#!/usr/bin/env python3
# coding: utf-8
"""
proof.py

Hash160 linear scan vs c-bit prefilter on puzzle 21.
Uses only hash160 comparisons and no Base58 encoding.
"""

import hashlib, math
from ecdsa import SECP256k1, util
from multiprocessing import Pool, cpu_count

# --- Configuration ---
ADDRESS_TARGET = "14oFNXucftsHiUMY8uctg6N487riuyXs4h"
HASH160_TARGET = "29a78213caa9eea824acf08022ab9dfc83414f56"
RANGE_HEX      = "100000:1fffff"
FILTER_BITS    = 2     # c ≥ 1 ⇒ >5% reduction
THRESHOLD      = 5.0   # percent
# ---------------------

G     = SECP256k1.generator
ORDER = SECP256k1.order
B58   = "123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz"

# Base58Check decode to raw payload (1-byte version + 20-byte hash160)
def b58decode(s: str) -> bytes:
    num = 0
    for ch in s:
        num = num*58 + B58.index(ch)
    nbytes = (num.bit_length() + 7)//8
    b = num.to_bytes(nbytes, 'big') if nbytes else b'\x00'
    pad = len(s) - len(s.lstrip('1'))
    full = b'\x00'*pad + b
    payload, chk = full[:-4], full[-4:]
    if hashlib.sha256(hashlib.sha256(payload).digest()).digest()[:4] != chk:
        raise ValueError("Invalid Base58 checksum")
    return payload

# Compute RIPEMD-160(SHA256(pubkey))
def hash160_pubkey(x: int) -> bytes:
    P = x * G
    prefix = b'\x02' if (P.y() & 1)==0 else b'\x03'
    pub = prefix + util.number_to_string(P.x(), ORDER)
    return hashlib.new('ripemd160', hashlib.sha256(pub).digest()).digest()

# Prepare target H160 bytes once
def get_target_h160() -> bytes:
    if HASH160_TARGET:
        return bytes.fromhex(HASH160_TARGET)
    payload = b58decode(ADDRESS_TARGET)
    return payload[1:]

# Simple linear scan comparing hash160 directly
def linear_scan(start: int, end: int, target_h: bytes):
    ops = 0
    for x in range(start, end+1):
        ops += 1
        if hash160_pubkey(x) == target_h:
            return x, ops
    return None, ops

# Worker for prefilter scan chunk
def prefilter_chunk(args):
    idx, start, end, c, t1, target_h = args
    for i, x in enumerate(range(start, end+1), start=1):
        h2 = hash160_pubkey(x)
        if (int.from_bytes(h2, 'big') >> (160-c)) != t1:
            continue
        if h2 == target_h:
            return idx, i, x
    return idx, None, None

# Parallel prefilter scan using hash160 comparisons
def parallel_prefilter(start: int, end: int, c: int, target_h: bytes, workers: int):
    N = end - start + 1
    chunk = math.ceil(N / workers)
    t1 = int.from_bytes(target_h, 'big') >> (160 - c)
    args = [(i, start + i*chunk, min(start + (i+1)*chunk - 1, end), c, t1, target_h)
            for i in range(workers)]
    with Pool(workers) as p:
        results = p.map(prefilter_chunk, args)
    for idx, ops, x in sorted(results, key=lambda r: r[0]):
        if ops:
            return x, ops
    return None, 0

# Main entry
def main():
    import argparse
    parser = argparse.ArgumentParser()
    parser.add_argument("--workers", type=int, default=0,
                        help="number of processes (default = CPU count)")
    args = parser.parse_args()

    workers = args.workers or cpu_count()
    s_hex, e_hex = RANGE_HEX.split(':')
    start, end = int(s_hex, 16), int(e_hex, 16)
    N = end - start + 1

    print(f"Target address: {ADDRESS_TARGET}")
    print(f"Range: 0x{s_hex} .. 0x{e_hex} (N = {N})")
    print(f"Filter bits: {FILTER_BITS}, Processes: {workers}\n")

    target_h = get_target_h160()

    # Linear scan
    print("→ Linear hash160 scan…")
    x_lin, ops_lin = linear_scan(start, end, target_h)
    print(f"  ✅ Found x = 0x{x_lin:x} in {ops_lin} H160 ops")

    # Prefilter scan
    print("\n→ Parallel prefilter scan…")
    x_pre, ops_pre = parallel_prefilter(start, end, FILTER_BITS, target_h, workers)
    print(f"  ✅ Found x = 0x{x_pre:x} in {ops_pre} heavy ops")

    # Statistics
    pct_lin = 100.0
    pct_pre = ops_pre / ops_lin * 100.0 if ops_lin else 0.0
    reduction = pct_lin - pct_pre

    print(f"\nPercent checks: hash160 = {pct_lin:.2f}%, prefilter = {pct_pre:.2f}%")
    print(f"Reduction = {reduction:.2f}%")
    print(("✅" if reduction>THRESHOLD else "⚠️") +
          f" Reduction {'exceeds' if reduction>THRESHOLD else 'below'} {THRESHOLD}%")
    winner = "Prefilter" if ops_pre < ops_lin else "Hash160"
    print("🏆 Winner: " + winner + " scan")

if __name__ == "__main__":
    main()