"""XML -> PDF (pretty text dump, monospace).

Validation is explicit: lxml must parse the document, otherwise the job
fails with "Invalid XML: <reason>" (never a render failure). A valid
document is rendered as its text content — every text node and tail in
document order, one per line, whitespace-only nodes dropped — inside
<pre> with PRE_CSS. Attribute values are intentionally not dumped: the
contract is that element text survives extraction.
"""
from __future__ import annotations

from pathlib import Path

from lxml import etree

from . import common
from .text_converter import decode_bytes


def convert(path: Path, job_id: str, progress_cb=None, output_dir=None,
            source_name=None) -> str:
    """Render an XML file to a monospace text-dump PDF."""
    raw = path.read_bytes()
    if not raw.strip():
        raise ValueError("empty file: nothing to convert")
    text = decode_bytes(raw)
    try:
        root = etree.fromstring(text.encode("utf-8"))
    except etree.XMLSyntaxError as exc:
        raise ValueError(f"Invalid XML: {exc}") from exc

    lines: list[str] = []
    for el in root.iter():
        for chunk in (el.text, el.tail):
            if not chunk:
                continue
            piece = " ".join(chunk.split())
            if piece:
                lines.append(piece)
    if not lines:
        raise ValueError("empty file: XML has no text content")
    body = "\n".join(lines)

    def _build():
        return f"<html><body><pre>{common.escape(body)}</pre></body></html>", path.name

    return common.convert_single(
        path, job_id, build_html=_build, css=common.PRE_CSS,
        progress_cb=progress_cb, output_dir=output_dir,
        name_src=source_name or path.name,
    )