Move issues related files into models/issues (#19931)

* Move access and repo permission to models/perm/access

* fix test

* fix git test

* Move functions sequence

* Some improvements per @KN4CK3R and @delvh

* Move issues related code to models/issues

* Move some issues related sub package

* Merge

* Fix test

* Fix test

* Fix test

* Fix test

* Rename some files

models/issues/issue_user.go

@@ -0,0 +1,87 @@
+// Copyright 2017 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 issues
+
+import (
+	"context"
+	"fmt"
+
+	"code.gitea.io/gitea/models/db"
+	repo_model "code.gitea.io/gitea/models/repo"
+)
+
+// IssueUser represents an issue-user relation.
+type IssueUser struct {
+	ID          int64 `xorm:"pk autoincr"`
+	UID         int64 `xorm:"INDEX"` // User ID.
+	IssueID     int64
+	IsRead      bool
+	IsMentioned bool
+}
+
+func init() {
+	db.RegisterModel(new(IssueUser))
+}
+
+// NewIssueUsers inserts an issue related users
+func NewIssueUsers(ctx context.Context, repo *repo_model.Repository, issue *Issue) error {
+	assignees, err := repo_model.GetRepoAssignees(ctx, repo)
+	if err != nil {
+		return fmt.Errorf("getAssignees: %v", err)
+	}
+
+	// Poster can be anyone, append later if not one of assignees.
+	isPosterAssignee := false
+
+	// Leave a seat for poster itself to append later, but if poster is one of assignee
+	// and just waste 1 unit is cheaper than re-allocate memory once.
+	issueUsers := make([]*IssueUser, 0, len(assignees)+1)
+	for _, assignee := range assignees {
+		issueUsers = append(issueUsers, &IssueUser{
+			IssueID: issue.ID,
+			UID:     assignee.ID,
+		})
+		isPosterAssignee = isPosterAssignee || assignee.ID == issue.PosterID
+	}
+	if !isPosterAssignee {
+		issueUsers = append(issueUsers, &IssueUser{
+			IssueID: issue.ID,
+			UID:     issue.PosterID,
+		})
+	}
+
+	return db.Insert(ctx, issueUsers)
+}
+
+// UpdateIssueUserByRead updates issue-user relation for reading.
+func UpdateIssueUserByRead(uid, issueID int64) error {
+	_, err := db.GetEngine(db.DefaultContext).Exec("UPDATE `issue_user` SET is_read=? WHERE uid=? AND issue_id=?", true, uid, issueID)
+	return err
+}
+
+// UpdateIssueUsersByMentions updates issue-user pairs by mentioning.
+func UpdateIssueUsersByMentions(ctx context.Context, issueID int64, uids []int64) error {
+	for _, uid := range uids {
+		iu := &IssueUser{
+			UID:     uid,
+			IssueID: issueID,
+		}
+		has, err := db.GetEngine(ctx).Get(iu)
+		if err != nil {
+			return err
+		}
+
+		iu.IsMentioned = true
+		if has {
+			_, err = db.GetEngine(ctx).ID(iu.ID).Cols("is_mentioned").Update(iu)
+		} else {
+			_, err = db.GetEngine(ctx).Insert(iu)
+		}
+		if err != nil {
+			return err
+		}
+	}
+	return nil
+}