"""Enhanced Beancount data structures for Conservancy

The classes in this module are interface-compatible with Beancount's core data

structures, and provide additional business logic that we want to use

throughout Conservancy tools.

"""

# Copyright © 2020  Brett Smith

#

# This program is free software: you can redistribute it and/or modify

# it under the terms of the GNU Affero General Public License as published by

# the Free Software Foundation, either version 3 of the License, or

# (at your option) any later version.

#

# This program is distributed in the hope that it will be useful,

# but WITHOUT ANY WARRANTY; without even the implied warranty of

# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

# GNU Affero General Public License for more details.

#

# You should have received a copy of the GNU Affero General Public License

# along with this program.  If not, see <https://www.gnu.org/licenses/>.

import collections

import datetime

import decimal

import functools

from beancount.core import account as bc_account

from beancount.core import amount as bc_amount

from beancount.core import convert as bc_convert

from beancount.core import position as bc_position

from typing import (

    cast,

    Callable,

    Hashable,

    Iterable,

    Iterator,

    MutableMapping,

    Optional,

    Sequence,

    TypeVar,

    Union,

)

from .beancount_types import (

    Directive,

    MetaKey,

    MetaValue,

    Posting as BasePosting,

    Transaction,

)

DecimalCompat = Union[decimal.Decimal, int]

LINK_METADATA = frozenset([

    'approval',

    'check',

    'contract',

    'invoice',

    'purchase-order',

    'receipt',

    'rt-id',

    'statement',

])

class Account(str):

    """Account name string

    This is a string that names an account, like Assets:Bank:Checking

    or Income:Donations. This class provides additional methods for common

    account name parsing and queries.

    """

    __slots__ = ()

    SEP = bc_account.sep

    def is_cash_equivalent(self) -> bool:

        return (

            self.is_under('Assets:') is not None

            and self.is_under('Assets:Prepaid', 'Assets:Receivable') is None

        )

    def is_checking(self) -> bool:

        return self.is_cash_equivalent() and ':Check' in self

    def is_credit_card(self) -> bool:

        return self.is_under('Liabilities:CreditCard') is not None

    def is_opening_equity(self) -> bool:

        return self.is_under('Equity:Funds', 'Equity:OpeningBalance') is not None

    def is_under(self, *acct_seq: str) -> Optional[str]:

        """Return a match if this account is "under" a part of the hierarchy

        Pass in any number of account name strings as arguments. If this

        account is under one of those strings in the account hierarchy, the

        first matching string will be returned. Otherwise, None is returned.

        You can use the return value of this method as a boolean if you don't

        care which account string is matched.

        An account is considered to be under itself:

          Account('Expenses:Tax').is_under('Expenses:Tax') # returns 'Expenses:Tax'

        To do a "strictly under" search, end your search strings with colons:

          Account('Expenses:Tax').is_under('Expenses:Tax:') # returns None

          Account('Expenses:Tax').is_under('Expenses:') # returns 'Expenses:'

        This method does check that all the account boundaries match:

          Account('Expenses:Tax').is_under('Exp') # returns None

        """

        for prefix in acct_seq:

            if self.startswith(prefix) and (

                prefix.endswith(self.SEP)

                or self == prefix

                or self[len(prefix)] == self.SEP

            ):

                return prefix

        return None

class Amount(bc_amount.Amount):

    """Beancount amount after processing

    Beancount's native Amount class declares number to be Optional[Decimal],

    because the number is None when Beancount first parses a posting that does

    not have an amount, because the user wants it to be automatically balanced.

    As part of the loading process, Beancount replaces those None numbers

    with the calculated amount, so it will always be a Decimal. This class

    overrides the type declaration accordingly, so the type checker knows

    that our code doesn't have to consider the possibility that number is

    None.

    """

    number: decimal.Decimal

    # beancount.core._Amount is the plain namedtuple.

    # beancore.core.Amount adds instance methods to it.

    # b.c.Amount.__New__ calls `b.c._Amount.__new__`, which confuses type

    # checking. See <https://github.com/python/mypy/issues/1279>.

    # It works fine if you use super(), which is better practice anyway.

    # So we override __new__ just to call _Amount.__new__ this way.

    def __new__(cls, number: decimal.Decimal, currency: str) -> 'Amount':

        return super(bc_amount.Amount, Amount).__new__(cls, number, currency)

class Metadata(MutableMapping[MetaKey, MetaValue]):

    """Transaction or posting metadata

    This class wraps a Beancount metadata dictionary with additional methods

    for common parsing and query tasks.

    """

    __slots__ = ('meta',)

    def __init__(self, source: MutableMapping[MetaKey, MetaValue]) -> None:

        self.meta = source

    def __iter__(self) -> Iterator[MetaKey]:

        return iter(self.meta)

    def __len__(self) -> int:

        return len(self.meta)

    def __getitem__(self, key: MetaKey) -> MetaValue:

        return self.meta[key]

    def __setitem__(self, key: MetaKey, value: MetaValue) -> None:

        self.meta[key] = value

    def __delitem__(self, key: MetaKey) -> None:

        del self.meta[key]

    def get_links(self, key: MetaKey) -> Sequence[str]:

        try:

            value = self.meta[key]

        except KeyError:

            return ()

        if isinstance(value, str):

            return value.split()

        else:

            raise TypeError("{} metadata is a {}, not str".format(

                key, type(value).__name__,

            ))

    def run(self, groups: PostGroups) -> None:

        for index, invoice in enumerate(groups):

            for line in self._report(groups[invoice], index):

                print(line, file=self.out_file)

class AgingODS(core.BaseODS[AccrualPostings, Optional[data.Account]]):

    COLUMNS = [

        'Date',

        'Entity',

        'Invoice Amount',

        'Booked Amount',

        'Ticket',

        'Invoice',

    ]

    COL_COUNT = len(COLUMNS)

    def __init__(self,

                 rt_client: rt.Rt,

                 date: datetime.date,

                 logger: logging.Logger,

    ) -> None:

        super().__init__()

        self.rt_client = rt_client

        self.rt_wrapper = rtutil.RT(self.rt_client)

        self.date = date

        self.logger = logger

    def init_styles(self) -> None:

        super().init_styles()

        self.style_widecol = self.replace_child(

            self.document.automaticstyles,

            odf.style.Style,

            name='WideCol',

        )

        self.style_widecol.setAttribute('family', 'table-column')

        self.style_widecol.addElement(odf.style.TableColumnProperties(

            columnwidth='1.25in',

        ))

    def section_key(self, row: AccrualPostings) -> Optional[data.Account]:

        if isinstance(row.account, str):

            return row.account

        else:

            return None

    def start_spreadsheet(self) -> None:

        for accrual_type in AccrualAccount:

            self.use_sheet(accrual_type.name.title())

            for index in range(self.COL_COUNT):

                stylename = self.style_widecol if index else ''

                self.sheet.addElement(odf.table.TableColumn(stylename=stylename))

            self.add_row(*(

                self.string_cell(name, stylename=self.style_bold)

                for name in self.COLUMNS

            ))

            self.lock_first_row()

    def start_section(self, key: Optional[data.Account]) -> None:

        if key is None:

            return

        self.age_thresholds = list(AccrualAccount.by_account(key).value.aging_thresholds)

        self.age_balances = [core.MutableBalance() for _ in self.age_thresholds]

        accrual_date = self.date - datetime.timedelta(days=self.age_thresholds[-1])

        self.use_sheet(acct_parts[1])

        self.add_row()

        self.add_row(self.string_cell(

            f"{' '.join(acct_parts[2:])} {acct_parts[1]} Aging Report"

            f" Accrued by {accrual_date.isoformat()} Unpaid by {self.date.isoformat()}",

            stylename=self.merge_styles(self.style_bold, self.style_centertext),

            numbercolumnsspanned=self.COL_COUNT,

        ))

        self.add_row()

    def end_section(self, key: Optional[data.Account]) -> None:

        if key is None:

            return

        self.add_row()

        text_style = self.merge_styles(self.style_bold, self.style_endtext)

        text_span = self.COL_COUNT - 1

        for threshold, balance in zip(self.age_thresholds, self.age_balances):

            years, days = divmod(threshold, 365)

            years_text = f"{years} {'Year' if years == 1 else 'Years'}"

            days_text = f"{days} Days"

            if years and days:

                age_text = f"{years_text} {days_text}"

            elif years:

                age_text = years_text

            else:

                age_text = days_text

            self.add_row(

                self.string_cell(

                    f"Total Aged Over {age_text}: ",

                    stylename=text_style,

                    numbercolumnsspanned=text_span,

                ),

                *(odf.table.TableCell() for _ in range(1, text_span)),

                self.balance_cell(balance),

            )

    def _link_seq(self, row: AccrualPostings, key: MetaKey) -> Iterator[Tuple[str, str]]:

        for href in row.all_meta_links(key):

            text: Optional[str] = None

            rt_ids = self.rt_wrapper.parse(href)

            if rt_ids is not None:

                ticket_id, attachment_id = rt_ids

                if attachment_id is None:

                    text = f'RT#{ticket_id}'

                href = self.rt_wrapper.url(ticket_id, attachment_id) or href

            else:

                # '..' pops the ODS filename off the link path. In other words,

                # make the link relative to the directory the ODS is in.

                href = f'../{href}'

            if text is None:

                href_path = Path(urlparse.urlparse(href).path)

                text = urlparse.unquote(href_path.name)

            yield (href, text)

    def write_row(self, row: AccrualPostings) -> None:

        age = (self.date - row[0].meta.date).days

        if row.end_balance.ge_zero():

            for index, threshold in enumerate(self.age_thresholds):

                if age >= threshold:

                    self.age_balances[index] += row.end_balance

                    break

            else:

                return

        raw_balance = row.balance()

    ('Assets:Cash', True),

    ('Assets:Cash:EUR', True),

    ('Assets:Prepaid:Expenses', False),

    ('Assets:Prepaid:Vacation', False),

    ('Assets:Receivable:Accounts', False),

    ('Assets:Receivable:Fraud', False),

    ('Expenses:Other', False),

    ('Equity:OpeningBalance', False),

    ('Income:Other', False),

    ('Liabilities:CreditCard', False),

])

def test_is_cash_equivalent(acct_name, expected):

    assert data.Account(acct_name).is_cash_equivalent() == expected

@pytest.mark.parametrize('acct_name,expected', [

    ('Assets:Bank:Check9999', True),

    ('Assets:Bank:CheckCard', True),

    ('Assets:Bank:Checking', True),

    ('Assets:Bank:Savings', False),

    ('Assets:Cash', False),

    ('Assets:Check9999', True),

    ('Assets:CheckCard', True),

    ('Assets:Checking', True),

    ('Assets:Prepaid:Expenses', False),

    ('Assets:Receivable:Accounts', False),

    ('Expenses:Other', False),

    ('Equity:OpeningBalance', False),

    ('Income:Other', False),

    ('Liabilities:CreditCard', False),

])

def test_is_checking(acct_name, expected):

    assert data.Account(acct_name).is_checking() == expected

@pytest.mark.parametrize('acct_name,expected', [

    ('Assets:Cash', False),

    ('Assets:Prepaid:Expenses', False),

    ('Assets:Receivable:Accounts', False),

    ('Expenses:Other', False),

    ('Equity:OpeningBalance', False),

    ('Income:Other', False),

    ('Liabilities:CreditCard', True),

    ('Liabilities:CreditCard:Visa', True),

    ('Liabilities:Payable:Accounts', False),

    ('Liabilities:UnearnedIncome:Donations', False),

])

def test_is_credit_card(acct_name, expected):

    assert data.Account(acct_name).is_credit_card() == expected

@pytest.mark.parametrize('acct_name,expected', [

    ('Assets:Cash', False),

    ('Assets:Prepaid:Expenses', False),

    ('Assets:Receivable:Accounts', False),

    ('Expenses:Other', False),

    ('Equity:Funds:Restricted', True),

    ('Equity:Funds:Unrestricted', True),

    ('Equity:OpeningBalance', True),

    ('Equity:Retained:Costs', False),

    ('Income:Other', False),

    ('Liabilities:CreditCard', False),

    ('Liabilities:Payable:Accounts', False),

    ('Liabilities:UnearnedIncome:Donations', False),

])

def test_is_opening_equity(acct_name, expected):

    assert data.Account(acct_name).is_opening_equity() == expected