import json
import uuid
from dataclasses import dataclass
from typing import Optional

from secure_sms.security import b64u_decode, b64u_encode


FRAME_PREFIX = "@SSM1"
FRAME_CHUNK_SIZE = 92


@dataclass
class ParsedFrame:
    category: str
    packet_id: str
    part_no: int
    total_parts: int
    chunk: str
    mode: Optional[str] = None


def _split_payload(encoded_payload: str) -> list[str]:
    return [
        encoded_payload[index:index + FRAME_CHUNK_SIZE]
        for index in range(0, len(encoded_payload), FRAME_CHUNK_SIZE)
    ] or [""]


def encode_plain_body(text: str) -> str:
    return b64u_encode(text.encode("utf-8"))


def decode_plain_body(encoded_text: str) -> str:
    return b64u_decode(encoded_text).decode("utf-8")


def encode_control_payload(payload: dict) -> str:
    packed = json.dumps(payload, ensure_ascii=False, separators=(",", ":")).encode("utf-8")
    return b64u_encode(packed)


def decode_control_payload(encoded_payload: str) -> dict:
    return json.loads(b64u_decode(encoded_payload).decode("utf-8"))


def build_control_frames(payload: dict, packet_id: Optional[str] = None) -> list[str]:
    packet_id = packet_id or uuid.uuid4().hex[:10]
    encoded_payload = encode_control_payload(payload)
    parts = _split_payload(encoded_payload)
    return [
        f"{FRAME_PREFIX}|CTL|{packet_id}|{index + 1}|{len(parts)}|{chunk}"
        for index, chunk in enumerate(parts)
    ]


def build_message_frames(mode: str, encoded_payload: str, packet_id: Optional[str] = None) -> list[str]:
    packet_id = packet_id or uuid.uuid4().hex[:10]
    parts = _split_payload(encoded_payload)
    return [
        f"{FRAME_PREFIX}|MSG|{mode}|{packet_id}|{index + 1}|{len(parts)}|{chunk}"
        for index, chunk in enumerate(parts)
    ]


def parse_frame(raw_text: str) -> Optional[ParsedFrame]:
    if not raw_text.startswith(FRAME_PREFIX):
        return None
    if raw_text.startswith(f"{FRAME_PREFIX}|CTL|"):
        parts = raw_text.split("|", 5)
        if len(parts) != 6:
            return None
        _, _, packet_id, part_no, total_parts, chunk = parts
        return ParsedFrame(
            category="control",
            packet_id=packet_id,
            part_no=int(part_no),
            total_parts=int(total_parts),
            chunk=chunk,
        )
    if raw_text.startswith(f"{FRAME_PREFIX}|MSG|"):
        parts = raw_text.split("|", 6)
        if len(parts) != 7:
            return None
        _, _, mode, packet_id, part_no, total_parts, chunk = parts
        return ParsedFrame(
            category="message",
            mode=mode,
            packet_id=packet_id,
            part_no=int(part_no),
            total_parts=int(total_parts),
            chunk=chunk,
        )
    return None