import re
from lxml import etree
from typing import Optional


_10B51_PATTERNS = [
    r"10b5-1",
    r"rule 10b5",
    r"adopted a plan",
    r"10b5\(1\)",
]


def _is_10b51(text: str) -> bool:
    text_lower = text.lower()
    return any(re.search(p, text_lower) for p in _10B51_PATTERNS)


def _text(el, tag: str) -> Optional[str]:
    node = el.find(".//" + tag)
    if node is not None and node.text:
        return node.text.strip()
    return None


def _float(el, tag: str) -> Optional[float]:
    val = _text(el, tag)
    if val is None:
        return None
    try:
        return float(val.replace(",", ""))
    except ValueError:
        return None


def parse_form4(xml_bytes: bytes, accession_number: str, filed_date: str) -> list[dict]:
    try:
        root = etree.fromstring(xml_bytes)
    except etree.XMLSyntaxError:
        return []

    ticker = _text(root, "issuerTradingSymbol") or ""
    cik = _text(root, "issuerCik") or ""
    insider_name = _text(root, "rptOwnerName") or ""
    role = _text(root, "officerTitle") or _text(root, "isDirector") or ""

    footnotes_text = " ".join(
        (node.text or "") for node in root.findall(".//footnote")
    )
    global_10b51 = _is_10b51(footnotes_text)

    transactions = root.findall(".//nonDerivativeTransaction")
    results = []

    for tx in transactions:
        flag = _text(tx, "transactionAcquiredDisposedCode")
        if not flag:
            continue

        shares = _float(tx, "transactionShares")
        price = _float(tx, "transactionPricePerShare")
        total_value = _float(tx, "transactionTotalValue")
        if total_value is None and shares is not None and price is not None:
            total_value = shares * price
        post_tx_shares = _float(tx, "sharesOwnedFollowingTransaction")
        tx_date = _text(tx, "transactionDate") or filed_date

        tx_footnote_ids = [
            fn.get("id", "") for fn in tx.findall(".//footnoteId")
        ]
        tx_footnote_text = " ".join(
            (root.find(f".//footnote[@id='{fid}']") or etree.Element("x")).text or ""
            for fid in tx_footnote_ids
        )
        is_10b51 = int(global_10b51 or _is_10b51(tx_footnote_text))

        results.append(
            {
                "accession_number": accession_number,
                "ticker": ticker.upper(),
                "cik": cik,
                "insider_name": insider_name,
                "role": role,
                "transaction_date": tx_date,
                "filed_date": filed_date,
                "shares": shares,
                "price": price,
                "total_value": total_value,
                "flag": flag.upper(),
                "is_10b51": is_10b51,
                "post_tx_shares": post_tx_shares,
            }
        )

    return results