"""funds.py - Funds report from Beancount

This tool produces a report of account balances for restricted funds,

including income, expenses, and realized gain/loss over a given time period.

Restricted funds are designated with the "project" metadata.

Specify the date range you want to report with the ``--begin`` and ``--end``

options.

Select the accounts you want to report with the ``--account`` option. You can

specify this option multiple times. The report will include at least one sheet

for each account you specify. Subaccounts will be reported on that sheet as

well.

Select the postings you want to report by passing metadata search terms in

``name=value`` format.

Run ``ledger-report --help`` for abbreviations and other options.

Examples

--------

Generate a report of all restricted funds in ODS format over the last year::

      fund-report

Query a specific restricted fund and get a quick balance on the terminal::

      fund-report <PROJECT>

"""

# 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 argparse

import collections

import datetime

import enum

import locale

import logging

import sys

from typing import (

    Dict,

    Iterable,

    Iterator,

    List,

    Mapping,

    Optional,

    Sequence,

    TextIO,

    Tuple,

    Union,

)

from ..beancount_types import (

    MetaValue,

)

from decimal import Decimal

from pathlib import Path

import odf.table  # type:ignore[import]

from beancount.parser import printer as bc_printer

from . import core

from .. import books

from .. import cliutil

from .. import config as configmod

from .. import data

AccountsMap = Mapping[data.Account, core.PeriodPostings]

FundPosts = Tuple[MetaValue, AccountsMap]

EQUITY_ACCOUNTS = ['Equity', 'Income', 'Expenses']

INFO_ACCOUNTS = [

    'Assets:Receivable',

    'Assets:Prepaid',

    'Liabilities:Payable',

    'Liabilities:UnearnedIncome',

]

PROGNAME = 'fund-report'

UNRESTRICTED_FUND = 'Conservancy'

logger = logging.getLogger('conservancy_beancount.reports.fund')

class ODSReport(core.BaseODS[FundPosts, None]):

    def __init__(self, start_date: datetime.date, stop_date: datetime.date) -> None:

        super().__init__()

        self.start_date = start_date

        self.stop_date = stop_date

    def section_key(self, row: FundPosts) -> None:

        return None

    def start_spreadsheet(self, *, expanded: bool=True) -> None:

        headers = [["Fund"], ["Balance as of", self.start_date.isoformat()]]

        if expanded:

            sheet_name = "With Breakdowns"

            headers += [["Income"], ["Expenses"], ["Equity"]]

        else:

            sheet_name = "Fund Report"

            headers += [["Additions"], ["Releases from", "Restrictions"]]

        headers.append(["Balance as of", self.stop_date.isoformat()])

        if expanded:

            headers += [

                ["Of which", "Receivable"],

                ["Of which", "Prepaid Expenses"],

                ["Of which", "Payable"],

                ["Of which", "Unearned Income"],

            ]

        self.use_sheet(sheet_name)

        for header in headers:

            first_line = header[0]

            if first_line == 'Fund':

                width = 2.0

            elif first_line == 'Balance as of':

                width = 1.5

            elif first_line == 'Of which':

                width = 1.3

            else:

                width = 1.2

            col_style = self.column_style(width)

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

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

        row = self.add_row(*(

            self.multiline_cell(header, stylename=center_bold)

            for header in headers

        ))

        row.firstChild.setAttribute(

            'stylename', self.merge_styles(self.style_endtext, self.style_bold),

        )

        self.lock_first_row()

        self.lock_first_column()

        self.add_row()

        self.add_row(self.string_cell(

            f"Fund Report From {self.start_date.isoformat()} To {self.stop_date.isoformat()}",

            stylename=center_bold,

            numbercolumnsspanned=6,

        ))

        self.add_row()

    def end_spreadsheet(self) -> None:

        start_sheet = self.sheet

        self.set_open_sheet(self.sheet)

        self.start_spreadsheet(expanded=False)

        bal_indexes = [0, 1, 2, 4]

        totals = [core.MutableBalance() for _ in bal_indexes]

        threshold = Decimal('.5')

        for fund, balances in self.balances.items():

            balances = [balances[index] for index in bal_indexes]

            if (not all(bal.clean_copy(threshold).le_zero() for bal in balances)

                and fund != UNRESTRICTED_FUND):

                self.write_balances(fund, balances)

                for total, bal in zip(totals, balances):

                    total += bal

        self.write_balances('', totals, self.merge_styles(

            self.border_style(core.Border.TOP, '.75pt'),

            self.border_style(core.Border.BOTTOM, '1.5pt', 'double'),

        ))

        self.document.spreadsheet.childNodes.reverse()

        self.sheet = start_sheet

        acct_order = ['Income', 'Expenses', 'Equity']

        key_order = [core.OPENING_BALANCE_NAME, *acct_order, core.ENDING_BALANCE_NAME]

        balances: Dict[str, core.Balance] = {key: core.MutableBalance() for key in key_order}

        for acct_s, balance in core.account_balances(accounts_map, acct_order):

            if acct_s in balances:

                balances[acct_s] = balance

            else:

                acct_root, _, _ = acct_s.partition(':')

                balances[acct_root] += balance

        for key in key_order:

            if key == 'Expenses':

                yield balances[key]

            else:

                yield -balances[key]

        for info_key in INFO_ACCOUNTS:

            for _, balance in core.account_balances(accounts_map, [info_key]):

                pass

            yield core.normalize_amount_func(info_key)(balance)

    def write_balances(self,

                       fund: str,

                       balances: Iterable[core.Balance],

                       style: Union[None, str, odf.style.Style]=None,

    ) -> odf.table.TableRow:

        return self.add_row(

            self.string_cell(fund, stylename=self.style_endtext),

            *(self.balance_cell(bal, stylename=style) for bal in balances),

        )

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

        fund, accounts_map = row

        self.balances[fund] = list(self._row_balances(accounts_map))

        if fund != UNRESTRICTED_FUND:

            self.write_balances(fund, self.balances[fund])

    def write(self, rows: Iterable[FundPosts]) -> None:

        self.balances: Dict[str, Sequence[core.Balance]] = collections.OrderedDict()

        super().write(rows)

        try:

            unrestricted = self.balances[UNRESTRICTED_FUND]

        except KeyError:

            pass

        else:

            self.add_row()

            self.write_balances("Unrestricted", unrestricted)

class TextReport:

    def __init__(self,

                 start_date: datetime.date,

                 stop_date: datetime.date,

                 out_file: TextIO) -> None:

        self.start_date = start_date

        self.stop_date = stop_date

        self.out_file = out_file

    def _account_balances(self,

                          fund: str,

                          account_map: AccountsMap,

    ) -> Iterator[Tuple[str, Sequence[str]]]:

        total_fmt = f'{fund} balance as of {{}}'

        for acct_s, balance in core.account_balances(account_map, EQUITY_ACCOUNTS):

            if acct_s is core.OPENING_BALANCE_NAME:

                acct_s = total_fmt.format(self.start_date.isoformat())

            elif acct_s is core.ENDING_BALANCE_NAME:

                acct_s = total_fmt.format(self.stop_date.isoformat())

            yield acct_s, (-balance).format(None, sep='\0').split('\0')

        for _, account in core.sort_and_filter_accounts(account_map, INFO_ACCOUNTS):

            balance = account_map[account].stop_bal

            if not balance.is_zero():

                balance = core.normalize_amount_func(account)(balance)

                yield account, balance.format(None, sep='\0').split('\0')

    def write(self, rows: Iterable[FundPosts]) -> None:

        output = [

            line

            for fund, account_map in rows

            for line in self._account_balances(fund, account_map)

        ]

        acct_width = max(len(acct_s) for acct_s, _ in output) + 2

        bal_width = max(len(s) for _, bal_s in output for s in bal_s)

        bal_width = max(bal_width, 8)

        line_fmt = f'{{:>{acct_width}}}  {{:>{bal_width}}}'

        print(line_fmt.replace('{:>', '{:^').format("ACCOUNT", "BALANCE"),

              file=self.out_file)

        fund_start = f' balance as of {self.start_date.isoformat()}'

        for acct_s, bal_seq in output:

            if acct_s.endswith(fund_start):

                print(line_fmt.format('―' * acct_width, '―' * bal_width),

                      file=self.out_file)

            bal_iter = iter(bal_seq)

            print(line_fmt.format(acct_s, next(bal_iter)), file=self.out_file)

            for bal_s in bal_iter:

                print(line_fmt.format('', bal_s), file=self.out_file)

class ReportType(enum.Enum):

    TEXT = TextReport

    ODS = ODSReport

    TXT = TEXT

    SPREADSHEET = ODS

    @classmethod

    def from_arg(cls, s: str) -> 'ReportType':

        try:

            return cls[s.upper()]

        except KeyError:

            raise ValueError(f"no report type matches {s!r}") from None

class ReturnFlag(enum.IntFlag):

    LOAD_ERRORS = 1

    NOTHING_TO_REPORT = 8

def parse_arguments(arglist: Optional[Sequence[str]]=None) -> argparse.Namespace:

    parser = argparse.ArgumentParser(prog=PROGNAME)

    cliutil.add_version_argument(parser)

    parser.add_argument(

        '--begin', '--start', '-b',

        dest='start_date',

        metavar='DATE',

        type=cliutil.date_arg,

        help="""Date to start reporting entries, inclusive, in YYYY-MM-DD format.

The default is one year ago.

""")

    parser.add_argument(

        '--end', '--stop', '-e',

        dest='stop_date',

        metavar='DATE',

        type=cliutil.date_arg,

        help="""Date to stop reporting entries, exclusive, in YYYY-MM-DD format.

The default is a year after the start date.

""")

    parser.add_argument(

        '--report-type', '-t',

        metavar='TYPE',

        type=ReportType.from_arg,

        help="""Type of report to generate. `text` gives a plain two-column text

report listing accounts and balances over the period, and is the default when

you search for a specific project/fund. `ods` produces a higher-level

spreadsheet, meant to provide an overview of all funds, and is the default when

you don't specify a project/fund.

""")

    parser.add_argument(

        '--output-file', '-O',

        metavar='PATH',

        type=Path,

        help="""Write the report to this file, or stdout when PATH is `-`.

The default is stdout for text reports, and a generated filename for ODS

reports.

""")

    cliutil.add_loglevel_argument(parser)

    parser.add_argument(

        'search_terms',

        metavar='FILTER',

        type=cliutil.SearchTerm.arg_parser('project', 'rt-id'),

        nargs=argparse.ZERO_OR_MORE,

        help="""Report on postings that match this criteria. The format is

NAME=TERM. TERM is a link or word that must exist in a posting's NAME

metadata to match. A single ticket number is a shortcut for

`rt-id=rt:NUMBER`. Any other word is a shortcut for `project=TERM`.

""")

    args = parser.parse_args(arglist)

    if args.report_type is None:

        if any(term.meta_key == 'project' for term in args.search_terms):

            args.report_type = ReportType.TEXT

        else:

            args.report_type = ReportType.ODS

    return args

def diff_year(date: datetime.date, diff: int) -> datetime.date:

    new_year = date.year + diff

    try:

        return date.replace(year=new_year)

    except ValueError:

        # The original date is Feb 29, which doesn't exist in the new year.

        if diff < 0:

            return datetime.date(new_year, 2, 28)

        else:

            return datetime.date(new_year, 3, 1)

def main(arglist: Optional[Sequence[str]]=None,

         stdout: TextIO=sys.stdout,

         stderr: TextIO=sys.stderr,

         config: Optional[configmod.Config]=None,

) -> int:

    args = parse_arguments(arglist)

    cliutil.set_loglevel(logger, args.loglevel)

    if config is None:

        config = configmod.Config()

        config.load_file()