From 12637d32f9e133338ea4a86112849425f0570d4a Mon Sep 17 00:00:00 2001
From: Antioch Peverell <apeverell@protonmail.com>
Date: Wed, 22 Jul 2020 13:32:09 +0100
Subject: [PATCH] include height even for spent outputs in get_outputs api
 (#3400)

---
 api/src/types.rs   | 26 ++++++++++++++------------
 chain/src/chain.rs |  9 +++------
 2 files changed, 17 insertions(+), 18 deletions(-)

diff --git a/api/src/types.rs b/api/src/types.rs
index 09a43a8ccb..58ff751023 100644
--- a/api/src/types.rs
+++ b/api/src/types.rs
@@ -293,12 +293,18 @@ impl OutputPrintable {
 		};
 
 		let out_id = core::OutputIdentifier::from(output);
-		let res = chain.get_unspent(&out_id)?;
-		let (spent, block_height) = if let Some(output_pos) = res {
-			(false, Some(output_pos.height))
-		} else {
-			(true, None)
-		};
+		let pos = chain.get_unspent(&out_id)?;
+
+		let spent = pos.is_none();
+
+		// If output is unspent then we know its pos and height from the output_pos index.
+		// We use the header height directly for spent pos.
+		// Note: There is an interesting edge case here and we need to consider if the
+		// api is currently doing the right thing here:
+		// An output can be spent and then subsequently reused and the new instance unspent.
+		// This would result in a height that differs from the provided block height.
+		let output_pos = pos.map(|x| x.pos).unwrap_or(0);
+		let block_height = pos.map(|x| x.height).or(block_header.map(|x| x.height));
 
 		let proof = if include_proof {
 			Some(output.proof_bytes().to_hex())
@@ -317,8 +323,6 @@ impl OutputPrintable {
 			}
 		};
 
-		let output_pos = chain.get_output_pos(&output.commit).unwrap_or(0);
-
 		Ok(OutputPrintable {
 			output_type,
 			commit: output.commit,
@@ -743,8 +747,7 @@ mod test {
 
 	#[test]
 	fn serialize_output_printable() {
-		let hex_output =
-			"{\
+		let hex_output = "{\
 			 \"output_type\":\"Coinbase\",\
 			 \"commit\":\"083eafae5d61a85ab07b12e1a51b3918d8e6de11fc6cde641d54af53608aa77b9f\",\
 			 \"spent\":false,\
@@ -761,8 +764,7 @@ mod test {
 
 	#[test]
 	fn serialize_output() {
-		let hex_commit =
-			"{\
+		let hex_commit = "{\
 			 \"commit\":\"083eafae5d61a85ab07b12e1a51b3918d8e6de11fc6cde641d54af53608aa77b9f\",\
 			 \"height\":0,\
 			 \"mmr_index\":0\
diff --git a/chain/src/chain.rs b/chain/src/chain.rs
index 927169bae6..ef2c0c7376 100644
--- a/chain/src/chain.rs
+++ b/chain/src/chain.rs
@@ -499,12 +499,9 @@ impl Chain {
 		}
 	}
 
-	/// TODO - where do we call this from? And do we need a rewind first?
-	/// For the given commitment find the unspent output and return the
-	/// associated Return an error if the output does not exist or has been
-	/// spent. This querying is done in a way that is consistent with the
-	/// current chain state, specifically the current winning (valid, most
-	/// work) fork.
+	/// Returns Ok(Some(pos)) if output is unspent.
+	/// Returns Ok(None) if output is spent.
+	/// Returns Err if something went wrong beyond not finding the output.
 	pub fn get_unspent(&self, output_ref: &OutputIdentifier) -> Result<Option<CommitPos>, Error> {
 		self.txhashset.read().get_unspent(output_ref)
 	}