"""Convert Office documents to PDF for downstream parsing."""

from __future__ import annotations

import platform
import shutil
import subprocess
from pathlib import Path

_PPT_EXTENSIONS = {".ppt", ".pptx", ".ppsx"}
_WORD_EXTENSIONS = {".doc", ".docx"}


def _find_soffice() -> Path | None:
    for candidate in (
        "soffice",
        r"C:\Program Files\LibreOffice\program\soffice.exe",
        r"C:\Program Files (x86)\LibreOffice\program\soffice.exe",
        "/usr/bin/libreoffice",
        "/usr/bin/soffice",
    ):
        if candidate in ("soffice", "libreoffice"):
            found = shutil.which(candidate)
            if found:
                return Path(found)
        elif Path(candidate).is_file():
            return Path(candidate)
    return None


def _convert_via_libreoffice(source: Path, out_dir: Path) -> Path:
    soffice = _find_soffice()
    if soffice is None:
        raise RuntimeError("LibreOffice (soffice) not found")

    out_dir.mkdir(parents=True, exist_ok=True)
    subprocess.run(
        [
            str(soffice),
            "--headless",
            "--convert-to",
            "pdf",
            "--outdir",
            str(out_dir),
            str(source.resolve()),
        ],
        check=True,
        capture_output=True,
        text=True,
        timeout=180,
    )
    pdf_path = out_dir / f"{source.stem}.pdf"
    if not pdf_path.is_file():
        raise RuntimeError(f"LibreOffice did not produce PDF: {pdf_path}")
    return pdf_path


def _convert_via_powerpoint(source: Path, out_dir: Path) -> Path:
    if platform.system() != "Windows":
        raise RuntimeError("PowerPoint COM conversion is only available on Windows")

    out_dir.mkdir(parents=True, exist_ok=True)
    pdf_path = out_dir / f"{source.stem}.pdf"
    src = str(source.resolve())
    dst = str(pdf_path.resolve())
    script = f"""
$ErrorActionPreference = 'Stop'
$pp = New-Object -ComObject PowerPoint.Application
try {{
  $pres = $pp.Presentations.Open('{src.replace("'", "''")}', $true, $true, $false)
  try {{
    $pres.SaveAs('{dst.replace("'", "''")}', 32)
  }} finally {{
    $pres.Close()
  }}
}} finally {{
  $pp.Quit()
}}
"""
    subprocess.run(
        ["powershell", "-NoProfile", "-NonInteractive", "-Command", script],
        check=True,
        capture_output=True,
        text=True,
        timeout=180,
    )
    if not pdf_path.is_file():
        raise RuntimeError(f"PowerPoint did not produce PDF: {pdf_path}")
    return pdf_path


def _convert_via_word(source: Path, out_dir: Path) -> Path:
    if platform.system() != "Windows":
        raise RuntimeError("Word COM conversion is only available on Windows")

    out_dir.mkdir(parents=True, exist_ok=True)
    pdf_path = out_dir / f"{source.stem}.pdf"
    src = str(source.resolve())
    dst = str(pdf_path.resolve())
    script = f"""
$ErrorActionPreference = 'Stop'
$word = New-Object -ComObject Word.Application
$word.Visible = $false
try {{
  $doc = $word.Documents.Open('{src.replace("'", "''")}', $false, $true)
  try {{
    $doc.SaveAs2('{dst.replace("'", "''")}', 17)
  }} finally {{
    $doc.Close([ref]$false)
  }}
}} finally {{
  $word.Quit()
}}
"""
    subprocess.run(
        ["powershell", "-NoProfile", "-NonInteractive", "-Command", script],
        check=True,
        capture_output=True,
        text=True,
        timeout=180,
    )
    if not pdf_path.is_file():
        raise RuntimeError(f"Word did not produce PDF: {pdf_path}")
    return pdf_path


def convert_to_pdf(source: Path, out_dir: Path) -> Path:
    """Convert an Office file to PDF. Tries LibreOffice, then format-specific COM on Windows."""
    source = source.resolve()
    if not source.is_file():
        raise FileNotFoundError(source)

    errors: list[str] = []
    try:
        return _convert_via_libreoffice(source, out_dir)
    except Exception as exc:  # noqa: BLE001 — collect and try next backend
        errors.append(f"libreoffice: {exc}")

    ext = source.suffix.lower()
    fallbacks: list = []
    if ext in _PPT_EXTENSIONS:
        fallbacks.append(_convert_via_powerpoint)
    elif ext in _WORD_EXTENSIONS:
        fallbacks.append(_convert_via_word)

    for converter in fallbacks:
        try:
            return converter(source, out_dir)
        except Exception as exc:  # noqa: BLE001
            errors.append(f"{converter.__name__}: {exc}")

    detail = "; ".join(errors) if errors else "no converter available"
    raise RuntimeError(
        f"Failed to convert {source.name} to PDF. "
        f"Install LibreOffice or Microsoft Office. Details: {detail}"
    )


def is_presentation(path: Path) -> bool:
    return path.suffix.lower() in _PPT_EXTENSIONS


def is_word_document(path: Path) -> bool:
    return path.suffix.lower() in _WORD_EXTENSIONS