# Клиент A/B-загрузчика ProtoCAN с оконной передачей блоков по восемь байт. Ответы принимаются
# только для целевого адреса и текущей сессии; продвижение по этапам зависит от подтверждения,
# а не от факта отправки.

"""Legacy ProtoCAN Boot client ported from Gui_Android CanFirmwareProtocol.kt."""
from __future__ import annotations

from dataclasses import dataclass
import struct

from .protocan import ProtoCanId
from .transport import build_frame


@dataclass(frozen=True)
class CanBootTarget:
    device_type: int = 0
    device: int = 13
    product_type: int = 0x166
    hardware_min: int = 0
    hardware_max: int = 255
    session_id: int = 1

    def __post_init__(self):
        if not 0 <= self.device_type <= 7 or not 0 <= self.device <= 15:
            raise ValueError("Адрес ProtoCAN: Device Type 0…7, Device 0…15")
        if not 0 <= self.product_type <= 65535:
            raise ValueError("Product Type вне диапазона u16")
        if not 0 <= self.hardware_min <= self.hardware_max <= 255:
            raise ValueError("Неверный диапазон аппаратных ревизий")
        if not 1 <= self.session_id <= 255:
            raise ValueError("Session ID должен быть 1…255")


class CanBootTransfer:
    """Windowed 8-byte blocks; control 0x9, slots 0xA/0xB, status 0xC."""
    def __init__(self, image, target: CanBootTarget):
        if not 0 < len(image.data) <= 512 * 1024:
            raise ValueError("ProtoCAN Boot: размер образа 1…512 КиБ")
        if target.product_type == 0x2833 and len(image.data) > 0x1FE00:
            raise ValueError("F28335 M95M02 A/B: образ не должен превышать 130560 байт")
        if not 0 <= image.version <= 0xFFFFFFFF:
            raise ValueError("Версия образа вне диапазона u32")
        self.image, self.target = image, target
        self.stage = "enter"
        self.next_block = 0
        self.slot = None
        self.finished = False
        self._window_end = 0

    @property
    def response_timeout_ms(self):
        return 15000 if self.stage in ("enter", "verify", "commit") else 1500

    @property
    def percent(self):
        return min(100, self.next_block * 8 * 100 // len(self.image.data))

    def _frame(self, kind, body, data=b""):
        t = self.target
        return build_frame(ProtoCanId.build(1, 0, t.device_type, t.device, kind, body), data, to_can=True)

    def _control(self, command, data=b""):
        return [self._frame(9, self.target.session_id << 8 | command, data)]

    def start(self):
        return self._control(2)

    def abort(self):
        return self._control(10)

    def accepts(self, frame):
        p = ProtoCanId.parse(frame.can_id)
        t = self.target
        return (not frame.to_can and frame.ide and not frame.rtr and not frame.is_error
                and p.msg_type == 12 and p.pm == 1 and p.device_type == t.device_type
                and p.device == t.device and p.body >> 8 == t.session_id and len(frame.data) == 8)

    # Окно содержит до 16 блоков. Последний неполный блок заполняется 0xFF,
    # но метаданные образа сохраняют исходную длину без этого дополнения.
    def _window(self):
        total = (len(self.image.data) + 7) // 8
        self._window_end = min(total, self.next_block + 16)
        return [self._frame(10 + self.slot, i, self.image.data[i * 8:(i + 1) * 8].ljust(8, b"\xff"))
                for i in range(self.next_block, self._window_end)]

    def handle_status(self, frame):
        if not self.accepts(frame):
            return [], ""
        command = ProtoCanId.parse(frame.can_id).body & 255
        expected_command = {"enter": 2, "image": 3, "compat": 4, "erase": 5,
                            "data": 0, "verify": 6, "commit": 7, "reboot": 9}.get(self.stage)
        # Позднее подтверждение предыдущего этапа нельзя применять к новому:
        # оно не продвигает автомат и не считается ошибкой текущего запроса.
        if command != expected_command:
            return [], ""
        status, slot, expected = struct.unpack_from("<BBH", frame.data)
        if status == 1:
            return [], "Загрузчик занят"
        if status not in (0, 8) or (status == 8 and self.stage != "data"):
            raise RuntimeError(f"ProtoCAN Boot: ошибка 0x{status:02X}")
        if self.stage == "enter":
            self.stage = "image"
            return self._control(3, struct.pack("<II", len(self.image.data), self.image.crc32)), "Передача метаданных"
        if self.stage == "image":
            self.stage = "compat"
            t = self.target
            return self._control(4, struct.pack("<HBBI", t.product_type, t.hardware_min, t.hardware_max, self.image.version)), "Проверка совместимости"
        if self.stage == "compat":
            if slot not in (0, 1):
                raise RuntimeError("ProtoCAN Boot: неверный слот")
            self.slot, self.stage = slot, "erase"
            return self._control(5), "Стирание неактивного слота"
        if self.stage in ("erase", "data"):
            total = (len(self.image.data) + 7) // 8
            # The final index of a 512 KiB image wraps the u16 status field.
            if self.stage == "data" and expected == 0 and self._window_end == 65536 and status == 0:
                expected = 65536
            limit = total if self.stage == "erase" else self._window_end
            if expected > limit:
                raise RuntimeError("ProtoCAN Boot: подтверждён непереданный блок")
            if self.stage == "data" and status == 0 and expected < self.next_block:
                return [], ""
            self.next_block = expected
            if expected == total:
                self.stage = "verify"
                return self._control(6), "Проверка CRC32"
            self.stage = "data"
            return self._window(), "Передача блоков ProtoCAN Boot"
        if self.stage == "verify":
            self.stage = "commit"
            return self._control(7), "Активация образа"
        if self.stage == "commit":
            self.stage = "reboot"
            return self._control(9), "Перезапуск прибора"
        self.stage, self.finished = "finished", True
        if self.target.product_type == 0x2833:
            return [], "Образ принят; после перезапуска приложение подтвердит пробный запуск"
        return [], "Прошивка ProtoCAN Boot завершена"


class CanBootServices:
    """Read-only passport queries and explicit session service commands.

    Replies use message D, body=(page<<8)|command. IDENTIFY/discovery reply body=1.
    All multibyte values are little endian; version is major:8/minor:8/patch:16.
    """
    def __init__(self, target: CanBootTarget):
        self.target = target

    def request(self, command: int, page: int = 0):
        if command not in (1, 8, 11, 12, 13, 14, 15):
            raise ValueError("Unsupported service command")
        if not 0 <= page <= 255 or (page and command not in (14, 15)):
            raise ValueError("Invalid service page")
        t = self.target
        payload = bytes([page]) if command in (14, 15) else b""
        return build_frame(ProtoCanId.build(1, 0, t.device_type, t.device, 9,
                           t.session_id << 8 | command), payload, to_can=True)

    @staticmethod
    def discover():
        return build_frame(ProtoCanId.build(1, 0, 7, 15, 13, 0), b"", to_can=True)

    def decode(self, frame, *, discovery=False):
        p = ProtoCanId.parse(frame.can_id)
        if (frame.to_can or not frame.ide or frame.rtr or frame.is_error or p.pm != 1
                or p.msg_type not in (12, 13) or len(frame.data) != 8):
            return None
        if discovery:
            if p.msg_type != 13 or p.body != 1:
                return None
        elif (p.device_type, p.device) != (self.target.device_type, self.target.device):
            return None
        if p.msg_type == 12:
            if p.body >> 8 != self.target.session_id:
                return None
            status, slot, next_block, crc32 = struct.unpack("<BBHI", frame.data)
            return {"kind": "status", "device_type": p.device_type, "device": p.device,
                    "command": p.body & 255, "status": status, "target_slot": slot,
                    "next_block": next_block, "crc32": crc32}
        command, page = p.body & 255, p.body >> 8
        d = frame.data
        result = {"kind": "passport", "device_type": p.device_type, "device": p.device, "command": command, "page": page}
        if command == 1 and page == 0:
            product, hardware, protocol, version = struct.unpack("<HBBI", d)
            result.update(product_type=product, hardware_revision=hardware, protocol_version=protocol,
                          firmware_version=version, version=(version >> 24, (version >> 16) & 255, version & 65535))
        elif command == 12 and page == 0:
            result.update(protocol_version=d[0], state=d[1], active_slot=d[2], target_slot=d[3],
                          session_id=d[4], slot_count=d[5], last_status=d[6])
        elif command == 13 and page == 0:
            flags, capacity = struct.unpack("<II", d)
            result.update(capabilities=flags, slot_capacity=capacity)
        elif command == 14:
            result["name_fragment"] = d.split(b"\0", 1)[0].decode("ascii", errors="replace")
        elif command == 15:
            if page == 0:
                size, page_size, mode, running = struct.unpack("<IHBB", d)
                result.update(memory_bytes=size, page_bytes=page_size, bootloader=bool(mode), running_slot=running)
            elif page == 1:
                result["slot_offsets"] = struct.unpack("<II", d)
            elif page == 2:
                active, pending, attempted, healthy, timeout = struct.unpack("<BBBBI", d)
                result.update(active_slot=active, pending_slot=pending, trial_attempted=bool(attempted),
                              storage_healthy=bool(healthy), session_timeout_ms=timeout)
            elif page == 3:
                result["parameters_offset"], result["parameters_bytes"] = struct.unpack("<II", d)
            else:
                return None
        else:
            return None
        return result


class CanBootPingExchange:
    """PING adapter with the same request/feed shape as the SETProtocol client."""
    def __init__(self, target: CanBootTarget):
        self.services = CanBootServices(target)

    def request(self):
        return [self.services.request(12)]

    def feed(self, frame):
        reply = self.services.decode(frame)
        return reply if reply and reply["kind"] == "passport" and reply["command"] == 12 else None