"""Text extraction from PDF (poppler pdftotext)."""
import os
import subprocess

FFFD = "\ufffd"


def extract(pdf_path: str, out_path: str) -> dict:
    """Run pdftotext and report basic text-layer statistics.

    Returns a dict with path, chars, words, fffd_count, and a short
    quality verdict (useful for deciding how much cleanup a book needs).
    """
    if not os.path.exists(pdf_path):
        raise FileNotFoundError(pdf_path)
    if not os.path.exists(out_path):
        subprocess.run(
            ["pdftotext", pdf_path, out_path],
            check=True,
            capture_output=True,
            text=True,
        )
    text = open(out_path, encoding="utf-8").read()
    words = len(text.split())
    fffd = text.count(FFFD)
    if words == 0:
        verdict = "NO TEXT LAYER: the PDF appears to be a pure image scan. " \
                  "OCR it first (e.g. ocrmypdf) or the pipeline has nothing to read."
    elif fffd > words * 0.01:
        verdict = "HEAVY OCR DAMAGE: many unreadable glyphs (U+FFFD). " \
                  "Run `scan` and build a fix config before synthesizing."
    elif fffd > 0:
        verdict = "MINOR OCR DAMAGE: some unreadable glyphs. " \
                  "Run `scan` to see them; a fix config is recommended."
    else:
        verdict = "CLEAN TEXT LAYER: no replacement characters found."
    return {
        "path": out_path,
        "chars": len(text),
        "words": words,
        "fffd": fffd,
        "verdict": verdict,
    }