'''
Plugin that closes an account by transferring its whole balance to another account.
'''
__copyright__ = 'Copyright (c) 2020  Kristóf Marussy <kristof@marussy.com>'
__license__ = 'GNU GPLv2'

from typing import Any, Dict, List, NamedTuple, Optional, Tuple

from beancount.core.data import Balance, Close, Directive, Entries, Meta, Posting, Transaction
from beancount.core.flags import FLAG_OKAY
from beancount.core.number import ZERO

__plugins__ = ('close_with_balance_assertions',)

CLOSE_TO_META = 'close-to'
CLOSING_META = 'closing'


class ClosingBalanceError(NamedTuple):
    source: Optional[Meta]
    message: str
    entry: Directive


def close_with_balance_assertions(entries: Entries,
                                  options_map: Dict[str, Any],
                                  config_str: Optional[str] = None) -> \
                                  Tuple[Entries, List[ClosingBalanceError]]:
    new_entries: Entries = []
    errors: List[ClosingBalanceError] = []
    for entry in entries:
        new_entries.append(entry)
        if isinstance(entry, Balance) and CLOSE_TO_META in entry.meta:
            close_to_account = entry.meta[CLOSE_TO_META]
            if not isinstance(close_to_account, str):
                errors.append(ClosingBalanceError(
                    entry.meta,
                    f'{CLOSE_TO_META} must be a string, got {close_to_account} instead',
                    entry))
                continue
            if entry.tolerance is not None and entry.tolerance != ZERO:
                errors.append(ClosingBalanceError(
                    entry.meta,
                    f'Closing an account requires {ZERO} tolerance, got {entry.tolerance} instead',
                    entry))
                continue
            if entry.diff_amount is not None:
                errors.append(ClosingBalanceError(
                    entry.meta,
                    f'Not closing {entry.account} with {entry.diff_amount} failed balance check',
                    entry))
                continue
            new_meta = dict(entry.meta)
            del new_meta[CLOSE_TO_META]
            if entry.amount.number != ZERO:
                new_entries.append(Transaction(
                    new_meta,
                    entry.date,
                    FLAG_OKAY,
                    None,
                    f'Closing {entry.account}',
                    set(),
                    set(),
                    [
                        Posting(entry.account, -entry.amount, None, None, None,
                                {CLOSING_META: True}),
                        Posting(close_to_account, entry.amount, None, None, None, None)
                    ]))
            new_entries.append(Close(new_meta, entry.date, entry.account))
    return new_entries, errors