function _init()
   init_data()
   init_sound()
   init_mapgen()
   init_player(32, 32)
   generate_map(0, 0)
   debug = false
end


function _update()
   handle_input()
   handle_map_update()
end

function _draw()
   rectfill(0, 0, 127, 127, 0)
   -- the screen is 128x128 pixels, so it fits 16x16 sprites
   map(camera_pos_x, camera_pos_y, 0, 0, 16, 16)
   draw_player()
   if debug then
      render_debug_info()
   end
end

-- decide whether we need to regenerate the map.
-- if so, call generate_map appropriately and reset coordinates.
function handle_map_update()
   if out_of_bounds(camera_pos_x, camera_pos_y) then
      -- out_of_bounds() checks all screen bounds
      -- we need to regenerate the map, so we generate a map chunk that
      -- places the player in the middle of it.
      generate_map(player_pos_x-32, player_pos_y-32)
      camera_pos_x, camera_pos_y = 24, 24
   end
end

function out_of_bounds(pos_x, pos_y)
   return pos_x < 0 or pos_x > 48 or
      pos_y < 0 or pos_y > 48
end

function debug_res()
   print("mem: " + stat(0))
   print("cpu: " + stat(1))
   print("fps: " .. stat(9) .. " / " .. stat(8))
end

function debug_sfx()
   print("Music pattern: " .. stat(24))
end

function debug_map()
   print("Local: " .. camera_pos_x .. " " .. camera_pos_y)
   print("Global: " .. player_pos_x .. " " .. player_pos_y)
   print(get_biome_name(player_pos_x, player_pos_y))
end

function debug_mod_buffer()
   for k,v in pairs(mod_buffer) do
      print(k .. ": " .. tostr(v))
   end
end