module ImageProcessing::Chainable

def branch(options)
  options = options.merge(processor_class: self::Processor) unless self.is_a?(Builder)
  Builder.new(options)
end

def call(file = nil, destination: nil, **call_options)
  options = default_options
  options = options.merge(source: file) if file
  options = options.merge(destination: destination) if destination
  branch(options).call!(**call_options)
end

def convert(format)
  branch default_options.merge(format: format)
end

def custom(&block)
  block ? operation(:custom, block) : self
end

def default_options
  @default_options ||= {
    source:          nil,
    loader:          {},
    saver:           {},
    format:          nil,
    operations:      [],
    processor_class: nil,
  }
end

def loader(**options)
  loader = default_options[:loader].merge(options)
  branch default_options.merge(loader: loader)
end

def method_missing(name, *args)
  if name.to_s.end_with?("!")
    send(name.to_s.chomp("!"), *args).call
  elsif name.to_s.end_with?("?")
    super
  else
    operation(name, *args)
  end
end

def operation(name, *args)
  operations = default_options[:operations] + [[name, args]]
  branch default_options.merge(operations: operations)
end

def saver(**options)
  saver = default_options[:saver].merge(options)
  branch default_options.merge(saver: saver)
end

def source(file)
  branch default_options.merge(source: file)
end