# Copyright © Albert Lane. All Rights Reserved.
# Proprietary and Confidential — Albert Lane Proprietary Software License.
# Unauthorized use, copying, modification, or distribution is prohibited.
# License inquiries: https://albertlane.net
"""t1237 canonical 2-of-2 digests (SPEC.md §2-4). Must match host/host_main.cpp and worker/src/binding.js byte for byte."""
import hashlib
import struct

from eth_account import Account
from eth_account.messages import encode_defunct

import lane_isa_pb2 as pb

CANONICAL_ROBOT_ADDRESS = "0xc136ab7d8775f58253f3c10c1af93cbb9ff16df6"
DOMAIN_HUMAN = b"LANE-VM/2of2/v1/human"
DELTA_STATE = b"PENDING_EXECUTION"
SECP256K1_N = 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEBAAEDCE6AF48A03BBFD25E8CD0364141


def sha256(b: bytes) -> bytes:
    return hashlib.sha256(b).digest()


def instr_bytes(instr: "pb.Instruction") -> bytes:
    return instr.SerializeToString(deterministic=True)


def h_human(packet_id: int, timestamp: int, instr: bytes, payload: bytes) -> bytes:
    return sha256(DOMAIN_HUMAN + struct.pack(">QQ", packet_id, timestamp) + sha256(instr) + sha256(payload))


def h_robot(human_sig: bytes, instr: bytes) -> bytes:
    return sha256(human_sig + instr + DELTA_STATE)


def personal_sign(digest: bytes, private_key) -> bytes:
    """EIP-191 personal_sign over the 64-char lowercase hex of the digest. Returns 65 bytes r||s||v (v in 27/28)."""
    return bytes(Account.sign_message(encode_defunct(text=digest.hex()), private_key=private_key).signature)


def recover(digest: bytes, sig: bytes) -> str:
    """Address (lowercase 0x…) that produced sig over hex(digest); raises on malformed input."""
    if len(sig) != 65:
        raise ValueError("signature must be 65 bytes")
    if int.from_bytes(sig[32:64], "big") > SECP256K1_N // 2:
        raise ValueError("high-s signature rejected")
    if sig[64] not in (0, 1, 27, 28):
        raise ValueError("bad recovery id v")
    return Account.recover_message(encode_defunct(text=digest.hex()), signature=sig).lower()


def normalize_address(a) -> str:
    s = (a or "").strip().lower()
    if s.startswith("0x"):
        s = s[2:]
    if len(s) != 40 or any(c not in "0123456789abcdef" for c in s) or s == "0" * 40:
        return ""
    return "0x" + s