coordinates.gd

## returns an array of tetris column coordinates "just beneath" the current tetromino
func coordinates_below_current_mino() -> Array[Vector2i]:

  # this is a dictionary, we'll use it to find just one coordinate in each column
	var lowest_by_column :Dictionary = {}
  
  # here we are looping through all 4 of the `Vector2i` values in the position of the currently falling block
  # each one will be stored in the `block` variable every time through the loop - worth noting these are just
  # offsets, so values like (0,1), etc.
	for block: Vector2i in current_tetromino_array[rotation_index]:
  
    # current_position is a Vector2i the player is manipulating (as well as "gravity") to move the block around the board
    # Vector2i.DOWN is just (0,1)
    # So this `coord` Vector2i holds a position on the board "below" the current block in our loop
		var coord: Vector2i = current_position + block + Vector2i.DOWN
    
    # if the coords x position exists in our dictionary, AND it's y is greater than the one we have stored
    # overwrite it (so there is only one per column in the dictionary, and it's the lowest one)
		if lowest_by_column.has(coord.x) and coord.y > lowest_by_column[coord.x].y:
			lowest_by_column[coord.x] = coord
      
    # otherwise, write it to the dictionary... but wait, this is a bug!
    # we should only get here `if not lowest_by_column.has(coord.x)`
    # so `if coord.y > lowest_by_column[coord.x].y` should be INSIDE the if above, and not
    # part of the same condition! D'oh!
		else:
			lowest_by_column[coord.x] = coord

  # the rest of this function is just turning our dictionary's values() array into an `Array[Vector2i]`
  # this is only necessary because GodotScript's isn't very good at being strongly typed (And dictionaries don't have types yet)
	var ret: Array[Vector2i] = []
	for val: Vector2i in lowest_by_column.values():
		ret.append(val)
    
  # finally, return our value
	return ret