module Lays

# File lib/lays.rb, line 21
def [](layer)
  set_layer(layer)
  layers[layer]
end

# File lib/lays.rb, line 15
def []=(layer, content)
  set_layer(layer)
  layers[layer].content = content
  @result = nil
end

# File lib/lays.rb, line 59
def height
  layers.count
end

# File lib/lays.rb, line 30
def layers
  @layers ||= {}
end

# File lib/lays.rb, line 38
def render
  result = []
  lays = layers.sort {|a, b| a[0] <=> b[0] }
  lays.each do |key, layer|
    content = layer.content
    content.split("\n").each_with_index.map do |line, i|
      line.each_char.each_with_index do |c, j|
        result[i] ||= []
        if space_char_for(layer, c)
          result[i][j] = " "
        elsif !transparent_char_for(layer, c)
          result[i][j] = c
        elsif key == lays.first.first
          result[i][j] = " "
        end
      end
    end
  end
  result.map {|a|a.join}.join("\n")
end

# File lib/lays.rb, line 26
def set_layer(id)
  layers[id] ||= Layer.new
end

# File lib/lays.rb, line 88
def space_char
  @space_char
end

# File lib/lays.rb, line 83
def space_char=(char)
  @space_char = char
  @transparent_char = nil
end

# File lib/lays.rb, line 92
def space_char_for(layer, char)
  char == layer.space_char || char == space_char
end

# File lib/lays.rb, line 34
def to_s
  @result ||= render
end

# File lib/lays.rb, line 74
def transparent_char
  @transparent_char ||= " "
end

# File lib/lays.rb, line 69
def transparent_char=(char)
  @transparent_char = char
  @space_char = nil
end

# File lib/lays.rb, line 78
def transparent_char_for(layer, char)
  transparent = layer.transparent_char || transparent_char
  char == transparent
end

# File lib/lays.rb, line 63
def width
  layers.max { |a, b|
    a.last.content.size <=> b.last.content.size
  }.last.content.size
end