# Adds methods to the UIViewController class to make defining a layout and
# stylesheet very easy.  Also provides rotation methods that analyze
class UIViewController
  include Teacup::Layout

  class << self
    attr_reader :layout_definition

    # Define the layout of a controller's view.
    #
    # This function is analogous to Teacup::Layout#layout, though it is
    # designed so you can create an entire layout in a declarative manner in
    # your controller.
    #
    # The hope is that this declarativeness will allow us to automatically
    # deal with common iOS programming tasks (like releasing views when
    # low-memory conditions occur) for you. This is still not implemented
    # though.
    #
    # @param name  The stylename for your controller's view.
    #
    # @param properties  Any extra styles that you want to apply.
    #
    # @param &block  The block in which you should define your layout.
    #                It will be instance_exec'd in the context of a
    #                controller instance.
    #
    # @example
    #   MyViewController < UIViewController
    #     layout :my_view do
    #       subview UILabel, title: "Test"
    #       subview UITextField, {
    #         frame: [[200, 200], [100, 100]]
    #         delegate: self
    #       }
    #       subview UIView, :shiny_thing) {
    #         subview UIView, :centre_of_shiny_thing
    #       }
    #     end
    #   end
    #
    def layout(stylename=nil, properties={}, &block)
      @layout_definition = [stylename, properties, block]
    end

    def stylesheet(new_stylesheet=nil)
      if new_stylesheet.nil?
        return @stylesheet
      end

      @stylesheet = new_stylesheet
    end

  end # class << self

  # Assigning a new stylesheet triggers {restyle!}.
  #
  # Assigning a stylesheet is an *alternative* to returning a Stylesheet in
  # the {stylesheet} method. Note that {restyle!} calls {stylesheet}, so while
  # assigning a stylesheet will trigger {restyle!}, your stylesheet will not
  # be picked up if you don't return it in a custom stylesheet method.
  #
  # @return Teacup::Stylesheet
  #
  # @example
  #
  #   stylesheet = Teacup::Stylesheet[:ipadhorizontal]
  #   stylesheet = :ipadhorizontal
  def stylesheet=(new_stylesheet)
    super
    if self.viewLoaded?
      self.view.restyle!
    end
  end

  def top_level_view
    return self.view
  end


  # Instantiate the layout from the class, and then call layoutDidLoad.
  #
  # If you want to use Teacup in your controller, please hook into layoutDidLoad,
  # not viewDidLoad.
  def viewDidLoad
    # look for a layout_definition in the list of ancestors
    layout_definition = nil
    my_stylesheet = self.stylesheet
    parent_class = self.class
    while parent_class != NSObject and not (layout_definition && my_stylesheet)
      if not my_stylesheet and parent_class.respond_to?(:stylesheet)
        my_stylesheet = parent_class.stylesheet
      end

      if not layout_definition and parent_class.respond_to?(:layout_definition)
        layout_definition = parent_class.layout_definition
      end
      parent_class = parent_class.superclass
    end

    should_restyle = Teacup.should_restyle_and_block

    if my_stylesheet and not self.stylesheet
      self.stylesheet = my_stylesheet
    end

    if layout_definition
      stylename, properties, block = layout_definition
      layout(view, stylename, properties, &block)
    end

    if should_restyle
      Teacup.should_restyle!
      self.view.restyle!
    end

    if defined? NSLayoutConstraint
      self.view.apply_constraints
    end

    layoutDidLoad
  end

  def layoutDidLoad
    true
  end

  # This method *used* to be useful for the `shouldAutorotateToOrientation`
  # method, but the iOS 6 update deprecates that method.  Instead, use the
  # `supportedInterfaceOrientations` and return `autorotateMask`.
  def autorotateToOrientation(orientation)
    if view.stylesheet and view.stylesheet.is_a?(Teacup::Stylesheet) and view.stylename
      properties = view.stylesheet.query(view.stylename, self, orientation)

      # check for orientation-specific properties
      case orientation
      when UIInterfaceOrientationPortrait
        # portrait is "on" by default, must be turned off explicitly
        if properties.supports?(:portrait) == nil and properties.supports?(:upside_up) == nil
          return true
        end

        return (properties.supports?(:portrait) or properties.supports?(:upside_up))
      when UIInterfaceOrientationPortraitUpsideDown
        if UIDevice.currentDevice.userInterfaceIdiom == UIUserInterfaceIdiomPhone
          # iphone must have an explicit upside-down style, otherwise this returns
          # false
          return properties.supports?(:upside_down)
        else
          # ipad can just have a portrait style
          return (properties.supports?(:portrait) or properties.supports?(:upside_down))
        end
      when UIInterfaceOrientationLandscapeLeft
        return (properties.supports?(:landscape) or properties.supports?(:landscape_left))
      when UIInterfaceOrientationLandscapeRight
        return (properties.supports?(:landscape) or properties.supports?(:landscape_right))
      end

      return false
    end

    # returns the system default
    if device == UIUserInterfaceIdiomPhone
      return orientation != UIInterfaceOrientationPortraitUpsideDown
    else
      return true
    end
  end

  # You can use this method in `supportedInterfaceOrientations`, and it will
  # query the stylesheet for the supported orientations, based on what
  # orientations are defined.  At a minimum, to opt-in to this feature, you'll
  # need to define styles like `style :root, landscape: true`
  def autorotateMask
    device = UIDevice.currentDevice.userInterfaceIdiom
    if view.stylesheet and view.stylesheet.is_a?(Teacup::Stylesheet) and view.stylename
      properties = view.stylesheet.query(view.stylename, self, orientation)

      orientations = 0
      if properties.supports?(:portrait) or properties.supports?(:upside_up)
        orientations |= UIInterfaceOrientationPortrait
      end

      if device == UIUserInterfaceIdiomPhone
        # :portrait does not imply upside_down on the iphone
        if properties.supports?(:upside_down)
          orientations |= UIInterfaceOrientationPortraitUpsideDown
        end
      else
        # but does on the ipad
        if properties.supports?(:portrait) or properties.supports?(:upside_down)
          orientations |= UIInterfaceOrientationPortraitUpsideDown
        end
      end

      if properties.supports?(:landscape) or properties.supports?(:landscape_left)
        orientations |= UIInterfaceOrientationLandscapeLeft
      end

      if properties.supports?(:landscape) or properties.supports?(:landscape_right)
        orientations |= UIInterfaceOrientationLandscapeRight
      end

      if orientations == 0
        orientations |= UIInterfaceOrientationPortrait
      end
      return orientations
    end

    # returns the system default
    if device == UIUserInterfaceIdiomPhone
      return UIInterfaceOrientationMaskAllButUpsideDown
    else
      return UIInterfaceOrientationMaskAll
    end
  end

  # restyles the view!  be careful about putting styles in your stylesheet that
  # you change in your controller.  anything that might change over time should
  # be applied in your controller using `style`
  def willAnimateRotationToInterfaceOrientation(orientation, duration:duration)
    view.restyle!(orientation)
  end

  ##|
  ##|  Motion-Layout support
  ##|

  # Calling this method uses Nick Quaranto's motion-layout gem to provide ASCII
  # art style access to autolayout.  It assigns all the subviews by stylename,
  # and assigns `self.view` as the target view.  Beyond that, it's up to you to
  # implement the layout methods:
  #
  #     auto do
  #       metrics 'margin' => 20
  #       vertical "|-[top]-margin-[bottom]-|"
  #       horizontal "|-margin-[top]-margin-|"
  #       horizontal "|-margin-[bottom]-margin-|"
  #     end
  def auto(layout_view=self.view, layout_subviews={}, &layout_block)
    raise "gem install 'motion-layout'" unless defined? Motion::Layout

    Teacup.get_subviews(self.view).each do |view|
      if view.stylename && ! layout_subviews[view.stylename.to_s]
        layout_subviews[view.stylename.to_s] = view
      end
    end

    Motion::Layout.new do |layout|
      layout.view layout_view
      layout.subviews layout_subviews
      layout.instance_eval(&layout_block)
    end
  end

end


module Teacup

module_function
  def get_subviews(target)
    [target] + target.subviews.map { |subview|
      get_subviews(subview).select{ |v| v.stylename }
    }.flatten
  end

end