-- Tilemap entity, it dynamically rebuilds its draw cache thingy
-- You just need to worry not and use the tile getting/setting functions

TILESIZE = 16
function new_tilemap(width, height)
  local map = new_entity()
  add_comp(map, "Tilemap", width, height)

  return map
end

local function ID(map, x, y)
  return x + y * map.width + 1
end

-- local function POS(map, id)
--   id = id - 1
--   return id % map.width, math.floor(id / map.width)
-- end

register_comp("Tilemap", function(tilemap, width, height)
  tilemap.tiledata = {}
  for i=1, width*height do
    tilemap.tiledata[i] = 0
  end
  tilemap.width = width
  tilemap.height = height
  tilemap.cache = {}
  tilemap.cachesize = 0
  tilemap.needs_rebuild = false
end)

function rebuild_tilemap(map)
  map.cache = {}

  for x = 0, map.width - 1 do
    for y = 0, map.height - 1 do

      local tile = get_tile(map, x, y)
      if tile ~= 0 then
        map.cachesize = map.cachesize + 1
        map.cache[map.cachesize] = {
          x = x * TILESIZE, y = y * TILESIZE,
        }
      end
    end
  end
end

function tilemap_draw_sys(tilemap)
  if tilemap.needs_rebuild then
    rebuild_tilemap(tilemap)
    tilemap.needs_rebuild = false
  end

  for i=1, tilemap.cachesize do
    local tile = tilemap.cache[i]
    lg.circle("fill", tile.x, tile.y, 4)
  end
end

function get_tile(map, x, y)
  return map.tiledata[ID(map, x, y)]
end

function queue_tilemap_rebuild(tilemap)
  tilemap.needs_rebuild = true
end

function set_tile(map, x, y, tileid)
  map.tiledata[ID(map, x, y)] = tileid
  map.needs_rebuild = true
end

function remove_tile(map, x, y)
  map.tiledata[ID(map, x, y)] = 0
  map.needs_rebuild = true
end