"""A4 page geometry helpers for portrait / landscape sections."""

from __future__ import annotations

from docx.enum.section import WD_ORIENT
from docx.enum.text import WD_PARAGRAPH_ALIGNMENT
from docx.oxml.ns import qn
from docx.shared import Mm, Pt

from .util import create_element

# GOST-like A4 margins (same as styles._apply_common_page_and_body)
MARGIN_LEFT = Mm(30)
MARGIN_RIGHT = Mm(10)
MARGIN_TOP = Mm(20)
MARGIN_BOTTOM = Mm(20)

A4_SHORT = Mm(210)
A4_LONG = Mm(297)


def is_landscape_section(section) -> bool:
    """True if section is (or should be treated as) landscape A4."""
    try:
        if section.orientation == WD_ORIENT.LANDSCAPE:
            return True
    except Exception:
        pass
    return int(section.page_width) > int(section.page_height)


def apply_section_geometry(section, *, landscape: bool) -> None:
    """
    Set orientation and page size.

    Set orientation first (python-docx may swap w/h on change), then force A4 dims.
    """
    target = WD_ORIENT.LANDSCAPE if landscape else WD_ORIENT.PORTRAIT
    try:
        section.orientation = target
    except Exception:
        pass

    if landscape:
        section.page_width = A4_LONG
        section.page_height = A4_SHORT
    else:
        section.page_width = A4_SHORT
        section.page_height = A4_LONG

    section.left_margin = MARGIN_LEFT
    section.right_margin = MARGIN_RIGHT
    section.top_margin = MARGIN_TOP
    section.bottom_margin = MARGIN_BOTTOM

    # Explicit orient on pgSz for Word.
    pg_sz = section._sectPr.find(qn("w:pgSz"))
    if pg_sz is None:
        pg_sz = section._sectPr._add_pgSz()
    if landscape:
        pg_sz.set(qn("w:orient"), "landscape")
        # Re-assert after XML tweak (some builds reshuffle).
        section.page_width = A4_LONG
        section.page_height = A4_SHORT
    else:
        if pg_sz.get(qn("w:orient")) is not None:
            del pg_sz.attrib[qn("w:orient")]
        section.page_width = A4_SHORT
        section.page_height = A4_LONG

    # Vertical align: center on landscape (figures/tables only); top on portrait
    sect_pr = section._sectPr
    for el in list(sect_pr.findall(qn("w:vAlign"))):
        sect_pr.remove(el)
    if landscape:
        sect_pr.append(create_element("w:vAlign", {"w:val": "center"}))


def content_size(*, landscape: bool) -> tuple:
    """Return (max_height, max_width) usable content area for LayoutTracker."""
    if landscape:
        page_w, page_h = A4_LONG, A4_SHORT
    else:
        page_w, page_h = A4_SHORT, A4_LONG
    max_height = page_h - MARGIN_TOP - MARGIN_BOTTOM
    max_width = page_w - MARGIN_LEFT - MARGIN_RIGHT
    return max_height, max_width


def apply_centered_page_footer(section) -> None:
    """Centered PAGE field, Times New Roman 12 (body section style)."""
    footer = section.footer
    footer.is_linked_to_previous = False
    if not footer.paragraphs:
        footer.add_paragraph()
    paragraph = footer.paragraphs[0]
    paragraph.clear()
    paragraph.paragraph_format.first_line_indent = 0
    paragraph.alignment = WD_PARAGRAPH_ALIGNMENT.CENTER
    run = paragraph.add_run()
    run.font.name = "Times New Roman"
    run.font.size = Pt(12)
    paragraph._p.append(create_element("w:fldSimple", {
        "w:instr": "PAGE \\* MERGEFORMAT",
    }))


def clear_section_footer(section) -> None:
    """Empty footer (no PAGE) — for title / assignment / TOC sections."""
    footer = section.footer
    footer.is_linked_to_previous = False
    for p in footer.paragraphs:
        p.clear()
    if not footer.paragraphs:
        footer.add_paragraph()


def ensure_continuous_page_numbers(document) -> None:
    """
    After docxcompose of title/assignment: no PAGE on early sections,
    continuous numbering (do not restart at 1 on body section).
    """
    from docx.oxml.ns import qn

    sections = list(document.sections)
    if not sections:
        return

    # Heuristic: sections before the first that already has a PAGE field /
    # or first N-1 if title was prepended — clear footer on all but keep
    # continuous pgNumType. Body renderer already puts PAGE on body section;
    # after compose, early sections may inherit footers — clear empty ones
    # that belong to front matter (no Heading-like body content is hard to
    # detect), so: clear footer on every section that has no PAGE field, and
    # strip w:pgNumType start=1 everywhere.
    for section in sections:
        sect_pr = section._sectPr
        for child in list(sect_pr):
            if child.tag == qn("w:pgNumType"):
                # Keep continuous: remove start attribute if present
                if child.get(qn("w:start")) is not None:
                    del child.attrib[qn("w:start")]