"""Matter onboarding payloads: the "MT:..." QR string and the 11-digit manual code.

Implements the Matter spec (5.1.3 QR payload, 5.1.4 manual pairing code):
bit fields packed LSB-first, Base38 in 3-byte chunks, Verhoeff check digit.

The sensorbox firmware uses the Matter SDK example commissionable data
(CONFIG_EXAMPLE_COMMISSIONABLE_DATA_PROVIDER): every v1.0 box advertises
VID 0xFFF1 / PID 0x8000 / discriminator 3840 with passcode 20202021, which is
exactly the sticker (QR "MT:Y.K9042C00KA0648G00", manual 3497-011-2332).
VID/PID/discriminator are taken from the box's own log when available; the
passcode is never logged, so the known default is used.
"""

from __future__ import annotations

import re
from dataclasses import dataclass

BASE38 = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ-."
RENDEZVOUS_BLE = 1 << 1
DEFAULT_PASSCODE = 20202021          # Matter SDK test passcode used by the v1.0 firmware
DEFAULT = dict(vendor_id=0xFFF1, product_id=0x8000, discriminator=3840)

# chip[DIS]: Advertise commission parameter vendorID=65521 productID=32768 discriminator=3840/15 cm=1 cp=0
_ADVERTISE = re.compile(r"vendorID=(\d+) productID=(\d+) discriminator=(\d+)")


@dataclass(frozen=True)
class SetupPayload:
    vendor_id: int = DEFAULT["vendor_id"]
    product_id: int = DEFAULT["product_id"]
    discriminator: int = DEFAULT["discriminator"]
    passcode: int = DEFAULT_PASSCODE
    rendezvous: int = RENDEZVOUS_BLE
    flow: int = 0                     # standard commissioning flow
    version: int = 0
    from_log: bool = False            # VID/PID/discriminator read from this box's log
    qr: str | None = None             # exact payload reported by the box ("KOTA: matter qr=MT:...")
    manual: str | None = None         # exact 11-digit manual code reported by the box

    @property
    def from_box(self) -> bool:
        return self.qr is not None

    def qr_text(self) -> str:
        if self.qr:
            return self.qr
        fields = [(self.version, 3), (self.vendor_id, 16), (self.product_id, 16), (self.flow, 2),
                  (self.rendezvous, 8), (self.discriminator, 12), (self.passcode, 27), (0, 4)]
        value, shift = 0, 0
        for v, bits in fields:
            if not 0 <= v < (1 << bits):
                raise ValueError(f"field value {v} does not fit in {bits} bits")
            value |= v << shift
            shift += bits
        return "MT:" + _base38(value.to_bytes(shift // 8, "little"))

    def manual_code(self) -> str:
        if self.manual:
            return self.manual
        short = self.discriminator >> 8                       # upper 4 bits
        chunk1 = short >> 2                                   # vid_pid_present = 0
        chunk2 = ((short & 0x3) << 14) | (self.passcode & 0x3FFF)
        chunk3 = self.passcode >> 14
        digits = f"{chunk1}{chunk2:05d}{chunk3:04d}"
        return digits + str(verhoeff_check(digits))

    def manual_code_pretty(self) -> str:
        c = self.manual_code()
        return f"{c[:4]}-{c[4:7]}-{c[7:]}"


def _base38(data: bytes) -> str:
    out = []
    for i in range(0, len(data), 3):
        chunk = data[i:i + 3]
        value = int.from_bytes(chunk, "little")
        for _ in range({3: 5, 2: 4, 1: 2}[len(chunk)]):
            value, rem = divmod(value, 38)
            out.append(BASE38[rem])
    return "".join(out)


_D = [[0, 1, 2, 3, 4, 5, 6, 7, 8, 9], [1, 2, 3, 4, 0, 6, 7, 8, 9, 5], [2, 3, 4, 0, 1, 7, 8, 9, 5, 6],
      [3, 4, 0, 1, 2, 8, 9, 5, 6, 7], [4, 0, 1, 2, 3, 9, 5, 6, 7, 8], [5, 9, 8, 7, 6, 0, 4, 3, 2, 1],
      [6, 5, 9, 8, 7, 1, 0, 4, 3, 2], [7, 6, 5, 9, 8, 2, 1, 0, 4, 3], [8, 7, 6, 5, 9, 3, 2, 1, 0, 4],
      [9, 8, 7, 6, 5, 4, 3, 2, 1, 0]]
_P = [[0, 1, 2, 3, 4, 5, 6, 7, 8, 9], [1, 5, 7, 6, 2, 8, 3, 0, 9, 4], [5, 8, 0, 3, 7, 9, 6, 1, 4, 2],
      [8, 9, 1, 6, 0, 4, 3, 5, 2, 7], [9, 4, 5, 3, 1, 2, 6, 8, 7, 0], [4, 2, 8, 6, 5, 7, 3, 9, 0, 1],
      [2, 7, 9, 3, 8, 0, 6, 4, 1, 5], [7, 0, 4, 6, 9, 1, 3, 2, 5, 8]]
_INV = [0, 4, 3, 2, 1, 5, 6, 7, 8, 9]


def verhoeff_check(digits: str) -> int:
    c = 0
    for i, d in enumerate(reversed(digits)):
        c = _D[c][_P[(i + 1) % 8][int(d)]]
    return _INV[c]


def payload_from_log(lines: list[str], qr: str | None = None, manual: str | None = None) -> SetupPayload:
    """Firmware 1.0.16+ reports its exact QR payload and manual code
    ("KOTA: matter ... qr=MT:... manual=..."); older firmware: use the
    advertised VID/PID/discriminator if seen; defaults otherwise."""
    base = SetupPayload()
    for text in reversed(lines):
        if m := _ADVERTISE.search(text):
            base = SetupPayload(int(m.group(1)), int(m.group(2)), int(m.group(3)), from_log=True)
            break
    if qr:
        return SetupPayload(base.vendor_id, base.product_id, base.discriminator, from_log=True,
                            qr=qr, manual=manual if manual and manual.isdigit() else None)
    return base