import os

from embit import script
from embit.bip32 import HDKey
from embit.ec import PrivateKey

from app.config import settings
from app.wallet.keystore import decrypt_xprv, encrypt_xprv
from app.wallet.plm_network import ACCOUNT_PATH, PLM_MAINNET

_account_key: HDKey | None = None


def generate_master_key(overwrite: bool = False) -> None:
    """One-time ops bootstrap: create a random master seed, encrypt it, write it to
    disk. Not exposed via any API endpoint — run manually before first launch."""
    if os.path.exists(settings.master_key_path) and not overwrite:
        raise FileExistsError(f"{settings.master_key_path} already exists")
    root = HDKey.from_seed(os.urandom(32), version=PLM_MAINNET["xprv"])
    with open(settings.master_key_path, "wb") as f:
        f.write(encrypt_xprv(root.to_base58(version=PLM_MAINNET["xprv"])))


def _load_account_key() -> HDKey:
    global _account_key
    if _account_key is None:
        with open(settings.master_key_path, "rb") as f:
            token = f.read()
        root = HDKey.from_base58(decrypt_xprv(token))
        _account_key = root.derive(ACCOUNT_PATH)
    return _account_key


def derive_user_key(derivation_index: int) -> HDKey:
    return _load_account_key().derive(f"0/{derivation_index}")


def derive_user_address(derivation_index: int) -> str:
    pub = derive_user_key(derivation_index).to_public()
    return script.p2wpkh(pub).address(network=PLM_MAINNET)


def derive_user_wif(derivation_index: int) -> str:
    """Exports a user's raw private key (WIF) for manual server-side intervention
    (e.g. sweeping funds back to a user, or out, if something gets stuck). This is
    a custodial system — the server already holds the master key this is derived
    from — but callers must still treat the result as a live secret: log access,
    never persist it, never return it over an unauthenticated channel."""
    key = derive_user_key(derivation_index)
    return PrivateKey(key.secret, compressed=True, network=PLM_MAINNET).wif(network=PLM_MAINNET)


def derive_pool_key() -> HDKey:
    """The "indirizzo padre" from the flowchart: all bets are sent here, and
    payouts are signed with this key. Reserved on branch 1 of the account (branch 0
    is user addresses), index 0 — not a spec requirement, an implementation choice
    to keep it in the same encrypted master key rather than a separate secret."""
    return _load_account_key().derive("1/0")


def derive_pool_address() -> str:
    pub = derive_pool_key().to_public()
    return script.p2wpkh(pub).address(network=PLM_MAINNET)