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

Hash160 linear scan vs double c-bit on puzzle 21.
Uses only hash160 comparisons and no Base58 encoding. Added a progress bars tqdm.
"""

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

# --- Configuration ---
ADDRESS_TARGET        = "114oFNXucftsHiUMY8uctg6N487riuyXs4h"
HASH160_TARGET        = "29a78213caa9eea824acf08022ab9dfc83414f56"
RANGE_HEX             = "100000:1fffff"
FILTER_BITS           = 2     # c ≥ 1 ⇒ >5% reduction
SHA_PREFILTER_BITS    = 8     # double bits
THRESHOLD             = 5.0   # percent
# -------------------------------

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


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

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()

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


def linear_scan(start: int, end: int, target_h: bytes):
    ops = 0
    for x in tqdm(range(start, end+1), desc="Linear scan", unit="key"):
        ops += 1
        if hash160_pubkey(x) == target_h:
            return x, ops
    return None, ops


def prefilter_chunk(args):
    idx, start, end, c, d, t1, t2, target_h = args
    # si d>0 et t2 défini, on fait le SHA256-prefilter
    for i, x in enumerate(range(start, end+1), start=1):
        # 1er filtre: SHA256(pub)
        P = x * G
        prefix = b'\x02' if (P.y() & 1)==0 else b'\x03'
        pub = prefix + util.number_to_string(P.x(), ORDER)
        sha = hashlib.sha256(pub).digest()
        if d and t2 is not None:
            if (int.from_bytes(sha, 'big') >> (256 - d)) != t2:
                continue

        # 2e filtre + comparaison finale: RIPEMD-160
        rip = hashlib.new('ripemd160', sha).digest()
        if (int.from_bytes(rip, 'big') >> (160 - c)) != t1:
            continue
        if rip == target_h:
            return idx, i, x
    return idx, None, None


def parallel_prefilter(start: int, end: int, c: int, d: int,
                       target_h: bytes, t2: int, workers: int):
    N     = end - start + 1
    chunk = math.ceil(N / workers)
    t1    = int.from_bytes(target_h, 'big') >> (160 - c)

    args = []
    for i in range(workers):
        s = start + i*chunk
        e = min(start + (i+1)*chunk - 1, end)
        args.append((i, s, e, c, d, t1, t2, target_h))

    with Pool(workers) as p:
        # imap_unordered + barre de progression sur les chunks
        for idx, ops, x in tqdm(p.imap_unordered(prefilter_chunk, args),
                                 total=len(args),
                                 desc="Prefilter chunks",
                                 unit="chunk"):
            if ops:
                return x, ops
    return None, 0


def main():
    import argparse
    parser = argparse.ArgumentParser()
    parser.add_argument("--workers", type=int, default=0,
                        help="nombre de processus (défaut = CPU count)")
    parser.add_argument("--pubkey", type=str, default=None,
                        help="hex compressed pubkey cible (pour SHA256-prefilter)")
    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}, SHA256 bits: {SHA_PREFILTER_BITS}, "
          f"Processes: {workers}\n")

    target_h = get_target_h160()

    # Calculate the SHA256-prefilter threshold if pubkey is provided
    t2 = None
    if args.pubkey:
        pub_bytes = bytes.fromhex(args.pubkey)
        sha_target = hashlib.sha256(pub_bytes).digest()
        t2 = int.from_bytes(sha_target, 'big') >> (256 - SHA_PREFILTER_BITS)

    # 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\n")

    # Prefilter scan
    print("→ Parallel double-prefilter scan…")
    x_pre, ops_pre = parallel_prefilter(start, end,
                                        FILTER_BITS,
                                        SHA_PREFILTER_BITS,
                                        target_h,
                                        t2,
                                        workers)
    print(f"  ✅ Found x = 0x{x_pre:x} in {ops_pre} heavy ops\n")

    # 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"Percent 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()