"""Utils."""

import base64
import getpass
import sys
from typing import Optional

import keyring

KEYRING_SYSTEM = "pyicloud://icloud-password"


def get_password(username: str, interactive=sys.stdout.isatty()) -> Optional[str]:
    """Get the password from a username.
    Returns the password if found in keyring or if interactive is True.
    Returns None if no password is found and interactive is False."""
    result: Optional[str] = get_password_from_keyring(username)
    if result:
        return result

    if interactive:
        return getpass.getpass(f"Enter iCloud password for {username}: ")


def password_exists_in_keyring(username: str) -> bool:
    """Return true if the password of a username exists in the keyring."""
    return get_password_from_keyring(username) is not None


def get_password_from_keyring(username: str) -> Optional[str]:
    """Get the password from a username."""
    return keyring.get_password(KEYRING_SYSTEM, username)


def store_password_in_keyring(username: str, password: str) -> None:
    """Store the password of a username."""
    return keyring.set_password(
        KEYRING_SYSTEM,
        username,
        password,
    )


def delete_password_in_keyring(username: str) -> None:
    """Delete the password of a username."""
    return keyring.delete_password(
        KEYRING_SYSTEM,
        username,
    )


def underscore_to_camelcase(word: str, initial_capital: bool = False) -> str:
    """Transform a word to camelCase."""
    words: list[str] = [x.capitalize() or "_" for x in word.split("_")]
    if not initial_capital:
        words[0] = words[0].lower()

    return "".join(words)


def camelcase_to_underscore(camel_str: str) -> str:
    """
    Convert camelCase string to snake_case.

    Examples:
        startDate -> start_date
        localStartDate -> local_start_date
        hasAttachments -> has_attachments
    """
    result: list[str] = []
    for i, char in enumerate(camel_str):
        if char.isupper() and i > 0:
            result.append("_")
        result.append(char.lower())
    return "".join(result)


def b64url_decode(s: str) -> bytes:
    """Decode a base64url encoded string."""
    return base64.urlsafe_b64decode(s + "=" * (-len(s) % 4))


def b64_encode(b: bytes) -> str:
    """Encode bytes to a base64 encoded string."""
    return base64.b64encode(b).decode()