feat: implement and test leaving a group

.env.sample

@@ -9,4 +9,7 @@ PORT=
 
 ## URI of the group to which the joining person should be added (required)
 ## The service will need read and write access to the group
-GROUP_TO_JOIN=
+GROUP_TO_JOIN=""
+
+## comma-separated list of URIs of the groups from which the person can be removed if present (required)
+GROUPS_TO_LEAVE=""

CHANGELOG.md

@@ -7,6 +7,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Added
+
+- Implement and test leaving a group
+
 ## [0.1.0] - 2025-01-07
 
 ### Added

src/app.ts

@@ -5,7 +5,7 @@ import { solidIdentity } from '@soid/koa'
 import Koa from 'koa'
 import helmet from 'koa-helmet'
 import serve from 'koa-static'
-import { processRequest, verifyReqest } from './controllers/inbox.js'
+import { processRequest, verifyRequest } from './controllers/inbox.js'
 import { loadConfig } from './middlewares/loadConfig.js'
 import { solidAuth } from './middlewares/solidAuth.js'
 import { validateBody } from './middlewares/validate.js'
@@ -16,6 +16,7 @@ export interface AppConfig {
   readonly webId: string
   readonly isBehindProxy?: boolean
   readonly groupToJoin: string
+  readonly groupsToLeave: string[]
 }
 
 const createApp = async (config: AppConfig) => {
@@ -40,7 +41,7 @@ const createApp = async (config: AppConfig) => {
       }
       */
     validateBody(schema.notification),
-    verifyReqest,
+    verifyRequest,
     processRequest,
   )
 

src/config/helpers.ts

@@ -1,10 +1,10 @@
-export const stringToBoolean = (value: string | undefined): boolean => {
+export const envToBoolean = (value: string | undefined): boolean => {
   if (value === 'false') return false
   if (value === '0') return false
   return !!value
 }
 
-// export const stringToArray = (value: string) => {
-//   if (!value) return []
-//   return value.split(/\s*,\s*/)
-// }
+export const envToArray = (value: string | undefined) => {
+  if (!value) return []
+  return value.split(/\s*,\s*/)
+}

src/config/index.ts

@@ -1,5 +1,5 @@
 import { ConfigError } from '../utils/errors.js'
-import { stringToBoolean } from './helpers.js'
+import { envToArray, envToBoolean } from './helpers.js'
 
 // define environment variables via .env file, or via environment variables directly
 
@@ -16,11 +16,13 @@ const baseUrl =
 
 export const webId = new URL('/profile/card#bot', baseUrl).toString()
 
-export const isBehindProxy = stringToBoolean(process.env.BEHIND_PROXY)
+export const isBehindProxy = envToBoolean(process.env.BEHIND_PROXY)
 
 if (!process.env.GROUP_TO_JOIN)
   throw new ConfigError(
     'Please specify GROUP_TO_JOIN in environment variables.',
   )
 
 export const groupToJoin = process.env.GROUP_TO_JOIN
+
+export const groupsToLeave = envToArray(process.env.GROUPS_TO_LEAVE)

src/controllers/inbox.ts

@@ -1,39 +1,74 @@
 import { getAuthenticatedFetch } from '@soid/koa'
 import { type Middleware } from 'koa'
-import assert from 'node:assert'
 import { solid, vcard } from 'rdf-namespaces'
 import { AppConfig } from '../app.js'
 import { HttpError, ValidationError } from '../utils/errors.js'
 
-export const verifyReqest: Middleware<{
+export const verifyRequest: Middleware<{
   user: string
   config: AppConfig
 }> = async (ctx, next) => {
   const actor = ctx.request.body.actor.id
   const authenticatedUser = ctx.state.user
   const object = ctx.request.body.object.id
-  const group = ctx.state.config.groupToJoin
+  const { groupToJoin, groupsToLeave } = ctx.state.config
+  const task: 'Join' | 'Leave' = ctx.request.body.type
 
   if (actor !== authenticatedUser)
     ctx.throw(
       403,
       `Actor does not match authenticated agent.\nActor: ${actor}\nAuthenticated agent: ${authenticatedUser}`,
     )
 
-  if (object !== group)
-    throw new ValidationError(
-      `Object does not match expected group.\nExpected: ${group}\nActual: ${object}`,
-      [],
-    )
+  switch (task) {
+    case 'Join': {
+      if (object !== groupToJoin)
+        throw new ValidationError(
+          `Object does not match expected group.\nExpected: ${groupToJoin}\nActual: ${object}`,
+          [],
+        )
+      break
+    }
+    case 'Leave': {
+      if (!groupsToLeave.includes(object))
+        throw new ValidationError(
+          `Object does not match any of the expected groups.\nExpected: ${groupsToLeave.join(',')}\nActual: ${object}`,
+          [],
+        )
+      break
+    }
+    default: {
+      throw new Error(`Unrecognized task: ${task}`)
+    }
+  }
 
   await next()
 }
 
 export const processRequest: Middleware<{
   user: string
   config: AppConfig
+}> = async (ctx, next) => {
+  const task: 'Join' | 'Leave' = ctx.request.body.type
+
+  switch (task) {
+    case 'Join': {
+      return await joinGroup(ctx, next)
+    }
+    case 'Leave': {
+      return await leaveGroup(ctx, next)
+    }
+    default:
+      throw new Error('Unexpected task')
+  }
+}
+
+const joinGroup: Middleware<{
+  user: string
+  config: AppConfig
 }> = async ctx => {
-  const group = ctx.state.config.groupToJoin
+  const group = ctx.request.body.object.id
+
   const authFetch = await getAuthenticatedFetch(ctx.state.config.webId)
   const response = await authFetch(group, {
     headers: { 'content-type': 'text/n3' },
@@ -47,10 +82,34 @@ export const processRequest: Middleware<{
     throw new HttpError(
       `Adding person ${ctx.state.user} to group ${group} failed.`,
       response,
+      500,
     )
 
-  assert(response.ok)
-
   ctx.status = 200
   ctx.set('location', group)
 }
+
+const leaveGroup: Middleware<{
+  user: string
+  config: AppConfig
+}> = async ctx => {
+  const group = ctx.request.body.object.id
+
+  const authFetch = await getAuthenticatedFetch(ctx.state.config.webId)
+  const response = await authFetch(group, {
+    headers: { 'content-type': 'text/n3' },
+    method: 'PATCH',
+    body: `_:remove a <${solid.InsertDeletePatch}>;
+        <${solid.deletes}> { <${group}> <${vcard.hasMember}> <${ctx.state.user}> . }.
+      `,
+  })
+
+  if (!response.ok)
+    throw new HttpError(
+      `Removing person ${ctx.state.user} from group ${group} failed.`,
+      response,
+      response.status === 409 ? 409 : 500,
+    )
+
+  ctx.status = 200
+}

src/index.ts

@@ -1,8 +1,14 @@
 /* eslint-disable no-console */
 import { createApp } from './app.js'
-import { groupToJoin, isBehindProxy, port, webId } from './config/index.js'
+import {
+  groupsToLeave,
+  groupToJoin,
+  isBehindProxy,
+  port,
+  webId,
+} from './config/index.js'
 
-createApp({ webId, isBehindProxy, groupToJoin }).then(app =>
+createApp({ webId, isBehindProxy, groupToJoin, groupsToLeave }).then(app =>
   app.listen(port, async () => {
     console.log(`community inbox service is listening on port ${port}`)
   }),

src/schema.ts

@@ -1,7 +1,7 @@
 import { JSONSchemaType } from 'ajv/dist/2020.js'
 
 export const notification: JSONSchemaType<{
-  type: 'Join'
+  type: 'Join' | 'Leave'
   id: string
   '@context': 'https://www.w3.org/ns/activitystreams'
   actor: { type: 'Person'; id: string }
@@ -17,7 +17,7 @@ export const notification: JSONSchemaType<{
       const: 'https://www.w3.org/ns/activitystreams',
     },
     id: { type: 'string' },
-    type: { type: 'string', enum: ['Join'] },
+    type: { type: 'string', enum: ['Join', 'Leave'] },
     actor: {
       type: 'object',
       properties: {