"""
This code adapted from the library "pptree," Copyright (c) 2017 Clément Michard
and released under the MIT license: https://github.com/clemtoy/pptree
"""
import io


def render_tree(current_node, nameattr='name', left_child='left',
                           right_child='right', indent='', last='updown',
                           buffer=None):
    """Print a tree-like structure, `current_node`.

    This is a mostly-direct-copy of the print_tree() function from the ppbtree
    module of the pptree library, but instead of printing to standard out, we
    write to a StringIO buffer, then use that buffer to accumulate written lines
    during recursive calls to render_tree().
    """
    if buffer is None:
        buffer = io.StringIO()
    if hasattr(current_node, nameattr):
        name = lambda node: getattr(node, nameattr)
    else:
        name = lambda node: str(node)

    up = getattr(current_node, left_child, None)
    down = getattr(current_node, right_child, None)

    if up is not None:
        next_last = 'up'
        next_indent = '{0}{1}{2}'.format(indent, ' ' if 'up' in last else '|', ' ' * len(str(name(current_node))))
        render_tree(up, nameattr, left_child, right_child, next_indent, next_last, buffer)

    if last == 'up':
        start_shape = '┌'
    elif last == 'down':
        start_shape = '└'
    elif last == 'updown':
        start_shape = ' '
    else:
        start_shape = '├'

    if up is not None and down is not None:
        end_shape = '┤'
    elif up:
        end_shape = '┘'
    elif down:
        end_shape = '┐'
    else:
        end_shape = ''

    print('{0}{1}{2}{3}'.format(indent, start_shape, name(current_node), end_shape),
          file=buffer)

    if down is not None:
        next_last = 'down'
        next_indent = '{0}{1}{2}'.format(indent, ' ' if 'down' in last else '|', ' ' * len(str(name(current_node))))
        render_tree(down, nameattr, left_child, right_child, next_indent, next_last, buffer)

    return f"\n{buffer.getvalue()}"