Add config options to hide issue events (#17414)

* Add config option to hide issue events
Adds a config option `HIDE_ISSUE_EVENTS` to hide most issue events (changed labels, milestones, projects...) on the issue detail page.
If this is true, only the following events (comment types) are shown:
* plain comments
* closed/reopned/merged
* reviews

* Make configurable using a list

* Add docs

* Add missing newline

* Fix merge issues

* Allow changes per user settings

* Fix lint

* Rm old docs

* Apply suggestions from code review

* Use bitsets

* Rm comment

* fmt

* Fix lint

* Use variable/constant to provide key

* fmt

* fix lint

* refactor

* Add a prefix for user setting key

* Add license comment

* Add license comment

* Update services/forms/user_form_hidden_comments.go

Co-authored-by: Gusted <williamzijl7@hotmail.com>

* check len == 0

Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>
Co-authored-by: zeripath <art27@cantab.net>
Co-authored-by: Gusted <williamzijl7@hotmail.com>
Co-authored-by: 6543 <6543@obermui.de>

services/forms/user_form_hidden_comments.go

@@ -0,0 +1,105 @@
+// Copyright 2021 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 forms
+
+import (
+	"math/big"
+
+	"code.gitea.io/gitea/models"
+	"code.gitea.io/gitea/modules/context"
+	"code.gitea.io/gitea/modules/log"
+)
+
+type hiddenCommentTypeGroupsType map[string][]models.CommentType
+
+// hiddenCommentTypeGroups maps the group names to comment types, these group names comes from the Web UI (appearance.tmpl)
+var hiddenCommentTypeGroups = hiddenCommentTypeGroupsType{
+	"reference": {
+		/*3*/ models.CommentTypeIssueRef,
+		/*4*/ models.CommentTypeCommitRef,
+		/*5*/ models.CommentTypeCommentRef,
+		/*6*/ models.CommentTypePullRef,
+	},
+	"label": {
+		/*7*/ models.CommentTypeLabel,
+	},
+	"milestone": {
+		/*8*/ models.CommentTypeMilestone,
+	},
+	"assignee": {
+		/*9*/ models.CommentTypeAssignees,
+	},
+	"title": {
+		/*10*/ models.CommentTypeChangeTitle,
+	},
+	"branch": {
+		/*11*/ models.CommentTypeDeleteBranch,
+		/*25*/ models.CommentTypeChangeTargetBranch,
+	},
+	"time_tracking": {
+		/*12*/ models.CommentTypeStartTracking,
+		/*13*/ models.CommentTypeStopTracking,
+		/*14*/ models.CommentTypeAddTimeManual,
+		/*15*/ models.CommentTypeCancelTracking,
+		/*26*/ models.CommentTypeDeleteTimeManual,
+	},
+	"deadline": {
+		/*16*/ models.CommentTypeAddedDeadline,
+		/*17*/ models.CommentTypeModifiedDeadline,
+		/*18*/ models.CommentTypeRemovedDeadline,
+	},
+	"dependency": {
+		/*19*/ models.CommentTypeAddDependency,
+		/*20*/ models.CommentTypeRemoveDependency,
+	},
+	"lock": {
+		/*23*/ models.CommentTypeLock,
+		/*24*/ models.CommentTypeUnlock,
+	},
+	"review_request": {
+		/*27*/ models.CommentTypeReviewRequest,
+	},
+	"pull_request_push": {
+		/*29*/ models.CommentTypePullRequestPush,
+	},
+	"project": {
+		/*30*/ models.CommentTypeProject,
+		/*31*/ models.CommentTypeProjectBoard,
+	},
+	"issue_ref": {
+		/*33*/ models.CommentTypeChangeIssueRef,
+	},
+}
+
+// UserHiddenCommentTypesFromRequest parse the form to hidden comment types bitset
+func UserHiddenCommentTypesFromRequest(ctx *context.Context) *big.Int {
+	bitset := new(big.Int)
+	for group, commentTypes := range hiddenCommentTypeGroups {
+		if ctx.FormBool(group) {
+			for _, commentType := range commentTypes {
+				bitset = bitset.SetBit(bitset, int(commentType), 1)
+			}
+		}
+	}
+	return bitset
+}
+
+// IsUserHiddenCommentTypeGroupChecked check whether a hidden comment type group is "enabled" (checked on UI)
+func IsUserHiddenCommentTypeGroupChecked(group string, hiddenCommentTypes *big.Int) (ret bool) {
+	commentTypes, ok := hiddenCommentTypeGroups[group]
+	if !ok {
+		log.Critical("the group map for hidden comment types is out of sync, unknown group: %v", group)
+		return
+	}
+	if hiddenCommentTypes == nil {
+		return false
+	}
+	for _, commentType := range commentTypes {
+		if hiddenCommentTypes.Bit(int(commentType)) == 1 {
+			return true
+		}
+	}
+	return false
+}