142 lines
4.0 KiB
Python
142 lines
4.0 KiB
Python
from typing import Callable, List, NewType, Optional, Tuple
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from frappe.utils import flt
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FifoBin = NewType("FifoBin", List[float])
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# Indexes of values inside FIFO bin 2-tuple
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QTY = 0
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RATE = 1
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class FifoValuation:
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"""Valuation method where a queue of all the incoming stock is maintained.
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New stock is added at end of the queue.
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Qty consumption happens on First In First Out basis.
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Queue is implemented using "bins" of [qty, rate].
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ref: https://en.wikipedia.org/wiki/FIFO_and_LIFO_accounting
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"""
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def __init__(self, state: Optional[List[FifoBin]]):
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self.queue: List[FifoBin] = state if state is not None else []
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def __repr__(self):
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return str(self.queue)
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def __iter__(self):
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return iter(self.queue)
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def __eq__(self, other):
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if isinstance(other, list):
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return self.queue == other
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return self.queue == other.queue
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def get_state(self) -> List[FifoBin]:
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"""Get current state of queue."""
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return self.queue
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def get_total_stock_and_value(self) -> Tuple[float, float]:
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total_qty = 0.0
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total_value = 0.0
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for qty, rate in self.queue:
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total_qty += flt(qty)
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total_value += flt(qty) * flt(rate)
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return _round_off_if_near_zero(total_qty), _round_off_if_near_zero(total_value)
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def add_stock(self, qty: float, rate: float) -> None:
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"""Update fifo queue with new stock.
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args:
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qty: new quantity to add
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rate: incoming rate of new quantity"""
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if not len(self.queue):
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self.queue.append([0, 0])
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# last row has the same rate, merge new bin.
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if self.queue[-1][RATE] == rate:
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self.queue[-1][QTY] += qty
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else:
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# Item has a positive balance qty, add new entry
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if self.queue[-1][QTY] > 0:
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self.queue.append([qty, rate])
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else: # negative balance qty
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qty = self.queue[-1][QTY] + qty
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if qty > 0: # new balance qty is positive
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self.queue[-1] = [qty, rate]
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else: # new balance qty is still negative, maintain same rate
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self.queue[-1][QTY] = qty
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def remove_stock(
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self, qty: float, outgoing_rate: float = 0.0, rate_generator: Callable[[], float] = None
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) -> List[FifoBin]:
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"""Remove stock from the queue and return popped bins.
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args:
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qty: quantity to remove
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rate: outgoing rate
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rate_generator: function to be called if queue is not found and rate is required.
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"""
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if not rate_generator:
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rate_generator = lambda : 0.0 # noqa
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consumed_bins = []
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while qty:
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if not len(self.queue):
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# rely on rate generator.
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self.queue.append([0, rate_generator()])
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index = None
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if outgoing_rate > 0:
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# Find the entry where rate matched with outgoing rate
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for idx, fifo_bin in enumerate(self.queue):
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if fifo_bin[RATE] == outgoing_rate:
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index = idx
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break
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# If no entry found with outgoing rate, collapse stack
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if index is None: # nosemgrep
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new_stock_value = sum(d[QTY] * d[RATE] for d in self.queue) - qty * outgoing_rate
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new_stock_qty = sum(d[QTY] for d in self.queue) - qty
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self.queue = [[new_stock_qty, new_stock_value / new_stock_qty if new_stock_qty > 0 else outgoing_rate]]
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break
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else:
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index = 0
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# select first bin or the bin with same rate
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fifo_bin = self.queue[index]
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if qty >= fifo_bin[QTY]:
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# consume current bin
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qty = _round_off_if_near_zero(qty - fifo_bin[QTY])
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to_consume = self.queue.pop(index)
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consumed_bins.append(list(to_consume))
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if not self.queue and qty:
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# stock finished, qty still remains to be withdrawn
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# negative stock, keep in as a negative bin
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self.queue.append([-qty, outgoing_rate or fifo_bin[RATE]])
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consumed_bins.append([qty, outgoing_rate or fifo_bin[RATE]])
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break
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else:
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# qty found in current bin consume it and exit
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fifo_bin[QTY] = _round_off_if_near_zero(fifo_bin[QTY] - qty)
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consumed_bins.append([qty, fifo_bin[RATE]])
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qty = 0
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return consumed_bins
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def _round_off_if_near_zero(number: float, precision: int = 7) -> float:
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"""Rounds off the number to zero only if number is close to zero for decimal
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specified in precision. Precision defaults to 7.
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"""
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if abs(0.0 - flt(number)) < (1.0 / (10 ** precision)):
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return 0.0
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return flt(number)
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