[feature] User muting (#2960)

* User muting

* Address review feedback

* Rename uniqueness constraint on user_mutes to match convention

* Remove unused account_id from where clause

* Add UserMute to NewTestDB

* Update test/envparsing.sh with new and fixed cache stuff

* Address tobi's review comments

* Make compiledUserMuteListEntry.expired consistent with UserMute.Expired

* Make sure mute_expires_at is serialized as an explicit null for indefinite mutes

---------

Co-authored-by: tobi <tobi.smethurst@protonmail.com>

internal/filter/usermute/usermute.go

@@ -0,0 +1,80 @@
+// GoToSocial
+// Copyright (C) GoToSocial Authors admin@gotosocial.org
+// SPDX-License-Identifier: AGPL-3.0-or-later
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package usermute
+
+import (
+	"time"
+
+	statusfilter "github.com/superseriousbusiness/gotosocial/internal/filter/status"
+	"github.com/superseriousbusiness/gotosocial/internal/gtsmodel"
+)
+
+type compiledUserMuteListEntry struct {
+	ExpiresAt     time.Time
+	Notifications bool
+}
+
+func (e *compiledUserMuteListEntry) appliesInContext(filterContext statusfilter.FilterContext) bool {
+	switch filterContext {
+	case statusfilter.FilterContextHome:
+		return true
+	case statusfilter.FilterContextNotifications:
+		return e.Notifications
+	case statusfilter.FilterContextPublic:
+		return true
+	case statusfilter.FilterContextThread:
+		return true
+	case statusfilter.FilterContextAccount:
+		return false
+	}
+	return false
+}
+
+func (e *compiledUserMuteListEntry) expired(now time.Time) bool {
+	return !e.ExpiresAt.IsZero() && !e.ExpiresAt.After(now)
+}
+
+type CompiledUserMuteList struct {
+	byTargetAccountID map[string]compiledUserMuteListEntry
+}
+
+func NewCompiledUserMuteList(mutes []*gtsmodel.UserMute) (c *CompiledUserMuteList) {
+	c = &CompiledUserMuteList{byTargetAccountID: make(map[string]compiledUserMuteListEntry, len(mutes))}
+	for _, mute := range mutes {
+		c.byTargetAccountID[mute.TargetAccountID] = compiledUserMuteListEntry{
+			ExpiresAt:     mute.ExpiresAt,
+			Notifications: *mute.Notifications,
+		}
+	}
+	return
+}
+
+func (c *CompiledUserMuteList) Len() int {
+	if c == nil {
+		return 0
+	}
+	return len(c.byTargetAccountID)
+}
+
+func (c *CompiledUserMuteList) Matches(accountID string, filterContext statusfilter.FilterContext, now time.Time) bool {
+	if c == nil {
+		return false
+	}
+	e, found := c.byTargetAccountID[accountID]
+	return found && e.appliesInContext(filterContext) && !e.expired(now)
+}