From e634c3c5020b491005fb8a7be946f75075639171 Mon Sep 17 00:00:00 2001
From: Gnuxie <50846879+Gnuxie@users.noreply.github.com>
Date: Mon, 15 Apr 2024 23:33:13 +0100
Subject: [PATCH] Add PolicyChangeNotification protection. (#346)

Fixes https://github.com/the-draupnir-project/Draupnir/issues/335.
---
 .../DefaultEnabledProtectionsMigration.ts     |  22 +++
 src/protections/DraupnirProtectionsIndex.ts   |   1 +
 src/protections/PolicyChangeNotification.tsx  | 135 ++++++++++++++++++
 3 files changed, 158 insertions(+)
 create mode 100644 src/protections/PolicyChangeNotification.tsx

diff --git a/src/protections/DefaultEnabledProtectionsMigration.ts b/src/protections/DefaultEnabledProtectionsMigration.ts
index e82be589..5368d839 100644
--- a/src/protections/DefaultEnabledProtectionsMigration.ts
+++ b/src/protections/DefaultEnabledProtectionsMigration.ts
@@ -5,6 +5,7 @@
 
 import { ActionError,ActionException,ActionExceptionKind,DRAUPNIR_SCHEMA_VERSION_KEY, MjolnirEnabledProtectionsEvent, MjolnirEnabledProtectionsEventType, Ok, SchemedDataManager, Value, findProtection } from "matrix-protection-suite";
 import { RedactionSynchronisationProtection } from "./RedactionSynchronisation";
+import { PolicyChangeNotification } from "./PolicyChangeNotification";
 
 export const DefaultEnabledProtectionsMigration = new SchemedDataManager<MjolnirEnabledProtectionsEvent>([
     async function enableBanPropagationByDefault(input) {
@@ -73,5 +74,26 @@ export const DefaultEnabledProtectionsMigration = new SchemedDataManager<Mjolnir
             enabled: [...enabledProtections],
             [DRAUPNIR_SCHEMA_VERSION_KEY]: 3,
         });
+    },
+    async function enablePolicyChangeNotification(input) {
+        if (!Value.Check(MjolnirEnabledProtectionsEvent, input)) {
+            return ActionError.Result(
+                `The data for ${MjolnirEnabledProtectionsEventType} is corrupted.`
+            );
+        }
+        const enabledProtections = new Set(input.enabled);
+        const protection = findProtection(PolicyChangeNotification.name);
+        if (protection === undefined) {
+            const message = `Cannot find the ${PolicyChangeNotification.name} protection`;
+            return ActionException.Result(message, {
+                exception: new TypeError(message),
+                exceptionKind: ActionExceptionKind.Unknown
+            });
+        }
+        enabledProtections.add(protection.name);
+        return Ok({
+            enabled: [...enabledProtections],
+            [DRAUPNIR_SCHEMA_VERSION_KEY]: 4,
+        });
     }
 ]);
diff --git a/src/protections/DraupnirProtectionsIndex.ts b/src/protections/DraupnirProtectionsIndex.ts
index f8cfd9ee..9c399e3c 100644
--- a/src/protections/DraupnirProtectionsIndex.ts
+++ b/src/protections/DraupnirProtectionsIndex.ts
@@ -12,6 +12,7 @@ import './JoinWaveShortCircuit';
 import './RedactionSynchronisation';
 import './MessageIsMedia';
 import './MessageIsVoice';
+import './PolicyChangeNotification';
 import './TrustedReporters';
 import './WordList';
 
diff --git a/src/protections/PolicyChangeNotification.tsx b/src/protections/PolicyChangeNotification.tsx
new file mode 100644
index 00000000..25182da8
--- /dev/null
+++ b/src/protections/PolicyChangeNotification.tsx
@@ -0,0 +1,135 @@
+// SPDX-FileCopyrightText: 2022 - 2024 Gnuxie <Gnuxie@protonmail.com>
+// SPDX-FileCopyrightText: 2022 The Matrix.org Foundation C.I.C.
+//
+// SPDX-License-Identifier: AFL-3.0 AND Apache-2.0
+//
+// SPDX-FileAttributionText: <text>
+// This modified file incorporates work from mjolnir
+// https://github.com/matrix-org/mjolnir
+// </text>
+
+import { AbstractProtection, ActionResult, Logger, MatrixRoomReference, Ok, PolicyListRevision, PolicyRoomManager, PolicyRoomRevisionIssuer, PolicyRuleChange, ProtectedRoomsSet, ProtectionDescription, StringRoomID, UnknownSettings, describeProtection, isError } from "matrix-protection-suite";
+import { DraupnirProtection } from "./Protection";
+import { Draupnir } from "../Draupnir";
+import { DocumentNode } from "../commands/interface-manager/DeadDocument";
+import { JSXFactory } from "../commands/interface-manager/JSXFactory";
+import { renderMentionPill, renderRoomPill } from "../commands/interface-manager/MatrixHelpRenderer";
+import { renderMatrixAndSend } from "../commands/interface-manager/DeadDocumentMatrix";
+
+const log = new Logger('PolicyChangeNotification');
+
+export type PolicyChangeNotificationCapabilitites = {};
+
+export type PolicyChangeNotificationProtectionDescription = ProtectionDescription<
+    Draupnir,
+    UnknownSettings<string>,
+    PolicyChangeNotificationCapabilitites
+>;
+
+type ChangesByRoomID = Map<StringRoomID, PolicyRuleChange[]>;
+
+export class PolicyChangeNotification
+    extends AbstractProtection<PolicyChangeNotificationProtectionDescription>
+    implements DraupnirProtection<PolicyChangeNotificationProtectionDescription> {
+
+    constructor(
+        description: PolicyChangeNotificationProtectionDescription,
+        capabilities: PolicyChangeNotificationCapabilitites,
+        protectedRoomsSet: ProtectedRoomsSet,
+        private readonly draupnir: Draupnir,
+    ) {
+        super(description, capabilities, protectedRoomsSet, [], []);
+    }
+
+    public async handlePolicyChange(revision: PolicyListRevision, changes: PolicyRuleChange[]): Promise<ActionResult<void>> {
+        if (changes.length === 0) {
+            return Ok(undefined);
+        }
+        const changesByList: ChangesByRoomID = new Map();
+        for (const change of changes) {
+            const entry = changesByList.get(change.event.room_id);
+            if (entry === undefined) {
+                changesByList.set(change.event.room_id, [change]);
+            } else {
+                entry.push(change);
+            }
+        }
+        const groupedChanges = await groupRulesByIssuer(this.draupnir.policyRoomManager, changesByList);
+        if (isError(groupedChanges)) {
+            return groupedChanges;
+        }
+        try {
+            await renderMatrixAndSend(
+                <root>{renderGroupedChanges(groupedChanges.ok)}</root>,
+                this.draupnir.managementRoomID,
+                undefined,
+                this.draupnir.client
+            );
+        } catch (e) {
+            log.error(`couldn't send change to management room`, e);
+        }
+        return Ok(undefined);
+    }
+}
+
+type GroupedChange = {
+    issuer: PolicyRoomRevisionIssuer,
+    changes: PolicyRuleChange[],
+}
+
+async function groupRulesByIssuer(policyRoomManager: PolicyRoomManager, changesByList: ChangesByRoomID): Promise<ActionResult<GroupedChange[]>> {
+    const groupedChanges: GroupedChange[] = []
+    for (const [roomID, changes] of changesByList) {
+        const issuer = await policyRoomManager.getPolicyRoomRevisionIssuer(MatrixRoomReference.fromRoomID(roomID));
+        if (isError(issuer)) {
+            return issuer;
+        } else {
+            groupedChanges.push({
+                issuer: issuer.ok,
+                changes: changes
+            })
+        }
+    }
+    return Ok(groupedChanges);
+}
+
+function renderListChange(change: PolicyRuleChange): DocumentNode {
+    return <fragment>
+        <li>
+            {renderMentionPill(change.sender, change.sender)} <code>{change.changeType}</code> &#32;
+            {change.rule.kind} (<code>{change.rule.recommendation}</code>) &#32;
+            <code>{change.rule.entity}</code> ({change.rule.reason})
+        </li>
+    </fragment>
+}
+
+function renderListChanges({ issuer, changes }: GroupedChange): DocumentNode {
+    return <fragment>
+        {renderRoomPill(issuer.room)} (shortcode: {issuer.currentRevision.shortcode ?? 'no shortcode'}) &#32;
+        updated with {changes.length} {changes.length === 1 ? 'change' : 'changes'}:
+        <ul>{changes.map(renderListChange)}</ul>
+    </fragment>
+}
+
+function renderGroupedChanges(groupedChanges: GroupedChange[]): DocumentNode {
+    return <fragment>
+        {groupedChanges.map(renderListChanges)}
+    </fragment>
+}
+
+describeProtection<PolicyChangeNotificationCapabilitites, Draupnir>({
+    name: PolicyChangeNotification.name,
+    description: 'Provides notification of policy changes from watched lists.',
+    capabilityInterfaces: {},
+    defaultCapabilities: {},
+    factory(description, protectedRoomsSet, draupnir, capabilities, _settings) {
+        return Ok(
+            new PolicyChangeNotification(
+                description,
+                capabilities,
+                protectedRoomsSet,
+                draupnir
+            )
+        );
+    }
+});