"""Text-fidelity regression tests: em dashes and CJK must survive
EPUB -> WeasyPrint -> pypdf merge without mojibake.

Markers below were verified against test_book.epub ground truth:
the source contains 3 em dashes and the CJK runs listed in CJK_MARKERS.
These tests lock in the UTF-8 HTML-string decoding fix (app.py L258-265):
passing decoded text (not file paths) to WeasyPrint prevents Latin-1
sniffing from turning em dashes/CJK into mojibake.
"""
import io

from pypdf import PdfReader

from tests.helpers import download_bytes, pdf_metadata_title, wait_for_job

EM_DASH = "\u2014"
CJK_MARKERS = ["中文测试段落", "天地玄黄", "宇宙洪荒", "日月盈昃", "辰宿列张"]
EXPECTED_TITLE = "Structured Test Book"
EXPECTED_AUTHOR = "Agent Zero"


def _converted_pdf(client, submit_epub):
    job_id = submit_epub(filename="book.epub").get_json()["job_id"]
    job = wait_for_job(client, job_id)
    assert job["status"] == "done", job
    return download_bytes(client, job["filename"]), job


def test_em_dashes_survive_conversion(client, submit_epub):
    data, _ = _converted_pdf(client, submit_epub)
    reader = PdfReader(io.BytesIO(data))
    full = "\n".join((p.extract_text() or "") for p in reader.pages)
    assert EM_DASH in full, "em dash missing from PDF text"
    assert full.count(EM_DASH) >= 3, f"expected >=3 em dashes, got {full.count(EM_DASH)}"


def test_cjk_text_survives_conversion(client, submit_epub):
    data, _ = _converted_pdf(client, submit_epub)
    reader = PdfReader(io.BytesIO(data))
    full = "\n".join((p.extract_text() or "") for p in reader.pages)
    for marker in CJK_MARKERS:
        assert marker in full, f"CJK marker {marker!r} missing from PDF text"


def test_no_latin1_mojibake(client, submit_epub):
    """Mojibake regression: em dash mis-decoded as Latin-1 reads 'â€"'."""
    data, _ = _converted_pdf(client, submit_epub)
    reader = PdfReader(io.BytesIO(data))
    full = "\n".join((p.extract_text() or "") for p in reader.pages)
    assert "â€" not in full, "Latin-1 mojibake detected for em dash"
    assert "ï¼" not in full, "CJK fullwidth colon mojibake detected"


def test_pdf_metadata_round_trip(client, submit_epub):
    data, _ = _converted_pdf(client, submit_epub)
    assert pdf_metadata_title(data) == EXPECTED_TITLE
    reader = PdfReader(io.BytesIO(data))
    assert reader.metadata["/Author"] == EXPECTED_AUTHOR


def test_page_count_matches_fixture(client, submit_epub):
    """The 6-page fixture must not silently drop or merge chapters."""
    data, _ = _converted_pdf(client, submit_epub)
    reader = PdfReader(io.BytesIO(data))
    assert len(reader.pages) == 6