"""Convert ESP CAN485 logs into bounded, independently timestamped curves."""
from __future__ import annotations

from collections import deque
from dataclasses import dataclass

from protocan.legacycan import PROJECTS, LegacyCanFormat, decode

from .can485_board import BoardFrame, SdLogImport, parse_sd_log


@dataclass
class CanLogChannel:
    name: str
    address: int
    points: deque


def _values(frame: BoardFrame):
    if frame.rtr:
        return
    prefix = f"{'EXT' if frame.extended else 'STD'} {frame.identifier:08X}"
    if frame.extended:
        for project in PROJECTS:
            if project.format is not LegacyCanFormat.ROTATING_THREE_WORDS:
                continue
            node = project.node_for(frame.identifier)
            if node is None:
                continue
            packet = decode(project.format, node, frame.identifier, frame.data)
            if packet is not None:
                for address, value in packet.present_values:
                    # Keep both CAN directions and nodes in separate curves.
                    yield (f"{prefix} · {node.name} · R{address:04X}", address, value)
            return
    # Unknown protocols stay explicitly raw; never guess a register layout.
    for offset in range(0, len(frame.data), 2):
        part = frame.data[offset:offset + 2]
        label = f"BE16 [{offset}:{offset + 1}]" if len(part) == 2 else f"байт [{offset}]"
        yield (f"{prefix} · {label}", offset, int.from_bytes(part, "big"))


def read_can_log(lines, *, reference_timestamp: float, capacity: int,
                 max_total_points: int = 1_000_000,
                 frame_limit: int = 100_000) -> tuple[list[CanLogChannel], SdLogImport]:
    imported = parse_sd_log(lines, reference_timestamp, limit=frame_limit)
    channels = {}
    for frame in imported.frames:
        for name, address, _value in _values(frame):
            channels.setdefault(name, address)
            if len(channels) > 4096:
                raise ValueError("CAN CSV: слишком много каналов (максимум 4096)")
    if not channels:
        raise ValueError("CAN CSV: нет данных для графиков")
    capacity = max(1, min(capacity, max_total_points // len(channels)))
    result = {name: CanLogChannel(name, address, deque(maxlen=capacity))
              for name, address in channels.items()}
    for frame in imported.frames:
        for name, _address, value in _values(frame):
            result[name].points.append((frame.timestamp * 1000, value))
    return list(result.values()), imported