From 74e05dddca1671ef48f5de48bfd56e2aab01293c Mon Sep 17 00:00:00 2001
From: Santiago Carmuega <santiago@carmuega.me>
Date: Thu, 16 Jun 2022 10:46:15 -0300
Subject: [PATCH] feat(traverse): Add output refs for inputs (#122)

---
 pallas-traverse/src/input.rs | 77 +++++++++++++++++++++++++++++++++++-
 pallas-traverse/src/lib.rs   |  5 ++-
 pallas-traverse/src/tx.rs    |  2 +-
 3 files changed, 80 insertions(+), 4 deletions(-)

diff --git a/pallas-traverse/src/input.rs b/pallas-traverse/src/input.rs
index 4804710..be87549 100644
--- a/pallas-traverse/src/input.rs
+++ b/pallas-traverse/src/input.rs
@@ -1,8 +1,26 @@
-use std::borrow::Cow;
+use std::{borrow::Cow, fmt::Display, ops::Deref};
 
+use pallas_codec::utils::CborWrap;
+use pallas_crypto::hash::Hash;
 use pallas_primitives::{alonzo, byron};
 
-use crate::MultiEraInput;
+use crate::{MultiEraInput, OutputRef};
+
+impl OutputRef<'_> {
+    pub fn tx_id(&self) -> &Hash<32> {
+        &self.0
+    }
+
+    pub fn tx_index(&self) -> u64 {
+        self.1
+    }
+}
+
+impl Display for OutputRef<'_> {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(f, "{}#{}", self.tx_id(), self.tx_index())
+    }
+}
 
 impl<'b> MultiEraInput<'b> {
     pub fn from_byron(input: &'b byron::TxIn) -> Self {
@@ -13,6 +31,20 @@ impl<'b> MultiEraInput<'b> {
         Self::AlonzoCompatible(Box::new(Cow::Borrowed(input)))
     }
 
+    pub fn output_ref(&self) -> Option<OutputRef> {
+        match self {
+            MultiEraInput::Byron(x) => match x.deref().deref() {
+                byron::TxIn::Variant0(CborWrap((tx, idx))) => {
+                    Some(OutputRef(Cow::Borrowed(tx), *idx as u64))
+                }
+                byron::TxIn::Other(_, _) => None,
+            },
+            MultiEraInput::AlonzoCompatible(x) => {
+                Some(OutputRef(Cow::Borrowed(&x.transaction_id), x.index))
+            }
+        }
+    }
+
     pub fn as_alonzo(&self) -> Option<&alonzo::TransactionInput> {
         match self {
             MultiEraInput::Byron(_) => None,
@@ -27,3 +59,44 @@ impl<'b> MultiEraInput<'b> {
         }
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use crate::*;
+
+    #[test]
+    fn test_expected_values() {
+        let blocks = vec![
+            include_str!("../../test_data/byron2.block"),
+            include_str!("../../test_data/alonzo1.block"),
+        ];
+
+        let mut expected = vec![
+            "da832fb5ef57df5b91817e9a7448d26e92552afb34f8ee5adb491b24bbe990d5#14",
+            "e059de2179400cd7e81ddb6683c0136c9d68119ff3a27a472ad2d98e2f1fbc9c#3",
+            "adeb5745e6dba2c05a98f0ad9162b947f1484e998b8b3335f98213e0c67f426e#0",
+            "f0fb258a6e741a02ae91b8dc7fe340b9e5b601a6048bf2a0c205f9cc6f51768d#1",
+            "c2e4e1f1d8217724b76d979166b16cb0cf5cd6506f70f48c618a085b10460c44#2",
+            "aaca2f41f4a17fe464481c69f1220a7bfd93b1a6854f52006094271204e7df7c#0",
+            "89185f2daf9ea3bdfdb5d1fef7eced7e890cb89b8821275c0bf0973be08c4ee9#1",
+            "bf1f12a83095ac6738ecce5e3e540ad2cff160c46af9137eb6dc0b971f0ac5de#0",
+            "df4ebe9ac3ad31a55a06f3e51ca0dbaa947aaf25857ab3a12fe9315cabec11d3#0",
+            "087138a5596168650835c8c00f488e167e869bd991ef0683d2dbf3696b0e6650#1",
+            "cc9f28625de0b5b9bbe8f61c9332bfda2c987162f85d2e42e437666c27826573#0",
+            "d0965859ce9b3025ccbe64f24e3cb30f7400252eb3e235c3604986c2fdd755db#1",
+        ];
+
+        for block_str in blocks {
+            let cbor = hex::decode(block_str).expect("invalid hex");
+            let block = MultiEraBlock::decode(&cbor).expect("invalid cbor");
+            for tx in block.txs() {
+                for input in tx.inputs() {
+                    if let Some(out) = input.output_ref() {
+                        let right = expected.remove(0);
+                        assert_eq!(out.to_string(), right);
+                    }
+                }
+            }
+        }
+    }
+}
diff --git a/pallas-traverse/src/lib.rs b/pallas-traverse/src/lib.rs
index 02ec310..58a9cc7 100644
--- a/pallas-traverse/src/lib.rs
+++ b/pallas-traverse/src/lib.rs
@@ -3,14 +3,15 @@
 use std::borrow::Cow;
 use std::fmt::Display;
 
+use pallas_crypto::hash::Hash;
 use pallas_primitives::{alonzo, byron};
 use thiserror::Error;
 
 pub mod block;
 pub mod cert;
 pub mod era;
-pub mod output;
 pub mod input;
+pub mod output;
 pub mod probe;
 mod support;
 pub mod tx;
@@ -68,6 +69,8 @@ pub enum MultiEraCert<'b> {
     AlonzoCompatible(Box<Cow<'b, alonzo::Certificate>>),
 }
 
+pub struct OutputRef<'a>(Cow<'a, Hash<32>>, u64);
+
 #[derive(Debug, Error)]
 pub enum Error {
     #[error("Invalid CBOR structure: {0}")]
diff --git a/pallas-traverse/src/tx.rs b/pallas-traverse/src/tx.rs
index f6707d1..d7e37df 100644
--- a/pallas-traverse/src/tx.rs
+++ b/pallas-traverse/src/tx.rs
@@ -3,7 +3,7 @@ use pallas_crypto::hash::Hash;
 use pallas_primitives::{alonzo, byron, ToHash};
 use std::borrow::Cow;
 
-use crate::{MultiEraCert, MultiEraOutput, MultiEraInput, MultiEraTx};
+use crate::{MultiEraCert, MultiEraInput, MultiEraOutput, MultiEraTx};
 
 impl<'b> MultiEraTx<'b> {
     pub fn from_byron(tx: &'b byron::MintedTxPayload<'b>) -> Self {