[Refactor] CombinedStatus and CommitStatus related functions & structs (#14026)

* RM unused struct

* rename (*CommitStatus) loadRepo() -> loadAttributes()

* move ToCommitStatus into its own file

* use CommitStatusState instead of StatusState

* move CombinedStatus convertion into convert package

* let models.GetLatestCommitStatus use repoID direct and accept ListOptions

* update swagger docs

* fix tests

* Fix swagger docs

* rm page

* fix swagger docs!!!

* return json null

* always return json

* rename api.Status to api.CommitStatus

* fix swagger docs

* sec swagger fix

modules/convert/status.go

@@ -0,0 +1,56 @@
+// Copyright 2020 The Gitea Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package convert
+
+import (
+	"code.gitea.io/gitea/models"
+	api "code.gitea.io/gitea/modules/structs"
+)
+
+// ToCommitStatus converts models.CommitStatus to api.CommitStatus
+func ToCommitStatus(status *models.CommitStatus) *api.CommitStatus {
+	apiStatus := &api.CommitStatus{
+		Created:     status.CreatedUnix.AsTime(),
+		Updated:     status.CreatedUnix.AsTime(),
+		State:       status.State,
+		TargetURL:   status.TargetURL,
+		Description: status.Description,
+		ID:          status.Index,
+		URL:         status.APIURL(),
+		Context:     status.Context,
+	}
+
+	if status.CreatorID != 0 {
+		creator, _ := models.GetUserByID(status.CreatorID)
+		apiStatus.Creator = ToUser(creator, false, false)
+	}
+
+	return apiStatus
+}
+
+// ToCombinedStatus converts List of CommitStatus to a CombinedStatus
+func ToCombinedStatus(statuses []*models.CommitStatus, repo *api.Repository) *api.CombinedStatus {
+
+	if len(statuses) == 0 {
+		return nil
+	}
+
+	retStatus := &api.CombinedStatus{
+		SHA:        statuses[0].SHA,
+		TotalCount: len(statuses),
+		Repository: repo,
+		URL:        "",
+	}
+
+	retStatus.Statuses = make([]*api.CommitStatus, 0, len(statuses))
+	for _, status := range statuses {
+		retStatus.Statuses = append(retStatus.Statuses, ToCommitStatus(status))
+		if status.State.NoBetterThan(retStatus.State) {
+			retStatus.State = status.State
+		}
+	}
+
+	return retStatus
+}