"""SGV UI oracle: snapshot/diff of ONE C000025 row (READ-ONLY; never writes to Firebird).

  python scripts/sgv_product_snapshot.py before <CODIGO>
      -> reads the whole row and saves docs/runs/snapshots/<CODIGO>_before.json
  (operator changes exactly ONE field in the SGV product screen and saves)
  python scripts/sgv_product_snapshot.py diff <CODIGO> [--ui-label "CFOP saída"]
      -> re-reads, prints FIELD/BEFORE/AFTER for every changed column, and (with --ui-label) records the
         result in docs/runs/sgv_ui_diff_ledger.json. A label is CONFIRMED only when exactly ONE
         non-technical column changed.
"""
import argparse
import json
import os
import sys
from datetime import date, datetime
from decimal import Decimal
from pathlib import Path

ROOT = Path(__file__).resolve().parents[1]
sys.path.insert(0, str(ROOT / "agent" / "src"))
SNAP_DIR = ROOT / "docs" / "runs" / "snapshots"
LEDGER = ROOT / "docs" / "runs" / "sgv_ui_diff_ledger.json"
# Columns the ERP rewrites by itself on every save; ignored ONLY because they are clearly automatic.
TECHNICAL = {"ULTIMA_ALTERACAO", "DATA_ALTERACAO", "DATA_ULTIMA_ALTERACAO", "USUARIO_ALTERACAO"}


def norm(v):
    if isinstance(v, (bytes, bytearray)):
        import hashlib
        return "blob:" + hashlib.sha256(bytes(v)).hexdigest()[:16]
    if isinstance(v, (datetime, date)):
        return v.isoformat()
    if isinstance(v, Decimal):
        return str(v)
    return v.strip() if isinstance(v, str) else v


def read_row(env, code):
    from gti_fiscal_agent.firebird_reader import _connect  # read-only isolation
    conn = _connect(env)
    try:
        cur = conn.cursor()
        cur.execute("SELECT * FROM C000025 WHERE CODIGO = ?", (code,))
        row = cur.fetchone()
        if row is None:
            raise SystemExit(f"product {code} not found")
        names = [c[0].strip() for c in cur.description]
        blob = {}
        return {n: norm(v) for n, v in zip(names, row)}
    finally:
        conn.close()


def compute_diff(before, after):
    out = []
    for f in sorted(set(before) | set(after)):
        if before.get(f) != after.get(f):
            out.append({"FIELD": f, "BEFORE": before.get(f), "AFTER": after.get(f), "technical": f in TECHNICAL})
    return out


def load_env():
    for line in (ROOT / ".env").read_text(encoding="utf-8").splitlines():
        if "=" in line and not line.startswith("#"):
            k, _, v = line.partition("="); os.environ.setdefault(k.strip(), v.strip())


def record(label, code, changes):
    real = [c for c in changes if not c["technical"]]
    ledger = json.loads(LEDGER.read_text(encoding="utf-8")) if LEDGER.exists() else []
    entry = {"ui_label": label, "product": code, "recorded": datetime.now().isoformat(timespec="seconds"), "changed_columns": [c["FIELD"] for c in real],
             "before": {c["FIELD"]: c["BEFORE"] for c in real}, "after": {c["FIELD"]: c["AFTER"] for c in real},
             "confirmed": len(real) == 1, "note": "" if len(real) == 1 else ("no column changed" if not real else "more than one column changed; repeat changing a single field")}
    ledger.append(entry)
    LEDGER.write_text(json.dumps(ledger, ensure_ascii=False, indent=1), encoding="utf-8")
    return entry


def main(argv=None):
    ap = argparse.ArgumentParser()
    ap.add_argument("action", choices=["before", "diff"]); ap.add_argument("codigo"); ap.add_argument("--ui-label")
    a = ap.parse_args(argv)
    load_env()
    SNAP_DIR.mkdir(parents=True, exist_ok=True)
    path = SNAP_DIR / f"{a.codigo}_before.json"
    if a.action == "before":
        path.write_text(json.dumps(read_row(os.environ, a.codigo), ensure_ascii=False, indent=1, default=str), encoding="utf-8")
        print(f"snapshot saved: {path}"); return
    if not path.exists():
        raise SystemExit("run 'before' first")
    changes = compute_diff(json.loads(path.read_text(encoding="utf-8")), read_row(os.environ, a.codigo))
    print(f"{'FIELD':<28}{'BEFORE':<28}AFTER")
    for c in changes:
        print(f"{c['FIELD']:<28}{str(c['BEFORE']):<28}{c['AFTER']}{'   (technical, ignored)' if c['technical'] else ''}")
    if a.ui_label:
        print(json.dumps(record(a.ui_label, a.codigo, changes), ensure_ascii=False))


if __name__ == "__main__":
    main()