from __future__ import annotations

from dataclasses import dataclass


def main():
    activity_tree = ActivityTree()
    activity_tree.activities[1] = Activity(id=1, parent=0, text="foo")
    activity_tree.activities[2] = Activity(id=2, parent=0, text="bar")
    activity_tree.activities[3] = Activity(id=3, parent=0, text="baz")
    activity_tree.activities[4] = Activity(id=4, parent=2, text="lorem")
    # activity_tree.activities[5] = Activity(id=5, parent=2, text="ipsum")
    # activity_tree.activities[6] = Activity(id=6, parent=2, text="dolar")
    activity_tree.activities[7] = Activity(id=7, parent=4, text="north")
    activity_tree.activities[8] = Activity(id=8, parent=4, text="east")
    activity_tree.activities[9] = Activity(id=9, parent=4, text="south")
    activity_tree.activities[10] = Activity(id=10, parent=4, text="west")

    # For each line we need to know:
    #   - the depth
    #   - whether there are later siblings
    #   - whether there are earlier siblings
    #
    # Draw order:
    #   - Find all leaves
    #   - Start with last child of root
    #   - If it has children, keep going down until you hit leaves

    for entry in activity_tree.get_draw_order():
        text = activity_tree.activities[entry.id].text
        leading_bars = "".join("𜹈  " if depth else "   " for depth in entry.depth)
        branch = "𜸨" if entry.has_later_siblings else "𜸛"
        print(f"{leading_bars}{branch}𜸟 {text}")


class ActivityTree:
    activities: dict[int, Activity]

    def __init__(self) -> None:
        self.activities = {}

    def get_draw_order(self) -> list[StackEntry]:
        draw_order = []
        stack = [
            StackEntry(
                id=child_id,
                depth=[],
                has_later_siblings=True,
                have_pulled_children=False,
            )
            for child_id in self.get_children_in_order(0)
        ]
        stack[-1].has_later_siblings = False
        while len(stack) > 0:
            current_entry = stack.pop()
            if current_entry.have_pulled_children:
                if current_entry.id != 0:
                    draw_order.append(current_entry)
                continue

            current_entry.have_pulled_children = True
            stack.append(current_entry)
            all_children = self.get_children_in_order(current_entry.id)
            for child_id in all_children:
                stack.append(
                    StackEntry(
                        id=child_id,
                        depth=current_entry.depth + [current_entry.has_later_siblings],
                        has_later_siblings=True,
                        have_pulled_children=False,
                    )
                )
            if len(all_children) > 0:
                stack[-1].has_later_siblings = False
        return draw_order

    def get_children_in_order(self, parent_id: int) -> list[int]:
        return sorted(
            child_id
            for child_id, child in self.activities.items()
            if child.parent == parent_id
        )

    def has_children(self, parent_id: int) -> bool:
        return any(
            child.parent == parent_id for _child_id, child in self.activities.items()
        )


@dataclass
class StackEntry:
    id: int
    depth: list[bool]
    has_later_siblings: bool
    have_pulled_children: bool  # Only used when building the draw order


@dataclass
class Activity:
    id: int
    parent: int
    text: str


if __name__ == "__main__":
    main()