from copy import copy

from docx.shared import Length


class LayoutState:
    def __init__(self, max_height: Length, max_width: Length):
        self.max_height: Length = max_height
        self.max_width: Length = max_width
        self._current_height: Length = Length(0)

    def new_page(self):
        self._current_height += self.remaining_page_height

    @property
    def current_page_height(self):
        return self._current_height % self.max_height

    @property
    def remaining_page_height(self) -> Length:
        return self.max_height - self.current_page_height

    @property
    def page(self):
        return self._current_height // self.max_height + 1

    def add_height(self, height: Length):
        self._current_height += height


class LayoutTracker:
    def __init__(self, max_height: Length, max_width: Length):
        self._state = LayoutState(max_height, max_width)
        self._is_new_page = False

    @property
    def current_state(self):
        return copy(self._state)

    @property
    def is_new_page(self):
        return self._is_new_page

    def add_height(self, height: Length):
        page = self._state.page
        self._state.add_height(height)
        self._is_new_page = self._state.page > page

    def can_fit_to_page(self, height: Length):
        return height <= self._state.remaining_page_height

    def new_page(self):
        self._state.new_page()

    def set_page_size(self, max_height: Length, max_width: Length) -> None:
        """Switch usable area (e.g. portrait ↔ landscape) and start a fresh page."""
        self._state.max_height = max_height
        self._state.max_width = max_width
        # Align to a page boundary under the *new* geometry.
        rem = self._state.remaining_page_height
        if rem != max_height:
            self._state.add_height(rem)
        self._is_new_page = True