historical: Move normalize_rate and _pretty_rate to base Formatter.

This reduces the number of method overrides to help readability,
and gets rid of the annoying format_rate/pretty_rate distinction.

.gitignore

@@ -1,4 +1,8 @@
+build/
+.cache/
 *.egg
 *.egg-info/
-.cache/
+.eggs
+.mypy_cache/
+.tox/
 __pycache__/

oxrlib/commands/historical.py

@@ -14,7 +14,7 @@ except ImportError:
 class Formatter:
     def __init__(self, cost_rates, price_rates=None,
                  signed_currencies=(), base_fmt='#,##0.###',
-                 rate_precision=5, denomination=None):
+                 rate_precision=6, denomination=None):
         self.cost_rates = cost_rates
         self.price_rates = price_rates
         self.base_fmt = base_fmt
@@ -43,17 +43,33 @@ class Formatter:
         return decimal.Decimal(amt_s)
 
     def normalize_rate(self, rate, prec=None):
-        return rate
+        if prec is None:
+            prec = self.rate_prec
+        _, digits, exponent = rate.normalize().as_tuple()
+        # Return ``prec`` nonzero digits of precision, if available.
+        prec -= min(0, exponent + len(digits))
+        quant_to = '1.{}'.format('0' * prec)
+        try:
+            qrate = rate.quantize(decimal.Decimal(quant_to))
+        except decimal.InvalidOperation:
+            # The original rate doesn't have that much precision, so use it raw.
+            qrate = rate
+        return qrate.normalize()
 
-    def format_rate(self, rate):
-        return "{:g}".format(rate)
+    def format_rate(self, rate, curr, fmt='{}', prec=None):
+        rate_s = self.format_currency(
+            self.normalize_rate(rate, prec),
+            curr,
+            currency_digits=False,
+        )
+        return fmt.format(rate_s)
 
     def format_rate_pair(self, from_curr, to_curr):
-        from_amt = 1
+        from_amt = decimal.Decimal(1)
         to_amt = self.cost_rates.convert(from_amt, from_curr, to_curr)
-        return "{} {} = {} {}".format(
-            self.format_rate(from_amt), from_curr,
-            self.format_rate(to_amt), to_curr,
+        return "{} = {}".format(
+            self.format_rate(from_amt, from_curr),
+            self.format_rate(to_amt, to_curr),
         )
 
     def format_rate_pair_bidir(self, from_curr, to_curr, sep='\n'):
@@ -71,55 +87,15 @@ class Formatter:
         )
 
 
-class LedgerFormatter(Formatter):
-    COST_FMT = '{{={}}}'
+class BeancountFormatter(Formatter):
+    COST_FMT = '{{{}}}'
     PRICE_FMT = ' @ {}'
 
     def price_rate(self, from_amt, from_curr, to_curr):
         if self.price_rates is None:
-            rates = self.cost_rates
+            return None
         else:
-            rates = self.price_rates
-        return rates.convert(from_amt, from_curr, to_curr)
-
-    def can_sign_currency(self, code):
-        return len(babel.numbers.get_currency_symbol(code)) == 1
-
-    def normalize_rate(self, rate, prec=None):
-        if prec is None:
-            prec = self.rate_prec
-        _, digits, exponent = rate.normalize().as_tuple()
-        # Return ``prec`` nonzero digits of precision, if available.
-        prec -= min(0, exponent + len(digits))
-        quant_to = '1.{}'.format('0' * prec)
-        try:
-            qrate = rate.quantize(decimal.Decimal(quant_to))
-        except decimal.InvalidOperation:
-            # The original rate doesn't have that much precision, so use it raw.
-            qrate = rate
-        return qrate.normalize()
-
-    def normalize_enough(self, rate, curr, from_amt, to_amt, prec=None):
-        if prec is None:
-            prec = self.rate_prec
-        # Starting from prec, find the least amount of precision to
-        # make sure from_amt converts exactly to to_amt.
-        for try_prec in itertools.count(prec):
-            try_rate = self.normalize_rate(rate, try_prec)
-            got_amt = self.currency_decimal(from_amt * try_rate, curr)
-            # If got_amt == to_amt, this is enough precision to do the
-            # conversion exactly, so we're done.
-            # If try_rate == rate, there's no more precision available, so stop.
-            if (got_amt == to_amt) or (try_rate == rate):
-                break
-        return try_rate
-
-    def _pretty_rate(self, fmt, rate, curr, from_amt=None, to_amt=None):
-        if to_amt is None:
-            rate = self.normalize_rate(rate)
-        else:
-            rate = self.normalize_enough(rate, curr, from_amt, to_amt)
-        return fmt.format(self.format_currency(rate, curr, currency_digits=False))
+            return self.price_rates.convert(from_amt, from_curr, to_curr)
 
     def format_rate_pair(self, from_curr, to_curr):
         from_amt = 1
@@ -128,11 +104,11 @@ class LedgerFormatter(Formatter):
         if price is None:
             price_s = ''
         else:
-            price_s = self._pretty_rate(self.PRICE_FMT, price, to_curr)
+            price_s = self.format_rate(price, to_curr, self.PRICE_FMT)
         return "{} {} {}{}".format(
             from_amt,
             from_curr,
-            self._pretty_rate(self.COST_FMT, cost, to_curr),
+            self.format_rate(cost, to_curr, self.COST_FMT),
             price_s,
         )
 
@@ -155,12 +131,10 @@ class LedgerFormatter(Formatter):
         if price is None:
             price_s = ''
         else:
-            price_s = self._pretty_rate(
-                self.PRICE_FMT, price, denomination, amount, to_amt,
-            )
+            price_s = self.format_rate(price, denomination, self.PRICE_FMT)
         return "{} {}{}".format(
             amt_s,
-            self._pretty_rate(self.COST_FMT, cost, denomination, amount, to_amt),
+            self.format_rate(cost, denomination, self.COST_FMT),
             price_s,
         )
 
@@ -172,9 +146,24 @@ class LedgerFormatter(Formatter):
         )
 
 
+class LedgerFormatter(BeancountFormatter):
+    COST_FMT = '{{={}}}'
+
+    def can_sign_currency(self, code):
+        return len(babel.numbers.get_currency_symbol(code)) == 1
+
+    def price_rate(self, from_amt, from_curr, to_curr):
+        if self.price_rates is None:
+            rates = self.cost_rates
+        else:
+            rates = self.price_rates
+        return rates.convert(from_amt, from_curr, to_curr)
+
+
 class Formats(enum.Enum):
     RAW = Formatter
     LEDGER = LedgerFormatter
+    BEANCOUNT = BeancountFormatter
 
     @classmethod
     def from_arg(cls, s):
@@ -190,11 +179,13 @@ def load_rates(config, loaders, date):
 
 def run(config, stdout, stderr):
     loaders = config.get_loaders()
-    cost_rates = load_rates(config, loaders, config.args.date)
+    date_rates = load_rates(config, loaders, config.args.date)
     if config.args.from_date is None:
+        cost_rates = date_rates
         price_rates = None
     else:
-        price_rates = load_rates(config, loaders, config.args.from_date)
+        cost_rates = load_rates(config, loaders, config.args.from_date)
+        price_rates = date_rates
     formatter = config.args.output_format.value(
         cost_rates,
         price_rates,

oxrlib/config.py

@@ -110,8 +110,9 @@ class Configuration:
         hist_parser.add_argument(
             '--output-format',
             type=historical.Formats.from_arg,
-            choices=[fmt.name.lower() for fmt in historical.Formats],
-            help="Output format. Choices are %(choices)s. Default `raw`.",
+            help="Output format."
+            " Choices are `raw`, `ledger`, `beancount`."
+            " Default `raw`.",
         )
         # --ledger and --no-ledger predate --output-format.
         hist_parser.add_argument(

oxrlib_example.ini

@@ -25,10 +25,10 @@ historical = {date}_{base}_rates.json
 base = USD
 
 # Write output in Ledger format.
-ledger = no
+output_format = ledger
 
-# Denominate Ledger books in this currency.
-# Ledger-formatted conversions will always show a rate to convert to this
+# Denominate books in this currency.
+# Formatted conversions will always show a rate to convert to this
 # currency, even when converting between two other currencies.
 # If not specified, output will show the rate for the currency you're
 # converting to.

setup.py

@@ -5,7 +5,7 @@ from setuptools import setup
 setup(
     name='oxrlib',
     description="Library to query the Open Exchange Rates (OXR) API",
-    version='1.7',
+    version='2.2',
     author='Brett Smith',
     author_email='brettcsmith@brettcsmith.org',
     license='GNU AGPLv3+',

tests/test_historical.py

@@ -40,6 +40,7 @@ class FakeConfig:
 output = pytest.fixture(lambda: io.StringIO())
 parametrize_format = pytest.mark.parametrize('output_format', [
     oxrhist.Formats.LEDGER,
+    oxrhist.Formats.BEANCOUNT,
 ])
 
 @pytest.fixture(scope='module')
@@ -85,20 +86,37 @@ def lines_from_run(config, 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 fx_sign is not None and fx_code in config.args.signed_currencies:
-        rate_fmt = f'{re.escape(fx_sign)}{{}}'
+    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:
-        rate_fmt = f'{{}} {re.escape(fx_code)}'
-    pattern = r'^{} {{={}}} @ {}$'.format(
-        re.escape(amount),
-        rate_fmt.format(cost),
-        rate_fmt.format(price),
-    )
+        cost_re = '{{{}}}'.format(rate_fmt.format(cost))
+        if config.args.from_date is None:
+            price_re = ''
+        else:
+            price_re = ' @ {}'.format(rate_fmt.format(price))
+    pattern = r'^{} {}{}$'.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 = '$'
+        if code in config.args.signed_currencies and sign is not None:
+            expected = f'{sign}{amount}\n'
+        else:
+            expected = f'{amount} {code}\n'
+    else:
+        expected = f'{amount} {code or "USD"}\n'
+    assert next(lines, "<EOF>") == expected
+
 def test_rate_list(single_responder, output, any_date):
     config = build_config(single_responder, any_date)
     lines = lines_from_run(config, output)
@@ -144,7 +162,7 @@ def test_ledger_conversion(single_responder, output, any_date, output_format):
                           amount=300, output_format=output_format)
     lines = lines_from_run(config, output)
     check_fx_amount(config, lines, '300 ALL', '0.00691', 'USD', '$')
-    assert next(lines) == '$2.08\n'
+    check_nonfx_amount(config, lines, '2.08')
     assert next(lines, None) is None
 
 @parametrize_format
@@ -173,7 +191,7 @@ def test_redundant_denomination(single_responder, output, any_date, output_forma
                           output_format=output_format, 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'
+    check_nonfx_amount(config, lines, '5.59')
     assert next(lines, None) is None
 
 @parametrize_format
@@ -182,7 +200,7 @@ def test_from_denomination(single_responder, output, any_date, output_format):
                           from_currency='USD', to_currency='ALL', amount=10,
                           output_format=output_format, denomination='USD')
     lines = lines_from_run(config, output)
-    assert next(lines) == '$10.00\n'
+    check_nonfx_amount(config, lines, '10.00')
     check_fx_amount(config, lines, '1,445 ALL', '0.00691', 'USD', '$')
     assert next(lines, None) is None
 
@@ -197,7 +215,7 @@ def test_rate_precision_added_as_needed(single_responder, output, any_date, outp
     # 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'
+    check_nonfx_amount(config, lines, '1,117.89')
     assert next(lines, None) is None
 
 @parametrize_format
@@ -207,8 +225,8 @@ def test_from_date_rates(alternate_responder, output, any_date, output_format):
                           from_date=any_date, output_format=output_format,
                           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')
+    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
@@ -218,6 +236,26 @@ def test_from_date_conversion(alternate_responder, output, any_date, output_form
                           from_date=any_date, output_format=output_format,
                           denomination='USD')
     lines = lines_from_run(config, output)
-    check_fx_amount(config, lines, '10.00 ANG', '0.558', 'USD', '$', '0.507')
-    check_fx_amount(config, lines, '20.52 AED', '0.272', 'USD', '$', '0.265')
+    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)