class OSMTileGrabber

# File lib/osm_tile_grabber/osm_tile_grabber.rb, line 8
def initialize(lat1, lon1, lat2, lon2, zoom)
        @lat1 = lat1
        @lon1 = lon1
        @lat2 = lat2
        @lon2 = lon2
        @zoom = zoom
end

# File lib/osm_tile_grabber/osm_tile_grabber.rb, line 16
def create_image(output_path)
        self.montage(self.download_tiles, output_path)
end

# File lib/osm_tile_grabber/osm_tile_grabber.rb, line 58
def download_tiles
        tile_files = []
        tile_numbers_needed.each do |row|
                row.each do |tn|
                        tile_file = Tempfile.new(["tile-#{@zoom}-#{tn[:x]}-#{tn[:y]}", ".png"])
                        open(link_from_tile_number(tn[:x], tn[:y]), "rb") do |read_file|
                                tile_file.write(read_file.read)
                        end
                        tile_files << tile_file
                end
        end
        return tile_files
end

# File lib/osm_tile_grabber/osm_tile_grabber.rb, line 44
def get_tile_number(lat_as_deg, lon_as_deg)
        lat_as_rad = lat_as_deg/180 * Math::PI
        n = 2.0 ** @zoom
        x = ((lon_as_deg + 180.0) / 360.0 * n).to_i
        y = ((1.0 - Math::log(Math::tan(lat_as_rad) + (1 / Math::cos(lat_as_rad))) / Math::PI) / 2.0 * n).to_i
  
        return {:x => x, :y =>y}
end

# File lib/osm_tile_grabber/osm_tile_grabber.rb, line 35
def image_dimensions
        top_left_tile = get_tile_number(@lat1, @lon1)
        bottom_right_tile = get_tile_number(@lat2, @lon2)
        
        x = bottom_right_tile[:x] - top_left_tile[:x]
        y = bottom_right_tile[:y] - top_left_tile[:y]
        return {x: x + 1, y: y + 1}
end

# File lib/osm_tile_grabber/osm_tile_grabber.rb, line 53
def link_from_tile_number(x,y)
        # TODO: Allow picking own tileserver
        "https://a.tile.openstreetmap.org/#{@zoom}/#{x}/#{y}.png"     
end

# File lib/osm_tile_grabber/osm_tile_grabber.rb, line 72
def montage(tiles, output_path)
        image_list = ImageList.new *tiles.map{|t| t.path}
        tile_string = "#{image_dimensions[:x]}x#{image_dimensions[:y]}"
        tiled_montage = image_list.montage do
                self.geometry = "+0+0"
                self.tile = tile_string
        end
        tiled_montage.write(output_path)
        return output_path
end

# File lib/osm_tile_grabber/osm_tile_grabber.rb, line 20
def tile_numbers_needed
        top_left_tile = get_tile_number(@lat1, @lon1)
        bottom_right_tile = get_tile_number(@lat2, @lon2)
        tile_matrix = []

        (top_left_tile[:y]..bottom_right_tile[:y]).each do |y|
                row = []
                (top_left_tile[:x]..bottom_right_tile[:x]).each do |x|
                        row << {x: x, y: y}
                end
                tile_matrix << row
        end
        return tile_matrix
end