
+		resp.Results[i] = &userSearchInfo{UserID: user.ID, UserName: user.Name, AvatarLink: user.AvatarLink(ctx)}
+		if setting.UI.DefaultShowFullName {
+			resp.Results[i].FullName = user.FullName
+		}
+	}
+	ctx.JSON(http.StatusOK, resp)
+}
diff --git a/routers/web/repo/pull.go b/routers/web/repo/pull.go
index 30004cefb7..070fc109dc 100644
--- a/routers/web/repo/pull.go
+++ b/routers/web/repo/pull.go
@@ -792,10 +792,13 @@ func ViewPullFiles(ctx *context.Context) {
 
 	setCompareContext(ctx, baseCommit, commit, ctx.Repo.Owner.Name, ctx.Repo.Repository.Name)
 
-	if ctx.Data["Assignees"], err = repo_model.GetRepoAssignees(ctx, ctx.Repo.Repository); err != nil {
-		ctx.ServerError("GetAssignees", err)
+	assigneeUsers, err := repo_model.GetRepoAssignees(ctx, ctx.Repo.Repository)
+	if err != nil {
+		ctx.ServerError("GetRepoAssignees", err)
 		return
 	}
+	ctx.Data["Assignees"] = makeSelfOnTop(ctx, assigneeUsers)
+
 	handleTeamMentions(ctx)
 	if ctx.Written() {
 		return
diff --git a/routers/web/repo/release.go b/routers/web/repo/release.go
index b8c5f67f45..5083056ebb 100644
--- a/routers/web/repo/release.go
+++ b/routers/web/repo/release.go
@@ -333,13 +333,12 @@ func NewRelease(ctx *context.Context) {
 		}
 	}
 	ctx.Data["IsAttachmentEnabled"] = setting.Attachment.Enabled
-	var err error
-	// Get assignees.
-	ctx.Data["Assignees"], err = repo_model.GetRepoAssignees(ctx, ctx.Repo.Repository)
+	assigneeUsers, err := repo_model.GetRepoAssignees(ctx, ctx.Repo.Repository)
 	if err != nil {
-		ctx.ServerError("GetAssignees", err)
+		ctx.ServerError("GetRepoAssignees", err)
 		return
 	}
+	ctx.Data["Assignees"] = makeSelfOnTop(ctx, assigneeUsers)
 
 	upload.AddUploadContext(ctx, "release")
 	ctx.HTML(http.StatusOK, tplReleaseNew)
@@ -496,11 +495,12 @@ func EditRelease(ctx *context.Context) {
 	ctx.Data["attachments"] = rel.Attachments
 
 	// Get assignees.
-	ctx.Data["Assignees"], err = repo_model.GetRepoAssignees(ctx, rel.Repo)
+	assigneeUsers, err := repo_model.GetRepoAssignees(ctx, rel.Repo)
 	if err != nil {
-		ctx.ServerError("GetAssignees", err)
+		ctx.ServerError("GetRepoAssignees", err)
 		return
 	}
+	ctx.Data["Assignees"] = makeSelfOnTop(ctx, assigneeUsers)
 
 	ctx.HTML(http.StatusOK, tplReleaseNew)
 }
diff --git a/routers/web/web.go b/routers/web/web.go
index 6b62ff6f83..36304493c9 100644
--- a/routers/web/web.go
+++ b/routers/web/web.go
@@ -1228,7 +1228,10 @@ func RegisterRoutes(m *web.Route) {
 
 	m.Group("/{username}/{reponame}", func() {
 		m.Group("", func() {
-			m.Get("/{type:issues|pulls}", repo.Issues)
+			m.Group("/{type:issues|pulls}", func() {
+				m.Get("", repo.Issues)
+				m.Get("/posters", repo.IssuePosters)
+			})
 			m.Get("/{type:issues|pulls}/{index}", repo.ViewIssue)
 			m.Group("/{type:issues|pulls}/{index}/content-history", func() {
 				m.Get("/overview", repo.GetContentHistoryOverview)