Issue due date (#3794)

* Started adding deadline to ui

* Implemented basic issue due date managing

* Improved UI for due date managing

* Added at least write access to the repo in order to modify issue due dates

* Ui improvements

* Added issue comments creation when adding/modifying/removing a due date

* Show due date in issue list

* Added api support for issue due dates

* Fixed lint suggestions

* Added deadline to sdk

* Updated css

* Added support for adding/modifiying deadlines for pull requests via api

* Fixed comments not created when updating or removing a deadline

* update sdk (will do properly once go-gitea/go-sdk#103 is merged)

* enhanced updateIssueDeadline

* Removed unnessecary Issue.DeadlineString

* UI improvements

* Small improvments to comment creation
+ ui & validation improvements

* Check if an issue is overdue is now a seperate function

* Updated go-sdk with govendor as it was merged

* Simplified isOverdue method

* removed unessecary deadline to 0 set

* Update swagger definitions

* Added missing return

* Added an explanary comment

* Improved updateIssueDeadline method so it'll only update `deadline_unix`

* Small changes and improvements
* no need to explicitly load the issue when updating a deadline, just use whats already there
* small optimisations

* Added check if a deadline was modified before updating it

* Moved comment creating logic into its own function

* Code cleanup for creating deadline comment

* locale improvement

* When modifying a deadline, the old deadline is saved with the comment

* small improvments to xorm session handling when updating an issue deadline
+ style nitpicks

* style nitpicks

* Moved checking for if the user has write acces to middleware

3 files changed, 74 insertions, 3 deletions

diff --git a/models/issue.go b/models/issue.go
index 190b387530..7f83d59842 100644
--- a/models/issue.go
+++ b/models/issue.go
@@ -47,9 +47,10 @@ type Issue struct {
 	Ref             string
 
 	DeadlineUnix util.TimeStamp `xorm:"INDEX"`
-	CreatedUnix  util.TimeStamp `xorm:"INDEX created"`
-	UpdatedUnix  util.TimeStamp `xorm:"INDEX updated"`
-	ClosedUnix   util.TimeStamp `xorm:"INDEX"`
+
+	CreatedUnix util.TimeStamp `xorm:"INDEX created"`
+	UpdatedUnix util.TimeStamp `xorm:"INDEX updated"`
+	ClosedUnix  util.TimeStamp `xorm:"INDEX"`
 
 	Attachments      []*Attachment `xorm:"-"`
 	Comments         []*Comment    `xorm:"-"`
@@ -79,6 +80,11 @@ func (issue *Issue) loadTotalTimes(e Engine) (err error) {
 	return nil
 }
 
+// IsOverdue checks if the issue is overdue
+func (issue *Issue) IsOverdue() bool {
+	return util.TimeStampNow() >= issue.DeadlineUnix
+}
+
 func (issue *Issue) loadRepo(e Engine) (err error) {
 	if issue.Repo == nil {
 		issue.Repo, err = getRepositoryByID(e, issue.RepoID)
@@ -348,6 +354,9 @@ func (issue *Issue) APIFormat() *api.Issue {
 			apiIssue.PullRequest.Merged = issue.PullRequest.MergedUnix.AsTimePtr()
 		}
 	}
+	if issue.DeadlineUnix != 0 {
+		apiIssue.Deadline = issue.DeadlineUnix.AsTimePtr()
+	}
 
 	return apiIssue
 }
@@ -1522,3 +1531,30 @@ func updateIssue(e Engine, issue *Issue) error {
 func UpdateIssue(issue *Issue) error {
 	return updateIssue(x, issue)
 }
+
+// UpdateIssueDeadline updates an issue deadline and adds comments. Setting a deadline to 0 means deleting it.
+func UpdateIssueDeadline(issue *Issue, deadlineUnix util.TimeStamp, doer *User) (err error) {
+
+	// if the deadline hasn't changed do nothing
+	if issue.DeadlineUnix == deadlineUnix {
+		return nil
+	}
+
+	sess := x.NewSession()
+	defer sess.Close()
+	if err := sess.Begin(); err != nil {
+		return err
+	}
+
+	// Update the deadline
+	if err = updateIssueCols(sess, &Issue{ID: issue.ID, DeadlineUnix: deadlineUnix}, "deadline_unix"); err != nil {
+		return err
+	}
+
+	// Make the comment
+	if _, err = createDeadlineComment(sess, doer, issue, deadlineUnix); err != nil {
+		return fmt.Errorf("createRemovedDueDateComment: %v", err)
+	}
+
+	return sess.Commit()
+}
diff --git a/models/issue_comment.go b/models/issue_comment.go
index ea83c356ee..aedb124863 100644
--- a/models/issue_comment.go
+++ b/models/issue_comment.go
@@ -60,6 +60,12 @@ const (
 	CommentTypeAddTimeManual
 	// Cancel a stopwatch for time tracking
 	CommentTypeCancelTracking
+	// Added a due date
+	CommentTypeAddedDeadline
+	// Modified the due date
+	CommentTypeModifiedDeadline
+	// Removed a due date
+	CommentTypeRemovedDeadline
 )
 
 // CommentTag defines comment tag type
@@ -485,6 +491,34 @@ func createAssigneeComment(e *xorm.Session, doer *User, repo *Repository, issue
 	})
 }
 
+func createDeadlineComment(e *xorm.Session, doer *User, issue *Issue, newDeadlineUnix util.TimeStamp) (*Comment, error) {
+
+	var content string
+	var commentType CommentType
+
+	// newDeadline = 0 means deleting
+	if newDeadlineUnix == 0 {
+		commentType = CommentTypeRemovedDeadline
+		content = issue.DeadlineUnix.Format("2006-01-02")
+	} else if issue.DeadlineUnix == 0 {
+		// Check if the new date was added or modified
+		// If the actual deadline is 0 => deadline added
+		commentType = CommentTypeAddedDeadline
+		content = newDeadlineUnix.Format("2006-01-02")
+	} else { // Otherwise modified
+		commentType = CommentTypeModifiedDeadline
+		content = newDeadlineUnix.Format("2006-01-02") + "|" + issue.DeadlineUnix.Format("2006-01-02")
+	}
+
+	return createComment(e, &CreateCommentOptions{
+		Type:    commentType,
+		Doer:    doer,
+		Repo:    issue.Repo,
+		Issue:   issue,
+		Content: content,
+	})
+}
+
 func createChangeTitleComment(e *xorm.Session, doer *User, repo *Repository, issue *Issue, oldTitle, newTitle string) (*Comment, error) {
 	return createComment(e, &CreateCommentOptions{
 		Type:     CommentTypeChangeTitle,
diff --git a/models/pull.go b/models/pull.go
index 6862d11a1d..5f4a6e2054 100644
--- a/models/pull.go
+++ b/models/pull.go
@@ -207,6 +207,7 @@ func (pr *PullRequest) APIFormat() *api.PullRequest {
 		Base:      apiBaseBranchInfo,
 		Head:      apiHeadBranchInfo,
 		MergeBase: pr.MergeBase,
+		Deadline:  apiIssue.Deadline,
 		Created:   pr.Issue.CreatedUnix.AsTimePtr(),
 		Updated:   pr.Issue.UpdatedUnix.AsTimePtr(),
 	}