Add draft `pydantic`-`QWidget` ORM system

Move all the ``pydantic`` finagling to an `_orm.py` and
just keep an `Allocator` as the backing model for our pp controls
in the position module. This all needs to be tied together in some sane
with with facility for multiple symbols/streams per chart for when we
get to charting-trading aggregate feeds.

piker/ui/_orm.py

@@ -0,0 +1,129 @@
+# piker: trading gear for hackers
+# Copyright (C) Tyler Goodlet
+
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Affero General Public License for more details.
+
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+"""
+micro-ORM for coupling ``pydantic`` models with Qt input/output widgets.
+
+"""
+from __future__ import annotations
+from typing import (
+    Optional, Generic,
+    TypeVar, Callable,
+    Literal,
+)
+import enum
+import sys
+
+from pydantic import BaseModel, validator
+from pydantic.generics import GenericModel
+from PyQt5.QtWidgets import (
+    QWidget,
+    QComboBox,
+)
+
+from ._forms import (
+    # FontScaledDelegate,
+    FontAndChartAwareLineEdit,
+)
+
+
+DataType = TypeVar('DataType')
+
+
+class Field(GenericModel, Generic[DataType]):
+    widget_factory: Optional[
+        Callable[
+            [QWidget, 'Field'],
+            QWidget
+        ]
+    ]
+    value: Optional[DataType] = None
+
+
+class Selection(Field[DataType], Generic[DataType]):
+    '''Model which maps to a finite set of drop down entries declared as
+    a ``dict[str, DataType]``.
+
+    '''
+    widget_factory = QComboBox
+    options: dict[str, DataType]
+    # value: DataType = None
+
+    @validator('value')  # , always=True)
+    def set_value_first(
+        cls,
+
+        v: DataType,
+        values: dict[str, DataType],
+
+    ) -> DataType:
+        '''If no initial value is set, use the first in
+        the ``options`` dict.
+
+        '''
+        # breakpoint()
+        options = values['options']
+        if v is None:
+            return next(options.values())
+        else:
+            assert v in options, f'{v} is not in {options}'
+            return v
+
+
+# class SizeUnit(Enum):
+
+#     currency = '$ size'
+#     percent_of_port = '% of port'
+#     shares = '# shares'
+
+
+# class Weighter(str, Enum):
+#     uniform = 'uniform'
+
+
+class Edit(Field[DataType], Generic[DataType]):
+    '''An edit field which takes a number.
+    '''
+    widget_factory = FontAndChartAwareLineEdit
+
+
+class AllocatorPane(BaseModel):
+
+    account = Selection[str](
+        options=dict.fromkeys(
+            ['paper', 'ib.paper', 'ib.margin'],
+            'paper',
+        ),
+    )
+
+    allocate = Selection[str](
+        # options=list(Size),
+        options={
+            '$ size': 'currency',
+            '% of port': 'percent_of_port',
+            '# shares': 'shares',
+        },
+        # TODO: save/load from config and/or last session
+        # value='currency'
+    )
+    weight = Selection[str](
+        options={
+            'uniform': 'uniform',
+        },
+        # value='uniform',
+    )
+    size = Edit[float](value=1000)
+    slots = Edit[int](value=4)

piker/ui/_position.py

@@ -18,12 +18,17 @@
 Position info and display
 
 """
-from typing import Optional
+from __future__ import annotations
+import enum
 from functools import partial
 from math import floor
+import sys
+from typing import Optional
 
+from bidict import bidict
 from pyqtgraph import functions as fn
-from pydantic import BaseModel
+from pydantic import BaseModel, validator
+# from pydantic.generics import GenericModel
 # from PyQt5.QtCore import QPointF
 # from PyQt5.QtGui import QGraphicsPathItem
 
@@ -56,6 +61,70 @@ class Position(BaseModel):
     fills: list[Status] = []
 
 
+def mk_pp_alloc(
+
+    accounts: dict[str, Optional[str]] = {
+        'paper': None,
+        'ib.paper': 'DU1435481',
+        'ib.margin': 'U10983%',
+    },
+
+) -> Allocator:  # noqa
+
+    # lol we have to do this module patching bc ``pydantic``
+    # needs types to exist at module level:
+    # https://pydantic-docs.helpmanual.io/usage/postponed_annotations/
+    mod = sys.modules[__name__]
+
+    accounts = bidict(accounts)
+    Account = mod.Account = enum.Enum('Account', accounts)
+
+    size_units = bidict({
+        '$ size': 'currency',
+        '% of port': 'percent_of_port',
+        '# shares': 'shares',
+    })
+    SizeUnit = mod.SizeUnit = enum.Enum(
+        'SizeUnit',
+        size_units.inverse
+    )
+
+    class Allocator(BaseModel):
+
+        account: Account = None
+        _accounts: dict[str, Optional[str]] = accounts
+
+        size_unit: SizeUnit = 'currency'
+        _size_units: dict[str, Optional[str]] = size_units
+
+        disti_weight: str = 'uniform'
+
+        size: float
+        slots: int
+
+        _position: Position = None
+
+        def get_order_info(
+            self,
+            price: float,
+
+        ) -> dict:
+            units, r = divmod(
+                round((self.size / self.slots)),
+                price,
+            )
+            print(f'# shares: {units}, r: {r}')
+
+    # Allocator.update_forward_refs()
+
+    return Allocator(
+        account=None,
+        size_unit=size_units.inverse['currency'],
+        size=2000,
+        slots=4,
+    )
+
+
 class PositionTracker:
     '''Track and display a real-time position for a single symbol
     on a chart.