import hashlib
import time

def hash256(data):
 """Double-SHA256."""
 return hashlib.sha256(hashlib.sha256(data).digest()).digest()

def mine_block(header_prefix, target_hex):
 target = int(target_hex, 16)
 nonce = 0
 start_time = time.time()

 print(f"--- Mining Started ---")
 print(f"[*] Target: {target_hex}")

 while nonce < 2**32:
 # 1. Append nonce (4-byte little-endian) to header prefix
 # header_prefix is 76 bytes, nonce is 4 bytes = 80 byte header
 header = header_prefix + nonce.to_bytes(4, 'little')

 # 2. Hash
 block_hash = hash256(header)
 hash_val = int.from_bytes(block_hash, 'little')

 # 3. Check against target
 if hash_val < target:
 elapsed = time.time() - start_time
 print(f"\n[SUCCESS] Block Mined!")
 print(f"[*] Nonce: {nonce}")
 print(f"[*] Hash: {block_hash[::-1].hex()}")
 print(f"[*] Time: {elapsed:.2f} seconds")
 return nonce, block_hash

 # Status update every 1M hashes
 if nonce % 1000000 == 0 and nonce > 0:
 print(f"[*] Progress: {nonce/1000000:.0f}M hashes...")

 nonce += 1

 return None

# --- Simulation ---

# Mock 76-byte header (Version, PrevHash, Merkle, Time, Bits)
mock_header_prefix = b'\x02\x00\x00\x00' + b'\x00'*32 + b'\x00'*32 + b'\x64\xb0\x11\xc9' + b'\x2a\x6f\x06\x17'

# We will set a VERY EASY target for this simulation (4 leading hex zeroes)
easy_target = "0000ffff" + "f"*56 

mine_block(mock_header_prefix, easy_target)