import re

from .constants import BACKEND_TELEGRAM, PREFIXES
from .models import Command

NAME_RE = re.compile(r"^[a-z][a-z0-9_]{0,31}$")
QUOTES = {'"': '"', "“": "”", "„": "“"}


def tokenize(text: str) -> list[str]:
    tokens: list[str] = []
    current: list[str] = []
    in_token = False
    closing: str | None = None
    for char in text:
        if closing:
            if char == closing:
                closing = None
            else:
                current.append(char)
        elif char in QUOTES and not in_token:
            closing, in_token = QUOTES[char], True
        elif char.isspace():
            if in_token:
                tokens.append("".join(current))
                current, in_token = [], False
        else:
            current.append(char)
            in_token = True
    if in_token:
        tokens.append("".join(current))
    return tokens


def parse(backend: str, text: str, bot_name: str | None = None) -> Command | None:
    prefix = PREFIXES.get(backend)
    text = text.strip()
    if not prefix or not text.startswith(prefix):
        return None
    body = text[len(prefix):]
    if not body or body[0].isspace():
        return None
    parts = body.split(None, 1)
    head, rest = parts[0], parts[1] if len(parts) > 1 else ""
    head, _, addressed = head.partition("@")
    if addressed and (backend != BACKEND_TELEGRAM or (bot_name and addressed.lower() != bot_name.lower().lstrip("@"))):
        return None
    name = head.lower()
    if not NAME_RE.match(name):
        return None
    rest = rest.strip()
    return Command(name, tuple(tokenize(rest)), rest)