utils: introduce format_plural and move format functions to strings.py

core/src/apps/binance/layout.py

@@ -7,9 +7,9 @@ from trezor.messages import (
     BinanceTransferMsg,
     ButtonRequestType,
 )
+from trezor.strings import format_amount
 from trezor.ui.scroll import Paginated
 from trezor.ui.text import Text
-from trezor.utils import format_amount
 
 from . import helpers
 

core/src/apps/cardano/layout/__init__.py

@@ -1,9 +1,10 @@
 from micropython import const
 
 from trezor import ui
+from trezor.strings import format_amount
 from trezor.ui.scroll import Paginated
 from trezor.ui.text import Text
-from trezor.utils import chunks, format_amount
+from trezor.utils import chunks
 
 from apps.common.confirm import confirm, hold_to_confirm
 

core/src/apps/ethereum/layout.py

@@ -2,8 +2,9 @@ from ubinascii import hexlify
 
 from trezor import ui
 from trezor.messages import ButtonRequestType
+from trezor.strings import format_amount
 from trezor.ui.text import Text
-from trezor.utils import chunks, format_amount
+from trezor.utils import chunks
 
 from apps.common.confirm import require_confirm, require_hold_to_confirm
 from apps.common.layout import split_address

core/src/apps/lisk/layout.py

@@ -1,7 +1,8 @@
 from trezor import ui
 from trezor.messages import ButtonRequestType
+from trezor.strings import format_amount
 from trezor.ui.text import Text
-from trezor.utils import chunks, format_amount
+from trezor.utils import chunks
 
 from .helpers import get_vote_tx_text
 

core/src/apps/management/recovery_device/homescreen.py

@@ -2,7 +2,7 @@ import storage
 import storage.device
 import storage.recovery
 import storage.recovery_shares
-from trezor import utils, wire, workflow
+from trezor import strings, utils, wire, workflow
 from trezor.crypto import slip39
 from trezor.crypto.hashlib import sha256
 from trezor.errors import MnemonicError
@@ -213,10 +213,7 @@ async def _request_share_next_screen(ctx: wire.GenericContext) -> None:
             ctx, content, "Enter", _show_remaining_groups_and_shares
         )
     else:
-        if remaining[0] == 1:
+        text = strings.format_plural("{count} more {plural}", remaining[0], "share")
-            text = "1 more share"
-        else:
-            text = "%d more shares" % remaining[0]
         content = layout.RecoveryHomescreen(text, "needed to enter")
         await layout.homescreen_dialog(ctx, content, "Enter share")
 

core/src/apps/management/recovery_device/layout.py

@@ -1,5 +1,5 @@
 import storage.recovery
-from trezor import ui, wire
+from trezor import strings, ui, wire
 from trezor.crypto.slip39 import MAX_SHARE_COUNT
 from trezor.messages import ButtonRequestType
 from trezor.messages.ButtonAck import ButtonAck
@@ -99,10 +99,11 @@ async def show_remaining_shares(
     for remaining, group in groups:
         if 0 < remaining < MAX_SHARE_COUNT:
             text = Text("Remaining Shares")
-            if remaining > 1:
+            text.bold(
-                text.bold("%s more shares starting" % remaining)
+                strings.format_plural(
-            else:
+                    "{count} more {plural} starting", remaining, "share"
-                text.bold("%s more share starting" % remaining)
+                )
+            )
             for word in group:
                 text.normal(word)
             pages.append(text)
@@ -111,10 +112,11 @@ async def show_remaining_shares(
         ):
             text = Text("Remaining Shares")
             groups_remaining = group_threshold - shares_remaining.count(0)
-            if groups_remaining > 1:
+            text.bold(
-                text.bold("%s more groups starting" % groups_remaining)
+                strings.format_plural(
-            elif groups_remaining > 0:
+                    "{count} more {plural} starting", groups_remaining, "group"
-                text.bold("%s more group starting" % groups_remaining)
+                )
+            )
             for word in group:
                 text.normal(word)
             pages.append(text)

core/src/apps/monero/layout/common.py

@@ -1,4 +1,4 @@
-from trezor import ui, utils
+from trezor import strings, ui, utils
 from trezor.messages import ButtonRequestType
 from trezor.messages.ButtonAck import ButtonAck
 from trezor.messages.ButtonRequest import ButtonRequest
@@ -59,7 +59,7 @@ def paginate_lines(lines, lines_per_page=5):
 
 
 def format_amount(value):
-    return "%s XMR" % utils.format_amount(value, 12)
+    return "%s XMR" % strings.format_amount(value, 12)
 
 
 def split_address(address):

core/src/apps/nem/layout.py

@@ -1,7 +1,7 @@
 from trezor import ui
 from trezor.messages import ButtonRequestType
+from trezor.strings import format_amount
 from trezor.ui.text import Text
-from trezor.utils import format_amount
 
 from .helpers import NEM_MAX_DIVISIBILITY
 

core/src/apps/nem/transfer/layout.py

@@ -8,8 +8,8 @@ from trezor.messages import (
     NEMTransactionCommon,
     NEMTransfer,
 )
+from trezor.strings import format_amount
 from trezor.ui.text import Text
-from trezor.utils import format_amount
 
 from ..helpers import (
     NEM_LEVY_PERCENTILE_DIVISOR_ABSOLUTE,

core/src/apps/ripple/layout.py

@@ -1,7 +1,7 @@
 from trezor import ui
 from trezor.messages import ButtonRequestType
+from trezor.strings import format_amount
 from trezor.ui.text import Text
-from trezor.utils import format_amount
 
 from . import helpers
 

core/src/apps/stellar/layout.py

@@ -1,4 +1,4 @@
-from trezor import ui, utils
+from trezor import strings, ui, utils
 from trezor.messages import ButtonRequestType
 from trezor.ui.text import Text
 
@@ -77,7 +77,7 @@ def format_amount(amount: int, ticker=True) -> str:
     t = ""
     if ticker:
         t = " XLM"
-    return utils.format_amount(amount, consts.AMOUNT_DECIMALS) + t
+    return strings.format_amount(amount, consts.AMOUNT_DECIMALS) + t
 
 
 def split(text):

core/src/apps/tezos/layout.py

@@ -1,8 +1,9 @@
 from trezor import ui
 from trezor.messages import ButtonRequestType
+from trezor.strings import format_amount
 from trezor.ui.scroll import Paginated
 from trezor.ui.text import Text
-from trezor.utils import chunks, format_amount
+from trezor.utils import chunks
 
 from apps.common.confirm import require_confirm, require_hold_to_confirm
 from apps.tezos.helpers import TEZOS_AMOUNT_DECIMALS

core/src/apps/wallet/sign_tx/layout.py

@@ -3,7 +3,8 @@ from ubinascii import hexlify
 
 from trezor import ui
 from trezor.messages import ButtonRequestType, OutputScriptType
-from trezor.utils import chunks, format_amount
+from trezor.strings import format_amount
+from trezor.utils import chunks
 
 _LOCKTIME_TIMESTAMP_MIN_VALUE = const(500000000)
 

core/src/apps/wallet/sign_tx/omni.py

@@ -1,6 +1,6 @@
 from ustruct import unpack
 
-from trezor.utils import format_amount
+from trezor.strings import format_amount
 
 currencies = {
     1: ("OMNI", True),

core/src/trezor/strings.py

@@ -0,0 +1,47 @@
+def format_amount(amount: int, decimals: int) -> str:
+    if amount < 0:
+        amount = -amount
+        sign = "-"
+    else:
+        sign = ""
+    d = pow(10, decimals)
+    s = (
+        ("%s%d.%0*d" % (sign, amount // d, decimals, amount % d))
+        .rstrip("0")
+        .rstrip(".")
+    )
+    return s
+
+
+def format_ordinal(number: int) -> str:
+    return str(number) + {1: "st", 2: "nd", 3: "rd"}.get(
+        4 if 10 <= number % 100 < 20 else number % 10, "th"
+    )
+
+
+def format_plural(string: str, count: int, plural: str):
+    """
+    Adds plural form to a string based on `count`.
+    !! Does not work with irregular words !!
+
+    Example:
+    >>> format_plural("We need {count} more {plural}", 3, "share")
+    'We need 3 more shares'
+    >>> format_plural("We need {count} more {plural}", 1, "share")
+    'We need 1 more share'
+    >>> format_plural("{count} {plural}", 4, "candy")
+    '4 candies'
+    """
+    if not all(s in string for s in ("{count}", "{plural}")):
+        # string needs to have {count} and {plural} inside
+        raise ValueError
+
+    if count == 0 or count > 1:
+        if plural[-1] == "y":
+            plural = plural[:-1] + "ies"
+        elif plural[-1] in "hsxz":
+            plural = plural + "es"
+        else:
+            plural = plural + "s"
+
+    return string.format(count=count, plural=plural)

core/src/trezor/utils.py

@@ -70,27 +70,6 @@ def chunks(items: Chunkable, size: int) -> Iterator[Chunkable]:
         yield items[i : i + size]
 
 
-def format_amount(amount: int, decimals: int) -> str:
-    if amount < 0:
-        amount = -amount
-        sign = "-"
-    else:
-        sign = ""
-    d = pow(10, decimals)
-    s = (
-        ("%s%d.%0*d" % (sign, amount // d, decimals, amount % d))
-        .rstrip("0")
-        .rstrip(".")
-    )
-    return s
-
-
-def format_ordinal(number: int) -> str:
-    return str(number) + {1: "st", 2: "nd", 3: "rd"}.get(
-        4 if 10 <= number % 100 < 20 else number % 10, "th"
-    )
-
-
 if False:
 
     class HashContext(Protocol):

core/tests/test_trezor.strings.py

@@ -0,0 +1,34 @@
+from common import *
+
+from trezor import strings
+
+
+class TestStrings(unittest.TestCase):
+
+    def test_format_amount(self):
+        VECTORS = [
+            (123456, 3, "123.456"),
+            (4242, 7, "0.0004242"),
+            (-123456, 3, "-123.456"),
+            (-4242, 7, "-0.0004242"),
+        ]
+        for v in VECTORS:
+            self.assertEqual(strings.format_amount(v[0], v[1]), v[2])
+
+
+    def test_format_plural(self):
+        VECTORS = [
+            ("We need {count} more {plural}", 3, "share", "We need 3 more shares"),
+            ("We need {count} more {plural}", 1, "share", "We need 1 more share"),
+            ("We need {count} more {plural}", 1, "candy", "We need 1 more candy"),
+            ("We need {count} more {plural}", 7, "candy", "We need 7 more candies"),
+        ]
+        for v in VECTORS:
+            self.assertEqual(strings.format_plural(v[0], v[1], v[2]), v[3])
+
+        with self.assertRaises(ValueError):
+            strings.format_plural("Hello", 1, "share")
+
+
+if __name__ == '__main__':
+    unittest.main()

core/tests/test_trezor.utils.py

@@ -13,16 +13,6 @@ class TestUtils(unittest.TestCase):
             self.assertEqual(c[i].stop, 100 if (i == 14) else (i + 1) * 7)
             self.assertEqual(c[i].step, 1)
 
-    def test_format_amount(self):
-        VECTORS = [
-            (123456, 3, "123.456"),
-            (4242, 7, "0.0004242"),
-            (-123456, 3, "-123.456"),
-            (-4242, 7, "-0.0004242"),
-        ]
-        for v in VECTORS:
-            self.assertEqual(utils.format_amount(v[0], v[1]), v[2])
-
 
 if __name__ == '__main__':
     unittest.main()