#!/usr/bin/env python3
"""Inherit source_citation from parent to atom controls.

Background
==========

citation_backfill.py fills source_citation on the *source-bearing* controls
(those with source_original_text — ~2-7 %) by re-linking them to the
re-ingested, article_label-bearing chunks. The remaining ~93 % are "atom"
controls (decompositions) that carry a parent_control_uuid but no own citation.
They cite the SAME norm as their parent, so the citation can be inherited —
no re-matching needed.

Self-written controls (license_rule = 3) are skipped (no external source).

Runs in idempotent iterations (atom -> master -> grandmaster) and prints
per-stage counts before any write. Safe to rerun — only fills rows whose
source_citation lacks an 'article'.

Usage::

    python3 scripts/atom_citation_inheritance.py --db-host 100.80.114.48 \\
        --db-password breakpilot123 --dry-run
    python3 scripts/atom_citation_inheritance.py --db-host 100.80.114.48 \\
        --db-password breakpilot123 --apply
"""

from __future__ import annotations

import argparse
import os
import sys

DB_URL = os.getenv("DATABASE_URL", "postgresql://breakpilot:breakpilot@localhost:5432/breakpilot_db")

# A row "needs" a citation when it has no article yet.
_NEEDS = (
    "(cc.source_citation IS NULL "
    " OR cc.source_citation->>'article' IS NULL "
    " OR cc.source_citation->>'article' = '')"
)
# A parent can supply one when it carries a real article.
_PARENT_HAS = (
    "p.source_citation IS NOT NULL "
    "AND p.source_citation->>'article' IS NOT NULL "
    "AND p.source_citation->>'article' <> ''"
)

SQL_REPORT = f"""
SET search_path TO compliance, public;
SELECT
  CASE WHEN cc.parent_control_uuid IS NULL THEN 'no_parent'
       WHEN ({_PARENT_HAS.replace('p.', 'p2.')}) THEN 'parent_has_article'
       ELSE 'parent_no_article' END AS bucket,
  COUNT(*) AS n
FROM canonical_controls cc
LEFT JOIN canonical_controls p2 ON cc.parent_control_uuid = p2.id
WHERE {_NEEDS}
  AND cc.license_rule IS DISTINCT FROM 3
GROUP BY 1 ORDER BY 2 DESC;
"""

SQL_INHERIT = f"""
SET search_path TO compliance, public;
UPDATE canonical_controls cc
SET source_citation = p.source_citation, updated_at = NOW()
FROM canonical_controls p
WHERE cc.parent_control_uuid = p.id
  AND {_NEEDS}
  AND {_PARENT_HAS}
  AND cc.license_rule IS DISTINCT FROM 3;
"""


def parse_args() -> argparse.Namespace:
    p = argparse.ArgumentParser(description=__doc__)
    p.add_argument("--db-url", default=DB_URL,
                   help="Postgres URL (default: $DATABASE_URL)")
    p.add_argument("--max-iterations", type=int, default=6,
                   help="Cap on inheritance iterations to avoid loops")
    g = p.add_mutually_exclusive_group(required=True)
    g.add_argument("--dry-run", action="store_true")
    g.add_argument("--apply", action="store_true")
    return p.parse_args()


def print_bucket(rows, label: str) -> None:
    print(f"\n## {label}")
    total = 0
    for bucket, n in rows:
        print(f"  {bucket:20}  {n:>8}")
        total += n
    print(f"  {'TOTAL':20}  {total:>8}")


def main() -> int:
    args = parse_args()
    try:
        import psycopg2
    except ImportError:
        print("error: psycopg2 not installed", file=sys.stderr)
        return 2

    conn = psycopg2.connect(args.db_url)
    conn.autocommit = False
    cur = conn.cursor()

    print("=" * 60)
    print(" Atom citation inheritance — source_citation via parent")
    print(f" Mode: {'DRY-RUN' if args.dry_run else 'APPLY'}")
    print("=" * 60)

    cur.execute(SQL_REPORT)
    print_bucket(cur.fetchall(), "Controls without article (need citation)")

    if args.dry_run:
        cur.execute(
            "SET search_path TO compliance, public; "
            f"SELECT COUNT(*) FROM canonical_controls cc "
            f"JOIN canonical_controls p ON cc.parent_control_uuid = p.id "
            f"WHERE {_NEEDS} AND {_PARENT_HAS} AND cc.license_rule IS DISTINCT FROM 3;"
        )
        print(f"\n## First inherit-pass would fill: {cur.fetchone()[0]} rows")
        print("\nNo writes performed. Use --apply to execute.")
        conn.rollback()
        return 0

    total = 0
    for i in range(1, args.max_iterations + 1):
        cur.execute(SQL_INHERIT)
        updated = cur.rowcount
        total += updated
        print(f"\n  iteration {i}: {updated} rows inherited")
        if updated == 0:
            break
    conn.commit()
    print(f"\n✓ Total atoms inherited: {total}")

    cur.execute(SQL_REPORT)
    print_bucket(cur.fetchall(), "Remaining without article")
    return 0


if __name__ == "__main__":
    raise SystemExit(main())