# ludic.base/ecs_table_remove.ludic - removing a row moves the last one into its place, so the
# rows stay dense; every index is told, and the slot's generation moves on
export function tb_remove<T>(tb: Table<T>, h: int) -> bool {
  if tb_row(tb, h) < 0 { return false }
  for k in 0 .. len(tb.on_remove) { tb.on_remove[k].run(h) }
  let r = tb_row(tb, h)
  if r < 0 { return false }
  for g in 0 .. len(tb.grids) { grid_unlink(tb.grids[g], r) }
  for k in 0 .. len(tb.idx) { ix_unfile(tb.idx[k], r) }
  let last = tb.n - 1
  if r != last { tb_move(tb, last, r) }
  tb_pop(tb)
  let s = h & ECS_SLOT
  tb.slot_row[s] = -1
  tb.slot_gen[s] = (tb.slot_gen[s] + 1) & ECS_GEN
  kept_push(tb.free, s)
  return true
}

function tb_move<T>(tb: Table<T>, from: int, to: int) -> void {
  tb.rec[to] = tb.rec[from]
  tb.ent[to] = tb.ent[from]
  tb.added[to] = tb.added[from]
  tb.changed[to] = tb.changed[from]
  for c in 0 .. len(tb.f) { tb.f[c][to] = tb.f[c][from] }
  for c in 0 .. len(tb.i) { tb.i[c][to] = tb.i[c][from] }
  tb.slot_row[tb.ent[to] & ECS_SLOT] = to
  let b = to >> 6
  if tb.blk[b] < tb.changed[to] { tb.blk[b] = tb.changed[to] }
  for g in 0 .. len(tb.grids) { grid_moved(tb.grids[g], from, to) }
  for k in 0 .. len(tb.idx) { ix_moved(tb.idx[k], from, to) }
}

function tb_pop<T>(tb: Table<T>) -> void {
  List.pop(tb.rec)
  List.pop(tb.ent)
  List.pop(tb.added)
  List.pop(tb.changed)
  for c in 0 .. len(tb.f) { List.pop(tb.f[c]) }
  for c in 0 .. len(tb.i) { List.pop(tb.i[c]) }
  for g in 0 .. len(tb.grids) { grid_shrink(tb.grids[g]) }
  for k in 0 .. len(tb.idx) { ix_shrink(tb.idx[k]) }
  tb.n -= 1
}

# every row gone; the slots keep their generations, so an old handle still misses
export function tb_clear<T>(tb: Table<T>) -> void {
  while tb.n > 0 { tb_remove(tb, tb.ent[tb.n - 1]) }
}