import argparse
import decimal
import io
import itertools
import json
import re

import pytest

from . import any_date, relpath

import oxrlib.commands.historical as oxrhist

class FakeResponder:
    def __init__(self, *response_paths):
        self.paths = itertools.cycle(response_paths)

    def _respond(self, *args, **kwargs):
        return next(self.paths).open()

    def __getattr__(self, name):
        return self._respond

    def should_cache(self):
        return False


class FakeConfig:
    def __init__(self, responder, argvars=None):
        self.responder = responder
        self.args = argparse.Namespace()
        if argvars is not None:
            for key in argvars:
                setattr(self.args, key, argvars[key])

    def get_loaders(self):
        return self.responder


output = pytest.fixture(lambda: io.StringIO())
parametrize_format = pytest.mark.parametrize('output_format', [
    oxrhist.Formats.LEDGER,
    oxrhist.Formats.BEANCOUNT,
])

@pytest.fixture(scope='module')
def single_responder():
    return FakeResponder(relpath('historical1.json'))

@pytest.fixture
def alternate_responder():
    return FakeResponder(
        relpath('historical1.json'),
        relpath('historical2.json'),
    )

def build_config(
        responder,
        date,
        amount=None,
        from_currency=None,
        to_currency=None,
        from_date=None,
        output_format=oxrhist.Formats.RAW,
        signed_currencies=None,
        denomination=None,
        base='USD',
):
    return FakeConfig(responder, {
        'date': date,
        'base': base,
        'amount': None if amount is None else decimal.Decimal(amount),
        'from_currency': from_currency,
        'to_currency': base if to_currency is None else to_currency,
        'from_date': from_date,
        'output_format': output_format,
        'signed_currencies': [base] if signed_currencies is None else signed_currencies,
        'denomination': denomination,
    })

def lines_from_run(config, output):
    oxrhist.run(config, output, output)
    output.seek(0)
    return iter(output)

def check_fx_amount(config, lines, amount, cost, fx_code, fx_sign=None, price=None):
    if price is None:
        price = cost
    rate_fmt = f'{{}} {re.escape(fx_code)}'
    cost = re.escape(cost) + r'\d*'
    price = re.escape(price) + r'\d*'
    if config.args.output_format is oxrhist.Formats.LEDGER:
        if fx_sign is not None and fx_code in config.args.signed_currencies:
            rate_fmt = f'{re.escape(fx_sign)}{{}}'
        cost_re = '{{={}}}'.format(rate_fmt.format(cost))
        price_re = ' @ {}'.format(rate_fmt.format(price))
    else:
        cost_re = '{{{}}}'.format(rate_fmt.format(cost))
        if config.args.from_date is None:
            price_re = ''
        else:
            price_re = ' @ {}'.format(rate_fmt.format(price))
    pattern = r'^{} {}{}$'.format(re.escape(amount), cost_re, price_re)
    line = next(lines, "<EOF>")
    assert re.match(pattern, line)

def check_nonfx_amount(config, lines, amount, code=None, sign=None):
    if config.args.output_format is oxrhist.Formats.LEDGER:
        if code is None:
            code = 'USD'
            sign = '$'
        if code in config.args.signed_currencies and sign is not None:
            expected = f'{sign}{amount}\n'
        else:
            expected = f'{amount} {code}\n'
    else:
        expected = f'{amount} {code or "USD"}\n'
    assert next(lines, "<EOF>") == expected

def test_rate_list(single_responder, output, any_date):
    config = build_config(single_responder, any_date)
    lines = lines_from_run(config, output)
    assert next(lines).startswith('1 AED = 0.27229')
    assert next(lines) == '1 USD = 3.67246 AED\n'
    assert next(lines).startswith('1 ALL = 0.0069189')
    assert next(lines) == '1 USD = 144.529793 ALL\n'
    assert next(lines).startswith('1 ANG = 0.55865')
    assert next(lines) == '1 USD = 1.79 ANG\n'

def test_one_rate(single_responder, output, any_date):
    config = build_config(single_responder, any_date, from_currency='ANG')
    lines = lines_from_run(config, output)
    assert next(lines).startswith('1 ANG = 0.55865')
    assert next(lines) == '1 USD = 1.79 ANG\n'
    assert next(lines, None) is None

def test_conversion(single_responder, output, any_date):
    config = build_config(single_responder, any_date, amount=10, from_currency='AED')
    lines = lines_from_run(config, output)
    assert next(lines) == '10.00 AED = 2.72 USD\n'
    assert next(lines, None) is None

def test_back_conversion(single_responder, output, any_date):
    config = build_config(single_responder, any_date,
                          amount=2, from_currency='USD', to_currency='ALL')
    lines = lines_from_run(config, output)
    assert next(lines) == '2.00 USD = 289 ALL\n'
    assert next(lines, None) is None

@parametrize_format
def test_ledger_rate(single_responder, output, any_date, output_format):
    config = build_config(single_responder, any_date,
                          from_currency='ANG', output_format=output_format)
    lines = lines_from_run(config, output)
    check_fx_amount(config, lines, '1 ANG', '0.5586', 'USD', '$')
    check_fx_amount(config, lines, '1 USD', '1.79', 'ANG')
    assert next(lines, None) is None

@parametrize_format
def test_ledger_conversion(single_responder, output, any_date, output_format):
    config = build_config(single_responder, any_date, from_currency='ALL',
                          amount=300, output_format=output_format)
    lines = lines_from_run(config, output)
    check_fx_amount(config, lines, '300 ALL', '0.00691', 'USD', '$')
    check_nonfx_amount(config, lines, '2.08')
    assert next(lines, None) is None

@parametrize_format
def test_signed_currencies(single_responder, output, any_date, output_format):
    config = build_config(single_responder, any_date, from_currency='AED',
                          output_format=output_format, signed_currencies=['EUR'])
    lines = lines_from_run(config, output)
    check_fx_amount(config, lines, '1 AED', '0.272', 'USD', '$')
    check_fx_amount(config, lines, '1 USD', '3.672', 'AED')
    assert next(lines, None) is None

@parametrize_format
def test_denomination(single_responder, output, any_date, output_format):
    config = build_config(single_responder, any_date,
                          from_currency='ANG', to_currency='AED', amount=10,
                          output_format=output_format, denomination='USD')
    lines = lines_from_run(config, output)
    check_fx_amount(config, lines, '10.00 ANG', '0.558', 'USD', '$')
    check_fx_amount(config, lines, '20.52 AED', '0.272', 'USD', '$')
    assert next(lines, None) is None

@parametrize_format
def test_redundant_denomination(single_responder, output, any_date, output_format):
    config = build_config(single_responder, any_date,
                          from_currency='ANG', to_currency='USD', amount=10,
                          output_format=output_format, denomination='USD')
    lines = lines_from_run(config, output)
    check_fx_amount(config, lines, '10.00 ANG', '0.558', 'USD', '$')
    check_nonfx_amount(config, lines, '5.59')
    assert next(lines, None) is None

@parametrize_format
def test_from_denomination(single_responder, output, any_date, output_format):
    config = build_config(single_responder, any_date,
                          from_currency='USD', to_currency='ALL', amount=10,
                          output_format=output_format, denomination='USD')
    lines = lines_from_run(config, output)
    check_nonfx_amount(config, lines, '10.00')
    check_fx_amount(config, lines, '1,445 ALL', '0.00691', 'USD', '$')
    assert next(lines, None) is None

@parametrize_format
def test_rate_precision_added_as_needed(single_responder, output, any_date, output_format):
    config = build_config(single_responder, any_date,
                          from_currency='RUB', to_currency='USD', amount=63805,
                          output_format=output_format, denomination='USD')
    lines = lines_from_run(config, output)
    # 63,805 / 57.0763 (the RUB rate) == $1,117.89
    # But using the truncated rate: 63,805 * .01752 == $1,117.86
    # Make sure the rate is specified with enough precision to get the
    # correct conversion amount.
    check_fx_amount(config, lines, '63,805.00 RUB', '0.0175204', 'USD', '$')
    check_nonfx_amount(config, lines, '1,117.89')
    assert next(lines, None) is None

@parametrize_format
def test_from_date_rates(alternate_responder, output, any_date, output_format):
    config = build_config(alternate_responder, any_date,
                          from_currency='ANG', to_currency='AED',
                          from_date=any_date, output_format=output_format,
                          denomination='USD')
    lines = lines_from_run(config, output)
    check_fx_amount(config, lines, '1 ANG', '1.909', 'AED', None, '2.051')
    check_fx_amount(config, lines, '1 AED', '0.523', 'ANG', None, '0.487')
    assert next(lines, None) is None

@parametrize_format
def test_from_date_conversion(alternate_responder, output, any_date, output_format):
    config = build_config(alternate_responder, any_date,
                          from_currency='ANG', to_currency='AED', amount=10,
                          from_date=any_date, output_format=output_format,
                          denomination='USD')
    lines = lines_from_run(config, output)
    check_fx_amount(config, lines, '10.00 ANG', '0.507', 'USD', '$', '0.558')
    check_fx_amount(config, lines, '19.10 AED', '0.265', 'USD', '$', '0.272')
    assert next(lines, None) is None

@parametrize_format
def test_rate_consistent_as_cost_and_price(alternate_responder, any_date, output_format):
    config_kwargs = {
        'responder': alternate_responder,
        'amount': 65000,
        'from_currency': 'RUB',
        'output_format': output_format,
        'signed_currencies': (),
    }
    config = build_config(date=any_date, **config_kwargs)
    with io.StringIO() as output:
        lines = lines_from_run(config, output)
        amount, _, _ = next(lines).partition('@')
        expected = amount.replace('\n', ' ')
    future_date = any_date.replace(year=any_date.year + 1)
    config = build_config(date=future_date, from_date=any_date, **config_kwargs)
    with io.StringIO() as output:
        lines = lines_from_run(config, output)
        assert next(lines, "<EOF>").startswith(expected)