Add auto-detection of first message in conversation

lib/discourse_chat/provider/slack/slack_command_controller.rb

@@ -52,9 +52,9 @@ module DiscourseChat::Provider::SlackProvider
         return { text: I18n.t("chat_integration.provider.slack.transcript.api_required") }
       end
 
-      requested_messages = 10
-
+      requested_messages = nil
       first_message_ts = nil
+
       slack_url_regex = /^https:\/\/\S+\.slack\.com\/archives\/\S+\/p([0-9]{16})\/?$/
       if tokens.size > 1 && match = slack_url_regex.match(tokens[1])
         first_message_ts = match.captures[0].insert(10, '.')
@@ -74,8 +74,10 @@ module DiscourseChat::Provider::SlackProvider
 
       if first_message_ts
         return error_message unless transcript.set_first_message_by_ts(first_message_ts)
+      elsif requested_messages
+        transcript.set_first_message_by_index(-requested_messages)
       else
-        transcript.set_first_message_by_index(-requested_messages) # Don't fail if this doesn't work, just use the default
+        transcript.set_first_message_by_index(-10) unless transcript.guess_first_message
       end
 
       return transcript.build_slack_ui

lib/discourse_chat/provider/slack/slack_transcript.rb

@@ -112,6 +112,36 @@ module DiscourseChat::Provider::SlackProvider
       @last_message_index = val if @messages[val]
     end
 
+    # Apply a heuristic to decide which is the first message in the current conversation
+    def guess_first_message(skip_messages: 5) # Can skip the last n messages
+
+      possible_first_messages = @messages[0..-skip_messages]
+
+      # Work through the messages in order. If a gap is found, this could be the first message
+      new_first_message_index = nil
+      previous_message_ts = @messages[-skip_messages].ts.split('.').first.to_i
+      possible_first_messages.each_with_index do |message, index|
+
+        # Calculate the time since the last message
+        this_ts = message.ts.split('.').first.to_i
+        time_since_previous_message = this_ts - previous_message_ts
+
+        # If greater than 3 minutes, this could be the first message
+        if time_since_previous_message > 3.minutes
+          new_first_message_index = index
+        end
+
+        previous_message_ts = this_ts
+      end
+
+      if new_first_message_index
+        @first_message_index = new_first_message_index
+        return true
+      else
+        return false
+      end
+    end
+
     def first_message
       return @messages[@first_message_index]
     end

spec/lib/discourse_chat/provider/slack/slack_command_controller_spec.rb

@@ -213,6 +213,18 @@ describe 'Slack Command Controller', type: :request do
             expect(json["attachments"].length).to eq(2)
             expect(json["attachments"][0]["ts"]).to eq("1501801629.052212")
           end
+
+          it 'can auto select' do
+            post "/chat-integration/slack/command.json",
+              text: "post",
+              channel_name: 'general',
+              channel_id: 'C6029G78F',
+              token: token
+
+            json = JSON.parse(response.body)
+            expect(json["attachments"].length).to eq(2)
+            expect(json["attachments"][0]["ts"]).to eq("1501615820.949638")
+          end
         end
 
         it 'deals with failed API calls correctly' do

spec/lib/discourse_chat/provider/slack/slack_transcript_spec.rb

@@ -176,6 +176,11 @@ RSpec.describe DiscourseChat::Provider::SlackProvider::SlackTranscript do
         expect(transcript.last_message_number).to eq(2)
       end
 
+      it 'can guess the first message' do
+        expect(transcript.guess_first_message(skip_messages:1)).to eq(true)
+        expect(transcript.first_message.ts).to eq('1501801629.052212')
+      end
+
       it 'handles usernames correctly' do
         expect(transcript.first_message.username).to eq('awesomeguy') # Normal user
         expect(transcript.messages[2].username).to eq(nil) # Unknown normal user