import os
import sys
import time

from vk_api import VkApi
from vk_api.exceptions import VkApiError


class VkService:
    def __init__(self):
        self.session = None
        self.api = None

    def set_token(self, token):
        self.session = VkApi(token=token)
        self.api = self.session.get_api()

    def clear(self):
        self.session = None
        self.api = None

    @staticmethod
    def build_auth_command(auth_url, output_path, entry_script_path=None):
        if getattr(sys, "frozen", False):
            return sys.executable, ["--auth", auth_url, output_path]
        script_path = entry_script_path or os.path.abspath(__file__)
        return sys.executable, [script_path, "--auth", auth_url, output_path]

    @staticmethod
    def vk_error_code(exc):
        error = getattr(exc, "error", None)
        if isinstance(error, dict):
            return error.get("error_code")
        return getattr(exc, "code", None)

    @classmethod
    def is_auth_error(cls, exc, formatted_message=None):
        code = cls.vk_error_code(exc)
        if code == 5:
            return True
        message = (formatted_message or str(exc)).lower()
        return "invalid_access_token" in message or "user authorization failed" in message

    @classmethod
    def is_retryable_error(cls, exc):
        return cls.vk_error_code(exc) in (6, 9, 10)

    def call_with_retry(self, func, *args, **kwargs):
        max_attempts = 5
        for attempt in range(1, max_attempts + 1):
            try:
                return func(*args, **kwargs)
            except VkApiError as e:
                if not self.is_retryable_error(e) or attempt == max_attempts:
                    raise
                delay = min(2.0, 0.35 * (2 ** (attempt - 1)))
                if self.vk_error_code(e) == 9:
                    delay = max(delay, 1.0)
                time.sleep(delay)