module Sprockets::Processing

def build_processors_uri(type, file_type, pipeline)
  query = encode_uri_query_params(
    type: type,
    file_type: file_type,
    pipeline: pipeline
  )
  "processors:#{query}"
end

def bundle_processors
  config[:bundle_processors]
end

def default_processors_for(type, file_type)
  bundled_processors = config[:bundle_processors][type]
  if bundled_processors.any?
    bundled_processors
  else
    self_processors_for(type, file_type)
  end
end

def pipelines
  config[:pipelines]
end

def postprocessors
  config[:postprocessors]
end

def preprocessors
  config[:preprocessors]
end

def processors_for(type, file_type, pipeline)
  pipeline ||= :default
  if fn = config[:pipelines][pipeline.to_sym]
    fn.call(self, type, file_type)
  else
    raise Error, "no pipeline: #{pipeline}"
  end
end

def register_bundle_metadata_reducer(mime_type, key, *args, &block)
  case args.size
  when 0
    reducer = block
  when 1
    if block_given?
      initial = args[0]
      reducer = block
    else
      initial = nil
      reducer = args[0].to_proc
    end
  when 2
    initial = args[0]
    reducer = args[1].to_proc
  else
    raise ArgumentError, "wrong number of arguments (#{args.size} for 0..2)"
  end
  self.config = hash_reassoc(config, :bundle_reducers, mime_type) do |reducers|
    reducers.merge(key => [initial, reducer])
  end
end

def register_bundle_processor(*args, &block)
  register_config_processor(:bundle_processors, *args, &block)
end

def register_config_processor(type, mime_type, processor = nil, &block)
  processor ||= block
  self.config = hash_reassoc(config, type, mime_type) do |processors|
    processors.unshift(processor)
    processors
  end
end

def register_pipeline(name, proc = nil, &block)
  proc ||= block
  self.config = hash_reassoc(config, :pipeline_exts) do |pipeline_exts|
    pipeline_exts.merge(".#{name}".freeze => name.to_sym)
  end
  self.config = hash_reassoc(config, :pipelines) do |pipelines|
    pipelines.merge(name.to_sym => proc)
  end
end

def register_postprocessor(*args, &block)
  register_config_processor(:postprocessors, *args, &block)
  compute_transformers!(self.config[:registered_transformers])
end

def register_preprocessor(*args, &block)
  register_config_processor(:preprocessors, *args, &block)
  compute_transformers!(self.config[:registered_transformers])
end

def resolve_processors_cache_key_uri(uri)
  params = parse_uri_query_params(uri[11..-1])
  processors = processors_for(params[:type], params[:file_type], params[:pipeline])
  processors_cache_keys(processors)
end

def self_processors_for(type, file_type)
  processors = []
  processors.concat config[:postprocessors][type]
  if type != file_type && processor = config[:transformers][file_type][type]
    processors << processor
  end
  processors.concat config[:preprocessors][file_type]
  if processors.any? || mime_type_charset_detecter(type)
    processors << FileReader
  end
  processors
end

def unregister_bundle_processor(*args)
  unregister_config_processor(:bundle_processors, *args)
end

def unregister_config_processor(type, mime_type, proccessor)
  self.config = hash_reassoc(config, type, mime_type) do |processors|
    processors.delete(proccessor)
    processors
  end
end

def unregister_postprocessor(*args)
  unregister_config_processor(:postprocessors, *args)
  compute_transformers!(self.config[:registered_transformers])
end

def unregister_preprocessor(*args)
  unregister_config_processor(:preprocessors, *args)
  compute_transformers!(self.config[:registered_transformers])
end