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authorGravatar Joey Hess <joey@kitenet.net>2013-03-13 16:16:01 -0400
committerGravatar Joey Hess <joey@kitenet.net>2013-03-13 16:30:34 -0400
commit571cd1c57aeb4e8071b30caf529a0845e8ddc7cf (patch)
treee895c99334d675cec3f7996cb6c298fb7751b33b /Config
parent89cc1d2a38a1abaaecdfb7766739f3c2b5dbf963 (diff)
split cost out into its own module
Added a function to insert a new cost into a list, which could be used to asjust costs after a drag and drop.
Diffstat (limited to 'Config')
-rw-r--r--Config/Cost.hs79
1 files changed, 79 insertions, 0 deletions
diff --git a/Config/Cost.hs b/Config/Cost.hs
new file mode 100644
index 000000000..dd3968e78
--- /dev/null
+++ b/Config/Cost.hs
@@ -0,0 +1,79 @@
+{- Remote costs.
+ -
+ - Copyright 2011-2013 Joey Hess <joey@kitenet.net>
+ -
+ - Licensed under the GNU GPL version 3 or higher.
+ -}
+
+module Config.Cost where
+
+{- We use a float for a cost to ensure that there is a cost in
+ - between any two other costs. -}
+type Cost = Float
+
+{- Some predefined default costs.
+ - Users setting costs in config files can be aware of these,
+ - and pick values relative to them. So don't change. -}
+cheapRemoteCost :: Cost
+cheapRemoteCost = 100
+nearlyCheapRemoteCost :: Cost
+nearlyCheapRemoteCost = 110
+semiExpensiveRemoteCost :: Cost
+semiExpensiveRemoteCost = 175
+expensiveRemoteCost :: Cost
+expensiveRemoteCost = 200
+veryExpensiveRemoteCost :: Cost
+veryExpensiveRemoteCost = 1000
+
+{- Adjusts a remote's cost to reflect it being encrypted. -}
+encryptedRemoteCostAdj :: Cost
+encryptedRemoteCostAdj = 50
+
+{- Given an ordered list of costs, and the position of one of the items
+ - the list, inserts a new cost into the list, in between the item
+ - and the item after it.
+ -
+ - If both items have the same cost, one of them will have its cost
+ - adjusted to make room. The costs of other items in the list are left
+ - unchanged.
+ -
+ - To insert the new cost before any other in the list, specify a negative
+ - position. To insert the new cost at the end of the list, specify a
+ - position longer than the list.
+ -}
+insertCostAfter :: [Cost] -> Int -> [Cost]
+insertCostAfter [] _ = error "insertCostAfter: empty list"
+insertCostAfter l pos
+ | pos < 0 = costBetween 0 (l !! 0) : l
+ | nextpos > maxpos = l ++ [1 + l !! maxpos]
+ | item == nextitem =
+ let (_dup:new:l') = insertCostAfter lastsegment 0
+ in firstsegment ++ [costBetween item new, new] ++ l'
+ | otherwise =
+ firstsegment ++ [costBetween item nextitem ] ++ lastsegment
+ where
+ nextpos = pos + 1
+ maxpos = length l - 1
+
+ item = l !! pos
+ nextitem = l !! nextpos
+
+ (firstsegment, lastsegment) = splitAt (pos + 1) l
+
+costBetween :: Cost -> Cost -> Cost
+costBetween x y
+ | x == y = x
+ | x > y = y + (x - y) / 2
+ | otherwise = costBetween y x
+
+{- Make sure the remote cost numbers work out. -}
+prop_cost_sane :: Bool
+prop_cost_sane = False `notElem`
+ [ expensiveRemoteCost > 0
+ , cheapRemoteCost < nearlyCheapRemoteCost
+ , nearlyCheapRemoteCost < semiExpensiveRemoteCost
+ , semiExpensiveRemoteCost < expensiveRemoteCost
+ , cheapRemoteCost + encryptedRemoteCostAdj > nearlyCheapRemoteCost
+ , nearlyCheapRemoteCost + encryptedRemoteCostAdj < semiExpensiveRemoteCost
+ , nearlyCheapRemoteCost + encryptedRemoteCostAdj < expensiveRemoteCost
+ ]