module Periscope

# File lib/periscope.rb, line 7
def periscope(params = {})
  params.inject(periscope_default_scope) do |chain, (scope, param)|
    periscope_call(chain, scope.to_s, param)
  end
end

# File lib/periscope.rb, line 2
def scope_accessible(*scopes)
  options = scopes.last.is_a?(Hash) ? scopes.pop : {}
  scopes.each { |s| periscope_options[s.to_s] = options }
end

# File lib/periscope.rb, line 44
def periscope_blank?(value)
  return true unless value
  value.respond_to?(:blank?) ? value.blank? : value.empty?
end

# File lib/periscope.rb, line 23
def periscope_call(chain, scope, param)
  return chain unless options = periscope_options[scope]

  method = periscope_method(scope, options)
  values = periscope_values(param, options)

  if periscope_ignore?(values.first, options)
    chain
  else
    options[:boolean] ? chain.send(method) : chain.send(method, *values)
  end
end

# File lib/periscope.rb, line 19
def periscope_default_scope
  raise NotImplementedError
end

# File lib/periscope.rb, line 36
def periscope_ignore?(value, options)
  if options[:ignore_blank]
    periscope_blank?(value)
  elsif options[:boolean]
    !value
  end
end

# File lib/periscope.rb, line 49
def periscope_method(scope, options)
  options[:method] || [options[:prefix], scope, options[:suffix]].compact.join
end

# File lib/periscope.rb, line 15
def periscope_options
  @periscope_options ||= {}
end

# File lib/periscope.rb, line 53
def periscope_values(param, options)
  options[:parser] ? options[:parser].call(param) : [param]
end