legex/pdf_export/core.py

"""Font download, sanitization, and FPDF writing."""

from __future__ import annotations

import hashlib
import re
import urllib.request
from pathlib import Path

from fpdf import FPDF
from fpdf.enums import Align, WrapMode

FONT_DIR = Path(__file__).resolve().parent / "_fonts"

FONT_URLS = {
    "NotoSans-Regular.ttf": "https://raw.githubusercontent.com/googlefonts/noto-fonts/main/hinted/ttf/NotoSans/NotoSans-Regular.ttf",
    "SourceHanSansSC-Regular.otf": "https://raw.githubusercontent.com/adobe-fonts/source-han-sans/release/OTF/SimplifiedChinese/SourceHanSansSC-Regular.otf",
    "SourceHanSansK-Regular.otf": "https://raw.githubusercontent.com/adobe-fonts/source-han-sans/release/OTF/Korean/SourceHanSansK-Regular.otf",
}

EXTRA_FONT_URLS = {
    "SourceHanSansTC-Regular.otf": "https://raw.githubusercontent.com/adobe-fonts/source-han-sans/release/OTF/TraditionalChinese/SourceHanSansTC-Regular.otf",
    "NotoSansDevanagari-Regular.ttf": "https://raw.githubusercontent.com/googlefonts/noto-fonts/main/hinted/ttf/NotoSansDevanagari/NotoSansDevanagari-Regular.ttf",
    "NotoSansArmenian-Regular.ttf": "https://raw.githubusercontent.com/googlefonts/noto-fonts/main/hinted/ttf/NotoSansArmenian/NotoSansArmenian-Regular.ttf",
    "NotoSansGeorgian-Regular.ttf": "https://raw.githubusercontent.com/googlefonts/noto-fonts/main/hinted/ttf/NotoSansGeorgian/NotoSansGeorgian-Regular.ttf",
}


def ensure_fonts() -> None:
    FONT_DIR.mkdir(parents=True, exist_ok=True)
    all_fonts = {**FONT_URLS, **EXTRA_FONT_URLS}
    for name, url in all_fonts.items():
        dest = FONT_DIR / name
        if dest.exists() and dest.stat().st_size > 1000:
            continue
        print(f"Downloading font {name} …", flush=True)
        req = urllib.request.Request(url, headers={"User-Agent": "Mozilla/5.0"})
        with urllib.request.urlopen(req, timeout=600) as r, open(dest, "wb") as f:
            f.write(r.read())


def sanitize_pdf_text(s: str) -> str:
    s = str(s).replace("\t", "    ").replace("\r\n", "\n").replace("\r", "\n")
    # Drop NUL and other C0 control chars, fpdf cannot handle them
    s = re.sub(r"[\x00-\x08\x0b\x0c\x0e-\x1f]", "", s)
    s = s.replace("\uf0b7", "•").replace("\uf0a7", "•").replace("\uf0d8", "•")
    s = s.replace("\uf02d", "–")
    return s


def safe_slug(case_id: str | None, link: str | None, row_idx: int) -> str:
    raw = (case_id or "").strip()
    if not raw:
        h = hashlib.sha256(((link or "") + str(row_idx)).encode("utf-8")).hexdigest()[:12]
        raw = f"decision_{row_idx}_{h}"
    raw = raw.replace("\n", " ").strip()
    raw = re.sub(r'[\x00-\x1f<>:"/\\|?*]', "_", raw)
    raw = re.sub(r"\s+", "_", raw)
    raw = raw.strip("._") or f"row_{row_idx}"
    if len(raw) > 120:
        raw = raw[:120].rstrip("_")
    return raw


class UnicodePDF(FPDF):
    pass


def pdf_font_setup(pdf: FPDF, key: str) -> str:
    if key == "han_sc":
        pdf.add_font("HanSC", "", str(FONT_DIR / "SourceHanSansSC-Regular.otf"))
        return "HanSC"
    if key == "han_tc":
        pdf.add_font("HanTC", "", str(FONT_DIR / "SourceHanSansTC-Regular.otf"))
        return "HanTC"
    if key == "han_k":
        pdf.add_font("HanK", "", str(FONT_DIR / "SourceHanSansK-Regular.otf"))
        return "HanK"
    if key == "deva":
        pdf.add_font("Deva", "", str(FONT_DIR / "NotoSansDevanagari-Regular.ttf"))
        return "Deva"
    if key == "arm":
        pdf.add_font("Arm", "", str(FONT_DIR / "NotoSansArmenian-Regular.ttf"))
        return "Arm"
    if key == "geo":
        pdf.add_font("Geo", "", str(FONT_DIR / "NotoSansGeorgian-Regular.ttf"))
        return "Geo"
    pdf.add_font("NotoSans", "", str(FONT_DIR / "NotoSans-Regular.ttf"))
    return "NotoSans"


def write_one_pdf(
    path: Path,
    case_id: str,
    link: str,
    body: str,
    font_key: str,
    *,
    text_source: str | None = None,
) -> None:
    path.parent.mkdir(parents=True, exist_ok=True)
    pdf = UnicodePDF()
    pdf.set_auto_page_break(auto=True, margin=14)
    pdf.set_left_margin(14)
    pdf.set_right_margin(14)
    pdf.add_page()
    # Use one font for meta + body when the script is non-Latin: case_id often
    # contains Hangul etc., and NotoSans would miss those glyphs in the header.
    if font_key == "default":
        text_family = pdf_font_setup(pdf, "default")
    else:
        text_family = pdf_font_setup(pdf, font_key)
    pdf.set_font(text_family, size=11)
    head = [f"case_id: {case_id}", f"link: {link}"]
    if text_source:
        head.append(f"Quelle Text: {text_source}")
    head.append("")
    meta = sanitize_pdf_text("\n".join(head))
    # Latin header: WORD wrap; CJK header lines are short — WORD is fine with LEFT.
    pdf.multi_cell(0, 6, meta, align=Align.L, wrapmode=WrapMode.WORD)
    pdf.ln(2)
    pdf.set_font(text_family, size=10)
    text = body if (body and str(body).strip()) else "(kein Volltext in der Quelle)"
    body_txt = sanitize_pdf_text(text)
    if font_key == "default":
        pdf.multi_cell(0, 5, body_txt, align=Align.L, wrapmode=WrapMode.WORD)
    else:
        pdf.multi_cell(0, 5, body_txt, align=Align.L, wrapmode=WrapMode.CHAR)
    pdf.output(str(path))