"""Pure-function test helpers for the EPUB -> PDF converter suite.

No pytest fixtures here: every function takes its dependencies explicitly so
the helpers stay unit-testable and reusable.
"""
import io
import time
import zipfile

from pypdf import PdfReader

TERMINAL_STATUSES = ("done", "error")


def wait_for_job(client, job_id, timeout=90.0):
    """Poll GET /api/jobs/<job_id> until a terminal status; return snapshot."""
    deadline = time.time() + timeout
    last = None
    while time.time() < deadline:
        resp = client.get(f"/api/jobs/{job_id}")
        assert resp.status_code == 200, f"job lookup failed: {resp.status_code}"
        last = resp.get_json()
        if last["status"] in TERMINAL_STATUSES:
            return last
        time.sleep(0.05)
    raise TimeoutError(f"job {job_id} not terminal after {timeout}s: {last}")


def download_bytes(client, filename):
    """GET /download/<filename> and return the raw body (asserts 200)."""
    resp = client.get(f"/download/{filename}")
    assert resp.status_code == 200, (
        f"download failed for {filename}: {resp.status_code}"
    )
    return resp.data


def pdf_text(data_bytes):
    """Extract all text from a PDF byte string (pypdf)."""
    reader = PdfReader(io.BytesIO(data_bytes))
    return "\n".join((page.extract_text() or "") for page in reader.pages)


def pdf_page_count(data_bytes):
    return len(PdfReader(io.BytesIO(data_bytes)).pages)


def pdf_metadata_title(data_bytes):
    reader = PdfReader(io.BytesIO(data_bytes))
    meta = reader.metadata
    return meta.get("/Title") if meta else None


def make_zip_without_container():
    """A valid zip that is not an EPUB (no META-INF/container.xml)."""
    buf = io.BytesIO()
    with zipfile.ZipFile(buf, "w") as zf:
        zf.writestr("notes.txt", "hello, not an epub")
    return buf.getvalue()


_CONTAINER_XML = (
    '<?xml version="1.0" encoding="utf-8"?>'
    '<container version="1.0" xmlns="urn:oasis:names:tc:opendocument:xmlns:container">'
    '<rootfiles><rootfile full-path="OEBPS/book.opf" '
    'media-type="application/oebps-package+xml"/></rootfiles></container>'
)


def make_epub_zip(items, spine_ids, title="Synthetic", creator="Synth"):
    """Build a minimal EPUB byte string from (id, href, media_type, props) items."""
    manifest = "".join(
        f'<item id="{i}" href="{h}" media-type="{m}"'
        + (f' properties="{p}"' if p else "")
        + "/>"
        for i, h, m, p in items
    )
    refs = "".join(f'<itemref idref="{sid}"/>' for sid in spine_ids)
    opf = (
        '<?xml version="1.0" encoding="utf-8"?>'
        '<package xmlns="http://www.idpf.org/2007/opf" version="3.0" '
        'unique-identifier="uid">'
        '<metadata xmlns:dc="http://purl.org/dc/elements/1.1/">'
        f"<dc:title>{title}</dc:title><dc:creator>{creator}</dc:creator>"
        "</metadata>"
        f"<manifest>{manifest}</manifest>"
        f"<spine>{refs}</spine>"
        "</package>"
    )
    buf = io.BytesIO()
    with zipfile.ZipFile(buf, "w") as zf:
        zf.writestr("META-INF/container.xml", _CONTAINER_XML)
        zf.writestr("OEBPS/book.opf", opf)
    return buf.getvalue()


def build_epub_tree(base, *, items=None, spine_ids=None, pdir=None):
    """Materialize a minimal on-disk EPUB structure for parse_opf tests."""
    items = items or [
        ("ch1", "chapter1.xhtml", "application/xhtml+xml", ""),
        ("ch2", "chapter2.xhtml", "application/xhtml+xml", ""),
        ("img1", "img.png", "image/png", ""),
    ]
    spine_ids = (
        list(spine_ids)
        if spine_ids is not None
        else [i for i, h, m, p in items if "html" in m]
    )
    pdir_attr = f' page-progression-direction="{pdir}"' if pdir else ""
    manifest = "".join(
        f'<item id="{i}" href="{h}" media-type="{m}"'
        + (f' properties="{p}"' if p else "")
        + "/>"
        for i, h, m, p in items
    )
    refs = "".join(f'<itemref idref="{sid}"/>' for sid in spine_ids)
    opf = (
        '<?xml version="1.0" encoding="utf-8"?>'
        f'<package xmlns="http://www.idpf.org/2007/opf" version="3.0" '
        f'unique-identifier="uid"{pdir_attr}>'
        '<metadata xmlns:dc="http://purl.org/dc/elements/1.1/">'
        "<dc:title>Tree Book</dc:title>"
        "<dc:creator>Tree Author</dc:creator>"
        "<dc:language>en</dc:language>"
        "</metadata>"
        f"<manifest>{manifest}</manifest>"
        f"<spine>{refs}</spine>"
        "</package>"
    )
    (base / "META-INF").mkdir(parents=True, exist_ok=True)
    (base / "META-INF" / "container.xml").write_text(_CONTAINER_XML, encoding="utf-8")
    (base / "OEBPS").mkdir(parents=True, exist_ok=True)
    (base / "OEBPS" / "book.opf").write_text(opf, encoding="utf-8")
    for i, h, m, p in items:
        if "html" in m:
            (base / "OEBPS" / h).write_text(
                '<?xml version="1.0" encoding="utf-8"?>'
                "<html><body><p>chapter body</p></body></html>",
                encoding="utf-8",
            )
    return base