add logging workers with options by file format

lib/image_optim.rb

@@ -55,6 +55,8 @@ def initialize(options = {})
       config.for_worker(klass)
     end
 
+    log_workers_by_format if verbose
+
     config.assert_no_unused_options!
   end
 
@@ -164,6 +166,19 @@ def env_path
 
 private
 
+  def log_workers_by_format
+    $stderr << "Workers by format:\n"
+    @workers_by_format.each do |format, workers|
+      $stderr << "#{format}:\n"
+      workers.each do |worker|
+        $stderr << "  #{worker.class.bin_sym}:\n"
+        worker.options.each do |name, value|
+          $stderr << "    #{name}: #{value.inspect}\n"
+        end
+      end
+    end
+  end
+
   # Create hash with format mapped to list of workers sorted by run order
   def create_workers_by_format(&options_proc)
     by_format = {}

lib/image_optim/worker.rb

@@ -78,6 +78,13 @@ def initialize(image_optim, options = {})
       assert_no_unknown_options!(options)
     end
 
+    # Return hash with worker options
+    def options
+      self.class.option_definitions.each_with_object({}) do |option, h|
+        h[option.name] = send(option.name)
+      end
+    end
+
     # Optimize image at src, output at dst, must be overriden in subclass
     # return true on success
     def optimize(_src, _dst)