Add the ability to pin Issues (#24406)

This adds the ability to pin important Issues and Pull Requests. You can
also move pinned Issues around to change their Position. Resolves #2175.

## Screenshots

![grafik](https://user-images.githubusercontent.com/15185051/235123207-0aa39869-bb48-45c3-abe2-ba1e836046ec.png)

![grafik](https://user-images.githubusercontent.com/15185051/235123297-152a16ea-a857-451d-9a42-61f2cd54dd75.png)

![grafik](https://user-images.githubusercontent.com/15185051/235640782-cbfe25ec-6254-479a-a3de-133e585d7a2d.png)

The Design was mostly copied from the Projects Board.

## Implementation
This uses a new `pin_order` Column in the `issue` table. If the value is
set to 0, the Issue is not pinned. If it's set to a bigger value, the
value is the Position. 1 means it's the first pinned Issue, 2 means it's
the second one etc. This is dived into Issues and Pull requests for each
Repo.

## TODO
- [x] You can currently pin as many Issues as you want. Maybe we should
add a Limit, which is configurable. GitHub uses 3, but I prefer 6, as
this is better for bigger Projects, but I'm open for suggestions.
- [x] Pin and Unpin events need to be added to the Issue history.
- [x] Tests
- [x] Migration

**The feature itself is currently fully working, so tester who may find
weird edge cases are very welcome!**

---------

Co-authored-by: silverwind <me@silverwind.io>
Co-authored-by: Giteabot <teabot@gitea.io>

3 files changed, 101 insertions, 13 deletions

diff --git a/templates/repo/issue/list.tmpl b/templates/repo/issue/list.tmpl
index 7c2f73ca59..dab6652d21 100644
--- a/templates/repo/issue/list.tmpl
+++ b/templates/repo/issue/list.tmpl
@@ -2,6 +2,70 @@
 <div role="main" aria-label="{{.Title}}" class="page-content repository issue-list">
 	{{template "repo/header" .}}
 	<div class="ui container">
+
+	{{if .PinnedIssues}}
+		<div id="issue-pins" {{if .IsRepoAdmin}}data-is-repo-admin{{end}}>
+			{{range .PinnedIssues}}
+				<div class="pinned-issue-card gt-word-break" data-move-url="{{$.Link}}/pin_move" data-issue-id="{{.ID}}">
+					{{if eq $.Project.CardType 1}}
+						<div class="card-attachment-images">
+							{{range (index $.issuesAttachmentMap .ID)}}
+								<img src="{{.DownloadURL}}" alt="{{.Name}}">
+							{{end}}
+						</div>
+					{{end}}
+					<div class="content gt-p-0">
+						<div class="header gt-df gt-items-start">
+							<div class="pinned-issue-icon">
+								{{template "shared/issueicon" .}}
+							</div>
+							<a class="pinned-issue-title muted issue-title" href="{{.Link}}">{{.Title | RenderEmoji $.Context | RenderCodeBlock}}</a>
+							{{if $.IsRepoAdmin}}
+								<a role="button" class="pinned-issue-unpin muted gt-df gt-ac" data-tooltip-content={{$.locale.Tr "repo.issues.unpin_issue"}} data-issue-id="{{.ID}}" data-unpin-url="{{$.Link}}/unpin/{{.ID}}">
+									{{svg "octicon-x" 16}}
+								</a>
+							{{end}}
+						</div>
+						<div class="meta gt-my-2">
+							<span class="text light grey">
+								#{{.Index}}
+								{{$timeStr := TimeSinceUnix .GetLastEventTimestamp $.locale}}
+								{{if .OriginalAuthor}}
+									{{$.locale.Tr .GetLastEventLabelFake $timeStr (.OriginalAuthor|Escape) | Safe}}
+								{{else if gt .Poster.ID 0}}
+									{{$.locale.Tr .GetLastEventLabel $timeStr (.Poster.HomeLink|Escape) (.Poster.GetDisplayName | Escape) | Safe}}
+								{{else}}
+									{{$.locale.Tr .GetLastEventLabelFake $timeStr (.Poster.GetDisplayName | Escape) | Safe}}
+								{{end}}
+							</span>
+						</div>
+						{{- if .MilestoneID}}
+						<div class="meta gt-my-2">
+							<a class="milestone" href="{{$.RepoLink}}/milestone/{{.MilestoneID}}">
+								{{svg "octicon-milestone" 16 "gt-mr-2 gt-vm"}}
+								<span class="gt-vm">{{.Milestone.Name}}</span>
+							</a>
+						</div>
+						{{- end}}
+					</div>
+
+					{{if or .Labels .Assignees}}
+					<div class="extra content labels-list gt-p-0 gt-pt-2">
+						{{range .Labels}}
+							<a href="{{$.RepoLink}}/issues?labels={{.ID}}">{{RenderLabel $.Context .}}</a>
+						{{end}}
+						<div class="right floated">
+							{{range .Assignees}}
+								<a href="{{.HomeLink}}" data-tooltip-content="{{$.locale.Tr "repo.projects.column.assigned_to"}} {{.Name}}">{{avatar $.Context . 28 "mini gt-mr-3"}}</a>
+							{{end}}
+						</div>
+					</div>
+					{{end}}
+				</div>
+			{{end}}
+		</div>
+	{{end}}
+
 		<div class="list-header">
 			{{template "repo/issue/navbar" .}}
 			{{template "repo/issue/search" .}}
diff --git a/templates/repo/issue/view_content/comments.tmpl b/templates/repo/issue/view_content/comments.tmpl
index b65ebc68a2..5091201dde 100644
--- a/templates/repo/issue/view_content/comments.tmpl
+++ b/templates/repo/issue/view_content/comments.tmpl
@@ -11,7 +11,7 @@
 		26 = DELETE_TIME_MANUAL, 27 = REVIEW_REQUEST, 28 = MERGE_PULL_REQUEST,
 		29 = PULL_PUSH_EVENT, 30 = PROJECT_CHANGED, 31 = PROJECT_BOARD_CHANGED
 		32 = DISMISSED_REVIEW, 33 = COMMENT_TYPE_CHANGE_ISSUE_REF, 34 = PR_SCHEDULE_TO_AUTO_MERGE,
-		35 = CANCEL_SCHEDULED_AUTO_MERGE_PR -->
+		35 = CANCEL_SCHEDULED_AUTO_MERGE_PR, 36 = PIN_ISSUE, 37 = UNPIN_ISSUE -->
 		{{if eq .Type 0}}
 			<div class="timeline-item comment" id="{{.HashTag}}">
 			{{if .OriginalAuthor}}
@@ -835,6 +835,16 @@
 					{{else}}{{$.locale.Tr "repo.pulls.auto_merge_canceled_schedule_comment" $createdStr | Safe}}{{end}}
 				</span>
 			</div>
+		{{else if or (eq .Type 36) (eq .Type 37)}}
+			<div class="timeline-item event" id="{{.HashTag}}">
+				<span class="badge">{{svg "octicon-pin" 16}}</span>
+				{{template "shared/user/avatarlink" dict "Context" $.Context "user" .Poster}}
+				<span class="text grey muted-links">
+					{{template "shared/user/authorlink" .Poster}}
+					{{if eq .Type 36}}{{$.locale.Tr "repo.issues.pin_comment" $createdStr | Safe}}
+					{{else}}{{$.locale.Tr "repo.issues.unpin_comment" $createdStr | Safe}}{{end}}
+				</span>
+			</div>
 		{{end}}
 	{{end}}
 {{end}}
diff --git a/templates/repo/issue/view_content/sidebar.tmpl b/templates/repo/issue/view_content/sidebar.tmpl
index c8e65d0900..60d2f4a561 100644
--- a/templates/repo/issue/view_content/sidebar.tmpl
+++ b/templates/repo/issue/view_content/sidebar.tmpl
@@ -530,17 +530,31 @@
 
 		{{if and .IsRepoAdmin (not .Repository.IsArchived)}}
 			<div class="ui divider"></div>
-			<div class="ui watching">
-				<button class="fluid ui show-modal button {{if .Issue.IsLocked}} negative {{end}}" data-modal="#lock">
-					{{if .Issue.IsLocked}}
-						{{svg "octicon-key"}}
-						{{.locale.Tr "repo.issues.unlock"}}
-					{{else}}
-						{{svg "octicon-lock"}}
-						{{.locale.Tr "repo.issues.lock"}}
-					{{end}}
-				</button>
-			</div>
+
+			{{if or .PinEnabled .Issue.IsPinned}}
+				<form class="gt-mt-2" method="POST" {{if $.NewPinAllowed}}action="{{.Issue.Link}}/pin"{{else}}data-tooltip-content="{{.locale.Tr "repo.issues.max_pinned"}}"{{end}}>
+					{{$.CsrfTokenHtml}}
+					<button class="fluid ui button gt-df gt-jc {{if not $.NewPinAllowed}}disabled{{end}}">
+						{{if not .Issue.IsPinned}}
+							{{svg "octicon-pin" 16 "gt-mr-3"}}
+							{{.locale.Tr "pin"}}
+						{{else}}
+							{{svg "octicon-pin-slash" 16 "gt-mr-3"}}
+							{{.locale.Tr "unpin"}}
+						{{end}}
+					</button>
+				</form>
+			{{end}}
+
+			<button class="gt-mt-2 fluid ui show-modal button {{if .Issue.IsLocked}} negative {{end}}" data-modal="#lock">
+				{{if .Issue.IsLocked}}
+					{{svg "octicon-key"}}
+					{{.locale.Tr "repo.issues.unlock"}}
+				{{else}}
+					{{svg "octicon-lock"}}
+					{{.locale.Tr "repo.issues.lock"}}
+				{{end}}
+			</button>
 			<div class="ui tiny modal" id="lock">
 				<div class="header">
 					{{if .Issue.IsLocked}}
@@ -605,7 +619,7 @@
 					</form>
 				</div>
 			</div>
-			<button class="fluid ui show-modal button negative gt-mt-3" data-modal="#delete">
+			<button class="gt-mt-2 fluid ui show-modal button negative" data-modal="#delete">
 				{{svg "octicon-trash"}}
 				{{.locale.Tr "repo.issues.delete"}}
 			</button>