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())

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

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

def test_ledger_rate(single_responder, output, any_date):
    config = build_config(single_responder, any_date,
                          from_currency='ANG', ledger=True)
    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

def test_ledger_conversion(single_responder, output, any_date):
    config = build_config(single_responder, any_date,
                          from_currency='ALL', amount=300, ledger=True)
    lines = lines_from_run(config, output)
    check_fx_amount(config, lines, '300 ALL', '0.00691', 'USD', '$')
    assert next(lines) == '$2.08\n'
    assert next(lines, None) is None

def test_signed_currencies(single_responder, output, any_date):
    config = build_config(single_responder, any_date,
                          from_currency='AED', ledger=True, 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

def test_denomination(single_responder, output, any_date):
    config = build_config(single_responder, any_date,
                          from_currency='ANG', to_currency='AED', amount=10,
                          ledger=True, 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

def test_redundant_denomination(single_responder, output, any_date):
    config = build_config(single_responder, any_date,
                          from_currency='ANG', to_currency='USD', amount=10,
                          ledger=True, denomination='USD')
    lines = lines_from_run(config, output)
    check_fx_amount(config, lines, '10.00 ANG', '0.558', 'USD', '$')
    assert next(lines) == '$5.59\n'
    assert next(lines, None) is None

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

def test_rate_precision_added_as_needed(single_responder, output, any_date):
    config = build_config(single_responder, any_date,
                          from_currency='RUB', to_currency='USD', amount=63805,
                          ledger=True, 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 == $1,117.86
    # Make sure the rate is specified with enough precision to get the
    # correct conversion amount.
    check_fx_amount(config, lines, '63,805.00 RUB', '0.0175204', 'USD', '$')
    assert next(lines) == '$1,117.89\n'
    assert next(lines, None) is None

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

def test_from_date_conversion(alternate_responder, output, any_date):
    config = build_config(alternate_responder, any_date,
                          from_currency='ANG', to_currency='AED', amount=10,
                          from_date=any_date, ledger=True, denomination='USD')
    lines = lines_from_run(config, output)
    check_fx_amount(config, lines, '10.00 ANG', '0.558', 'USD', '$', '0.507')
    check_fx_amount(config, lines, '20.52 AED', '0.272', 'USD', '$', '0.265')
    assert next(lines, None) is None