"""test_reports_related_postings - Unit tests for RelatedPostings"""
# 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 datetime
import itertools

import pytest

from . import testutil

from conservancy_beancount import data
from conservancy_beancount.reports import core

_day_counter = itertools.count(1)
def next_date():
    return testutil.FY_MID_DATE + datetime.timedelta(next(_day_counter))

def txn_pair(acct, src_acct, dst_acct, amount, date=None, txn_meta={}, post_meta={}):
    if date is None:
        date = next_date()
    src_txn = testutil.Transaction(date=date, **txn_meta, postings=[
        (acct, amount, post_meta.copy()),
        (src_acct, -amount),
    ])
    dst_date = date + datetime.timedelta(days=1)
    dst_txn = testutil.Transaction(date=dst_date, **txn_meta, postings=[
        (acct, -amount, post_meta.copy()),
        (dst_acct, amount),
    ])
    return (src_txn, dst_txn)

def donation(amount, currency='USD', date=None, other_acct='Assets:Cash', **meta):
    if date is None:
        date = next_date()
    return testutil.Transaction(date=date, postings=[
        ('Income:Donations', -amount, currency, meta),
        (other_acct, amount, currency),
    ])

def test_balance():
    related = core.RelatedPostings()
    related.add(data.Posting.from_beancount(donation(10), 0))
    assert related.balance() == [testutil.Amount(-10)]
    related.add(data.Posting.from_beancount(donation(15), 0))
    assert related.balance() == [testutil.Amount(-25)]
    related.add(data.Posting.from_beancount(donation(20), 0))
    assert related.balance() == [testutil.Amount(-45)]

def test_balance_zero():
    related = core.RelatedPostings()
    related.add(data.Posting.from_beancount(donation(10), 0))
    related.add(data.Posting.from_beancount(donation(-10), 0))
    assert related.balance() == [testutil.Amount(0)]

def test_balance_multiple_currencies():
    related = core.RelatedPostings()
    related.add(data.Posting.from_beancount(donation(10, 'GBP'), 0))
    related.add(data.Posting.from_beancount(donation(15, 'GBP'), 0))
    related.add(data.Posting.from_beancount(donation(20, 'EUR'), 0))
    related.add(data.Posting.from_beancount(donation(25, 'EUR'), 0))
    assert set(related.balance()) == {
        testutil.Amount(-25, 'GBP'),
        testutil.Amount(-45, 'EUR'),
    }

def test_balance_multiple_currencies_one_zero():
    related = core.RelatedPostings()
    related.add(data.Posting.from_beancount(donation(10, 'EUR'), 0))
    related.add(data.Posting.from_beancount(donation(15, 'USD'), 0))
    related.add(data.Posting.from_beancount(donation(-10, 'EUR'), 0))
    assert set(related.balance()) == {
        testutil.Amount(-15, 'USD'),
        testutil.Amount(0, 'EUR'),
    }