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

Parallel linear scan vs c-bit prefilter on puzzle 29.
Use all CPUs by default; adjust --workers if you want this.
"""

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

# --- Configuration ---
ADDRESS_TARGET = "14oFNXucftsHiUMY8uctg6N487riuyXs4h"
HASH160_TARGET = "29a78213caa9eea824acf08022ab9dfc83414f56" # Skip b58decode (filter boost)
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 (only used if HASH160_TARGET is None)
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

# Serialize scalar x to compressed SEC-format pubkey
def serialize_pubkey(x: int) -> bytes:
    P = x * G
    prefix = b'\x02' if (P.y() & 1) == 0 else b'\x03'
    return prefix + util.number_to_string(P.x(), ORDER)

# Compute RIPEMD160(SHA256(pubkey))
def hash160_pubkey(x: int) -> bytes:
    pub = serialize_pubkey(x)
    return hashlib.new('ripemd160', hashlib.sha256(pub).digest()).digest()

# Derive full P2PKH address for display
def derive_address(x: int) -> str:
    h2 = hash160_pubkey(x)
    payload = b'\x00' + h2
    chk     = hashlib.sha256(hashlib.sha256(payload).digest()).digest()[:4]
    full    = payload + chk
    num = int.from_bytes(full, 'big')
    s = ""
    while num > 0:
        num, r = divmod(num, 58)
        s = B58[r] + s
    return '1' * full.startswith(b'\x00') + s

# Extract top-c bits from target hash160 (uses HASH160_TARGET if provided)
def get_filter_target(c: int) -> int:
    if HASH160_TARGET:
        raw = bytes.fromhex(HASH160_TARGET)
    else:
        payload = b58decode(ADDRESS_TARGET)
        raw = payload[1:]
    val = int.from_bytes(raw, 'big')
    return val >> (160 - c)

# Extract top-c bits from candidate hash160
def get_filter_candidate(x: int, c: int) -> int:
    h2  = hash160_pubkey(x)
    val = int.from_bytes(h2, 'big')
    return val >> (160 - c)

# Worker for linear scan chunk
def linear_chunk(args):
    idx, start, end = args
    for i, x in enumerate(range(start, end+1), start=1):
        if derive_address(x) == ADDRESS_TARGET:
            return idx, i, x
    return idx, None, None

# Worker for prefilter scan chunk
def prefilter_chunk(args):
    idx, start, end, c, t1 = args
    for i, x in enumerate(range(start, end+1), start=1):
        if get_filter_candidate(x, c) != t1:
            continue
        if derive_address(x) == ADDRESS_TARGET:
            return idx, i, x
    return idx, None, None

# Parallel linear scan
def parallel_linear(start: int, end: int, workers: int):
    N = end - start + 1
    chunk = math.ceil(N / workers)
    args = [(i, start + i*chunk, min(start + (i+1)*chunk - 1, end)) for i in range(workers)]
    with Pool(workers) as p:
        results = p.map(linear_chunk, args)
    for idx, ops, x in sorted(results, key=lambda r: r[0]):
        if ops:
            global_ops = idx * chunk + ops
            return x, global_ops
    return None, 0

# Parallel prefilter scan
def parallel_prefilter(start: int, end: int, c: int, workers: int):
    N = end - start + 1
    chunk = math.ceil(N / workers)
    t1 = get_filter_target(c)
    args = [(i, start + i*chunk, min(start + (i+1)*chunk - 1, end), c, t1) 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")

    # Linear scan
    print("→ Parallel linear scan…")
    x_lin, ops_lin = parallel_linear(start, end, workers)
    print(f"  ✅ Found x = 0x{x_lin:x} in {ops_lin} ops")

    # Prefilter scan
    print("\n→ Parallel prefilter scan…")
    x_pre, ops_pre = parallel_prefilter(start, end, FILTER_BITS, 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 heavy checks: linear = {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 "Linear"
    print("🏆 Winner: " + winner + " scan")

if __name__ == "__main__":
    main()