require 'rgeo'

module RGeoServer
  class BoundingBox
    attr_accessor :minx, :miny, :maxx, :maxy

    @@epsilon = 0.0001

    def self.epsilon
      @@epsilon
    end

    def self.epsilon= value
      @@epsilon = value
    end

    def initialize
      reset
    end

    def reset
      @minx = @miny = @maxx = @maxy = 0.0
      @empty = true
    end

    def add x, y
      if @empty
        @minx = @maxx = x
        @miny = @maxy = y
      end

      @minx = [@minx, x].min
      @miny = [@miny, y].min
      @maxx = [@maxx, x].max
      @maxy = [@maxy, y].max

      @empty = false
    end

    def min
      [@minx, @miny]
    end

    def max
      [@maxx, @maxy]
    end

    def expand rate = @@epsilon
      _minx, _miny = [@minx - rate, @miny - rate]
      _maxx, _maxy = [@maxx + rate, @maxy + rate]

      reset

      add _minx, _miny
      add _maxx, _maxy
    end

    def constrict rate = @@epsilon
      expand -rate
    end

    def to_geometry
      factory = RGeo::Cartesian::Factory.new

      point_min, point_max = unless [@minx, @miny] == [@maxx, @maxy]
        [factory.point(@minx, @miny), factory.point(@maxx, @maxy)]
      else
        [factory.point(@minx - @@epsilon, @miny - @@epsilon),
         factory.point(@maxx + @@epsilon, @maxy + @@epsilon)]
      end

      line_string = factory.line_string [point_min, point_max]
      line_string.envelope
    end

    def to_a
      [@minx, @miny, @maxx, @maxy]
    end

    def to_s
      to_a.join(', ')
    end

    def inspect
      "#<#{self.class} #{to_s}>"
    end
  end
end