
define [
  "underscore",
  "common/has_parent",
  "common/plot_widget",
  "common/textutils",
  "renderer/properties",
], (_, HasParent, PlotWidget, textutils, Properties) ->

  glyph_properties = Properties.glyph_properties
  line_properties  = Properties.line_properties
  text_properties  = Properties.text_properties

  # Legends:
  #
  # legend_padding is the boundary between the legend and the edge of the plot
  # legend_spacing goes between each legend entry and the edge of the legend,
  # as well as between 2 adjacent legend entries.  It is also the space between
  # the legend label, and the legend glyph.
  #
  # A legend in the top right corner looks like this
  #
  # plotborder
  # padding
  # legendborder
  # spacing
  # legendborder|spacing|label|spacing|glyph|spacing|legendborder|padding|plotborder
  # spacing
  # legendborder|spacing|label|spacing|glyph|spacing|legendborder|padding|plotborder
  # spacing
  # border

  class LegendView extends PlotWidget
    initialize: (options) ->
      super(options)
      @label_props = new text_properties(@, @model, 'label_')
      @border_props = new line_properties(@, @model, 'border_')
      if @mget('legend_names')
        @legend_names = @mget('legend_names')
      else
        @legends = @mget('legends')
        @legend_names =_.keys(@mget('legends'))
      @calc_dims()

    delegateEvents: (events) ->
      super(events)
      @listenTo(@plot_view.view_state, 'change', @calc_dims)

    calc_dims: (options) ->
      label_height = @mget('label_height')
      @glyph_height = @mget('glyph_height')
      label_width = @mget('label_width')
      @glyph_width = @mget('glyph_width')
      legend_spacing = @mget('legend_spacing')
      @label_height = _.max([textutils.getTextHeight(@label_props.font(@)), label_height, @glyph_height])
      @legend_height = @label_height
      #add legend spacing
      @legend_height = @legend_names.length * @legend_height + (1 + @legend_names.length) * legend_spacing
      ctx = @plot_view.ctx

      ctx.save()
      @label_props.set(ctx, @)
      text_widths = _.map(@legend_names, (txt) -> ctx.measureText(txt).width)
      ctx.restore()

      text_width = _.max(text_widths)
      @label_width = _.max([text_width, label_width])
      @legend_width = @label_width + @glyph_width + 3 * legend_spacing
      orientation = @mget('orientation')
      legend_padding = @mget('legend_padding')
      h_range = @plot_view.view_state.get('inner_range_horizontal')
      v_range = @plot_view.view_state.get('inner_range_vertical')
      if orientation == "top_right"
        x = h_range.get('end') - legend_padding - @legend_width
        y = v_range.get('end') - legend_padding
      else if orientation == "top_left"
        x = h_range.get('start') + legend_padding
        y = v_range.get('end') - legend_padding
      else if orientation == "bottom_left"
        x = h_range.get('start') + legend_padding
        y = v_range.get('start') + legend_padding + @legend_height
      else if orientation == "bottom_right"
        x = h_range.get('end') - legend_padding - @legend_width
        y = v_range.get('start') + legend_padding + @legend_height
      else if orientation == "absolute"
        [x,y] = @absolute_coords
      x = @plot_view.view_state.vx_to_sx(x)
      y = @plot_view.view_state.vy_to_sy(y)
      @box_coords = [x,y]

    render: () ->
      ctx = @plot_view.ctx
      ctx.save()

      ctx.fillStyle = @plot_model.get('background_fill')
      @border_props.set(ctx, @)
      ctx.beginPath()
      ctx.rect(@box_coords[0], @box_coords[1],
        @legend_width, @legend_height
      )
      ctx.fill()
      ctx.stroke()
      legend_spacing = @mget('legend_spacing')
      for legend_name, idx in @legend_names
        yoffset = idx * @label_height
        yspacing = (1 + idx) * legend_spacing
        y = @box_coords[1] +  @label_height / 2.0 + yoffset + yspacing
        x = @box_coords[0] + legend_spacing
        x1 = @box_coords[0] + 2 * legend_spacing + @label_width
        x2 = x1 + @glyph_width
        y1 = @box_coords[1] + yoffset + yspacing
        y2 = y1 + @glyph_height
        @label_props.set(ctx, @)
        ctx.fillText(legend_name, x, y)
        for renderer in @model.resolve_ref(@legends[legend_name])
          view = @plot_view.renderers[renderer.id]
          view.draw_legend(ctx, x1,x2,y1,y2)

      ctx.restore()

  class Legend extends HasParent
    default_view: LegendView
    type: 'Legend'

    display_defaults: () ->
      return {
        level: 'overlay'

        border_line_color: 'black'
        border_line_width: 1
        border_line_alpha: 1.0
        border_line_join: 'miter'
        border_line_cap: 'butt'
        border_line_dash: []
        border_line_dash_offset: 0

        label_standoff: 15
        label_text_font: "helvetica"
        label_text_font_size: "10pt"
        label_text_font_style: "normal"
        label_text_color: "#444444"
        label_text_alpha: 1.0
        label_text_align: "left"
        label_text_baseline: "middle"

        glyph_height: 20
        glyph_width: 20
        label_height: 20
        label_width: 50
        legend_padding: 10
        legend_spacing: 3
        orientation: "top_right"
        datapoint: null
      }

  class Legends extends Backbone.Collection
    model: Legend

  return {
    "Model": Legend,
    "Collection": new Legends()
    "View": LegendView,
  }
