feat(postcodes/RS): bulk-import 1,170 Serbia postcodes via Pošta Srbije (#1039) (#1466)

Source: Pošta Srbije catalogue redistributed via the nebjak/serbia-
zip-codes-js MIT package. Ships country-only — the source carries
city + zip_code only with no okrug (district) mapping (matches the
SE/SI/ZA/GR/VN/LV/KE precedent).

Refs #1039.

Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: dr5hn

bin/scripts/sync/import_serbia_postcodes.py

@@ -0,0 +1,143 @@
+#!/usr/bin/env python3
+"""Serbia -> contributions/postcodes/RS.json importer for #1039.
+
+Source data
+-----------
+The community ``nebjak/serbia-zip-codes-js`` package ships Pošta
+Srbije's catalogue as a flat JSON list of city + zip_code pairs:
+
+    [{"city": "Beograd", "zip_code": "11000"}, ...]
+
+Source URL: https://raw.githubusercontent.com/nebjak/serbia-zip-codes-js/master/data/serbia_zip_codes.json
+
+What this script does
+---------------------
+1. Fetches the JSON via urllib (curl is blocked).
+2. Ships country-only (the source has no okrug / district mapping).
+3. Writes contributions/postcodes/RS.json idempotently.
+
+License & attribution
+---------------------
+- Source: nebjak/serbia-zip-codes-js (MIT) which redistributes the
+  publicly published Pošta Srbije index.
+- Each row: ``source: "posta-srbije-via-nebjak"``
+
+Usage
+-----
+    python3 bin/scripts/sync/import_serbia_postcodes.py
+"""
+
+from __future__ import annotations
+
+import argparse
+import json
+import re
+import sys
+import urllib.request
+from pathlib import Path
+from typing import Dict, List
+
+
+SOURCE_URL = (
+    "https://raw.githubusercontent.com/nebjak/serbia-zip-codes-js/"
+    "master/data/serbia_zip_codes.json"
+)
+
+
+def fetch_json(url: str) -> List[dict]:
+    req = urllib.request.Request(
+        url, headers={"User-Agent": "csc-database-postcode-importer"}
+    )
+    with urllib.request.urlopen(req, timeout=60) as r:
+        return json.loads(r.read().decode("utf-8"))
+
+
+def main() -> int:
+    parser = argparse.ArgumentParser(description=__doc__)
+    parser.add_argument("--input", default=None)
+    parser.add_argument("--dry-run", action="store_true")
+    args = parser.parse_args()
+
+    rows = (
+        json.loads(Path(args.input).read_text(encoding="utf-8"))
+        if args.input
+        else fetch_json(SOURCE_URL)
+    )
+
+    project_root = Path(__file__).resolve().parents[3]
+    countries = json.load(
+        (project_root / "contributions/countries/countries.json").open(encoding="utf-8")
+    )
+    rs_country = next((c for c in countries if c.get("iso2") == "RS"), None)
+    if rs_country is None:
+        print("ERROR: RS not in countries.json", file=sys.stderr)
+        return 2
+    regex = re.compile(rs_country.get("postal_code_regex") or ".*")
+    print(f"Country: Serbia (id={rs_country['id']})")
+    print(f"Source rows: {len(rows):,}")
+
+    seen: set = set()
+    records: List[dict] = []
+    skipped_bad_regex = 0
+
+    for row in rows:
+        code = (row.get("zip_code") or "").strip()
+        if not code:
+            continue
+        if not regex.match(code):
+            skipped_bad_regex += 1
+            continue
+        city = (row.get("city") or "").strip()
+        key = (code, city.lower())
+        if key in seen:
+            continue
+        seen.add(key)
+
+        record: Dict[str, object] = {
+            "code": code,
+            "country_id": int(rs_country["id"]),
+            "country_code": "RS",
+        }
+        if city:
+            record["locality_name"] = city
+        record["type"] = "full"
+        record["source"] = "posta-srbije-via-nebjak"
+        records.append(record)
+
+    print(f"Skipped (regex fail):  {skipped_bad_regex:,}")
+    print(f"Records emitted:       {len(records):,}")
+
+    if args.dry_run:
+        return 0
+
+    target = project_root / "contributions/postcodes/RS.json"
+    target.parent.mkdir(parents=True, exist_ok=True)
+    if target.exists():
+        with target.open(encoding="utf-8") as f:
+            existing = json.load(f)
+        existing_seen = {
+            (r["code"], (r.get("locality_name") or "").lower()) for r in existing
+        }
+        merged = list(existing)
+        for r in records:
+            key = (r["code"], (r.get("locality_name") or "").lower())
+            if key not in existing_seen:
+                merged.append(r)
+                existing_seen.add(key)
+        merged.sort(key=lambda r: (r["code"], r.get("locality_name", "")))
+    else:
+        merged = sorted(records, key=lambda r: (r["code"], r.get("locality_name", "")))
+
+    with target.open("w", encoding="utf-8") as f:
+        json.dump(merged, f, ensure_ascii=False, indent=2)
+        f.write("\n")
+    size_kb = target.stat().st_size / 1024
+    print(
+        f"\n[OK] Wrote {target.relative_to(project_root)} "
+        f"({len(merged):,} rows, {size_kb:.0f} KB)"
+    )
+    return 0
+
+
+if __name__ == "__main__":
+    raise SystemExit(main())