Include difficulty as Double in object-encoded block header

Change-Id: Id0000000010fc50d9363200a7d4ea8c251a2f25a

src/Chainweb/BlockHeader/Internal.hs

@@ -1009,6 +1009,7 @@ blockHeaderProperties (ObjectEncoded b) =
     , "parent" .= _blockParent b
     , "adjacents" .= _blockAdjacentHashes b
     , "target" .= _blockTarget b
+    , "difficultyDouble" .= difficultyToDouble (targetToDifficulty (_blockTarget b))
     , "payloadHash" .= _blockPayloadHash b
     , "chainId" .= _chainId b
     , "weight" .= _blockWeight b
@@ -1205,4 +1206,3 @@ _rankedBlockPayloadHash h = RankedBlockPayloadHash
 rankedBlockPayloadHash :: Getter BlockHeader RankedBlockPayloadHash
 rankedBlockPayloadHash = to _rankedBlockPayloadHash
 {-# INLINE rankedBlockPayloadHash #-}
-

src/Chainweb/BlockWeight.hs

@@ -22,6 +22,7 @@ module Chainweb.BlockWeight
 (
 -- * Block Weight
   BlockWeight(..)
+, blockWeightToDouble
 , encodeBlockWeight
 , decodeBlockWeight
 , encodeBlockWeightBe
@@ -66,6 +67,9 @@ instance MerkleHashAlgorithm a => IsMerkleLogEntry a ChainwebHashTag BlockWeight
     {-# INLINE toMerkleNode #-}
     {-# INLINE fromMerkleNode #-}
 
+blockWeightToDouble :: BlockWeight -> Double
+blockWeightToDouble (BlockWeight diff) = difficultyToDouble diff
+
 encodeBlockWeight :: BlockWeight -> Put
 encodeBlockWeight (BlockWeight w) = encodeHashDifficulty w
 {-# INLINE encodeBlockWeight #-}
@@ -81,4 +85,3 @@ encodeBlockWeightBe (BlockWeight w) = encodeHashDifficultyBe w
 decodeBlockWeightBe :: Get BlockWeight
 decodeBlockWeightBe = BlockWeight <$> decodeHashDifficultyBe
 {-# INLINE decodeBlockWeightBe #-}
-

src/Chainweb/Difficulty.hs

@@ -14,6 +14,7 @@
 {-# LANGUAGE TypeOperators #-}
 
 {-# OPTIONS_GHC -fno-warn-orphans #-}
+{-# LANGUAGE TypeApplications #-}
 
 -- |
 -- Module: Chainweb.Difficulty
@@ -32,6 +33,7 @@ module Chainweb.Difficulty
 -- * PowHashNat
 , PowHashNat(..)
 , powHashNat
+, powHashNatToDouble
 , encodePowHashNat
 , decodePowHashNat
 , encodePowHashNatBe
@@ -50,6 +52,7 @@ module Chainweb.Difficulty
 
 -- * HashDifficulty
 , HashDifficulty(..)
+, difficultyToDouble
 , encodeHashDifficulty
 , decodeHashDifficulty
 , encodeHashDifficultyBe
@@ -89,6 +92,7 @@ import Chainweb.Utils
 import Chainweb.Utils.Serialization
 
 import Numeric.Additive
+import Data.Ratio
 
 -- -------------------------------------------------------------------------- --
 -- Large Word Orphans
@@ -141,6 +145,12 @@ powHashToWord256 :: (32 <= PowHashBytesCount) => PowHash -> Word256
 powHashToWord256 = either error id . runGetEitherS decodeWordLe . SB.fromShort . powHashBytes
 {-# INLINE powHashToWord256 #-}
 
+-- Strictly for presenting difficulty approximately to interfaces that can't understand Word256.
+powHashNatToDouble :: PowHashNat -> Double
+powHashNatToDouble (PowHashNat w) = realToFrac $
+    (fromIntegral w :: Integer) % (fromIntegral (maxBound @Word256) :: Integer)
+{-# INLINE powHashNatToDouble #-}
+
 encodePowHashNat :: PowHashNat -> Put
 encodePowHashNat (PowHashNat n) = encodeWordLe n
 {-# INLINE encodePowHashNat #-}
@@ -257,6 +267,9 @@ newtype HashDifficulty = HashDifficulty PowHashNat
     deriving newtype (AdditiveSemigroup, AdditiveAbelianSemigroup)
     deriving newtype (Num, Integral, Real)
 
+difficultyToDouble :: HashDifficulty -> Double
+difficultyToDouble (HashDifficulty phn) = powHashNatToDouble phn
+
 encodeHashDifficulty :: HashDifficulty -> Put
 encodeHashDifficulty (HashDifficulty x) = encodePowHashNat x
 {-# INLINE encodeHashDifficulty #-}
@@ -347,4 +360,3 @@ legacyAdjust (BlockDelay bd) (WindowWidth ww) (TimeSpan delta) (HashTarget oldTa
 
     newTarget :: HashTarget
     newTarget = HashTarget . PowHashNat $ maxTargetWord `div` ceiling newDiff
-