module Sprockets::Rails::Helper

def self.extended(obj)
  obj.singleton_class.class_eval do
    attr_accessor(*VIEW_ACCESSORS)
    remove_method :assets_environment
    def assets_environment
      if env = @assets_environment
        @assets_environment = env.cached
      else
        nil
      end
    end
  end
end

def self.included(klass)
  klass.class_attribute(*VIEW_ACCESSORS)
  klass.class_eval do
    remove_method :assets_environment
    def assets_environment
      if instance_variable_defined?(:@assets_environment)
        @assets_environment = @assets_environment.cached
      elsif env = self.class.assets_environment
        @assets_environment = env.cached
      else
        nil
      end
    end
  end
end

def asset_digest_path(path, options = {})
  resolve_asset do |resolver|
    resolver.digest_path path, options[:debug]
  end
end

def asset_integrity(path, options = {})
  path = path_with_extname(path, options)
  resolve_asset do |resolver|
    resolver.integrity path
  end
end

def asset_resolver_strategies
  @asset_resolver_strategies ||=
    Array(resolve_assets_with).map do |name|
      HelperAssetResolvers[name].new(self)
    end
end

def assets_environment
  if instance_variable_defined?(:@assets_environment)
    @assets_environment = @assets_environment.cached
  elsif env = self.class.assets_environment
    @assets_environment = env.cached
  else
    nil
  end
end

def assets_environment
  if env = @assets_environment
    @assets_environment = env.cached
  else
    nil
  end
end

def compute_asset_path(path, options = {})
  debug = options[:debug]
  if asset_path = resolve_asset_path(path, debug)
    File.join(assets_prefix || "/", legacy_debug_path(asset_path, debug))
  else
    message =  "The asset #{ path.inspect } is not present in the asset pipeline.\n"
    raise AssetNotFound, message unless unknown_asset_fallback
    if respond_to?(:public_compute_asset_path)
      message << "Falling back to an asset that may be in the public folder.\n"
      message << "This behavior is deprecated and will be removed.\n"
      message << "To bypass the asset pipeline and preserve this behavior,\n"
      message << "use the `skip_pipeline: true` option.\n"
      Sprockets::Rails.deprecator.warn(message, caller_locations)
    end
    super
  end
end

def compute_integrity?(options)
  if secure_subresource_integrity_context?
    case options['integrity']
    when nil, false, true
      options.delete('integrity') == true
    end
  else
    options.delete 'integrity'
    false
  end
end

def javascript_include_tag(*sources)
  options = sources.extract_options!.stringify_keys
  integrity = compute_integrity?(options)
  if options["debug"] != false && request_debug_assets?
    sources.map { |source|
      if asset = lookup_debug_asset(source, type: :javascript)
        if asset.respond_to?(:to_a)
          asset.to_a.map do |a|
            super(path_to_javascript(a.logical_path, debug: true), options)
          end
        else
          super(path_to_javascript(asset.logical_path, debug: true), options)
        end
      else
        super(source, options)
      end
    }.flatten.uniq.join("\n").html_safe
  else
    sources.map { |source|
      options = options.merge('integrity' => asset_integrity(source, type: :javascript)) if integrity
      super source, options
    }.join("\n").html_safe
  end
end

def legacy_debug_path(path, debug)
  if debug && !using_sprockets4?
    "#{path}?body=1"
  else
    path
  end
end

def lookup_debug_asset(path, options = {})
  path = path_with_extname(path, options)
  resolve_asset do |resolver|
    resolver.find_debug_asset path
  end
end

def path_with_extname(path, options)
  path = path.to_s
  "#{path}#{compute_asset_extname(path, options)}"
end

def request_debug_assets?
  debug_assets || (defined?(controller) && controller && params[:debug_assets])
rescue # FIXME: what exactly are we rescuing?
  false
end

def resolve_asset
  asset_resolver_strategies.detect do |resolver|
    if result = yield(resolver)
      break result
    end
  end
end

def resolve_asset_path(path, allow_non_precompiled = false) #:nodoc:
  resolve_asset do |resolver|
    resolver.asset_path path, digest_assets, allow_non_precompiled
  end
end

def secure_subresource_integrity_context?
  respond_to?(:request) && self.request && (self.request.local? || self.request.ssl?)
end

def stylesheet_link_tag(*sources)
  options = sources.extract_options!.stringify_keys
  integrity = compute_integrity?(options)
  if options["debug"] != false && request_debug_assets?
    sources.map { |source|
      if asset = lookup_debug_asset(source, type: :stylesheet)
        if asset.respond_to?(:to_a)
          asset.to_a.map do |a|
            super(path_to_stylesheet(a.logical_path, debug: true), options)
          end
        else
          super(path_to_stylesheet(asset.logical_path, debug: true), options)
        end
      else
        super(source, options)
      end
    }.flatten.uniq.join("\n").html_safe
  else
    sources.map { |source|
      options = options.merge('integrity' => asset_integrity(source, type: :stylesheet)) if integrity
      super source, options
    }.join("\n").html_safe
  end
end