Add reporting/flagging of messages

Add reporting/flagging of messages. Revival of https://github.com/troupe/gitter-webapp/pull/2564

• Add a report option to messages (UI) that calls the API to record the report
• API endpoint
  • Record report to Mongo collection chatmessagereports (perhaps redis in the future like we do for spam messages)
    • sent { type: Date, "default": Date.now }: When the report was sent
    • weight: Number: Factor of how much we consider of the individual report
    • reporterUserId: ObjectId: User who made the report
    • messageId: ObjectId: Offending bad message ID
    • messageUserId: ObjectId: Message author fromUserId (for an easy index when summing)
    • text: String: Message text at time of reporting
  • Count number of reports and check if over threshold. If over threshold, mark as bad user(hellban and if new user, delete messages)
• Deduplicate reports from a user on each message (only allow one report to be counted for a given user against a message)
• Weight calculations, baseWeight * userAgeWeight * messageAgeWeight
  • baseWeight (room admins have more weight)
    • Normal user: 1
    • Admin of room: 2.5
  • userAgeWeight (new users have little effect)
    • < 2 days: 0
    • < 2 weeks: 0.15
    • < 2 months: 0.3
    • < 6 months: 0.6
    • >= 6 months: 1
  • messageAgeWeight (old messages are hard to delete)
    • < 2 days: 1
    • < 21 days: 0.5
    • >= 21 days: 0
  • We want to avoid a troll insta-kill: A troll could create a room, add some people or mention them to come join, people respond "please stop, I'm not interested", and the troll could report.
    • We could also factor in room created date.
• Sum calculations:
  • Report sum threshold to indicate bad user/message (escalation levels):
    • 2 to delete individual message
    • 5 to hellban and if new user, clear all messages
  • How do we handle a user marking each bad message? How is the report sum calculated?
    • Only count 1 report from a given user against another user
  • Only sum reports within the last 5 days
• Add a dashboard that is only accessible to staff users, /-/admin/chat-message-reports

Testing locally

• mongo localhost:27017
• db.chatmessagereports.remove({})
• .

  db.chatmessagereports.insertOne({ 
    "fromUserId": new ObjectId(),
    "messageId": new ObjectId(),
    "text" : "fake-report",
    "messageUserId": ObjectId("58f14d5ec72b1fa342f7e259"),
    "weight" : 2.5,
  });

• set logging:level=info&&npm run dev

---

$ mklink "C:\Users\MLM\Documents\GitLab\gitter-secrets\webapp\env" "C:\Users\MLM\Documents\GitLab\gitter-secrets\env"
$ @FOR /f "tokens=*" %i IN ('bash /c/Users/MLM/Documents/GitLab/gitter-secrets/webapp/env test') DO @%i
$ npm run mocha -- test/api-tests/chat-api-tests.js

Todo

• Only clear all messages for new users
• Add basic dashboard to review reports
• Add some docs around what messages should be reported

Future ideas

• Add actions to report dashboard: hellban, delete message, see more messages from user, delete all messages from user
• Audit/review reports
  • Factor in past good reports (from reviews) into users baseWeight
  • Allow the community to review reports. They can only review reports from rooms they can acccess
• Add list of people who were banned
• Graph of reports (we can get this in Datadog with the stats though)

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Closes https://gitlab.com/gitlab-org/gitter/webapp/issues/954