from typing import Any, Dict, List

from .auth_password_policy_check_password import check_password
from .auth_password_policy_types import PasswordPolicy
from .auth_validate_password_change_types import PasswordChangeCheck


def _text(value: Any) -> str:
    # A non-string (a malformed JSON body) is an empty field, not an exception.
    return value if isinstance(value, str) else ""


def validate_password_change(
    current_password: str,
    new_password: str,
    current_password_matches: bool,
    email: str,
    name: str,
    policy: PasswordPolicy,
) -> PasswordChangeCheck:
    """A change-password form checked in one call: the current password must
    be given and correct, the new one must meet the policy and differ from it."""
    current, new = _text(current_password), _text(new_password)
    fields: Dict[str, str] = {}

    if current == "":
        fields["currentPassword"] = "Enter your current password."
    elif current_password_matches is not True:
        fields["currentPassword"] = "That is not your current password."

    # Checked even when empty, so a nonsensical policy always throws.
    check = check_password(new, email, name, policy)
    if new == "":
        fields["newPassword"] = "Enter a new password."
    else:
        messages: List[str] = [f.message for f in check.failures]
        if new == current:
            messages.append("Choose a password that is different from your current one.")
        if messages:
            fields["newPassword"] = " ".join(messages)

    return PasswordChangeCheck(valid=len(fields) == 0, fields=fields)