#!/usr/bin/env python3
"""Host probe v3 — socket-transport command ids (stdlib only).

A PCAPdroid capture of the working app showed ``{"cmdType":1101, ...}`` on
the wire: ``CommunicationCmd::cmd`` returns the *second* id field for
socket mode (QUERY_DEVICE_INFO 1101, APOWER 1307, BMS 1705, EMS 1707).
Earlier probes used the small ids (25/0/29/30) and were dropped silently.

Run on the SoftAP-joined host:
    python3 host_probe3.py --sn A03X2516013210060005 --ports 9000
"""

import argparse
import json
import socket
import time
import zlib

# Wire cmdType per CommunicationCmd::cmd (socket mode).
APOWER, QUERY_INFO, BMS, EMS = 0x51B, 0x44D, 0x6A9, 0x6AB
SNNO = [0]


def secret_key(sn):
    return format(sum(sn.encode()) & 0xFF, "x")


def build_envelope(sn, cmd, data=None, snno=None, ts=None, equip=None):
    SNNO[0] = (SNNO[0] % 9999) + 1
    env = {"cmdType": cmd, "equipNo": equip if equip is not None else sn,
           "type": 0,
           "timeStamp": ts if ts is not None else int(time.time()),
           "snno": snno if snno is not None else SNNO[0], "len": 0, "crc": ""}
    if data:
        compact = json.dumps(data, separators=(",", ":"))
        env["len"] = len(compact.encode())
        env["crc"] = format(zlib.crc32(compact.encode()), "X")
        env["dataArea"] = data
    return json.dumps(env, separators=(",", ":"))


def encrypt(json_str, key):
    parts = json_str.split(",")
    a = (parts[0] + "," + parts[1] + ",").encode()
    b = ",".join(parts[2:]).encode()
    n = int(key, 32)
    return a + bytes((b[i] + i + len(a) + n) & 0xFF
                     for i in range(len(b)))


def decrypt_data(wire, radix=32):
    try:
        i = wire.find(b"\x58")
        if i < 0:
            return ""
        j = wire.find(b"\x58", i + 1)
        if j < 0:
            return ""
        s = wire[:j].decode()
        probe = json.loads(s + "}")
        if not isinstance(probe, dict):
            return ""
        n = int(secret_key(str(probe.get("equipNo", ""))), radix)
        prefix = s + ","
        tail = wire[j + 1:]
        pl = len(prefix.encode())
        plain = bytes((t - k - pl - n) & 0xFF for k, t in enumerate(tail))
        return prefix + plain.decode()
    except Exception:
        return ""


def recv_all(sock, idle=6.0):
    out = bytearray()
    sock.settimeout(idle)
    while True:
        try:
            chunk = sock.recv(65536)
        except (socket.timeout, TimeoutError):
            break
        if not chunk:
            break
        out.extend(chunk)
    return bytes(out)


def run(label, host, port, tx, timeout, pre_read=0.0):
    rx_pre, rx, err, reply = b"", b"", None, None
    try:
        with socket.create_connection((host, port),
                                      timeout=timeout) as sock:
            if pre_read:
                rx_pre = recv_all(sock, idle=pre_read)
            if tx:
                sock.sendall(tx)
                rx = recv_all(sock)
            if rx:
                dec = decrypt_data(rx)
                reply = json.loads(dec) if dec else {"_raw": rx.hex()}
    except (ConnectionError, socket.error, TimeoutError) as exc:
        err = "%s: %s" % (type(exc).__name__, exc)
    print("--- %s -> %s:%d" % (label, host, port))
    print("  tx (%d B): %s" % (len(tx), tx.hex() or "(none)"))
    if rx_pre:
        print("  rx_pre (%d B): %s" % (len(rx_pre), rx_pre.hex()))
    print("  rx (%d B): %s" % (len(rx), rx.hex() or "(empty)"))
    if reply is not None:
        print("  reply: " + json.dumps(reply, default=str)[:2000])
    if err:
        print("  error: %s" % err)
    return rx


def main():
    ap = argparse.ArgumentParser()
    ap.add_argument("--sn", required=True)
    ap.add_argument("--host", default="10.100.1.1")
    ap.add_argument("--ports", default="9000")
    ap.add_argument("--timeout", type=float, default=5.0)
    args = ap.parse_args()
    key = secret_key(args.sn)
    print("secret key for %s: %s (radix 32)" % (args.sn, key))
    variants = [
        ("queryInfo/1101+SN", QUERY_INFO, None, None),
        ("queryInfo/1101+empty-SN", QUERY_INFO, None, ""),
        ("apower/1307+update2", APOWER, {"update": 2}, None),
        ("apower/1307+none", APOWER, None, None),
        ("bms/1705", BMS, None, None),
        ("ems/1707", EMS, None, None),
    ]
    for port in [int(p) for p in args.ports.split(",") if p.strip()]:
        for label, cmd, data, equip in variants:
            tx = encrypt(build_envelope(
                args.sn, cmd, data,
                equip=args.sn if equip is None else equip or "00000000",
            ), key)
            if run(label, args.host, port, tx, args.timeout,
                   pre_read=4.0 if label.startswith("queryInfo/1101+SN")
                   else 0.0):
                return


if __name__ == "__main__":
    main()