django-orchestra/orchestra/apps/services/rating.py

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import sys
from orchestra.utils.python import AttributeDict
def _compute(rates, metric):
value = 0
num = len(rates)
accumulated = 0
barrier = 1
next_barrier = None
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end = False
ix = 0
steps = []
while ix < num and not end:
fold = 1
# Multiple contractions
while ix < num-1 and rates[ix] == rates[ix+1]:
ix += 1
fold += 1
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if ix+1 == num:
quantity = metric - accumulated
next_barrier = quantity
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else:
quantity = rates[ix+1].quantity - rates[ix].quantity
next_barrier = quantity
if rates[ix+1].price > rates[ix].price:
quantity *= fold
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if accumulated+quantity > metric:
quantity = metric - accumulated
end = True
price = rates[ix].price
steps.append(AttributeDict(**{
'quantity': quantity,
'price': price,
'barrier': barrier,
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}))
accumulated += quantity
barrier += next_barrier
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value += quantity*price
ix += 1
return value, steps
def step_price(rates, metric):
# Step price
# TODO allow multiple plans
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group = []
minimal = (sys.maxint, [])
for plan, rates in rates.group_by('plan').iteritems():
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value, steps = _compute(rates, metric)
if plan.is_combinable:
group.append(steps)
else:
minimal = min(minimal, (value, steps), key=lambda v: v[0])
if len(group) == 1:
value, steps = _compute(rates, metric)
minimal = min(minimal, (value, steps), key=lambda v: v[0])
elif len(group) > 1:
# Merge
steps = []
for rates in group:
steps += rates
steps.sort(key=lambda s: s.price)
result = []
counter = 0
value = 0
ix = 0
targets = []
while counter < metric:
barrier = steps[ix].barrier
if barrier <= counter+1:
price = steps[ix].price
quantity = steps[ix].quantity
if quantity + counter > metric:
quantity = metric - counter
else:
for target in targets:
if counter + quantity >= target:
quantity = (counter+quantity+1) - target
steps[ix].quantity -= quantity
if not steps[ix].quantity:
steps.pop(ix)
break
else:
steps.pop(ix)
counter += quantity
value += quantity*price
if result and result[-1].price == price:
result[-1].quantity += quantity
else:
result.append(AttributeDict(quantity=quantity, price=price))
ix = 0
targets = []
else:
targets.append(barrier)
ix += 1
minimal = min(minimal, (value, result), key=lambda v: v[0])
return minimal[1]
def match_price(rates, metric):
candidates = []
selected = False
prev = None
for rate in rates.distinct():
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if prev and prev.plan != rate.plan:
if not selected and prev.quantity <= metric:
candidates.append(prev)
selected = False
if not selected and rate.quantity > metric:
candidates.append(prev)
selected = True
prev = rate
if not selected and prev.quantity <= metric:
candidates.append(prev)
candidates.sort(key=lambda r: r.price)
return [AttributeDict(**{
'quantity': metric,
'price': candidates[0].price,
})]