class Embulk::PluginRegistry

def initialize(category, search_prefix)
  @category = category
  @search_prefix = search_prefix
  @loaded_gems = {}
  @map = {}
end

def lookup(type)
  type = type.to_sym
  if value = @map[type]
    return value
  end
  if search(type)
    if value = @map[type]
      return value
    end
    raise PluginLoadError.new "Unknown #{@category} plugin '#{type}'. #{@search_prefix}#{type}.rb is installed but it does not correctly register plugin."
  else
    raise PluginLoadError.new "Unknown #{@category} plugin '#{type}'. #{@search_prefix}#{type}.rb is not installed. Run 'embulk gem search -rd embulk-#{@category}' command to find plugins."
  end
end

def register(type, value)
  type = type.to_sym
  @map[type] = value
end

def require_and_show(path, spec=nil)
  require path
  unless spec
    name, spec = Kernel::RUBYGEMS_ACTIVATION_MONITOR.synchronize do  # this lock is added as a workaround of https://github.com/jruby/jruby/issues/3652
      Gem.loaded_specs.find {|name,spec|
        #spec.files.include?(path)
        spec.contains_requirable_file?(path)
      }
    end
  end
  if spec
    unless @loaded_gems[spec.name]
      Embulk.logger.info "Loaded plugin #{spec.name} (#{spec.version})"
      @loaded_gems[spec.name]
    end
  else
    Embulk.logger.info "Loaded plugin #{path} from a load path"
  end
end

def search(type)
  name = "#{@search_prefix}#{type}"
  begin
    require_and_show name
    return true
  rescue LoadError => e
    # catch LoadError but don't catch ClassNotFoundException
    raise e if e.to_s =~ /java.lang.ClassNotFoundException/
    raise e if $LOAD_PATH.any? {|dir| File.exists? File.join(dir, "#{name}.rb") }
  end
  # search from $LOAD_PATH
  load_path_files = $LOAD_PATH.map do |lp|
    lpath = File.expand_path(File.join(lp, "#{name}.rb"))
    File.exist?(lpath) ? lpath : nil
  end
  paths = load_path_files.compact.sort  # sort to prefer newer version
  paths.each do |path|
    require_and_show path
    return true
  end
  # search gems
  if defined?(::Gem::Specification) && ::Gem::Specification.respond_to?(:find_all)
    specs = Kernel::RUBYGEMS_ACTIVATION_MONITOR.synchronize do  # this lock is added as a workaround of https://github.com/jruby/jruby/issues/3652
      Gem::Specification.find_all do |spec|
        spec.contains_requirable_file? name
      end
    end
    # prefer newer version
    specs = specs.sort_by {|spec| spec.version }
    if spec = specs.last
      spec.require_paths.each do |lib|
        require_and_show "#{spec.full_gem_path}/#{lib}/#{name}", spec
      end
      return true
    end
  end
  return false
end