refact

lib/domain/repository/last_callers_repository.rb

@@ -0,0 +1,41 @@
+# frozen_string_literal: true
+
+require 'csv'
+require 'time'
+require 'fileutils'
+
+# Append-only log of the last N logins. Stored as CSV so it survives restarts.
+class LastCallersRepository
+  Caller = Struct.new(:timestamp, :username, :session_id)
+
+  def initialize(path, limit: 50)
+    @path  = path
+    @limit = limit
+    @mu    = Mutex.new
+    @entries = load
+  end
+
+  def record(username, session_id)
+    entry = Caller.new(Time.now.iso8601, username, session_id)
+    @mu.synchronize do
+      @entries << entry
+      @entries.shift while @entries.size > @limit
+      FileUtils.mkdir_p(File.dirname(@path))
+      CSV.open(@path, 'a') { |csv| csv << [entry.timestamp, entry.username, entry.session_id] }
+    end
+    entry
+  end
+
+  def recent(n = 10)
+    @mu.synchronize { @entries.last(n).reverse }
+  end
+
+  private
+
+  def load
+    return [] unless File.exist?(@path)
+    CSV.read(@path).map { |row| Caller.new(*row) }
+  rescue StandardError
+    []
+  end
+end