historical: Add Ledger output formatting.

oxrlib/commands/historical.py

@@ -1,22 +1,99 @@
-from babel.numbers import format_currency
+import decimal
+import itertools
+import operator
+
+import babel.numbers
 
 from .. import rate as oxrrate
 
-CURRENCY_FMT = '#,##0.### ¤¤'
+class Formatter:
-RATE_FMT = '{from_amt:g} {from_curr} = {to_amt:g} {to_curr}'
+    def __init__(self, rate, signed_currencies=(), base_fmt='#,##0.###'):
+        self.rate = rate
+        self.base_fmt = base_fmt
+        self.base_fmt_noprec = base_fmt.rsplit('.', 1)[0]
+        self.signed_currencies = set(code for code in signed_currencies
+                                     if self.can_sign_currency(code))
 
-def format_conversion(rate, from_amt, from_curr, to_curr):
+    def can_sign_currency(self, code):
-    to_amt = rate.convert(from_amt, from_curr, to_curr)
+        return len(babel.numbers.get_currency_symbol(code)) == 1
-    return "{} = {}".format(
+
-        format_currency(from_amt, from_curr, CURRENCY_FMT),
+    def format_currency(self, amount, code, currency_digits=True):
-        format_currency(to_amt, to_curr, CURRENCY_FMT),
+        if currency_digits:
-    )
+            fmt = self.base_fmt
+        else:
+            fmt = '{}.{}'.format(self.base_fmt_noprec, '#' * -amount.as_tuple().exponent)
+        if code in self.signed_currencies:
+            fmt = '¤' + fmt
+        else:
+            fmt = fmt + ' ¤¤'
+        return babel.numbers.format_currency(amount, code, fmt, currency_digits=currency_digits)
+
+    def format_rate(self, rate):
+        return "{:g}".format(rate)
+
+    def format_rate_pair(self, from_curr, to_curr):
+        from_amt = 1
+        to_amt = self.rate.convert(from_amt, from_curr, 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'):
+        return "{}{}{}".format(
+            self.format_rate_pair(from_curr, to_curr),
+            sep,
+            self.format_rate_pair(to_curr, from_curr),
+        )
+
+    def format_conversion(self, from_amt, from_curr, to_curr):
+        to_amt = self.rate.convert(from_amt, from_curr, to_curr)
+        return "{} = {}".format(
+            self.format_currency(from_amt, from_curr),
+            self.format_currency(to_amt, to_curr),
+        )
+
+
+class LedgerFormatter(Formatter):
+    RATE_PREC = 5
+
+    def normalize_rate(self, rate, prec=None):
+        # Return prec nonzero digits of precision, if available.
+        if prec is None:
+            prec = self.RATE_PREC
+        _, digits, exponent = rate.normalize().as_tuple()
+        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, prec=None):
+        return str(self.normalize_rate(rate, prec))
+
+    def format_ledger_rate(self, rate, curr, prec=None):
+        nrate = self.normalize_rate(rate, prec)
+        rate_s = self.format_currency(nrate, curr, currency_digits=False)
+        return "{{={0}}} @ {0}".format(rate_s)
+
+    def format_rate_pair(self, from_curr, to_curr):
+        from_amt = 1
+        to_amt = self.rate.convert(from_amt, from_curr, to_curr)
+        return "{} {} {}".format(
+            from_amt, from_curr, self.format_ledger_rate(to_amt, to_curr))
+
+    def format_conversion(self, from_amt, from_curr, to_curr):
+        to_rate = self.rate.convert(1, from_curr, to_curr)
+        to_amt = self.rate.convert(from_amt, from_curr, to_curr)
+        return "{} {}\n{}".format(
+            self.format_currency(from_amt, from_curr),
+            self.format_ledger_rate(to_rate, to_curr),
+            self.format_currency(to_amt, to_curr),
+        )
 
-def format_rate_pair(rate, from_curr, to_curr):
-    amt = rate.convert(1, from_curr, to_curr)
-    yield RATE_FMT.format(from_amt=1, from_curr=from_curr, to_amt=amt, to_curr=to_curr)
-    amt = rate.convert(1, to_curr, from_curr)
-    yield RATE_FMT.format(from_amt=1, from_curr=to_curr, to_amt=amt, to_curr=from_curr)
 
 def run(config, stdout, stderr):
     loaders = config.get_loaders()
@@ -24,14 +101,19 @@ def run(config, stdout, stderr):
         rate = oxrrate.Rate.from_json_file(rate_json)
     if loaders.should_cache():
         config.cache.save_rate(rate)
+    if config.args.ledger:
+        formatter = LedgerFormatter(rate, config.args.signed_currencies)
+    else:
+        formatter = Formatter(rate)
     if not config.args.from_currency:
         for from_curr in sorted(rate.rates):
-            print(*format_rate_pair(rate, from_curr, config.args.to_currency),
+            print(formatter.format_rate_pair_bidir(from_curr, config.args.to_currency),
-                  sep='\n', file=stdout)
+                  file=stdout)
     elif config.args.amount is None:
-        print(*format_rate_pair(rate, config.args.from_currency, config.args.to_currency),
+        print(formatter.format_rate_pair_bidir(config.args.from_currency, config.args.to_currency),
-              sep='\n', file=stdout)
+              file=stdout)
-    else:
+    else:
-        print(format_conversion(rate, config.args.amount,
+        print(formatter.format_conversion(config.args.amount,
-                                config.args.from_currency, config.args.to_currency),
+                                          config.args.from_currency,
+                                          config.args.to_currency),
               file=stdout)

oxrlib/config.py

@@ -8,16 +8,15 @@ import pathlib
 from . import cache, loaders
 
 HOME_PATH = pathlib.Path(os.path.expanduser('~'))
-CONFFILE_SEED = """
-[Historical]
-base=USD
-"""
 
 def currency_code(s):
     if not ((len(s) == 3) and s.isalpha()):
         raise ValueError("bad currency code: {!r}".format(s))
     return s.upper()
 
+def currency_list(s):
+    return [currency_code(code.strip()) for code in s.split(',')]
+
 def date_from(fmt_s):
     def date_from_fmt(s):
         return datetime.datetime.strptime(s, fmt_s).date()
@@ -66,12 +65,29 @@ class Configuration:
             command='historical',
             amount=None,
             from_currency=None,
+            ledger=None,
         )
         hist_parser.add_argument(
             '--base',
             type=currency_code,
             help="Base currency (default USD)",
         )
+        hist_parser.add_argument(
+            '--ledger', '-L',
+            action='store_true',
+            help="Output the rate or conversion in Ledger format",
+        )
+        hist_parser.add_argument(
+            '--no-ledger',
+            action='store_false', dest='ledger',
+            help="Turn off an earlier --ledger setting",
+        )
+        hist_parser.add_argument(
+            '--signed-currency', '--sign-currency',
+            type=currency_code, action='append', dest='signed_currencies',
+            help="In Ledger output, use a sign for this currency if known. "
+            "Can be specified multiple times.",
+        )
         hist_parser.add_argument(
             'date',
             type=date_from('%Y-%m-%d'),
@@ -96,9 +112,19 @@ class Configuration:
         return prog_parser
 
     def _build_conffile(self):
-        conffile = configparser.ConfigParser()
+        return configparser.ConfigParser()
-        conffile.read_string(CONFFILE_SEED)
+
-        return conffile
+    def _read_from_conffile(self, argname, sectionname, fallback, convert_to=None,
+                            confname=None, getter='get', unset=None):
+        if getattr(self.args, argname) is not unset:
+            return
+        elif confname is None:
+            confname = argname
+        get_method = getattr(self.conffile, getter)
+        value = get_method(sectionname, confname, fallback=fallback)
+        if convert_to is not None:
+            value = self._convert_or_error(convert_to, value, confname)
+        setattr(self.args, argname, value)
 
     def _convert_or_error(self, argtype, s_value, argname=None, typename=None):
         try:
@@ -114,8 +140,9 @@ class Configuration:
             self.error(': '.join(errmsg))
 
     def _post_hook_historical(self):
-        if self.args.base is None:
+        self._read_from_conffile('base', 'Historical', 'USD', currency_code)
-            self.args.base = self.conffile.get('Historical', 'base')
+        self._read_from_conffile('signed_currencies', 'Historical', self.args.base, currency_list)
+        self._read_from_conffile('ledger', 'Historical', False, getter='getboolean')
         self.args.to_currency = self.args.base
         if self.args.word4 and (self.args.word3.lower() in self.PREPOSITIONS):
             self.args.word3 = self.args.word4

oxrlib_example.ini

@@ -23,3 +23,10 @@ historical = {date}_{base}_rates.json
 # Set the base currency.
 # Note that setting a base other than USD requires a paid OXR account.
 base = USD
+
+# Write output in Ledger format.
+ledger = no
+
+# Use signs for these currencies in Ledger output.
+# If not specified, defaults to the base currency.
+signed_currencies = USD, EUR

setup.py

@@ -5,7 +5,7 @@ from setuptools import setup
 setup(
     name='oxrlib',
     description="Library to query the Open Exchange Rates (OXR) API",
-    version='1.1',
+    version='1.2',
     author='Brett Smith',
     author_email='brettcsmith@brettcsmith.org',
     license='GNU AGPLv3+',

tests/test_historical.py

@@ -47,6 +47,8 @@ def build_config(
         amount=None,
         from_currency=None,
         to_currency=None,
+        ledger=False,
+        signed_currencies=None,
         base='USD',
 ):
     return FakeConfig(responder, {
@@ -55,6 +57,8 @@ def build_config(
         '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,
+        'ledger': ledger,
+        'signed_currencies': [base] if signed_currencies is None else signed_currencies,
     })
 
 def lines_from_run(config, output):
@@ -91,3 +95,25 @@ def test_back_conversion(historical1_responder, output):
     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(historical1_responder, output):
+    config = build_config(historical1_responder, from_currency='ANG', ledger=True)
+    lines = lines_from_run(config, output)
+    assert next(lines) == '1 ANG {=$0.55866} @ $0.55866\n'
+    assert next(lines) == '1 USD {=1.79 ANG} @ 1.79 ANG\n'
+    assert next(lines, None) is None
+
+def test_ledger_conversion(historical1_responder, output):
+    config = build_config(historical1_responder, from_currency='ALL', amount=300, ledger=True)
+    lines = lines_from_run(config, output)
+    assert next(lines) == '300 ALL {=$0.006919} @ $0.006919\n'
+    assert next(lines) == '$2.08\n'
+    assert next(lines, None) is None
+
+def test_signed_currencies(historical1_responder, output):
+    config = build_config(historical1_responder, from_currency='AED',
+                          ledger=True, signed_currencies=['EUR'])
+    lines = lines_from_run(config, output)
+    assert next(lines) == '1 AED {=0.2723 USD} @ 0.2723 USD\n'
+    assert next(lines) == '1 USD {=3.67246 AED} @ 3.67246 AED\n'
+    assert next(lines, None) is None