#!/usr/bin/env python3
"""Backfill marketplace_listings.inventory_id for a tenant (MercadoLibre).

For every listing already imported from MercadoLibre, fetch the ML item and
match it against local inventory by:
  1. seller_custom_field / seller_sku
  2. SELLER_SKU / PART_NUMBER / SELLER_PART_NUMBER attributes
     (item level and per variation)
  3. inventory.part_number, then inventory_sku_aliases.sku
     (exact match first, then normalized: spaces/dashes/dots stripped)
  4. the ML item id itself, as a last resort (some tenants store it as alias)

Dry-run by default: it reports what it *would* map without writing anything.
Pass --apply to persist inventory_id + inventory_match_source + matched_at.

Usage (from /home/Autopartes):
    python3 scripts/backfill_meli_listings.py --tenant 31                # dry-run
    python3 scripts/backfill_meli_listings.py --tenant 31 --apply
    python3 scripts/backfill_meli_listings.py --tenant 31 --apply --limit 10
    python3 scripts/backfill_meli_listings.py --tenant 31 --all          # re-check mapped too
    python3 scripts/backfill_meli_listings.py --tenant 31 --json

Requires MASTER_DB_URL + TENANT_DB_URL_TEMPLATE in the environment; if missing
they are loaded from /etc/nexus/pos.env.
"""

import argparse
import json
import os
import sys

sys.path.insert(0, os.path.join(os.path.dirname(os.path.abspath(__file__)), '..', 'pos'))


def _load_env():
    env_file = '/etc/nexus/pos.env'
    if os.environ.get('MASTER_DB_URL') or not os.path.exists(env_file):
        return
    for line in open(env_file):
        line = line.strip()
        if not line or line.startswith('#') or '=' not in line:
            continue
        key, value = line.split('=', 1)
        os.environ.setdefault(key.strip(), value.strip().strip('"').strip("'"))


def main():
    ap = argparse.ArgumentParser(description=__doc__,
                                 formatter_class=argparse.RawDescriptionHelpFormatter)
    ap.add_argument('--tenant', type=int, required=True, help='tenant id (e.g. 31 = Rached)')
    ap.add_argument('--apply', action='store_true',
                    help='write the matches (default: dry-run, read-only)')
    ap.add_argument('--limit', type=int, default=None, help='max listings to process')
    ap.add_argument('--all', action='store_true',
                    help='also re-check listings that already have an inventory_id')
    ap.add_argument('--json', action='store_true', help='print the full summary as JSON')
    args = ap.parse_args()

    _load_env()

    from tenant_db import get_tenant_conn
    from services import marketplace_external_service as meli

    conn = get_tenant_conn(args.tenant)
    try:
        summary = meli.backfill_listing_inventory(
            conn,
            limit=args.limit,
            only_unmapped=not args.all,
            dry_run=not args.apply,
        )
    finally:
        conn.close()

    if args.json:
        print(json.dumps(summary, indent=2, ensure_ascii=False, default=str))
        return 0

    mode = 'DRY-RUN (no writes)' if summary['dry_run'] else 'APPLIED'
    print(f"[tenant {args.tenant}] backfill inventory_id — {mode}")
    print(f"  scanned:   {summary['scanned']}")
    print(f"  matched:   {summary['matched']}")
    print(f"  unmatched: {summary['unmatched']}")
    print(f"  errors:    {summary['errors']}")

    unmatched = [d for d in summary['details'] if d.get('status') == 'unmatched']
    if unmatched:
        print("\n  Unmatched listings (ML item has no local part number/SKU):")
        for d in unmatched:
            cands = d.get('candidates') or []
            print(f"    listing {d['listing_id']} ({d['external_item_id']}) "
                  f"{(d.get('title') or '')[:45]!r} candidates={cands}")
    if summary['errors']:
        print("\n  Errors:")
        for d in summary['details']:
            if d.get('status') == 'error':
                print(f"    listing {d['listing_id']}: {d.get('error')}")
    if summary['dry_run'] and summary['matched']:
        print("\n  Re-run with --apply to persist these matches.")
    return 0


if __name__ == '__main__':
    sys.exit(main())