From a334864e38b8db3e7953fcd1c130cb08a0cbed35 Mon Sep 17 00:00:00 2001
From: Alexis Hernandez <alexis22229@gmail.com>
Date: Sun, 17 Feb 2019 23:28:46 -0700
Subject: [PATCH] server: allow to get block extractionMethod from the
 BlockService

---
 .../xsn/explorer/services/BlockService.scala  | 25 +++++++++++++++++++
 .../explorer/services/logic/BlockLogic.scala  | 14 ++++++++++-
 2 files changed, 38 insertions(+), 1 deletion(-)

diff --git a/server/app/com/xsn/explorer/services/BlockService.scala b/server/app/com/xsn/explorer/services/BlockService.scala
index f493db4..9b0cf19 100644
--- a/server/app/com/xsn/explorer/services/BlockService.scala
+++ b/server/app/com/xsn/explorer/services/BlockService.scala
@@ -101,6 +101,31 @@ class BlockService @Inject() (
     result.toFuture
   }
 
+  def extractionMethod(block: rpc.Block): FutureApplicationResult[BlockExtractionMethod] = {
+    if (block.tposContract.isDefined) {
+      Future.successful(Good(BlockExtractionMethod.TrustlessProofOfStake))
+    } else if (block.transactions.isEmpty) {
+      Future.successful(Good(BlockExtractionMethod.ProofOfWork))
+    } else {
+      isPoS(block)
+          .toFutureOr
+          .map {
+            case true => BlockExtractionMethod.ProofOfStake
+            case false => BlockExtractionMethod.ProofOfWork
+          }
+          .toFuture
+    }
+  }
+
+  private def isPoS(block: rpc.Block): FutureApplicationResult[Boolean] = {
+    val result = for {
+      coinbaseTxid <- blockLogic.getCoinbase(block).toFutureOr
+      coinbase <- xsnService.getTransaction(coinbaseTxid).toFutureOr
+    } yield blockLogic.isPoS(block, coinbase)
+
+    result.toFuture
+  }
+
   private def getBlockRewards(block: Block): FutureApplicationResult[BlockRewards] = {
     if (block.transactions.isEmpty) {
       Future.successful(Bad(BlockRewardsNotFoundError).accumulating)
diff --git a/server/app/com/xsn/explorer/services/logic/BlockLogic.scala b/server/app/com/xsn/explorer/services/logic/BlockLogic.scala
index 33b794d..872b2ca 100644
--- a/server/app/com/xsn/explorer/services/logic/BlockLogic.scala
+++ b/server/app/com/xsn/explorer/services/logic/BlockLogic.scala
@@ -1,7 +1,7 @@
 package com.xsn.explorer.services.logic
 
 import com.alexitc.playsonify.core.ApplicationResult
-import com.xsn.explorer.errors.{BlockNotFoundError, BlockhashFormatError}
+import com.xsn.explorer.errors.{BlockNotFoundError, BlockhashFormatError, TransactionNotFoundError}
 import com.xsn.explorer.models._
 import com.xsn.explorer.models.rpc.{Block, Transaction}
 import com.xsn.explorer.models.values.{Address, Blockhash, TransactionId}
@@ -20,6 +20,12 @@ class BlockLogic {
     Or.from(maybe, One(BlockNotFoundError))
   }
 
+  def getCoinbase(block: Block): ApplicationResult[TransactionId] = {
+    val maybe = block.transactions.headOption
+
+    Or.from(maybe, One(TransactionNotFoundError))
+  }
+
   /**
    * Get the coinstake transaction id for the given block.
    *
@@ -144,4 +150,10 @@ class BlockLogic {
 
     Good(TPoSBlockRewards(ownerReward, merchantReward, masternodeRewardMaybe))
   }
+
+  def isPoS(block: rpc.Block, coinbase: rpc.Transaction): Boolean = {
+    block.nonce == 0 &&
+        coinbase.vin.isEmpty &&
+        coinbase.vout.flatMap(_.address).isEmpty
+  }
 }