Support choose email when creating a commit via web UI (more) (#33445)

Follow #33432

routers/web/repo/webgit.go

@@ -0,0 +1,40 @@
+// Copyright 2025 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package repo
+
+import (
+	user_model "code.gitea.io/gitea/models/user"
+	"code.gitea.io/gitea/modules/log"
+	"code.gitea.io/gitea/modules/setting"
+	"code.gitea.io/gitea/modules/util"
+	"code.gitea.io/gitea/services/context"
+	files_service "code.gitea.io/gitea/services/repository/files"
+)
+
+func WebGitOperationCommonData(ctx *context.Context) {
+	// TODO: more places like "wiki page" and "merging a pull request or creating an auto merge merging task"
+	emails, err := user_model.GetActivatedEmailAddresses(ctx, ctx.Doer.ID)
+	if err != nil {
+		log.Error("WebGitOperationCommonData: GetActivatedEmailAddresses: %v", err)
+	}
+	if ctx.Doer.KeepEmailPrivate {
+		emails = append([]string{ctx.Doer.GetPlaceholderEmail()}, emails...)
+	}
+	ctx.Data["CommitCandidateEmails"] = emails
+	ctx.Data["CommitDefaultEmail"] = ctx.Doer.GetEmail()
+}
+
+func WebGitOperationGetCommitChosenEmailIdentity(ctx *context.Context, email string) (_ *files_service.IdentityOptions, valid bool) {
+	if ctx.Data["CommitCandidateEmails"] == nil {
+		setting.PanicInDevOrTesting("no CommitCandidateEmails in context data")
+	}
+	emails, _ := ctx.Data["CommitCandidateEmails"].([]string)
+	if email == "" {
+		return nil, true
+	}
+	if util.SliceContainsString(emails, email, true) {
+		return &files_service.IdentityOptions{GitUserEmail: email}, true
+	}
+	return nil, false
+}