Paginate through slack channels

app/services/slack/loads_slack_channels.rb

@@ -11,16 +11,26 @@ class LoadsSlackChannels
 
     def call(types:)
       response = retry_when_rate_limited do
-        ClientWrapper.client.conversations_list(types: approved_types(types), limit: 1000)
+        ClientWrapper.client.conversations_list(types: approved_types(types), limit: 1000, exclude_archived: true)
       end
 
-      (response&.channels || []).reject { |ch| ch.is_archived }
+      get_paged_channels(cursor: response&.response_metadata&.next_cursor, channels: response&.channels || [], types: types)
     end
 
     private
 
     def approved_types(types)
       types.split(",").select { |t| SLACK_CHANNEL_TYPES.include?(t) }.join(",")
     end
+
+    def get_paged_channels(cursor:, channels:, types:)
+      while cursor.present?
+        response = ClientWrapper.client.conversations_list(cursor: cursor, types: approved_types(types), limit: 1000, exclude_archived: true)
+        channels.append(response.channels)
+        cursor = response.response_metadata&.next_cursor
+      end
+
+      channels.flatten
+    end
   end
 end

spec/lib/slack/loads_slack_channels_spec.rb

@@ -18,17 +18,16 @@
       is_mpim: true,
       user: Slack::Messages::Message.new(id: "USER_ID")
     )
-    archived_slack_public_channel = Slack::Messages::Message.new(
+    Slack::Messages::Message.new(
       id: "PUBLIC_CHANNEL_ID_2",
       is_channel: true,
       is_archived: true
     )
 
-    expect(@slack_client).to receive(:conversations_list).with(types: "public_channel,mpim", limit: 1000) {
+    expect(@slack_client).to receive(:conversations_list).with(types: "public_channel,mpim", limit: 1000, exclude_archived: true) {
       Slack::Messages::Message.new(ok: true, channels: [
         slack_public_channel,
-        slack_mpim_channel,
-        archived_slack_public_channel
+        slack_mpim_channel
       ])
     }
 
@@ -37,13 +36,34 @@
     expect(channels).to eq([slack_public_channel, slack_mpim_channel])
   end
 
+  it "loads all active channels when requiring pagination" do
+    slack_public_channels = (0..1010).map do |ch|
+      Slack::Messages::Message.new(
+        id: "PUBLIC_CHANNEL_ID_#{ch}",
+        is_channel: true
+      )
+    end
+
+    response_metadata = Slack::Messages::Message.new(next_cursor: "cursor")
+    expect(@slack_client).to receive(:conversations_list).with(types: "public_channel", limit: 1000, exclude_archived: true) {
+      Slack::Messages::Message.new(ok: true, response_metadata: response_metadata, channels: slack_public_channels[0..999])
+    }
+    expect(@slack_client).to receive(:conversations_list).with(types: "public_channel", limit: 1000, exclude_archived: true, cursor: response_metadata.next_cursor) {
+      Slack::Messages::Message.new(ok: true, channels: slack_public_channels[1000..])
+    }
+
+    channels = subject.call(types: "public_channel")
+
+    expect(channels).to eq(slack_public_channels)
+  end
+
   it "ignores unrecognized channel types" do
     slack_public_channel = Slack::Messages::Message.new(
       id: "PUBLIC_CHANNEL_ID_1",
       is_channel: true
     )
 
-    expect(@slack_client).to receive(:conversations_list).with(types: "public_channel", limit: 1000) {
+    expect(@slack_client).to receive(:conversations_list).with(types: "public_channel", limit: 1000, exclude_archived: true) {
       Slack::Messages::Message.new(ok: true, channels: [slack_public_channel])
     }