require "scratchpad/interpolator"
require "scratchpad/version"

require 'toml'
require 'gtk2'

class Array
  def x
    self[0]
  end

  def x=(val)
    self[0]=val
  end

  def y
    self[1]
  end

  def y=(val)
    self[1]=val
  end
end

module Scratchpad

# 便利関数
def distance(p1, p2)
  x1, y1 = p1
  x2, y2 = p2

  return Math.sqrt((x1 - x2)**2 + (y1 - y2)**2)
end

def chess_distance(p1, p2)
  x1, y1 = p1
  x2, y2 = p2

  return [(x1 - x2).abs, (y1 - y2).abs].max
end

def midpoint(p1, p2)
  x1, y1 = p1
  x2, y2 = p2

  return [(x1 + x2) * 0.5, (y1 + y2) * 0.5]
end

def color_bytes_to_floats(bytes)
  raise 'wrong range' unless bytes.all? { |x| x >= 0 && x <= 255 }
  raise 'wrong dimension' unless bytes.size.between?(3, 4)

  return bytes.map { |b| b / 255.0 }
end

def plus(v1, v2)
  [v1.x + v2.x, v1.y + v2.y]
end

def vector(p1, p2)
  [p2.x - p1.x, p2.y - p1.y]
end

def dot_product(v1, v2)
  return v1.x * v2.x + v1.y * v2.y
end

def scalar_times(factor, v)
  v.map { |x| factor * x }
end

def vec_lerp(alpha, v1, v2)
  return plus(scalar_times(alpha, v1), scalar_times(1.0-alpha, v2))
end

# /便利関数

class Pen
  include Math
  extend Scratchpad

  attr_reader :x, :y
  attr_accessor :color

  BLUE   = color_bytes_to_floats [0, 3, 126]
  ORANGE = color_bytes_to_floats [255, 109, 50]
  GREEN  = color_bytes_to_floats [0, 124, 126]

  def initialize
    @is_down = false
    @interpolator = Interpolator.new
    @path = []
    @color = BLUE
  end

  # [[x, y, radius]*]
  def path
    f =  proc { |x|
      [-5.0/10.0 * x + 8.0, 0.3].max
      #x
    }
    @path.map { |x, y, velocity|
      [x, y, sqrt(f.(velocity))]
    }
  end

  def down(ev)
    @is_down = true
  end

  def up(ev)
    @is_down = false
  end
  
  def move(ev)
    @path = @interpolator.feed(ev.x, ev.y, @is_down)
  end

  def down?
    @is_down
  end

  def radius
    2.0
  end
end

class SheetModel < GLib::Object
  type_register
  signal_new('changed', GLib::Signal::ACTION, nil, nil)
  
  include Math
  include Cairo

  attr_reader :surface, :pen, :debug_surface, :outline_surface

  def initialize(width, height)
    super()
    @surface         = ImageSurface.new(Cairo::FORMAT_ARGB32, width, height)
    @debug_surface   = ImageSurface.new(Cairo::FORMAT_ARGB32, width, height)
    @outline_surface = ImageSurface.new(Cairo::FORMAT_ARGB32, width, height)

    cr = Context.new(@surface)
    cr.set_operator(Cairo::OPERATOR_OVER)
    cr.line_cap = cr.line_join = :round
    @context = cr

    @pen = Pen.new

    @portion = :all
  end

  def cr
    @context
  end

  def clear
    clear_surface(@surface)
    clear_surface(@outline_surface)
    clear_surface(@debug_surface)
    signal_emit('changed')
  end

  def clear_surface(surface)
    c = Context.new(surface)
    c.save do
      c.set_operator(Cairo::OPERATOR_SOURCE)
      c.set_source_rgba(0, 0, 0, 0)
      c.paint
    end
    c.destroy
  end

  def pen_down(ev)
    @pen.down(ev)
    @portion = :latter_half
  end

  def pen_up(ev)
    @pen.up(ev)
    @portion = :first_half
  end

  def normalize(ary)
    sum = ary.max
    ary.map { |x| x / sum }
  end

  def update
    if @pen.down?
      case @portion 
      when :all
        path = @pen.path

        stroke_outline(path)

        cr.set_source_rgba(@pen.color)
        cr.line_width = @pen.radius
        stroke_path(cr, path)
      when :latter_half
        path = @pen.path[5..10] || []

        stroke_outline(path)

        cr.set_source_rgba(@pen.color)
        cr.line_width = @pen.radius
        stroke_path(cr, path)
      end
      @portion = :all
      signal_emit('changed')
    else
      if @portion == :first_half
        path = @pen.path[0..4] || []

        stroke_outline(path)

        cr.set_source_rgba(@pen.color)
        cr.line_width = @pen.radius
        stroke_path(cr, path)

        @portion = :all
        signal_emit('changed')
      end
    end
  end

  def stroke_outline(path)
    cr = Cairo::Context.new(@outline_surface)
    cr.line_cap = cr.line_join = :round
    cr.set_source_rgba([1, 1, 1, 1.0])
    cr.line_width = @pen.radius * 3
    stroke_path(cr, path)
  end

  def stroke_path(cr, path)
    path.each.with_index do |(x, y, radius), i|
      if i == 0
	cr.move_to(x, y)
      else
        cr.line_to(x, y)
      end
    end
    cr.stroke
  end

  def pen_move(ev)
    @pen.move(ev)
    update
  end
end

class SheetView < Gtk::DrawingArea
  include Scratchpad

  def initialize()
    super()
    self.app_paintable = true

    @dirty = true

    set_size_request(800, 600)
    signal_connect('expose-event') do
      draw
      true
    end

    # モーションノティファイ。
    @last_point = nil
    signal_connect('motion-notify-event') do |self_, ev|
      handle_motion_notify_event(ev)
    end

    # ボタンプレス。このイベントは同じ座標へのモーションノティファイの
    # 後に来る。
    signal_connect('button-press-event') do |self_, ev|
      # デバッグ描画。ボタン押下座標に赤の四角を描く。
      c = Cairo::Context.new(@model.debug_surface)
      c.set_source_rgba([1, 0, 0])
      c.rectangle(ev.x - 2, ev.y - 2, 4, 4)
      c.fill
      c.destroy

      if ev.button == 1
        @model.pen_down(ev)
      elsif ev.button == 2
        # 押し間違いを防ぐ。
        unless @model.pen.down?
          @model.clear
        end
      elsif ev.button == 3
        # 押し間違いを防ぐ。
        unless @model.pen.down?
          menu_popup(ev)
        end
      end
    end

    # ボタンリリース。このイベントは同じ座標へのモーションノティファイ
    # の後に来る。
    signal_connect('button-release-event') do |self_, ev|
      # デバッグ描画。ボタンリリース座標に赤の四角を描く。
      c = Cairo::Context.new(@model.debug_surface)
      c.set_source_rgba([1, 0, 0])
      c.rectangle(ev.x - 2, ev.y - 2, 4, 4)
      c.fill
      c.destroy

      if ev.button == 1 && @model.pen.down?
        @model.pen_move(ev)
        @model.pen_up(ev)
      end
    end

    @model = SheetModel.new(screen.width, screen.height)
    @model.signal_connect('changed') do
      @dirty = true
    end

    # POINTER_MOTION_HINT_MASKを付けるとこちらの反応が遅い場合にポイン
    # ター座標を省略する。
    self.events |= Gdk::Event::BUTTON_PRESS_MASK |
                   Gdk::Event::BUTTON_RELEASE_MASK |
                   # Gdk::Event::POINTER_MOTION_HINT_MASK |
                   Gdk::Event::POINTER_MOTION_MASK

  end

  def tick
    return if @last_motion_notify_event.nil?

    t = Time.now
    if (t - @last_motion_notify_event_time) > 0.033
      handle_motion_notify_event(@last_motion_notify_event)
      @last_motion_notify_event_time = t
    end
  end

  def handle_motion_notify_event(ev)
    @last_motion_notify_event = ev.dup
    @last_motion_notify_event_time = Time.now

    ev.x = ev.x + 0.5
    ev.y = ev.y + 0.5

    # デバッグ描画。ポインター座標に緑の四角を描く。
    c = Cairo::Context.new(@model.debug_surface)
    c.set_source_rgba([0, 1, 0])
    c.rectangle(ev.x - 1, ev.y - 1, 2, 2)
    c.fill
    c.destroy

    if @last_point == nil
      @last_point = [ev.x, ev.y]
      @model.pen_move(ev)
    else
      # 1サンプル時間あたり距離30以上移動した場合は完全にポインター
      # 座標にならう。
      d = distance(@last_point, [ev.x, ev.y])
      alpha = if d <= 5.0 then 0.30 else 0.60 end
      p [d, alpha] if $DEBUG
      @last_point = vec_lerp(alpha, [ev.x, ev.y], @last_point)
      ev.x, ev.y = @last_point
      @model.pen_move(ev)
    end
  end

  def dirty?
    @dirty
  end

  def create_context_menu
    menu = Gtk::Menu.new

    item1 = Gtk::MenuItem.new('クリア')
    item1.signal_connect('activate') do
      @model.clear
    end
    menu.append(item1)

    menu.append(Gtk::MenuItem.new)

    item2 = Gtk::MenuItem.new('青')
    item2.signal_connect('activate') do 
      @model.pen.color = Pen::BLUE
    end
    menu.append(item2)

    item3 = Gtk::MenuItem.new('オレンジ')
    item3.signal_connect('activate') do
      @model.pen.color = Pen::ORANGE
    end
    menu.append(item3)

    item4 = Gtk::MenuItem.new('緑')
    item4.signal_connect('activate') do
      @model.pen.color = Pen::GREEN
    end
    menu.append(item4)

    menu.show_all

    return menu
  end

  def menu_popup(button_event)
    menu = create_context_menu
    menu.popup(nil, nil, button_event.button, button_event.time)
  end

  def draw
    cr = window.create_cairo_context

    cr.set_operator(Cairo::OPERATOR_SOURCE)
    cr.set_source_rgba(1.0, 1.0, 1.0, 0.5)
    cr.paint 

    cr.set_operator(Cairo::OPERATOR_OVER)

    cr.set_source(@model.outline_surface)
    cr.paint

    cr.set_source(@model.surface)
    cr.paint

    if $DEBUG
      cr.set_source(@model.debug_surface)
      cr.paint
    end

    cr.destroy
  end

  def invalidate
    window.invalidate(window.clip_region, true)
    window.process_updates(true)
    @dirty = false
  end     
end

class MainWindow < Gtk::Window
  def initialize
    super()

    self.title = "Scratchpad"

    set_rgba_colormap
    signal_connect('screen-changed') do
      set_rgba_colormap
    end
  end

  def set_rgba_colormap
    self.colormap = screen.rgba_colormap || screen.rgb_colormap
  end
end

class Program
  include Gtk

  def initialize
    Signal.trap(:INT) {
      STDERR.puts("Interrupted")
      quit
    }
  end

  def quit
    Gtk.main_quit
  end

  def run
    win = MainWindow.new
    win.signal_connect('delete-event') do
      quit
    end

    win.maximize
    sheet = SheetView.new
    win.add sheet
    win.show_all

    Gtk.timeout_add(33) do
      sheet.tick
      if sheet.dirty?
        sheet.invalidate
      end
      true
    end

    Gtk.main
  end
end

end