src/fetch_wiktionary_examples.py

#!/usr/bin/env python3
"""Build the `wiktionary_examples` source from the official Polish Wiktionary dump.

Extracts usage-example sections (`{{przykłady}}`) from Polish-language entries
of pl.wiktionary.org and emits a `.jsonl.zst` file in the format expected by
`src/build_dynaword.py` (fields: text / license / author).

Unlike most sources in this registry, this one is NOT routed through
SpeakLeash's redistribution — it is parsed directly from the Wikimedia dump.
The `provenance` field in sources.py records this.

One document = one headword; its example sentences are concatenated,
newline-separated, in source order. A quotation from a third-party work (used
under the Art. 29 quotation right, not licensed CC BY-SA by Wiktionary
contributors) is dropped: a line carrying a `{{źródło|...}}` template or a
`<ref>`, a hand-written source such as "(B. Prus: Lalka)" or "(z Internetu)",
or an omission mark "(…)". Its citation goes to a side-car file for auditing
(not part of the corpus).

Only the standard library is required for parsing; `zstandard` is used for
output compression (falls back to plain .jsonl with a warning).

Usage:
  # download the dump yourself, then:
  python3 src/fetch_wiktionary_examples.py \
      --dump plwiktionary-latest-pages-articles.xml.bz2 \
      

  # dump URL:
  # https://dumps.wikimedia.org/plwiktionary/latest/plwiktionary-latest-pages-articles.xml.bz2
"""
from __future__ import annotations

import argparse
import bz2
import html
import json
import re
import sys
from pathlib import Path
from urllib.parse import quote
from xml.etree import ElementTree as ET

SOURCE_NAME = "wiktionary_examples"
# pl.wiktionary's footer links CC BY-SA 4.0 (Wikimedia Terms of Use, June 2023).
# Older revisions were contributed under 3.0, whose §4(b) allows an adaptation
# to be licensed under a later version with the same elements.
LICENSE = "CC-BY-SA-4.0"
PAGE_URL = "https://pl.wiktionary.org/wiki/"

# Gates mirrored from build_dynaword.py so the preview count matches the build.
MIN_CHARS = 200
MIN_EXAMPLE_CHARS = 10

# `== <headword> ({{język polski}}) ==` opens the Polish section of an entry.
PL_HEADING = re.compile(r"^==\s*(.+?)\s*\(\{\{język polski\}\}\)\s*==\s*$", re.M)
NEXT_HEADING = re.compile(r"^==[^=]", re.M)

# Blocks run until the next section marker, a `{{template}}` opening a line.
# Inline templates such as `{{tłum}}` or `{{pot}}` inside an example don't end it.
EXAMPLES_BLOCK = re.compile(
    r"\{\{przykłady\}\}(.*?)(?=^\{\{[a-ząćęłńóśźż]+\}\}|\Z)", re.S | re.M
)
# Numbered lines: `: (1.1) <sentence>`
NUMBERED_LINE = re.compile(r"^:\s*\(([\d.]+)\)\s*(.+?)\s*$", re.M)
SENSE_NUMBER = re.compile(r"\(\d+\.\d+\)")

# Fields of {{źródło}} and of the templates used inside <ref>: {{NKJP}}, {{cytuj}},
# {{cytuj stronę}}, {{KJP}}, {{Gloger1900}}.
CITATION_FIELDS = ("autor", "autorzy", "tytuł", "tytul", "tytuł_pub", "rozdział", "rozdzial",
                   "hasło", "rok", "data", "isbn", "url")
CITATION_TEMPLATES = ("{{źródło", "{{zrodlo")
# `<ref>source</ref>`, or `<ref name="x" />` reusing a source given elsewhere on the page.
REF = re.compile(r"<ref\b([^>]*?)(?:/>|>(.*?)</ref\s*>)", re.I | re.S)

# Quotations whose source is written by hand instead of with {{źródło}}, matched
# on the cleaned sentence. Patterns come from a survey of the 20261001 dump.
_UP = "A-ZĄĆĘŁŃÓŚŹŻ"
_LOW = "a-ząćęłńóśźż"
_END = r"[\s.!?…]*$"
ATTRIBUTION_TAILS = (
    # A capital opening a word or an initial: "(B. Prus: Lalka)", "(Adam Mickiewicz)",
    # "(Kogel-mogel)", "(Mt 4:19)", "(W leśniczówce …)". Acronyms and formulas
    # ("(ZSRR)", "(C/kg)") don't match.
    # ponytail: also drops a few glosses like "(Alligator missisippiensis)";
    # losing a sentence is cheaper than shipping a quotation.
    re.compile(rf"\(\s*[\"„“]?[{_UP}](?:[{_LOW}]|\.|\s)[^()]*\){_END}"),
    # "(z Internetu)", "(z Wikipedii)", "(z Odysei)": "from <source>".
    re.compile(rf"\(\s*z\s+[{_UP}{_LOW}][{_LOW}]*\){_END}", re.I),
    re.compile(rf"\(\s*(?:źródło|wywiad|tytuł|słowa|cytat|za:)[^()]*\){_END}", re.I),
    # Unparenthesised tag after the sentence: "…Gałczyńskiego. Internet".
    re.compile(rf"(?<=[.!?…\]”\"])\s*(?:z\s+)?(?:internet\w*|wikipedi\w*){_END}", re.I),
)
# "(…)" / "[...]" mark an omission: the line was cut from someone else's text.
EXCERPT_MARK = re.compile(r"[(\[]\s*(?:…|\.\.\.)\s*[)\]]")


def split_templates(text: str) -> tuple[str, list[str]]:
    """Remove `{{...}}` spans, counting braces so nested templates are handled.

    A regex cannot do this correctly: `{{źródło|tytuł={{...}}}}` occurs in the
    dump and a non-greedy match closes at the wrong brace pair.
    """
    kept: list[str] = []
    removed: list[str] = []
    i = 0
    while i < len(text):
        if text.startswith("{{", i):
            depth, j = 0, i
            while j < len(text):
                if text.startswith("{{", j):
                    depth += 1
                    j += 2
                elif text.startswith("}}", j):
                    depth -= 1
                    j += 2
                    if depth == 0:
                        break
                else:
                    j += 1
            removed.append(text[i:j])
            i = j
        else:
            kept.append(text[i])
            i += 1
    return "".join(kept), removed


def describe_citation(template: str) -> str:
    """Flatten a `{{źródło|autor=…|tytuł=…}}` template into a readable string; the
    template's name when it has none of CITATION_FIELDS (e.g. `{{zWikiprojektu|…}}`)."""
    name, *chunks = template.strip("{}").split("|")
    fields: dict[str, str] = {}
    for chunk in chunks:
        if "=" in chunk:
            key, value = chunk.split("=", 1)
            key = key.strip().lower()
            # clean() would delete a bare URL, which is the whole point of `url`.
            fields[key] = value.strip() if key == "url" else clean(value)
    parts = [fields[k] for k in CITATION_FIELDS if fields.get(k)]
    return " | ".join(parts) or "{{" + name.strip() + "}}"


def unlink(text: str) -> str:
    """`[[target|label]]` -> label, `[[word]]` -> word, external links -> label."""
    for _ in range(5):
        stripped = re.sub(r"\[\[([^\[\]|]*)\|(.*?)\]\]", r"\2", text)
        stripped = re.sub(r"\[\[([^\[\]|]+?)\]\]", r"\1", stripped)
        if stripped == text:
            break
        text = stripped
    # Safety net for malformed nesting, e.g. `[[zaskoczyć|zaskoczył[y]]]`.
    text = re.sub(r"\[\[[^\[\]]*?\|", "[[", text)
    text = text.replace("[[", "").replace("]]", "")
    text = re.sub(r"\[https?://\S+\s+([^\]]+)\]", r"\1", text)
    text = re.sub(r"\[https?://\S+\]", "", text)
    text = re.sub(r"https?://\S+", "", text)
    return text


def clean(text: str) -> str:
    """Strip wiki and HTML markup. Square brackets are kept deliberately:
    `[…]` marks an omission and `[= gloss]` an editorial insertion — both are
    philological convention inside quotations, not markup residue."""
    text = re.sub(r"<ref[^>]*>.*?</ref>", "", text, flags=re.S)
    text = re.sub(r"<ref[^>]*/>", "", text)
    text = re.sub(r"<br\s*/?>", " ", text, flags=re.I)   # a line break separates words
    text = re.sub(r"<[^>]+>", "", text)
    text = unlink(text)
    text = re.sub(r"'{2,}", "", text)
    text = html.unescape(html.unescape(text))   # some entities are double-encoded
    text = text.replace("\u00a0", " ")
    text = SENSE_NUMBER.sub("", text)
    text = re.sub(r"\(\s*\)", "", text)   # left behind by a stripped template
    text = re.sub(r"\s+", " ", text)
    return text.strip(" -–—•\t")


def polish_section(wikitext: str) -> tuple[str, str] | None:
    match = PL_HEADING.search(wikitext)
    if not match:
        return None
    headword = match.group(1).strip()
    rest = wikitext[match.end():]
    end = NEXT_HEADING.search(rest)
    if end:
        rest = rest[: end.start()]
    return headword, rest


def is_cited(raw: str, templates: list[str]) -> bool:
    """A line with a source attached is a quotation from a third-party work (Art. 29
    quotation right), not a contributor's own CC BY-SA text."""
    return "<ref" in raw.lower() or any(t.startswith(CITATION_TEMPLATES) for t in templates)


def cited_sources(raw: str, templates: list[str]) -> list[str]:
    """The sources a cited line gives, for the audit side-car."""
    sources = [describe_citation(t) for t in templates if t.startswith(CITATION_TEMPLATES)]
    for ref in REF.finditer(raw):
        attributes, body = ref.groups()
        if body is None:
            sources.append(f"<ref{attributes.rstrip()}/>")
            continue
        text, inner = split_templates(body)
        # {{źródło}} inside a <ref> is already in `templates`.
        sources += [describe_citation(t) for t in inner if not t.startswith(CITATION_TEMPLATES)]
        sources.append(clean(text))
    return [source for source in sources if source]


def hand_attribution(sentence: str) -> str | None:
    """The source a quotation names without {{źródło}}, or "(…)" for an excerpt
    that names none; None for a contributor's own example."""
    for pattern in ATTRIBUTION_TAILS:
        match = pattern.search(sentence)
        if match:
            return match.group(0).strip(" .!?…")
    match = EXCERPT_MARK.search(sentence)
    return match.group(0) if match else None


def examples_and_citations(section: str) -> tuple[list[str], list[str], int]:
    """(example sentences, citations of the dropped quotations, number of dropped lines).

    A line is a quotation when it carries {{źródło}}/<ref> or a hand-written
    source (see hand_attribution)."""
    match = EXAMPLES_BLOCK.search(section)
    if not match:
        return [], [], 0
    examples, citations, dropped = [], [], 0
    for _, raw in NUMBERED_LINE.findall(match.group(1)):
        without_templates, templates = split_templates(raw)
        if is_cited(raw, templates):
            dropped += 1
            citations.extend(cited_sources(raw, templates) or ["(no source text)"])
            continue
        sentence = clean(without_templates)
        attribution = hand_attribution(sentence)
        if attribution:
            dropped += 1
            citations.append(attribution)
            continue
        if len(sentence) >= MIN_EXAMPLE_CHARS:
            examples.append(sentence)
    return examples, sorted(set(citations)), dropped


def page_url(title: str) -> str:
    return PAGE_URL + quote(title.replace(" ", "_"), safe="/:()',!")


def credit(title: str) -> str:
    """BY-SA 4.0 §3(a)(2) allows attribution by a URI; the page history lists the authors."""
    return f"Wikisłownik contributors, {page_url(title)}"


def iter_pages(dump_path: Path):
    """Yield (namespace, page id, title, wikitext) for every page, streaming the bz2 dump."""
    with bz2.open(dump_path, "rb") as handle:
        for _, element in ET.iterparse(handle, events=("end",)):
            if element.tag.rsplit("}", 1)[-1] != "page":
                continue
            values = {}
            for child in element.iter():
                tag = child.tag.rsplit("}", 1)[-1]
                # The page's own <id> precedes its revision's <id>.
                if tag in ("ns", "id", "title", "text") and tag not in values:
                    values[tag] = child.text
            yield ((values.get("ns") or "").strip(), (values.get("id") or "").strip(),
                   values.get("title") or "", values.get("text") or "")
            element.clear()


def main() -> None:
    parser = argparse.ArgumentParser(description=__doc__)
    parser.add_argument("--dump", required=True,
                        help="plwiktionary-latest-pages-articles.xml.bz2")
    parser.add_argument("--out", default=".",
                        help="directory to write <source>.jsonl.zst into")
    parser.add_argument("--min-chars", type=int, default=MIN_CHARS,
                        help=f"document length gate (default {MIN_CHARS}, "
                             "matching build_dynaword.py)")
    args = parser.parse_args()

    dump_path = Path(args.dump).expanduser()
    if not dump_path.exists():
        sys.exit(f"dump not found: {dump_path}")
    out_dir = Path(args.out).expanduser()
    out_dir.mkdir(parents=True, exist_ok=True)

    pages = entries = with_examples = with_citations = quoted_lines = example_lines = 0
    documents: list[dict] = []
    citation_index: list[dict] = []

    for namespace, page_id, title, wikitext in iter_pages(dump_path):
        pages += 1
        if pages % 100_000 == 0:
            print(f"  {pages:,} pages scanned, {entries:,} Polish entries",
                  flush=True)
        if namespace != "0":
            continue
        section = polish_section(wikitext)
        if section is None:
            continue
        entries += 1
        headword, body = section
        examples, citations, dropped = examples_and_citations(body)
        quoted_lines += dropped
        if citations:
            with_citations += 1
            citation_index.append({"id": f"{SOURCE_NAME}_{page_id}", "headword": headword,
                                   "citations": citations})
        if not examples:
            continue
        with_examples += 1
        example_lines += len(examples)
        documents.append({"id": f"{SOURCE_NAME}_{page_id}", "text": "\n".join(examples),
                          "license": LICENSE, "author": credit(title)})

    kept = [d for d in documents if len(d["text"]) >= args.min_chars]
    chars = sum(len(d["text"]) for d in kept)

    print()
    print(f"pages scanned:            {pages:,}")
    print(f"Polish entries:           {entries:,}")
    print(f"entries with examples:    {with_examples:,}")
    print(f"entries with attribution: {with_citations:,}")
    print(f"quoted lines dropped:     {quoted_lines:,}")
    print(f"example lines kept:       {example_lines:,}")
    print(f"documents >= {args.min_chars} chars:  {len(kept):,}")
    print(f"characters:               {chars:,}")

    payload = "\n".join(
        json.dumps(document, ensure_ascii=False) for document in kept
    ) + "\n"

    plain = out_dir / f"{SOURCE_NAME}.jsonl"
    plain.write_text(payload, encoding="utf-8")

    try:
        import zstandard as zstd
    except ImportError:
        print(f"\nwrote {plain} — install `zstandard` (or run `zstd {plain.name}`) "
              "to produce the .jsonl.zst the build expects")
    else:
        compressed = out_dir / f"{SOURCE_NAME}.jsonl.zst"
        compressed.write_bytes(zstd.ZstdCompressor(level=10).compress(
            payload.encode("utf-8")))
        plain.unlink()
        print(f"\nwrote {compressed}")

    audit = out_dir / f"{SOURCE_NAME}.citations.jsonl"
    audit.write_text(
        "\n".join(json.dumps(row, ensure_ascii=False) for row in citation_index) + "\n",
        encoding="utf-8",
    )
    print(f"wrote {audit} (attribution audit trail, not part of the corpus)")
    print()
    print(f"next: python3 src/build_dynaword.py --sources {SOURCE_NAME} "
          f"--speakleash-dir {out_dir} --out .")


if __name__ == "__main__":
    main()