django-orchestra/orchestra/contrib/plans/ratings.py

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import sys
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from django.utils.translation import ugettext_lazy as _
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from orchestra.utils.python import AttrDict
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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
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steps.append(AttrDict(**{
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'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
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def _prepend_missing(rates):
"""
Support for incomplete rates
When first rate (quantity=5, price=10) defaults to nominal_price
"""
if rates:
first = rates[0]
if first.quantity == 0:
first.quantity = 1
elif first.quantity > 1:
if not isinstance(rates, list):
rates = list(rates)
service = first.service
rate_class = type(first)
rates.insert(0,
rate_class(service=service, plan=first.plan, quantity=1, price=service.nominal_price)
)
return rates
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def step_price(rates, metric):
# Step price
group = []
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minimal = (sys.maxsize, [])
for plan, rates in rates.group_by('plan').items():
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rates = _prepend_missing(rates)
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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:
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result.append(AttrDict(quantity=quantity, price=price))
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ix = 0
targets = []
else:
targets.append(barrier)
ix += 1
minimal = min(minimal, (value, result), key=lambda v: v[0])
return minimal[1]
step_price.verbose_name = _("Step price")
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step_price.help_text = _("All rates with a quantity lower than the metric are applied. "
"Nominal price will be used when initial block is missing.")
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def match_price(rates, metric):
candidates = []
selected = False
prev = None
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rates = _prepend_missing(rates.distinct())
for rate in rates:
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if prev:
if prev.plan != rate.plan:
if not selected and prev.quantity <= metric:
candidates.append(prev)
selected = False
if not selected and rate.quantity > metric:
if prev.quantity <= metric:
candidates.append(prev)
selected = True
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prev = rate
if not selected and prev.quantity <= metric:
candidates.append(prev)
candidates.sort(key=lambda r: r.price)
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if candidates:
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return [AttrDict(**{
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'quantity': metric,
'price': candidates[0].price,
})]
return None
match_price.verbose_name = _("Match price")
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match_price.help_text = _("Only <b>the rate</b> with a) inmediate inferior metric and b) lower price is applied. "
"Nominal price will be used when initial block is missing.")
def best_price(rates, metric):
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candidates = []
selected = False
prev = None
rates = _prepend_missing(rates.distinct())
for rate in rates:
if prev:
if prev.plan != rate.plan:
if not selected and prev.quantity <= metric:
candidates.append(prev)
selected = False
if not selected and rate.quantity > metric:
if prev.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)
if candidates:
return [AttrDict(**{
'quantity': metric,
'price': candidates[0].price,
})]
return None
best_price.verbose_name = _("Best price")
best_price.help_text = _("Produces the best possible price given all active rating lines.")