"""Page numbering and table of contents of a merged document.

This is where the chunking approach usually breaks, so the numbers are read back
out of the produced PDF instead of being trusted.
"""

from __future__ import annotations

import re

import pytest

pytest.importorskip("weasyprint")
pytest.importorskip("pypdf")

from app.config import Settings  # noqa: E402
from app.engines.weasy import WeasyPrintEngine  # noqa: E402
from app.models import ChunkSettings, ConvertRequest, PageNumbers, Source, TocSettings  # noqa: E402
from app.services.pipeline import ConversionPipeline  # noqa: E402
from tests.conftest import build_document  # noqa: E402

pytestmark = pytest.mark.asyncio


def page_texts(path) -> list[str]:
    from pypdf import PdfReader

    with open(path, "rb") as handle:
        return [page.extract_text() or "" for page in PdfReader(handle).pages]


def make_pipeline() -> ConversionPipeline:
    return ConversionPipeline({"weasyprint": WeasyPrintEngine()}, Settings())


async def test_page_numbers_are_continuous_across_chunks(tmp_path) -> None:
    request = ConvertRequest(
        source=Source(html=build_document(sections=12, paragraphs_per_section=8)),
        engine="weasyprint",
        page_numbers=PageNumbers(enabled=True, format="{page} / {pages}"),
        chunking=ChunkSettings(enabled=True, pages_per_chunk=2),
    )

    result = await make_pipeline().run(request, tmp_path)
    texts = page_texts(result.path)

    assert result.page_count == len(texts)
    assert result.page_count > 3, "dokument musi mit vic stranek, jinak test nic neoveruje"

    for index, text in enumerate(texts, start=1):
        assert f"{index} / {result.page_count}" in text.replace("\n", " ")


async def test_table_of_contents_points_to_the_real_pages(tmp_path) -> None:
    request = ConvertRequest(
        source=Source(html=build_document(sections=10, paragraphs_per_section=8)),
        engine="weasyprint",
        toc=TocSettings(enabled=True, depth=1, title="Obsah"),
        chunking=ChunkSettings(enabled=True, pages_per_chunk=2),
    )

    result = await make_pipeline().run(request, tmp_path)
    texts = page_texts(result.path)
    toc_text = " ".join(texts[:2]).replace("\n", " ")

    for index in range(10):
        heading = f"Kapitola {index + 1}"
        match = re.search(re.escape(heading) + r"\s+(\d+)", toc_text)
        assert match, f"v obsahu chybi polozka {heading}"

        declared_page = int(match.group(1))
        actual_pages = [
            number for number, text in enumerate(texts, start=1) if heading in text.replace("\n", " ")
        ]
        # The first occurrence after the table of contents is the heading itself.
        assert declared_page in actual_pages, f"{heading} deklaruje stranku {declared_page}"


async def test_unchunked_document_uses_css_counters(tmp_path) -> None:
    request = ConvertRequest(
        source=Source(html=build_document(sections=4, paragraphs_per_section=6)),
        engine="weasyprint",
        page_numbers=PageNumbers(enabled=True, format="{page} / {pages}"),
        chunking=ChunkSettings(enabled=False),
    )

    result = await make_pipeline().run(request, tmp_path)
    texts = page_texts(result.path)

    assert f"1 / {result.page_count}" in texts[0].replace("\n", " ")